Publications

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2018
K, wa Gachigi. "Changes in Phytochemical content during different growth stages in tubers of five varieties of Potato (Solanum tuberosum L.)." Current Research in Nutrition and Food Science. 2018;6(1):1-11. Abstractgeoffrey_kipkoech_kirui.pdfWebsite

Potato (Solanum tuberosum L.) synthesizes a variety of bioactive metabolites including phenolic compounds and glycoalkaloids that protects against insects and diseases, and may influence its nutritional quality. Phenolics provide valuable health promoting antioxidants, whereas glycoalkaloid concentrations exceeding the upper safety limit of 20 mg/100 g fresh weight (Fwt) are potential neurotoxins. Therefore, efficient selection for tuber nutritional quality is dependent upon safe and reliable analytical methods. The aim of this study was to determine the changes in the concentration of glycoalkaloids and phenolic compounds during different growth stages in tubers of five selected potato varieties grown in Kenya. α-chaconine and α-solanine were separated and identified by HPLC. Total glycoalkaloids (TGA) and phenolics were determined by UV spectrophotometry. Recovery efficiencies for validation of analytical methods ranged from 85.9-93.5%. Significant differences in TGA and phenolic contents were detected among potato varieties. Tuber TGA content ranged from 6.80 to 10.56 mg/100g Fwt in vars. Dutch Robijn and Tigoni, respectively, and were within the upper safety limit. The corresponding values for chlorogenic acid contents in the examined varieties ranged from 46.39 to 58.04 mg/100 g Fwt. Total phenolic concentration in the examined tuber extracts varied ranged from 129.24 to 192.52 mg CGA/g Fwt. Glycoalkaloid and phenolic production were significantly reduced from time of initiation to maturity at 55 and 125 days, respectively, after planting (DAP). These results demonstrate that tuber phytochemicals were strongly influenced by variety and level of maturity. For nutritional safety and quality purposes, harvesting of mature potato tubers after 125 DAP is recommended

2017
Odhiambo JA, Lukhoba CW, Dossaji SF. "Corms as an additional feature to identify Gladiolus spp.". In: XXI AETFAT congress.; 2017. Abstractuse_of_corms_as__additional_features_to_identify.ppt

Gladiolus is a genus that consists of underground corms and strikingly showy flowers. The corms are mostly rounded and symmetrical enveloped with fibrous tunics. Presently the main and sure way to identify these plants is by their use of showy flowers; however, this becomes a challenge in during the dry seasons when the plants don’t flower. This study investigated the use of corms as additional feature for identification of Gladiolus species found in Kenya; Gladiolus watsonoides, G. goetzenii, G. ukambanensis and G. newii. Physical and histological features of the corms were evaluated according to Rolls, 2011, to investigate any differences across the different species. Although the analysis of the cells of corms did not reveal any obvious differences, their outward morphologies including the colour, shape and texture of the tunics were different across the species investigated. Therefore, corms form an additional feature of taxonomic value for identification and collection of these plants in the absence of flowers.
Key words: Gladiolus, Corms, Identification

Musila FM, Lukhoba CW, Dossaji SF, Nguta JM. "Molecular Phylogeny of ten Kenyan Plectranthus species in the Coleus clade.". In: XXI AETFAT congress. Catholic University of Eastern Africa, Nairobi, Kenya; 2017. Abstractaetfat_2017-fredrick_m.ppt

Plectranthus is one important genus of flowering plants whose member species have a variety of uses in the horticultural and in the medical field. Plectranthus species are difficult to distinguish morphologically and many species have been given different names by different authors. Use of morphological characters is not sufficiently enough to delimit the genus successfully. Molecular, anatomical and biochemical markers are better in studying interspecific variation compared to gross morphological markers. So far no study on molecular phylogeny of the Kenyan Plectranthus species has been conducted. By comparing the same gene sequence across species within a genus, a phylogenetic tree can be constructed which can support or give new insights into the existing classification and rule out the confusion brought by synonymy. As a result, the current study used molecular characters to classify ten Plectranthus species in the Coleus clade within the Plectranthus genus. The molecular characters used in the study were DNA sequences of two chloroplast genes: MatK and Rbcl genes considered as universal molecular markers. Genomic DNA from the ten species was obtained followed by amplification and sequencing of the two genes in each species. From the results, a phylogenetic tree reconstructed using MatK genes groups P. caninus, P. otostegioides, P. barbatus and P. lanuginosus together and all the four species form a monophyletic group. These four species together with P.aegyptiacus form a larger monophyletic group. The same pattern can be observed in the phylogenetic tree created using the Rbcl genes. Again based on the MatK genes; P. pseudomarruboides, P. ornatus, P. montanous and P. amboinicus have been showed to be closely related and are monophyletic. Again these four species together with P.edulis form a larger monophyletc group. This close relationship of these species can also be observed in phylogenetic tree produced using the Rbcl genes. The present study has grouped the ten study Plectranthus species using molecular characters into phylogenies which are supported by previous studies and proved that molecular characters can aid in plant identification and phylogenetic studies.
Key words; Plectranthus, Molecular phylogeny, MatK gene, Rbcl gene.

Musi, C, MIRIKAU, N, D. "Antibacterial and antifungal activities of 10 Kenyan Plectranthus species in the Coleus clade." Journal of Pharmacy Research. 2017;11(8):1003-1014 . Abstractantibacterial_antifungal_plectranthus_2017.pdfWebsite

