Antagonistic effect of alkaloids and saponins on bioactivity in the quinine tree (Rauvolfia caffra sond.): further evidence to support biotechnology in traditional medicinal plants
1 Center for Biotechnology and Bioinformatics, University of Nairobi, P.O. Box 30197, Nairobi 00100, Kenya
2 Department of Chemistry, University of Nairobi, P.O. Box 30197, Nairobi 00100, Kenya
3 Department of Natural Science, Catholic University of Eastern Africa, P.O. Box 62157, Nairobi 00200, Kenya
4 Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000, Nairobi 00200, Kenya
5 Department of Medical Microbiology, College of Health Sciences, University of Nairobi, P.O. Box 19676, Nairobi 00202, Kenya
6 College of Agriculture & Vet Sciences, University of Nairobi, P.O. Box 30197, Nairobi 00100, Kenya
BMC Complementary and Alternative Medicine 2013, 13:285 doi:10.1186/1472-6882-13-285Published: 26 October 2013
The Quinine tree (Rauvolfia caffra) is used as a medicinal plant among traditional communities in many countries to manage tumors and other diseases associated with oxidative stress. To validate indigenous knowledge and possibly position this herb for technology uptake and utilization, we established the level of antioxidant activity in R. caffra, and probed for the presence of associated phytochemicals.
Antioxidant activity was determined on 1,1-diphenyl-2-picrylhydrazyl (DPPH) while major phytochemicals were identified by multiple tests on methanol fractions.
R. caffra showed promise as a cure, with antioxidant activity comparable to the commercially used drug quercetin (R. caffra = 79.7% ±1.9; quercetin = 82.6% ± 2.0). However, we found two phytochemicals with possible antagonistic effect: co-occurrence of alkaloids and saponins significantly reduced antioxidant activity (alkaloids only = 63%; alkaloids plus saponins = 15%; steroids, terpenoids and cardiac glycosides = 82%), thus alkaloids and saponins should be exclusive to each other in drug formulations.
Antagonistic relationship among phytochemicals would affect the efficacy of crude extracts as used in traditional medicine. Unlike in herbal medicine, use of modern biotechnology in extraction, purification and design of optimal combinations will ensure efficient drug formulations with optimum bioactivity and minimum toxicity. Metabolic pathway engineering under a controlled environment may optimize availability of desired compounds.