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Birech, Z, Ondieki AM, Opati RII, Mwangi PW.  2020.  Low cost Raman sample substrates from conductive silver paint smear for Raman spectroscopic screening of metabolic diseases in whole blood, 2020. 108:103063. AbstractWebsite

This work reports on a low cost, simple to prepare and chemically stable Raman substrates based on conductive silver paint smear. The substrates were characterized Raman spectroscopically and were found to be chemically stable within the first seven days when kept at room temperature as the spectroscopic profiles were unchanged. The substrates also suppressed the background signals emanating from glass centered around 750 cm−1 and 1370 cm−1 seen with 785 nm excitation and had negligible influence on Raman spectral profiles of rat’s blood samples applied onto them. The Raman spectral profiles of blood samples applied onto the substrates were found to be enhanced by a factor of 1.7 compared to those of thick blood smears on a clean microscope glass slide. The increased local field between the gaps formed by adjacent micron-sized silver solids in the paint smear were attributed to the observed intense signals observed from the blood samples applied onto them. The substrates were tried on Raman spectroscopic differentiation between blood from obese and normal; diabetic and normal Sprague Dawley rats. The prominent bands associated with fructose (638 and 812 cm−1), glucose (1127 cm−1) and branched chain amino acids (1033, 1217 and 1318 cm−1) were observed to vary in terms of intensity between the un-healthy (obese and diabetic) and healthy (normal) rats. The results reported here on the use of the easy to prepare, low cost Raman substrates have the potential of making surface-enhanced Raman spectroscopy accessible to less resourced laboratories in developing countries. The substrates can be applied in rapid Raman spectroscopic screening of various metabolic diseases.

Birech, Z, Mwangi PW, Sehmi PK, Nyaga NM.  2020.  Application of Raman spectroscopy in comparative study of antiobesity influence of oxytocin and freeze-dried extracts of Uvariodendron anisatum Verdeck (Annonaceae) in Sprague Dawley rats, 2020. Journal of Raman SpectroscopyJournal of Raman Spectroscopy. 51(3):398-405.: John Wiley & Sons, Ltd AbstractWebsite

Abstract Obesity is a condition affecting a substantial number of people in the world. Obese people have increased risks of developing chronic metabolic diseases such as type II diabetes, hypertension, and cancer, among others. Predicting potential development together with rapid diagnosis of the condition followed by early interventions is therefore necessary. This work investigated, first, utility of Raman spectroscopy in performing comparative antiobesity influence studies of oxytocin and a freeze-dried extract of a local herbal plant exhibiting oxytocin-like properties called Uvariodendron anisatum Verdeck (Annonaceae) (UAV) on diet induced obesity in Sprague Dawley rat models. Second, we looked for obesity biomarker Raman spectral bands. The blood extracted from the rats were applied onto conductive silver paste smeared glass slides and excited using a 785-nm laser. Raman spectra of blood from oxytocin- and UAV-treated rats displayed similar profiles with low doses of UAV (100 mg/kg of body weight) being more similar to oxytocin than high doses (200 mg/kg of body weight) as revealed by cosine similarity value of 0.997. Their profiles were also different from blood of obese and nonobese (normal controls) animals. A prominent peak in spectra of treated rats centred at 401 cm?1 can be oxytocin's biomarker band in blood. Comparison of average intensity trend of fructose bands at around 638 and 812 cm?1 between prepared fructose solution and blood of treated rats revealed elevated levels of fructose in blood of rats intraperitoneally injected oxytocin and UAV extracts. The result implied upregulation of fructose in oxytocin- and UAV-treated animals. Principal component analysis confirmed that Raman spectral profiles from blood of obese rats were different from those of nonobese rats with bands ascribed to fructose (638, 812, and 1,217 cm?1) and branched chain amino acids (BCAAs; 478, 1,318, and 1,443 cm?1), being utilized in the segregation of the spectral data sets. It also showed that spectra from oxytocin-treated and UAV-treated rat's blood were similar implying identical influence of the drugs on the animals. The study showed potential of Raman spectroscopy as tool for quick obesity (or metabolic syndrome) screening with intensity of Raman bands associated with fructose and BCAAs as biomarkers. Besides, the same bands may be used in comparative efficacy studies of antiobesity drugs. The results reported here are rare in literature.