Background Information: Plectranthus L’Hér. is an economically important genus with horticultural, medicinal and food uses. Most Plectranthus species are used in traditional medicine and have attracted the interest of researchers who have studied them in attempt to explore the bioactivities of their phytoconstituents.
Materials and Methods: The current study investigated the antimicrobial activities of 10 Kenyan Plectranthus species through disc diffusion and broth dilution method.
Results:Results indicated that, dichloromethane/methanol (1:1) total leaf extracts from Plectranthus barbatus displayed the highest antimicrobial activity compared to the other nine Plectranthus species with minimum inhibitory concentration (MIC) values of 25, 40, 100, 50, and 100 mg/ml against methicillin resistant Staphylococcus aureus (MRSA), Bacillus cereus, Escherichia coli, Candida albicans, and Aspergillus niger, respectively. At a concentration of 200 mg/ml, the antibacterial activity of total leaf extracts of P. barbatus (MIC value = 25 mg/ml) and Plectranthus lanuginosus (MIC value = 40 mg/ml) againstMRSA was not significantly different from positive control drug; amoxicillin. Similarity, at a concentration of 200 mg/ml,total leaf extracts from Plectranthus ornatus (MIC value= 50 mg/ml) and P. barbatus (MIC value = 50 mg/ml) exhibited antifungal activity against C. albicans which was not significantly different from that of the positive control; ketoconazole.
Conclusion: The study reports for the first time, the antimicrobial activity of Plectranthus pseudomarrubioides, Plectranthus edulis, Plectranthus aegyptiacus, Plectranthus Otostegioides, and Plectranthus lanuginosus. The study has demonstrated broad bacteriostatic activity of P. barbatus and thus recommends further studies on this plant aimed at discovery of novel antimicrobial agents.
KEY WORDS: Antimicrobial activity, Bioguidance, Minimum inhibitory concentration, Plectranthus

2016
Gakuubi MM, Wanzala W, Wagacha JM, Dossaji SF. "Bioactive properties of Tagetes minuta L. (Asteraceae) essential oils: A review." American Journal of Essential Oils and Natural Products. 2016;4(2):27-36. Abstract4-2-6.1_1.pdf

Mexican marigold (Tagetes minuta L.) and its accruing products have a long worldwide history of human uses such as food, therapeutics and aromatherapy which are inherent in the plant’s unique chemical composition and bioactivities. In the recent past, T. minuta essential oils (EOs) have received great attention in research, and their phytochemistry, bioactivities and uses remain the focus of considerable scientific studies. The interest in EOs is largely due to increased demand by consumers for natural-based products such as additives, drugs and pesticides, whose global acceptability and safety is highly regarded compared to synthetic products. The purpose of this review is to document the existing value addition and evidence-based multipurpose potential and considerations of T. minuta as a new generation crop as provided for by in-depth scientific studies of its EOs. Among the bioactivities and therapeutic properties attributed to T. minuta EOs include: antihelminthic, carminative, arthropod repellency, sedative, weedicidal, antiseptic, diaphoretic, spasmolytic, germicides, stomachic, antispasmodic, antiprotozoal, bactericidal, emmenagogue, nematicidal, insecticidal, fungicidal, antiviral and other microbicidal properties against a wide range of plant, human and animal pathogens, pests and parasites. Oil of T. minuta is therefore a potentially useful agent for protecting food crops on farm and in storage and livestock, thereby enhancing food security and improving human livelihoods. Nevertheless, increased value addition and the need for validation of traditionally claimed usages and applications of T. minuta EOs through in-depth scientific studies should be prioritized to globally position this plant as a new generation crop.

Gakuubi M, Wagacha J, Dossaji S, Wanzala W. "Chemical Composition and Antibacterial Activity of Essential Oils of Tagetes minuta (Asteraceae) against Selected Plant Pathogenic Bacteria." International Journal of Microbiology. 2016;2016:1-9. Abstracttagetes_2016.pdf

The objective of this study was to determine the chemical composition and antibacterial activity of essential oils (EOs) of Tagetes minuta against three phytopathogenic bacteria Pseudomonas savastanoi pv. phaseolicola, Xanthomonas axonopodis pv. phaseoli, and Xanthomonas axonopodis pv. manihotis.The essential oils were extracted using steam distillation method in a modified Clevengertype apparatus while antibacterial activity of the EOs was evaluated by disc diffusion method. Gas chromatography coupled to
mass spectrometry (GC/MS) was used for analysis of the chemical profile of the EOs. Twenty compounds corresponding to 96% of the total essential oils were identified with 70% and 30% of the identified components being monoterpenes and sesquiterpenes, respectively.The essential oils of T. minuta revealed promising antibacterial activities against the test pathogens with Pseudomonas savastanoi pv. phaseolicola being the most susceptible with mean inhibition zone diameters of 41.83 and 44.83mm after 24 and
48 hours, respectively. The minimum inhibitory concentrations and minimum bactericidal concentrations of the EOs on the test bacteria were in the ranges of 24–48mg/mL and 95–190mg/mL, respectively.These findings provide a scientific basis for the use of T. minuta essential oils as a botanical pesticide for management of phytopathogenic bacteria.

Gakuubi M, Wagacha J, Dossaji S, Wanzala W. "Chemical composition and antifungal activity of essential oils of Tagetes minuta (Asteraceae) against selected phytopathogenic fungi." American Journal of Essential Oils and Natural Products. 2016;4(3):16-26. Abstract4-3-5.1.pdfWebsite

Over the years, management of plant pathogenic fungi has primarily relied on the use of synthetic
chemical fungicides. However, in the recent past, exploration for biologically active compounds from
plants with the aim of discovery and development of novel and eco-friendly biopesticides to combat
current and emerging plant pathogenic fungi has received increased interest. This study aimed at
extraction and characterization of Tagetes minuta essential oils (EOs) as well as evaluation of their
antifungal activity against selected phytopathogenic fungi namely: Fusarium oxysporum, F. solani,
Aspergillus flavus, A. parasiticus and A. niger. Essential oils were extracted using the steam distillation
method in a modified Clevenger-type apparatus. The antifungal activity of the EOs was assessed by disc
diffusion method while gas chromatography - mass spectrometry (GC/MS) was used for characterization
of the chemical components of the EOs. Twenty compounds corresponding to 96% of the total essential
oils and constituting a mixture of monoterpenes (70%) and sesquiterpenes (30%) were identified in the
Eos. They included elixene and silphiperfol-6-ene, which are being reported for the first time in essential
oils of Tagetes minuta. The EOs of T. minuta exhibited potent antifungal activity against the studied
fungi with the highest growth inhibition observed in F. oxysporum and A. niger with mean inhibition
zones of 28.7mm after five days of incubation. Four out of the five test fungi fell within the category of
extremely sensitive (inhibition zone diameters ≥ 20mm) when subjected to the crude EOs. The minimum
inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) of the EOs against the
fungi were in the ranges of 24 - 95mg/mL and 24 - 190mg/mL, respectively. This study thus lays down
significant groundwork for a more comprehensive study on the practical feasibility of using T. minuta
EOs as possible alternative to synthetic fungicides in the management of economically important
phytopathogenic fungi.

