Hypoxis colchicifolia as a potential nutraceutical to address non-communicable diseases

Abstract

Cancer, hypertension and hyperglycaemia affect millions of individuals worldwide, with many succumbing to these diseases. Conventional medicine and treatments currently used to manage these diseases, although highly effective, have major side effects. Hypoxis colchicifolia is a traditional medicinal plant used in Southern African against an array of ailments. Providing a rationale and assessing the toxicity of the plant is essential for future use as a natural alternative to allopathic medicine. In this study H. colchicifolia corm and leaf extracts were qualitatively assessed for their phytochemical constituents. The total phenolic content was determined using the Folin Ciocalteu method, and toxicity screened using the brine shrimp lethality assay. The antioxidant potential was evaluated using the DPPH (1,1-diphenyl-2-picryl-hydrazyl), ABTS (2,2′-azinobis(3- ethylbenzothiazolline)-6-sulfonic acid), PM (Phosphomolybdenum), CUPRAC (Cupric ion reducing antioxidant capacity) and FRAP (Ferric Reducing Antioxidant Power) radical scavenging methods. This study also evaluated the in vitro anti-diabetic (α-amyalse and α-glucosidase), antihypertensive [ACE (angiotensin-converting enzyme)] and anticancer potential of H. colchicifolia corm as well as leaf solvent extracts (acetone, methanol and aqueous). All extracts showed the presence of key phytochemical constituents and produced no toxicity. There was a clear difference in the total phenolic content of the leaves compared to the corms. Extracts showed good antioxidant potential with different extracts inhibiting different free radicals, indicating selective antioxidant scavenging capacity. The extracts of leaves and corms cannot be used interchangeably as there are differences in the phytochemical composition. Results showed that H. colchicifolia extracts have a moderate anti-diabetic and anti-hypertensive potential. The acetone extract of fresh corms had the best α-amylase potential with an IC50 of 337 µg/mL and acetone extract of fresh corms leading the α-glucosidase inhibition with an IC50 of 22.06 µg/mL. The methanol extract of dried corms exhibited the greatest ACE inhibition with an IC50 of 368.20 µg/mL. Methanol extract of dried leaves showed the least cytotoxicity against non-cancerous cell line HEK-293. Methanol extract of dried leaves inhibited MCF-7 cell line with an IC50 of 3.24 µg/mL, which was lower than that of the positive control, camptothecin (IC50, 8.44 µg/mL). All extracts exhibited a greater inhibitory potential in A549 cells than camptothecin (IC50, 304.20 µg/mL), with aqueous extract of dried corms having the greatest potential of IC50 32.22 µg/mL. This study reveals that H. colchicifolia has potential to act as a therapeutic.