S.N. Ndwigah, G.N. Thoithi and I.O. Kibwage, Phytochemical Investigation and Anthelmintic Activity of Dombeya rotundifolia, Hochst. M.Pharm. (Pharmaceutiocal Analysis) Thesis. 2004-University of Nairobi..
University of Nairobi. : East and Central African Journal of Pharmaceutical Sciences Abstract
Dombeya rotundifolia (Hochst) is a shrub (or tree) and grows in woodland, wooded grassland and rocky mountain slopes from Ethiopia southwards to Kwazulu Natal, South Africa. It is widespread in Kenya and has many traditional uses. Roots are boiled and the soup used to treat rheumatism. Roots are pounded, soaked in water and the macerate given to children with diarrhea. Its stems and roots are used as an anthelmintic and to treat syphilis. It is also used to treat heart problems, nausea in pregnant women, headaches, haemorrhoids, dyspepsia, regulate the menses, to hasten the onset of labour and as an abortifacient. Dried entire plant is used in South Africa for treatment of diarrhea and in Tanzania for intestinal upset and to rid evil effects of witchcraft. It is also used to treat abdominal pains, intestinal ulceration, headaches, haemorrhage and as a tonic. Phytochemical studies were carried out on the methanol, chloroform, hot water and cold water extracts of Dombeya rotundifolia. All the extracts contained cardiac glycosides. The methanol, hot water and could water extracts contained saponins. None of the extracts contained alkaloids and anthraquinones. Fractionation of the chloroform extract yielded two compounds which were identified as lupeol and -sitosterol by spectroscopic methods. The extracts delayed the normal hatching of strongyle eggs while killing the eggs at high concentration. Many of the un-hatched eggs below the concentration of 5000 g/ml had developed and the larvae could be seen inside the shell but some were dead showing that the extracts retarded development of the eggs. The calculated LD50 for egg hatch assay was 2570 g/ml, 500.9 g/ml, 2709.4 g/ml and 1762.9 g/ml for the hot water, cold water, methanol and chloroform extracts, respectively. The calculated LD50 for the larvae mortality assay was 635.9 g/ml, 657.0 g/ml, 96.9 g/ml and 4195 g/ml for the hot water, cold water, methanol and chloroform extracts, respectively. The extracts killed the hatched larvae at high concentrations. The calculated LD50 for the larvae development assay was 1689.6 g/ml, 765.4 g/ml, 4909.8 g/ml and 3062 g/ml for the hot water, cold water, methanol and chloroform extracts, respectively. This showed that the extracts prevented the normal development of the larvae from Larvae1 to Larvae3 (adult stage). The most active extract in egg hatch and larvae development assay was the cold water extract, while methanol extract was the most active in larvae mortality assay. The hot water and could water extracts relaxed the isolated rabbit ileum, an effect similar to that of adrenaline, supporting the use of this plant to treat diarrhea. The methanol and chloroform extracts had no effects on the isolated rabbit ileum up to a dose of 40 mg (2 mg/ml). No extract had activity on guinea pig ileum. All the extracts had broncho-constrictive effect on guinea pig trachea. The chloroform extract had a marked negative chlorotropic and inotropic effects on the isolated rabbit heart. The methanol and the water extracts had no effects on the heart up to a dose of 20 mg. Starting with a tissue bath concentration of 0.5 mg/ml, both methanol and hot water extracts caused contraction of isolated rat uterus with activity at a concentration of 2 mg/ml being comparable to the effect of oxytocin 0.1 i.u/ml and acetylcholine 0.5 g/ml. Both chloroform and cold water extracts had no noticeable effect on the uterus upto a dose of 2 mg/ml. The oxytocin-like contractions of isolated rat uterus caused by methanol and hot water extracts supports the use of this plant decoction as an abortifacient. The extracts had high activity against Artemia salina showing they may have good pestcidal and cytotoxic activity. The LD50 of methanol, chloroform, hot water and cold water extracts were 470.7, 323.3, 30.2 and 38.5 g/ml, respectively. The LD50 of lupeol and -sitosterol was 116.2 and 95.9 g/ml, respectively. In this work, the isolation of any compound from Dombeya rotundifolia is reported for the first time. The compounds lupeol and -sitosterol were isolated from the stem bark. The present work shows there is a scientific basis for the traditional use of the plant Dombeya rotundifolia as anthelmintic, antidiarrhoeal and abortifacient.