Kiunga J, Lukhoba C, Dossaji S, Yenesew A. "A Survey of Traditional Medicinal Uses of Catha Edulis (Celastraceae) in Meru and Embu Counties of Kenya." Journal of Ethnobiology & Ethnomedicine. 2016;3(1):1-12. Abstractcatha_edulis_paper.pdfWebsite

Catha edulis (qat) is an evergreen tree or shrub whose young leaves and stems are widely chewed in Eastern Africa. The aim of the present study was to document ethnomedicinal value of Catha edulis as used traditionally by the Ameru andAembu communities of Kenya.

The study was conducted between the months of September (2014) and February (2015), and involved 42 key informants (32 males and 10 females) aged between 45 and 84 years. Snowball and purposeful sampling techniques were used in the selection of key respondents. A semi-structured questionnaire was administered to collect ethnomedicinal data using faceto-face interviews and discussions with key respondents

Eleven traditional varieties based on information from key informants were identified and described. Out of these, 5 were from Embu County while 6 were from Meru County. Plant samples were collected and deposited at the University of Nairobi herbarium as voucher specimens. A total of 13 ethnomedicinal uses of qat were documented. Of these, 62% were reported only in Meru County while 15% were reported only in Embu County. The remaining (23%) were reported in both Meru and Embu counties. The major parts of the plant reported to have medicinal value were leaves. Young stems and roots had scanty medicinal value. Chewing fresh material was identified as the major method of crude drug preparation, althoughin some cases such as in the treatment of diarrhea, gonorrhea and toothache, boiling of fresh material was reported. The main mode of administration of drug is oral and there was no precise dosage reported for any given ailment.

The present study indicates that there is a rich knowledge of ethnomedicinal uses of qat particularly in Meru which forms groundwork for further efficacious study of the plant as that may provide a lead to the discovery of novel bioactive therapeutic agents. In addition, the traditional varieties of C. edulis identified by some morphological characters of taxonomic importance provide a vital clue of possible existence of infraspecific taxa of C. edulis which, to date, has no documented infraspecific taxa.

KEY-WORDS: Qat, ethnomedicinal, traditional varieties, psychostimulant

2015
Chalo C, Lukhoba CW, Dossaji SF, Nguta JM. "Evaluation of Antimicrobial activity, Toxicity and Phytochemical composition of selected medicinal plants of Losho, Narok county, Kenya.". In: Nairobi Innovation week. university of nairobi; 2015. Abstract

In Kenya, microbial infections remain a threat to millions of lives of those individuals

Antibiotic effectiveness is threatened by increasing resistance of pathogenic microbes against most available drugs as new pathogens continue to emerge.

•Plants are a possible source of antimicrobial agents and could lead to the isolation of new and potentially effective antimicrobial compounds.

However for majority of herbal drugs, information on the efficacy, dosage safety and active principles is not well documented.

Antimicrobial activity, toxicity and phytochemical analysis of 4 most commonly used medicinal plants for treatment of ear, nose and throat infections (ENT), gastrointestinal disorders and skin ailments namely, Schrebera alata (Bark), Omorcarpum kirkii (Aerial part) ,Cussonia holstii (Bark)& Helichrysum forskahlii (Whole plant) was carried out .

Chalo M, Lukhoba CW, Dossaji SF, Nguta JM. "In vitro antimicrobial activity of selected medicinal plants traditionally used in Losho, Narok County, Kenya." International Research Journal of Pharmacy . 2015;6 (12):797-801.in_vitro_antimicrobial_chalo_et_al_2015.pdfWebsite
2014
Odhiambo JA, Dossaji SF, Lukhoba CW, Abiy Y. "Antifungal activity, brine shrimp cytotoxicity and phytochemical screening of Gladiolus watsonoides Baker (Iridaceae)." Journal of Pharmacy Research. 2014;8(9):1218-1222.gw_publication_2014.pdf
Ochora DO, Dossaji SF, Nguta JM, Akunda EM. "Antimalarial activity and acute toxicity of four plants traditionally used in treatment of malaria in Msambweni District of Kenya." European International Journal of Science and Technology. 2014;3(7):31-40.publication_sept_2014.pdf
Murithi CK, Dossaji SF, Nguta JM, w. Lukhoba C. "Antimalarial activity and in vivo toxicity of selected medicinal plants naturalised in Kenya." International Journal of Education and Research. 2014;2(4):395-406.published_paper_june_2014.pdf
Kitonde CK, Dossaji SF, Lukhoba CW, Jumba MM. "Antimicrobial activity and phytochemical screening of Senna didymobotry used to treat bacterial and fungal infections in Kenya." International Journal of Education and Research. 2014;2(No. 1):1-12. Abstractsenna_didymobotrya.pdf

Infectious diseases are prevalent and life threatening in Kenya. The majority of the sick are seeking
herbal remedies in search of effective, safe, and affordable treatments. This study aimed to
investigate the antimicrobial activity and presence of chemical compounds in different parts of
Senna didymobotrya. Results showed that, organic extracts of root with Mean inhibition zone (MIZ)
of 1.58 cm, recorded the highest activity against S. aureus than the standard antibiotic
(Streptomycin MIZ of 1.30 cm. Flavonoids were the chemical compoundshighly present. The
results of this study suggest that S. didymobotrya has significant antimicrobial properties and justify
its use in traditional herbal medicine for the management of microbial based diseases. Cytotoxicity
assays are highly recommended for S. didymobotrya in order to verify, validate and document its
safety in medicine.
Key words: Prevalent, Effective, Herbal, Senna didymobotrya.

