The biological activity of Kedrostis nana plant extracts: Antioxidant, antibacterial and cytotoxic effects

There has been an increased resurgence of infectious diseases globally which has caused great concern. This is due to the various bacterial species developing resistance to modern synthetic antibiotics. There is a dire need for new treatment or drugs to counteract this concern. Medicinal plants have been the go-to therapeutic treatment as they contain numerous bioactive compounds that have pharmacological activity. The appeal of medicinal plants is that they are cheaper, readily available or more accessible and more culturally acceptable than conventional Western medicines. However, the physiochemical composition and pharmacological activities of understudied medicinal plants need to be explored to substantiate the rationale of their use as lead drugs. One understudied medicinal plant is Kedrostis nana . This perennial is found in the Western and Eastern Cape, where it has been traditionally used to treat a host of ailments and diseases. The aim of this research was to investigate the biological activity of Kedrostis nana plant extracts. To achieve this, the extracts were subjected to antibacterial assessment using the INT assay, antioxidant evaluation via the DPPH assay and cytotoxicity testing by means of the MTT assay. Based on the antioxidant analysis, all extracts tested showed to have a moderate scavenging activity against free radicals. Varying levels of antioxidant activity was observed for the extracts, and these results were not concentration dependant. The antibacterial assessment showed that the aqueous leaves, stems and tuber extracts had a higher percentage inhibition against the various bacterial species compared to the chloroform, hexane and methanol extracts as MIC values ranged between 12,5 and 50 μg/mL. The aqueous extracts were used in cytotoxicity assessments against the Hek293 and HeLa cell lines. Overall, the aqueous leaf extract displayed the strongest antibacterial activity at a concentration below those that would affect the Hek293 cell viability. The aqueous extracts showed to have preferential toxicity to the cancer cell lines. The findings from this study provide a basis for further investigations that would validate K. nana for future drug development.