Chege, BM, Waweru MP, Frederick B, Nyaga NM.  2019.  The freeze-dried extracts of Rotheca myricoides (Hochst.) Steane & Mabb possess hypoglycemic, hypolipidemic and hypoinsulinemic on type 2 diabetes rat model, 2019. 244:112077. AbstractWebsite

Ethnopharmacological relevanceRotheca myricoides (Hochst.) Steane & Mabb is a plant species used in traditional medicine for the management of diabetes in the lower eastern part of Kenya (Kitui, Machakos and Makueni Counties, Kenya) that is mainly inhabited by the Kamba community.
This study investigated the antihyperglycaemic, antidyslipidemic and antihyperinsulinemic activity of the freeze-dried extracts of Rotheca myricoides (Hochst.) Steane & Mabb (RME) in an animal model of type 2 diabetes mellitus.
Type 2 diabetes was induced by dietary manipulation for 56 days via (high fat- high fructose diet) and intraperitoneal administration of streptozocin (30 mg/kg). Forty freshly-weaned Sprague Dawley rats were randomly assigned into the negative control (high fat/high fructose diet), low dose test (50mg/kg RME, high dose test (100mg/kg RME and positive control (Pioglitazone, 20mg/kg) groups. Fasting blood glucose and body weight were measured at weekly intervals. Oral glucose tolerance tests were performed on days 28 and 56. Lipid profile, hepatic triglycerides, fasting serum insulin levels and serum uric acid were determined on day 56.
The RME possessed significant antihyperglycemic [FBG: 6.5 ± 0.11 mmol/l (negative control) vs. 4.62 ± 0.13 mmol/l (low dose test) vs. 5.25 ± 0.15 mmol/l in (high dose test) vs. 4.33 ± 0.09 mmol/l (positive control): p < 0.0001] and antihyperinsulinemic effects [1.84 ± 0.19 (negative control) vs. (0.69 ± 0.13 (low dose test) vs. (0.83 ± 0.17 (high dose test) vs. (0.69 ± 0.10 (positive control): F (3, 36) = 0.6421: p < 0.0001. The extracts also possessed significant antidyslipidemic effects [LDL levels: 3.52 ± 0.19 mmol/l (negative control) vs. 0.33 ± 0.14 mmol/l (low dose test) vs. 0.34 ± 0.20 mmol/l (high dose test) vs. 0.33 ± 0.01 mmol/l (positive control): p < 0.0001].RME significantly lowered plasma uric acid levels, as well as hepatic triglycerides and hepatic weights. Network pharmacology analysis indicated that the observed pharmacological effects are mediated via the modulation of Peroxisome proliferator-activated gamma receptor.
The freeze dried extracts of Rotheca myricoides possessed significant antihyperglycemic and antidyslidemic effects. In addition it lowered serum uric levels, as well as hepatic triglycerides and hepatic weight. These results appear to validate the traditional use of this plant species in the management of diabetes mellitus.

Hammadi, R, Kúsz N, Mwangi PW, Kulmány Á, Zupkó I, Orvos P, Tálosi L, Hohmann J, Vasas A.  2019.  Isolation and Pharmacological Investigation of Compounds From Euphorbia matabelensis, 2019. Natural Product CommunicationsNatural Product Communications. 14(7):1934578X19863509.: SAGE Publications Inc AbstractWebsite

This work deals with the isolation and pharmacological investigations of compounds of Euphorbia matabelensis. After multiple separation process, including thin layer chromatography (TLC), vacuum liquid chromatography, preparative TLC, and high-performance liquid chromatography, 1 diterpene (ingenol) and 2 flavonoids (naringenin and eriodictyol) were obtained from the methanol extracts prepared from the stems and roots of the plant. The structures of the isolated compounds were determined by nuclear magnetic resonance (NMR) and MS measurements and comparison with literature data. All compounds were isolated for the first time from the plant. Eriodictyol was detected for the first time from a Euphorbia species. The compounds were tested for their antiproliferative (on HeLa, C33a, MCF-7, and MDA-MB-231 cell lines) and GIRK channel blocking activities. None of the compounds proved to be active in these test systems.