Kaigongi MM, Dossaji SF, Nguta JM, Lukhoba CW, Musila FM. "Antimicrobial Activity, Toxicity and Phytochemical Screening of Four Medicinal Plants Traditionally Used in Msambweni District, Kenya." Journal of Biology, Agriculture and Healthcare. 2014;4(28):6-12. Abstractkagongi_et_al._2014.pdf

This study was designed to evaluate the antimicrobial activity, toxicity and phytochemical composition of
organic and aqueous crude extracts of Zanthoxylum chalybeum Engl. (Rutaceae), Adansonia digitata L.
(Bombacaceae), Launaea cornuta (Hocht. ex Oliv. & Hern) C.Jeffrey (Compositae) and Grewia trichocarpa
Hochst. ex A.Rich (Tiliaceae) traditionally used by local communities of Msambweni District in Kenya.
Aqueous and organic [Chloroform: Methanol (1: 1)] crude extracts were evaluated for their in vitro antimicrobial activity against Methicillin resistant Staphylococcus aureus (MRSA), Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans using broth dilution and disc diffusion methods. Toxicity was determined using Brine-shrimp larvae (Artemia salina L. nauplii) assay. The crude extracts were screened to determine the presence of flavonoids, alkaloids, saponins and sesquiterpene lactones using standard techniques. It was observed that the organic crude extracts from all the species tested except L. cornuta exhibited dose dependent activity against B. cereus, MRSA, P. aeruginosa and C. albicans. None of the crude extracts showed any inhibition against E. coli. Adansonia digitata and Grewia trichocarpa had LC50>1000 μg/ml and were shown to be non-toxic to Brine shrimp larvae unlike those of Z. chalybeum and L. cornuta which both had LC50<500 ug/ml and were considered to be toxic. Phytochemical screening of the crude extracts showed that alkaloids, flavonoids, sesquiterpene lactones and saponins were present in the four plants tested.The study has shown that A. digitata and Z. chalybeum possess promising antimicrobial activity against microbes of health importance and could lead to the isolation of new and potentially effective antimicrobial compounds.
Keywords: Medicinal plants; Antimicrobial activity; Brine shrimp lethality test; Phytochemical analysis;
Msambweni district; Kenya.

Odhiambo J, Dossaji SF, Lukhoba C, Abiy Y. "Phytochemical screening of Dierama cupuliflorum Klatt. (Iridaceae)." Journal of Pharmacy Research. 2014;8 (4):589-592.phytochemical_screening__dierama_2014.pdf
Kitonde CK, Dossaji SF, Lukhoba CW, Jumba MM. "Phytochemistry and Utilization of Vernonia glabra (Steetz) Oliv. & Hiern.in Management of Food Spoilage and Poisoning Pathogens, in Kenya." European International Journal of Science and Technology. 2014;3(1):65-72. Abstractvernonia_glabra.pdf

Food spoilage and poisoning pathogens lead to pre- and post-harvest losses of crop produce and poisoning
of food and feed stuff; posing a great threat to food security and safety worldwide. This project aimed to
investigate the pesticidal activity and presence of chemical compounds in Vernonia glabra; as an alternative
control approach, to food crop protection. Organic extracts of leaves and flowers showed the highest
activity against S. aureus (mean inhibition zones of 1.85 and 1.78 respectively), than the standard antibiotic
(Streptomycin 1.30). Flavonoids were greatly present in all extracts screened. The results of this study
justify the use of V. glabra in traditional herbal medicine, and suggest that the plant has ideal
characteristics in the application as bio-pesticide control to crops and food stuff.

2013
Kitonde CK, Dossaji SF, Lukhoba CW, Jumba MM. "Phytochemistry and Utilization of Vernonia glabra (Steetz) Oliv. & Hiern. in the Management of Food Spoilage and Poisoning Pathogens, in Kenya.". In: 1st International Conference Pesticidal Plants. Vol. 10.; 2013:.
Kitonde C, Dossaji SF, Lukhoba CW, Jumba M. "Antimicrobial Activity and Phytochemical study of Vernonia glabra (Steetz) Oliv. & Hiern in Kenya." Afr J Tradit Complement Altern Med. 2013;10(1):149-157. Abstractkitonde_et_al._2013.pdf

Infectious diseases are prevalent and life threatening in Kenya. Majority of the sick are seeking herbal remedies in search of effective, safe, and affordable cure. This project aims to investigate the antimicrobial activity and presence of active phytochemical compounds in different parts of Vernonia glabra; a plant used by herbalists in various regions of Kenya, for the treatment of gastrointestinal problems. The plant sample was collected in January 2010 in Machakos, and different parts dried at room temperature under shade, ground into powder and extracted in Dichloromethane: Methanol in
the ratio 1:1, and water. These crude extracts were tested against Staphylococcus aureus, Escherichia coli, Candida albicans, and Aspergillus niger for antimicrobial activity using disc diffusion technique. Minimum inhibitory concentrations (MICs) for active crude extracts were done using disc diffusion technique after the failure of agar and broth dilution methods. It was observed that the organic crude extracts of flower, leaf, stem, root, and/or entire plant, showed activity against at least one of
the four micro-organisms screened, and at concentrations lower than the aqueous crude extracts. Organic crude extract of the leaf showed the highest activity against Staphylococcus aureus (mean inhibition zone of 1.85), recording higher activity than the commercially used standard antibiotic (Streptomycin mean inhibition zone of 1.30). The organic crude extract of flower showed significant activity only against S. aureus, with the lowest MIC of 1.5625 mg/100μl, compared to streptomycin with
M.I.C of 6.25 mg/100μl. Thin Layer Chromatography-Bioautography Agar-Overlay showed that, flower alkaloids (50% active), root sapogenins (43.8% active), and root terpenoids (38.5% active) were identified as the potential antibacterial compounds against S. aureus. These results suggest that, V. glabra contains phytochemicals of medicinal properties and justify the use of V. glabra in traditional herbal medicine for the treatment of microbial based diseases. However, research on toxicity which is missing in this study is recommended for V. glabra in order to verify, validate and document the safety
of this medicinal plant to the society.

Keywords: Vernonia glabra, Antimicrobial activity, and Phytochemicals.

