An in vitro assessment of the potential antidiabetic activity and cytotoxic effects of ethanolic and aqueous extracts from three invasive Australian acacias.
Acacia cyclops, Acacia saligna and Acacia mearnsii are characterized as prolific invasive alien plants (IAPs) presenting a substantial ecological and economic burden on South Africa. While conventionally these species are perceived as weeds having little value, this study attempts to demonstrate their respective potential as a phytomedicinal resource in the treatment of type 2 diabetes - thereby incentivizing their eradication. Moreover, this study aimed to assess the antidiabetic and cytotoxic effects of extracts from these three invasive Australian acacias in vitro. The α-glucosidase and α-amylase activities of ethanolic and aqueous extracts derived from aerial tissues of A. cyclops, A. saligna, and A. mearnsii were investigated, followed by a cytotoxicity assessment using Hoechst 33342-Propidium Iodide (PI) dual staining and quantitative fluorescence microscopy on the human colon (Caco-2) cell line. Of the extracts screened, A. saligna ethanolic bark demonstrated the highest inhibitory activity against α-amylase and α-glucosidase with an IC50 of 10.45 ± 3.79 μg/ml and 2.35 ± 0.61 μg/ml followed by leaf extract depicting strong α-glucosidase (IC50 of 3.64 ± 1.59 μg/ml) and moderate α-amylase (IC50 of 17.67 ± 3.84 μg/ml) inhibition. The IC50 values of all extracts were significantly (p < 0.05) lower than Acarbose (IC50 of 330.71 ± 28.36 μg/ml) and Epigallocatechin gallate (IC50 of 68.2 ± 8.34 μg/ml). All extracts were found to be nontoxic at test concentrations on Caco-2 cells as confirmed by Hoescht 33342-PI dual staining. Overall, the findings presented in this study provide the first concurrent account of three invasive Acacias in South Africa reporting on their potential as an alternative therapeutic option for the treatment of type 2 diabetes.