Chege, BM, Birech Z, Mwangi PW, Bukachi FO.  2019.  Utility of Raman spectroscopy in diabetes detection based on biomarker Raman bands and in antidiabetic efficacy studies of herbal extract Rotheca myricoides Hochst, 2019. Journal of Raman SpectroscopyJournal of Raman Spectroscopy. 50(10):1358-1366.: John Wiley & Sons, Ltd AbstractWebsite

Abstract Diabetes is a disease characterized by hyperglycaemia because of insufficient or nonproduction of insulin from the pancreas. Establishing prediabetic and diabetic condition often involves monitoring levels of glucose and some amino acids in blood using nonrapid and label-dependent methods. This work reports on a method with a potential of being used for quick label-free detection of diabetes mellitus type II based on Raman spectroscopy of blood applied onto a conductive silver-smeared glass slide. We show that Raman spectral profile from blood of streptozotocin-induced diabetic Sprague Dawley rats emanates from overlap of signals from valine, leucine, isoleucine, creatine, glucose, and fructose. The Raman spectral bands associated with these biomolecules have the potential of being used in prediabetic detection and diabetes prediction. Characteristic intense peaks in diabetic rat's blood spectra were centred at wave numbers 537 cm?1 associated with valine's CO2? rocking vibration, 829 cm?1 assigned to CH2 rocking vibration in leucine and 917?960 cm?1 ascribed to C?C and C?N stretching and CH3 rocking vibrations in various biomolecules. The average intensities of these bands were sensitive to antidiabetic drug administration on the rats as their values approached those of nondiabetic rats and so could be used as diabetes biomarker bands. Statistical analyses together with evaluation of average intensities of these biomarker bands showed that the herbal extract Rotheca myricoides Hochst had greater antidiabetic effect at low dose (50 mg/kg of body weight) than at high dose (100 mg/kg of body weight). A similar result was seen with area under curve values and could act as an additional parameter in diabetes detection and prediction.

Kamau, F, Strijdom H, Mwangi P, Blackhurst D, Imperial E, Salie R.  2019.  Antiretroviral drug-induced endothelial dysfunction is improved by dual PPARα/γ stimulation in obesity, 2019. 121:106577. AbstractWebsite

Obesity rates are rising in HIV-infected populations; however, the putative role of highly active antiretroviral therapy (HAART) in the development of endothelial and cardiovascular derangements in the presence of pre-existing overweight/obesity is unclear. Although dual peroxisome proliferator-activated receptors-alpha/gamma (PPARα/γ) stimulation mitigates HAART-induced metabolic dysfunction, vascular effects are unresolved. To investigate whether HAART induces vascular dysfunction in obesity and to explore the underlying mechanisms of PPARα/γ stimulation, male Wistar rats were placed on a high-calorie diet for 16 weeks. After 10 weeks, HAART (lopinavir/ritonavir, azidothymidine/lamivudine) with/without PPARα/γ agonist, Saroglitazar, was administered daily for six weeks. Excised thoracic aorta rings were subjected to isometric tension studies and Western blot measurements. HAART+Saroglitazar-treated obese animals recorded lower adiposity indices (4.3 ± 0.5%) vs. HAART only-treated obese rats (5.6 ± 0.3%; p < .01). Maximum acetylcholine-induced vasorelaxation (Rmax), was lower in obese+HAART group (76.10 ± 3.58%) vs. obese control (101.40 ± 4.75%; p < .01). However, Rmax was improved in obese+ HAART+Saroglitazar (101.00 ± 3.12%) vs. obese+HAART rats (p < .001). The mean LogEC50 was improved in obese+HAART+Saroglitazar vs. obese+HAART group; p = .003. Improved endothelial function in obese+ HAART+Saroglitazar group was associated with upregulation of eNOS, PKB/Akt and downregulated p22-phox expression vs. obese+HAART group. Therefore, PPARα/γ stimulation attenuated HAART-induced endothelial dysfunction by upregulating vasoprotective eNOS, PKB/Akt signaling and downregulating pro-oxidative p22-phox expression.