Musila MF, Dossaji SF, Nguta JM, Lukhoba CW, Munyao JM. "In vivo antimalarial activity, toxicity and phytochemical screening of selected antimalarial plants." Journal of Ethnopharmacology. 2013;146:557-561.published_paper.pdfhttp://dx.doi.org/10.1016/j.jep.2013.01.023
2012
Njoroge D, Anyango B, Dossaji SF. "Screening of Phyllanthus Species for Antimicrobial Properties, Chemical Sciences Journal." Chemical Sciences Journal. 2012;2012(CSJ-56):1-12. Abstractcsj-56_2012.pdf

The development of resistant pathogenic microorganism against conventional antibiotic drugs has risen to a point of global concern. New antimicrobial compounds with diverse chemical structures and novel mechanisms of action are therefore needed to curb the new and re-emerging infectious diseases. This study has identified two Phyllanthus species (Phyllanthus amarus, Phyllanthus odontadenius) sampled from Nairobi and Siaya counties in Kenya. In vitro activity of extracts of these species and correlated their efficacy was compared with the commercial extracts of P. niruri that are in the Kenyan market. Disk diffusion method was employed to screen the antimicrobial activities of both the extracts and two standard antibiotics; 0.32mg mL-1 gentamycin and 0.30 mg mL-1 Nystatin. The dichloromethane(DCM):methanol (1:1) extracts of Phyllanthus odontodenius showed the strongest activity against all the organisms both at 100 mg μL and 50 mg μL-1 followed by both the hot water and
cold water methanol extracts. The solvents in comparison to antibiotics showed 80% activity for methanol, 48% for DCM:MeOH 1:1, 43% in hot water and 28% for cold water. Thin layer chromatography (TLC) showed that the compounds found in the three species were identical. This study has shown that, the two species possess significant antimicrobial activity and justifies the use
of their extracts by herbalists in the treatment of many microbial diseases. Therefore, further bioassay guided fractionation, isolation and characterization studies of compounds from these extracts are needed to confirm the active components and mechanisms of action of these two species.

Keywords: Phyllanthus amarus; Phyllanthus odontadenius; Phyllanthus niruri; antimicrobial activity; infectious diseases.

2011
Kiitonde C, Lukhoba CW, Dossaji SF. "Antimicrobial and Phytochemical Study of Vernonia glabra (Steetz) Oliv. & Hiern. in Kenya.". In: Botany 2011 . Healing the Planet Symposium in St. Louis, Missouri, USA.: C. Kiitonde, C.W. Lukhoba & S.F. Dossaji; 2011. Abstract

Infectious diseases are prevalent and life threatening. In Kenya, a majority of the sick are seeking herbal remedies in such for effective, safe, and affordable cure. This project aims to investigate the antimicrobial activity and phytochemical compounds present in different parts of Vernonia glabra, a plant used by herbalists in various regions of Kenya claimed to treat different microbial infections. The plant was collected in January, 2010 in Machakos, and the different plant parts ground into powder and extracted in Dichloromethane:Methanol (1:1) and water. These were tested against bacterial and fungal organisms using disc diffusion technique. It was observed that the organic crude extracts of the flower, leaf, stem, root and/or entire plant, showed activity against at least one of the four test micro-organisms and at concentrations lower than the water crude extracts. The organic crude extract of the leaf showed the highest activity against Staphylococcus aureus (Mean inhibition, 1.83) and Aspergillus niger (mean inhibition, 1.43), and also recorded higher activity those of the standard ds. Organic crude extract of flower showed significant activity against one only organism- Staphylococcus aureus. Thin Layer Chromatography-Bioautography Agar Overlay, showed that saponins were eliciting over 60% of all the antimicrobial activity. These results suggest that Vernonia glabra may contain phytochemicals of medicinal properties and also justifies the use of Vernonia glabra in herbal medicine for the treatment of microbial diseases. In particular, the V. glabra leaf may contain broad spectrum antibacterial and antifungal agents that could be useful in the development of competent antimicrobial drugs. Further investigation to isolate, determine the pure and safe antimicrobial compounds is recommended for scientific verification and validation of the drugs from Vernonia glabra.

Odhiambo JA, Dossaji SF, Lukhoba CK. "Ethnomedicinal knowledge in the traditional management of human ailments in Lake Victoria Basin, Kenya.". In: Botany 2011 . J.A. Odhiambo, W. Lukhoba & S.F. Dossaji; 2011. Abstract

Though the majority of inhabitants in the Kenya rely on ethnomedicinal plant species to manage a wide range of human ailments, much the indigenous knowledge largely remains undocumented. An ethnomedicinal study was conducted to document the plant species used medicinally in the Lake Victoria Basin. Data was collected by interviewing the herbalists from the region. A total of thirty four plant species distributed in twenty one botanical families were identified. The plant family with highest number of plants used for medicine was Compositae, followed by Leguminosae then Labiatae. The herbals were prepared mainly as concoctions and decoctions and were majorly administered orally and dermally to treat ailments such as typhoid, malaria, and chest and skin related complications. A rich knowledge of medicinal plants was recognized and phytochemical and bioactivity analyses of these herbal plants are recommended to determine their safety and efficacy.

Odhiambo JA, Lukhoba CW, Dossaji SF. "Evaluation of Herbs as potential Drugs/Medicines." Afr. J. Traditional, Complimentary and Alternative Medicines, 8.. 2011;8:144-151. Abstractajtcam_2011.pdfWebsite

Use of herbs as combinations is a common practice with many herbal practitioners. The main idea behind this usually is the synergistic action expected to take place by the traditional healer hence being able to give better results as compared to one herb and also treat more than one ailment, even those not mentioned by the patient. However, other interactions such as additive and antagonism too take place when herbs are used in combinations. In this study, anti-aspergillus and anti-candida efficacy of crude extracts of five plants used in combination to treat malaria were investigated. Toddalia asiatica (root), Rhamnus staddo (root) , Momordica foetida (shoot), Podocarpus falcatus (bark), Aloe sp (secculent leaves) used by traditional health practitioners in the Kalenjin community were extracted using water and dichloromethane/methanol (1:1) and the crude extracts tested for in vitro antifungal activity singly and in combinations against Aspergillus niger and Candida albicans. Dichloromethane/methanol extracts of P. falcatus showed the highest activity (77.77% inhibition) against A.niger while M. foetida showed the highest activity (77.78% inhibition) against C. albicans. Aloe sp. Showed no activity against A. niger when tested singly. A.niger was more sensitive to the plants extracts than C.albicans. Aqueous extracts did not show any activity. Antagonism, additive and synergism were observed when combinations of the herbal plants were assayed. Findings in this study are a preliminary verification of the usefulness of using herbal plants in combinations as a prevalent practice among the traditional healers.

