Oxidative stress has been shown to play an important role in the development of anaemia in malaria. Indeed, increase in total antioxidant status has been shown to be important in recovery from malaria. The antioxidant activities of four medicinal plants traditionally used in the treatment of malaria in southwestern Nigeria were determined.
The ethanolic extracts of the leaves of Carica papaya
Linn. [Caricaceae] , stem bark of Magnifera indica
Linn. [Anacardiaceae], leaves of Psidium guajava
Linn. [Myrtaceae] and the leaves of Vernonia amygdalina
Del. [Compositae], were used in the present study. The plant parts commonly used in the locality in malaria therapy were employed in this study. The plants were screened for the presence of phytochemicals and, their effect on 2,2-Diphenyl-1-picryl-hydrazyl radical (DPPH) was used to determine their free radical scavenging activity.
Phytochemical screening of the plants showed the presence of flavonoids, terpenoids, saponins, tannins and reducing sugars. M. indica
did not contain cardiac glycosides and alkaloids while, P. guajava
also showed the absence of alkaloids and anthraquinones. Anthraquinones was similarly absent from V. amygdalina
. Concentrations of the plant extracts required for 50% inhibition of DPPH radical scavenging effect (IC50) were recorded as 0.04 mg/ml, 0.313 mg/ml, 0.58 mg/ml, 2.30 mg/ml and 0.054 mg/ml for P. guajava
, M. Indica
, C. papaya
, V. amygdalina
and Vitamin C, respectively.
All the plants showed potent inhibition of DPPH radical scavenging activity, P. guajava
being the most potent. The free radical scavenging (antioxidant) activities of these plants probably contribute to the effectiveness of the above plants in malaria therapy.