Birech, Z, Mwangi PW, Bukachi F, Mandela KM.  2017.  Application of Raman spectroscopy in type 2 diabetes screening in blood using leucine and isoleucine amino-acids as biomarkers and in comparative anti-diabetic drugs efficacy studies, 2017/09/19. PloS one. 12(9):e0185130-e0185130.: Public Library of Science AbstractWebsite

Diabetes is an irreversible condition characterized by elevated blood glucose levels. Currently, there are no predictive biomarkers for this disease and the existing ones such as hemoglobin A1c and fasting blood glucose are used only when diabetes symptoms are noticed. The objective of this work was first to explore the potential of leucine and isoleucine amino acids as diabetes type 2 biomarkers using their Raman spectroscopic signatures. Secondly, we wanted to explore whether Raman spectroscopy can be applied in comparative efficacy studies between commercially available anti-diabetic drug pioglitazone and the locally used anti-diabetic herbal extract Momordica spinosa (Gilg.)Chiov. Sprague Dawley (SD) rat's blood was used and were pipetted onto Raman substrates prepared from conductive silver paste smeared glass slides. Prominent Raman bands associated with glucose (926, 1302, 1125 cm-1), leucine (1106, 1248, 1302, 1395 cm-1) and isolecucine (1108, 1248, 1437 and 1585 cm-1) were observed. The Raman bands centered at 1125 cm-1, 1395 cm-1 and 1437 cm-1 associated respectively to glucose, leucine and isoleucine were chosen as biomarker Raman peaks for diabetes type 2. These Raman bands displayed decreased intensities in blood from diabetic SD rats administered antidiabetic drugs pioglitazone and herbal extract Momordica spinosa (Gilg.)Chiov. The intensity decrease indicated reduced concentration levels of the respective biomarker molecules: glucose (1125 cm-1), leucine (1395 cm-1) and isoleucine (1437 cm-1) in blood. The results displayed the power and potential of Raman spectroscopy in rapid (10 seconds) diabetes and pre-diabetes screening in blood (human or rat's) with not only glucose acting as a biomarker but also leucine and isoleucine amino-acids where intensities of respectively assigned bands act as references. It also showed that using Raman spectroscopic signatures of the chosen biomarkers, the method can be an alternative for performing comparative efficacy studies between known and new anti-diabetic drugs. Reports on use of Raman spectroscopy in type 2 diabetes mellitus screening with Raman bands associated with leucine and isoleucine molecules acting as reference is rare in literature. The use of Raman spectroscopy in pre-diabetes screening of blood for changes in levels of leucine and isoleucine amino acids is particularly interesting as once elevated levels are noticed, necessary interventions to prevent diabetes development can be initiated.


Kinuthia, DG, Muriithi AW, Mwangi PW.  2016.  Freeze dried extracts of Bidens biternata (Lour.) Merr. and Sheriff. show significant antidiarrheal activity in in-vivo models of diarrhea, 2016. 193:416-422. AbstractWebsite

