Antifungal, anti-oxidant activity and cytotoxicity of South African medicinal plants against mycotoxigenic fungi

Fungal strains belonging to genus Fusarium and Aspergillus are known to infect crops, resulting in threatened food security and less agricultural crop yields. The aim of the current work was to investigate the anti-mycotoxigenic activity, cytotoxic effect and antioxidant potential of selected South African medicinal plants extracts. The aqueous and organic extracts of the leaves from selected medicinal plants were investigated for their antifungal activity against various fungal strains that are known to infect crops and produce mycotoxins. Antioxidant activity, total phenolic and total flavonoids contents were also evaluated. Organic extract of Milletia grandis (E. Mey) Skeels revealed the lowest minimum inhibitory concentration (MIC) value of 0.01 mg/mL against Aspergillus ochraceous, Fusarium graminearum and Furasium oxysporum. Generally, organic extracts revealed significant antifungal activity compared to aqueous extracts. Carpobrutus eludis L. and Warburgia salutaris (G. Bertol) Chiov. revealed a potent cytotoxic effect yielding 50 % lethal concentration (LC(50)) value of 0.01 mg/mL against Bovine dermis and Vero cells respectively. Ricinus communis L. revealed a 50 % inhibitory concentration (IC(50)) value of 945 μg/mL against 2, 2 diphenyl-picryl-hydrazyl (DPPH). Generally, the plant species revealed lower flavonoids compared to phenolic contents. The biological activity of the selected plant extracts may be attributed to the high phenolic contents.