The antioxidant activities of crude extract of Phaulopsis fascisepala leaf were evaluated and compared with α-tocopherol and BHT as synthetic antioxidants and ascorbic acid as natural-based antioxidant. In vitro, we studied its antioxidative activities, radical-scavenging effects, Fe2+-chelating ability and reducing power. The total phenolic content was determined and expressed in gallic acid equivalent. The extract showed variable activities in all of these in vitro tests. The antioxidant effect of P. fascisepala was strongly dose dependent, increased with increasing leaf extract dose and then leveled off with further increase in extract dose. Compared to other antioxidants used in the study, α-Tocopherol, ascorbic acid and BHT, P. fascisepala leaf extract showed less scavenging effect on α,α,-diphenyl-β-picrylhydrazyl (DPPH) radical and less reducing power on Fe3+/ferricyanide complex but better Fe2+-chelating ability. These results revealed the in vitro antioxidant activity of P. fascisepala. Further investigations are necessary to verify these activities in vivo.

Purpose: 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. Methods: 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. Results: 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. Conclusion: 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.

The stem bark extract of S. ellipticum (Hochst) Pax was investigated for its antioxidant properties in this study. The extract was evaluated for antioxidant activity in vitro in terms of its ability to inhibit lipid peroxidation and its free radical scavenging, reducing and metal chelation powers. The total amount of phenolic compounds in the extract was also determined in terms of gallic acid equivalent. The extract produced effective free radical scavenging and reducing activities in a dose dependent fashion. The extract exhibited noticeable inhibition of lipid peroxidation of linoleic acid emulsion. These activities were less than that of ascorbic acid and 2,6-Di-tert-butyl-4-methylphenol used as positive controls. The extract however demonstrated poor iron chelating ability compared to ethylene diamine tetraacetic acid. The total phenolic content of the extract was 50.61 +/- 0.08 mg g(-1) in terms of gallic acid. This study showed that the stem bark extract of S. ellipticum exhibits significant antioxidant activity and is a good source of natural antioxidants.

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