Keywords:
Traditional medicine, herbal combinations, C. albicans, A.niger.

2010
Odhiambo JA, Lukhoba CW, Dossaji SF. "Ethnomedicial knowledge in traditional management of human ailments in Lake Victoria Basin,.". In: 51st annual Meeting of the Society for Economic Botany, Veracruz, Mexico. Vera Cruz, Mexico: J.A. Odhiambo, .W. Lukhoba*, S.F. Dossaji; 2010. Abstract

Though the majority of inhabitants in the Kenya rely on ethnomedicinal plant species to manage a wide range of human ailments, much the indigenous knowledge largely remains undocumented. An ethnomedicinal study was conducted to document the plant species used medicinally in the Lake Victoria Basin. Data was collected by interviewing the herbalists from the region. A total of thirty four plant species distributed in twenty one botanical families were identified. The plant family with highest number of plants used for medicine was Compositae, followed by Leguminosae then Labiatae. The herbals were prepared mainly as concoctions and decoctions and were majorly administered orally and dermally to treat ailments such as typhoid, malaria, and chest and skin related complications. A rich knowledge of medicinal plants was recognized and phytochemical and bioactivity analyses of these herbal plants are recommended to determine their safety and efficacy.

Odhimabo JA, Siboe GM, Lukhoba CW, Dossaji SF. "Antifungal activity of crude extracts of Gladiolus dalenii Van Geel (Iridaceae)." African Journal of Traditional, Complementary and Alternative medicine. 7 (1): 53-58, 2010. 2010;7(1):53-58. Abstractajtcam_publication.pdfWebsite

 
Bulb extracts of Gladiolus dalenii reportedly used in the treatment of fungal infections in HIV/AIDS patients in the Lake Victoria region were tested for antifungal activity using the disc diffusion assay technique. Commercially used antifungal drugs, Ketaconazole and Griseofulvin (Cosmos Pharmaceuticals) were used as standards. Dichloromethane (CH2CL2)/Methanol (MeOH) in the ratio 1:1. Soluble extracts showed antifungal activity against Aspergillus niger. Direct bioautography on silica gel Thin Layer Chromatography (TLC) and appropriate spraying agents were used to identify the active component in the extract. The activities of both the extracts were higher than that of Griseofulvin. CH2CL2 soluble extract in addition showed ability to delay sporulation in A.niger. The active group of compounds in the extracts was identified as alkaloids, which offer immense potential for development of new and valuable pharmaceutical products.
Key words: G. dalenii, Aspergillus niger, Antifungal activity

2009
Odhiambo JA, Siboe GM, Lukhoba CW, Dossaji SF. "Antifungal activity of crude extracts of selected medicinal plants used in combinations in Lake Victoria Basin, Kenya." Plant Product Research Journal. 2009;13:35-43. Abstractpublication_2009.pdfWebsite

Use of herbs as combinations is a common practice with many herbal practitioners. The main idea behind this usually is the synergistic action expected to take place by the traditional healer hence being able to give better results as compared to one herb and also treat more than one ailment, even those not mentioned by the patient. However, other interactions such as additive and antagonism too take place when herbs are used in combinations. In this study, anti-aspergillus and anti-candida efficacy of crude extracts of five plants used in combination to treat malaria were investigated. Toddalia asiatica (root), Rhamnus staddo (root) , Momordica foetida (shoot), Podocarpus falcatus (bark), Aloe sp (secculent leaves) used by traditional health practitioners in the Kalenjin community were extracted using water and dichloromethane/methanol (1:1) and the crude extracts tested for in vitro antifungal activity singly and in combinations against Aspergillus niger and Candida albicans. Dichloromethane/methanol extracts of P. falcatus showed the highest activity (77.77% inhibition) against A.niger while M. foetida showed the highest activity (77.78% inhibition) against C. albicans. Aloe sp. Showed no activity against A. niger when tested singly. A.niger was more sensitive to the plants extracts than C.albicans. Aqueous extracts did not show any activity. Antagonism, additive and synergism were observed when combinations of the herbal plants were assayed. Findings in this study are a preliminary verification of the usefulness of using herbal plants in combinations as a prevalent practice among the traditional healers.

Keywords:
Traditional medicine, herbal combinations, C. albicans, A.niger.

2001
Kariba RM, Siboe GM, Dossaji SF. "In vitro antifungal activity of Schizozygia coffaeoides Bail. (Apocynaceae) extracts." Journal of Ethnopharmacology. 2001;74:41-44. Abstract

Leaf extracts of Schizozygia coffaeoides were investigated gor antifungal activity using the disc diffusion essay technique. Petroleum ether 40o-60o C, dichloromethane-ethyl acetate (1:1) and methanol extracts were fungitoxic to Trichophyton mentagrphytes, Microsporum hypseum, Cladosporium cucumerinum and Candida albicans. The extracts were fungistatic in action.

1999
Oketch-Rabah HA, Dossaji SF, Mberu EK. "Antimalarial Activity of Some Kenyan Medicinal Plants." Pharmaceutical Biology (formerly International Journal of Pharmacognosy). 1999;37(5):329-334. Abstract

This paper describes the in vitro antimalarial activity of eight species of plants popularly used traditionally to treat malaria in Kenya. Organic and aqueous extracts from different parts of the plants were tested. Generally, a stronger antimalarial activity was observed in the organic extracts. The most active extracts were of Vernonia brachycalyx O. Hoffm. Schreber. (Compositae) leaves which showed an IC 50 of 6.6 g/ml for methylene chloride: ethyl acetate (1:1) extracts, while the aqueous and more polar methanolic extracts gave IC 50 values of 29.6 and 30 g/ml, respectively. The findings of this study support the use of this plant as a traditional remedy for malaria. The rest of the plants tested gave IC 50 values between 30–100 g/ml.