Ethnopharmacological relevance of the studyDiarrhea remains one of the main killers of children aged below five years. Traditional antidiarrheal remedies form a potentially viable source of novel low cost efficacious treatments in low resource settings. There is therefore a pressing need to scientifically evaluate these remedies.
Aim of the study
This study aimed to investigate the in vivo and in vitro antidiarrheal activity of freeze dried Bidens biternata, a herb used in traditional Ayurvedic medicine in the management of diarrhea.
Materials and methods
In the castor oil test, twenty (20) adult Sprague-Dawley rats were randomized to a negative control (normal saline, n=5), a positive control (5mg/kg loperamide, n=5), and two test groups. The low dose test group received 200mg/kg Bidens biternata extract (n=5) while the high dose test group received 400mg/kg B. biternata extract (n=5). Castor oil (4ml/kg) was then administered to the animals one hour after administration of the respective treatments after which the total mass of fecal output excreted after four (4) hours was determined. In the charcoal meal test fifteen (15) Sprague Dawley rats were randomized to a control group (normal saline 5ml/kg orally, n=5), a positive control group (atropine sulfate 0.1mg/kg i.p., n=5) and a test group (400mg/kg B. biternata extract, n=5). Charcoal meal was then administered via oral gavage to each rat thirty (30) minutes after the administration of the various treatments. The distance covered by the charcoal meal from the pylorus was then determined after sacrifice of the animals thirty minutes after the meal. In the enteropooling test twenty (20) Sprague-Dawley rats were randomized to a control group (5% v/v ethanol in normal saline, n=5), a positive control group (5mg/kg loperamide, n=5) and a test group (400mg/kg B. biternata extract, n=5). For each group prostaglandin E2 (PGE2) (100μg/kg) was administered immediately after the treatments. The animals were then sacrificed half an hour later and the volume of the small intestine contents determined. The effects of different concentrations of B. biternata extract (0.5. 1.0, 2.0, 3.0 and 5.0mg/ml) on jejunal contraction were investigated and a dose-response curve constructed using the experimental data after which The ED50 dose was determined. The effect of tamsulosin (α1 adrenergic blocker), yohimbine (α2 adrenergic blocker), propranolol (β adrenergic blocker) and naloxone (μ opioid blocker) on the contractile activity of the extract were also investigated. The experimental data were expressed as mean±standard error of mean (SEM) and then analyzed using one-way ANOVA followed by Tukey's post hoc test in cases of significance (set at p<0.05).
The freeze dried extracts of B. biternata had significant antidiarrheal effects in the castor oil induced diarrhea model (p<0.01) with the highest activity being observed at the 400mg/kg dosage level (1.66±0.81g vs. 4.54±0.51g control, p=0.01). B. biternata extract had significant effects on intestinal motility in the charcoal meal test compared to the control group (43.61±4.42% vs. 60.54±3.33%: p<0.05). B. biternata extract had a significant effect on PGE2 induced enteropooling (3.06±0.07ml vs. 4.74±0.10ml; p<0.001). The freeze dried extracts of B. biternata had a significant negative effect on the contractility of the isolated rabbit jejunum (p<0.001). The effects of the extract were significantly attenuated by tamsulosin (53.94±4.20% vs. 80.57±4.09%; p<0.01) and naloxone (53.94±4.20% vs. 73.89±7.26%; p<0.05). Yohimbine (p>0.05) and propranolol (p>0.05) however did not have any significant effect on the contractile activity of the extract.
The freeze dried extract of B. biternata possess significant antidiarrheal activity in both in vitro and in vivo models which appears to be mediated by modulating both the intestinal motility as well as the secretory activity. The results of this study also validate its traditional use as an antidiarrheal remedy.


Makamu, BL, Bukachi F, Mwangi PW.  2014.  RIMONABANT HAS PARADOXICAL EFFECTS ON cART ASSOCIATED METABOLIC DISEASE. 17th World Congress of Basic and Clinical Pharmacology. :231-232., Cape Town, South Africa: IUPHAR


Matheka, DM, Kilonzo JM, Munguti CM, Mwangi PW.  2013.  Pattern, knowledge and practices of HbA1C testing among diabetic patients in a Kenyan tertiary referral hospital., 2013. Globalization and health. 9:55. Abstract

Glycated haemoglobin (HbA1C) measurement is the currently accepted gold standard biochemical indicator of long-term glycemic control in diabetic patients. The level of knowledge as well as the frequency of use of this test among diabetic patients in Kenya is unknown. The current study aimed to document this among patients attending the diabetes clinic at a national referral hospital in Kenya.


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