Comparative Phytochemical Analysis, Antioxidant and Antibacterial Activities in the Leaves, Underground Stems and Roots of Bulbine abyssinica

Abstract

Bulbine abyssinica is a succulent medicinal plant indigenous to South Africa. The species has been commonly used traditionally by indigenous people for the treatment of various skin related ailments as well as the management of diabetes mellitus. To date, limited studies have been conducted on the underground stems and roots, as well as comparative analyses across the different plant parts of the species. Methanolic extracts of B. abyssinica leaves, underground stems and roots were used to perform phytochemical screening, quantitative phytochemical analyses, antioxidant and antibacterial assays. The leaves contained most of the phytochemical groups tested, as well as higher total phenolic (1841.7 ± 4.8 mg/100g GAE), total flavonoid (809.2 ± 75.6 mg/100g QE), total tannin (2850 ± 70.01 mg/100g GAE) and total proanthocyanidin (636.67 ± 1.67 mg/100g CE) contents compared to the underground stems and roots. The antioxidant activity results showed that the roots exhibited the strongest scavenging power against 2, 2 diphenylpicryhydrazyl (DPPH) (0.105 ± 0.01 mg/ml), whereas the leaves showed a higher antioxidant power against hydrogen peroxide (0.66 ± 0.07 mg/ml) and metal chelating radicals (2.68 ± 0.16 mg/ml). All three plant parts showed intermediate zones of inhibition (10 - 19 mm) against Staphylococcus aureus and Escherichia coli. The current study validates the use of different plant parts of B. abyssinica in the traditional medicine context, and suggests the plant’s potential application in the pharmaceutical and cosmetic industries.