1997
Oketch HA, Dossaji SF. "Antiprotozoal Compounds from Asparagus africanus." J. Natural Products. 1997;60(10):1071-1022.Website
Oketch-Rabah HA, Lemmich E, Dossaji SF, other autors +. "Two new Antiprotozoal 5-methylcoumarins from Vernonia brachycalyx." J. of Natural Products. 1997;60:458-461.Website
1995
Gakunju DM, Mberu E, Dossaji SF, Gray I, Waigh RD, Waterman PG, Watkins WM. "Antimalarial Activity of the Alkaloid Nitidine, isolated from a Kenyan Herbal remedy." Antimicrobial Agents & Chemotherapy, (39), 2606.. 1995;39:2606.-2609. AbstractWebsite

Bioassay guided fractionations of extracts of Toddalia asiatica, a plant used by Pokot tribe in Kenya to treat fevers, has yielded the alkaloid nitidine as the major antimalarial component. Fractions containing nitidine have in vitro 50% inhibitory concentrations against Plasmodium falciparum in the range of 9 to 108 ng/ml for range of chloroquine-susceptible and resistant strains. The results show a lack of cross-resistance between chloroquine and nitidine

1991
1989
Dossaji SF, Wrangham RW, Rodriguez E. "Selection of Plants with Medicinal Properties by Wild Chimpanzees." Fitoterepia. 1989;60(4):378-380. Abstract

In 1983 Wrangham and Nishida described an unusual feeding behavior in wild chimpanzees (Tan
troglodytes schweinfurthii) whereby the consumption of leaves of three species of Aspilia (Asteraceae) led them to suggest that such selection of certain plant species by the chimpanzees was for therapeutic purposes. In 1985 Rodriguez et al. confirmed that Aspilia mossambicensis and A pluriseta, which are also used medicinally by man, contain a potent antibiotic, thiarubrine A This important plant-primate interaction provided a new and valuable insight on how African primates select diets containing bioactive constitutents other than for nutritional benefits. Subsequent field studies in Africa have established that wild chimpanzees are using a variety of plant species as medicinal plants. These include Lippia, Hibiscus and Rubia. The significance of plant use by chimpanzees is discussed in this communicatio

1988
Marston A, Gafner F, Dossaji SF, Hostettmann K. "Fundigicidal and moluscicidal saponins from Dolichos kilimandascharicus; ." Phytochemistry. 1988;27(5):1325-1326. Abstract

—Three saponins with moUuscicidal and fungicidal activities have been isolated from the roots of Dolichos
kilimandscharicus. They were shown to be the 3-0-jS-D-glucopyranosides of hederagenin, bayogenin and medicagenic acid.

Adolf W, Seip EH, Dossaji SF, Hecker E. "Irritant Principles of Mezereon Family (Thymeleaceae), New skin irritants and tumour promoters of the daphnane and 1, 2-alkyldaphnane type from Synaptolepis kirkii and S. Retusa." Journal of Natural Products. 1988;51(4):662-674. Abstract

—Seventeen mostly new, skin irtitant diterpene esters (DTE) of the daphnane
and la-alkyldaphnane types were isolated from roots of Synaptolepis kirkii and Synaptolepis retusa.
The parent alcohols of the daphnane types are shown to be 5(J-hydroxyresiniferonol-6a,7o:- oxide [ 1 ] and 5p\e [2]. Ten of the daphnane types are 9,13,14-otthoesters and three ate conventional esters involving tertiary or secondary hydroxyl groups at C-13 or C-14, respectively. The latter may be considered immediate precursors of corresponding orthoesters. The four la-alkyldaphnane types are intramolecular 9,13, l4-ortho-(2- hexadecenoic acid)-esters in which, formally, the second to last C atom of the orthoester moiety
is linked covalently to C-lct of the diterpene parent alcohols 1 or 2. Thus, in the new structure,
a macrocyclic ring bridges the ct side of the diterpene moiety in an "ansa" type manner.
The irritancies on the mouse ear of the DTE obtained cover a wide range ( I 2 4 = 0.05-670
nmole- ). Some of them are considerably more irritant than the daphnane type standard simplexin.
Structure/activity investigations reveal that an ester group instead of a free hydroxyl group
at C-20 ("cryptic types"), or presence of a hydroxy or an acetoxy group in position 12 diminishes
the irritancies of the daphnane types isolated, similar to what is known in corresponding tigliane
types. In the standardized initiation/promotion protocol on the back skin of mice, some of the
irritant DTE exhibit tumot-promoting activities higher than that of simplexin

1985
Adolf W, Dossaji SF, Seip EH, Hecker E. "Skin irritant deterpene orthoesters of the daphanane type fropm Peddiea africana and P. Volkensii,." Phytochemistry. 1985;24:2047-2049. AbstractWebsite

From roots of Peddiea volkensii (Thymelaeaceae) the irritant factors and and from roots of P. africana
the irritant factor Aj were isolated. Their structures are the 9,13,14-ort/io-(2,4,6-decatrienoates) of 5/8-
hydroxyresiniferonol-6a,7a-oxide (Vi) and of 5^,12iS-dihydroxyresiniferonol-6a,7a-oxide (Aj) and the 12-0-acetate of the latter (Vj). Factors V i and do not exhibit tumour-promoting activity in the standard initiation-promotion protocol on mouse skin, although is a moderate irritant.

1983
Dossaji SF, Becker H, Exner J. "Flavone C-glycosides of Phorodendron tomentosum form different host trees,." Phytochemistry. 1983;22(1):311-312. Abstract

Apeginin, three known apigenin C-glycosides and isoschaftoside together with apeginin 4-O-glucoside have been identified in leaves of Phoradendron tomentosum growing on different hosts.

