Abstract
As part of an ongoing study of natural products from local medicinal plants, the methanol extract of stem bark of Rauvolfia caffra Sond was investigated for biological activity. Column chromatography and preparative thin-layer chromatography were used to isolate lupeol (1), raucaffricine (2), N-methylsarpagine (3), and spegatrine (4). The crude extract, fractions and isolated compounds were tested for anti-oxidant, antitrypanosomal and anti-proliferation activities. Two fractions displayed high DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging activity and reducing power with IC50 (The half maximal inhibitory concentration) and IC0.5 values of 0.022 ± 0.003 mg/mL and 0.036 ± 0.007 mg/mL, and 0.518 ± 0.044 mg/mL and 1.076 ± 0.136 mg/mL, respectively. Spegatrine (4) was identified as the main antioxidant compound in R. caffra with IC50 and IC0.5 values of 0.119 ± 0.067 mg/mL and 0.712 ± 0 mg/mL, respectively. One fraction displayed high antitrypanosomal activity with an IC50 value of 18.50 μg/mL. However, the major constituent of this fraction, raucaffricine (2), was not active. The crude extract, fractions and pure compounds did not display any cytotoxic effect at a concentration of 50 μg/mL against HeLa cells. This study shows directions for further in vitro studies on the antioxidant and antitrypanosomal activities of Rauvolfia caffra Sond.
Highlights
Trypanosomiasis is a fatal disease caused by the genus Trypanosoma, affecting humans and animals in many African countries [1,2,3]
The World Health Organization (WHO) estimates that over 70 million people in Sub-Saharan Africa are exposed to the risk of contracting this disease, which is deadly if left untreated [6]
Natural products from medicinal plants have played a vital role in the treatment of trypanosomiasis in various African countries [2]
Summary
Trypanosomiasis is a fatal disease caused by the genus Trypanosoma, affecting humans and animals in many African countries [1,2,3]. The World Health Organization (WHO) estimates that over 70 million people in Sub-Saharan Africa are exposed to the risk of contracting this disease, which is deadly if left untreated [6]. Treatment of this condition has been a challenge [7], the recent introduction of fexinidazole promises to alleviate some of the efficacy, toxicity and administration problems experienced with historical drug treatments [8]. Natural products from medicinal plants have played a vital role in the treatment of trypanosomiasis in various African countries [2]. Medicinal plants have a great potential to provide new antiprotozoal treatments
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