1981
Dossaji SF, Becker H. "HPLC-quantitative determination of valepopriates in Valeriana kilimandascharica,." Planta Medica . 1981;43(10):179-182. AbstractWebsite

Valepotriates, mainly isovaltrate and valtrate, have been separated and quantitatively estimated by reversed-phase HPLC in the leaves, flowers, stems and rhizomes of Valeriana kilimandascharica. The isovaltrate/valtrate concentration reaches a maximum of 5.89% in the leaves, 3.84% in the flowers, 3.17% in the stems and 5.15% in the rhizomes.

1980
Dossaji SF, Gitonga J, Bell EA. "Distribution and significance of amino acids in the leaves of Acacia and Crotalaria (Leguminosae)." Kenya J. of Science and Technology, 1, 19.. 1980;1:19-22. Abstract

Leaf extracts of 13 species of Acacia and 9 species of Crotalaria which are native to or estabhshed in Kenya were analysed by 2D paper chromatography and high voltage ionophoresis for their free protein and nonprotein amino acids. In addition to the presence of protein amino acids, both the genera contained nonprotein amino acids. Acacia species contained pipecolic acid, 4-OH pipecolic acid, 5-OH pipecolic
acid and homoarginine. They did not contain N-acetyldjenkolic which is found in the seeds of all but one of the species analysed. The leaf extracts of three species of Crotalaria contained the toxic amino acids, a-amino-p-oxalylaminopropionic acid and a-amino-y-oxalylaminobutyric acid.

Dossaji SF, Kubo I. "Quercetin 3-(2"-Galloyglucoside), a molluscicidal flavanoids form Polygonum senegalense:." Phytochemistry. 1980;19:482-483. Abstract

Valepotriates, mainly isovaltrate and valtrate, have been separated and quantitatively estimated by reversed-phase HPLC in the leaves, flowers, stems and rhizomes of Valeriana kilimandascharica. The isovaltrate/valtrate concentration reaches a maximum of 5.89% in the leaves, 3.84% in the flowers, 3.17% in the stems and 5.15% in the rhizomes.

1977
Dossaji SF, Kairu MG, Gondwe AT, Ouma JH. "On the evaluation of the molluscicidal properties of Polygonum senegalense." Lloydia (J. of Nat. Prod.). 1977;40(3):290-293.
1975
Dossaji SF, Mabry TJ, Bell EA. "Biflavonoids of the Cycadales." Biochemical Systematics and Ecology. 1975;2:171-175. Abstract

Biflavanoid patterns of leaves of 82 species of the order Cycadales comprising 3 families and 10
genera have been determined. The biflavanoidswere Identified byTLC, UV, NMR and MS studies. Pattern differences between species, when detected, involve the position or degree of methylation of the base compounds. On the other hand, differences in the biflavanoid patterns at the generic and family levels were sufficient to support taxonomic relationships. Thus, the absence of hinokiflavone and its derivatives clearly distinguish the Zamiaceae from the Cycadaceae and Stangeriaceae. The complete absence of biflavanoids in the latter family suggests an advanced evolutionary condition, but morphologically, this family has the most fern-like characters, and therefore has been considered by previous workers to be the most primitive of the cycads.

Dossaji SF, Mabry TJ, Wallace JW. "Chromatographic and UV-Visible spectral identification Biflavanoids." Rev. Latinomer Ouim... 1975;6:37-45. Abstract

Thin layer chromatography, coupled with UV-visible spectral data using various
diagnostic shift reagents, was used to differentiate between nineteen bioflavanoids which were
either unsubstituted, partially methylated, or fully methylated. These included biflavanoids of
the amentoflavone type (1-9), 2,3,Klihydroamentoflavone (12), hinokiflavone type (10-11),
2,3,-dihydrohinokiflavone (13), cupressuflavone type (14-16), agathisflavone type (17-18), and
morelloflavone (19).

1974
Carman NJ, Dossaji SF, Mabry TJ. "A populational survey of amino acids in Propsopis species from North and south America." Biochemical Systematics and Ecology. 1974;2:73-74. Abstract

Leaf extracts of 540 plants representing 24 species of the genus Prosopis from North and South America were analyzed by 2-D PC and high voltage electrophoresis for their protein and non-protein amino acids. In addition to the presence of the usual protein amino acids, most of the species examined contained high concentrations of the non-protein amino acids, pipecolic acid, 4-hydroxypipecolic acid and proline.

1973
Dossaji SF, Bell EA, Wallace JW. "Biflavones of Dioon." Phytochemistry. 1973;12:371-373. Abstract

Abstract—Seven biflavones, amentoflavone, bilobetin, sequoiaflavone, ginkgetin, sciadopitysin, 7,4',7',4"-
tetra-O-methylamentoflavone, and diooflavone (amentoflavone hexamethyl ether), were identified from
extracts of the cycad genus Dioon. The biflavones were identified by direct comparison with authentic
samples using m.m.p., co-chromatography in 3 solvents, and NMR studies of the acetates. This is the first
time amentoflavone hexamethyl ether has been identified as a natural product. After surveying numerous
species of the Cycadales, no evidence could be obtained for the occurrence of biflavones glycosides or of biflavones base upon any other nucleus than apeginin.

Dossaji SF, Bell EA. "Distribution of alpha-Amino-beta-Methylaminopropionic acid in Cycas." Phytochemistry. 1973;12:143-144. Abstract

alpha-Amino-beta-Methylaminopropionic acid, previously isolated from seeds of Cycas circinalis, has
now been identified either free or bound in all the other nine species of this genus.

1972
Dossaji SF, Herbin GA. "Occurrence of Macrozamin in the seeds of Encephalatos Hildebrandtii." Federation Proceedings. 1972;31(5):1470-1472. Abstract

A water-soluble hepatotoxin has been isolated
f r om the seeds of Encephalartos hildebrandtii (Zamiaceae)
and identified as macrozamin, methylazoxymethanol-;8-
primeveroside (CH3N=NCH20CiiHi909). a-Amino-)3-methyli
O
aminopropionic acid ( C H j — N H — C H 2 —CHCNHO—COOH),
reported to be present i n the seeds of Cycas circinalis (Gycadaceae),
was not detected i n either the seeds of Encephalartos hildebrandtii or
the leaves of Cycoj thuarsii.

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