Browsing by Author "Ngcobo, Nkosinathi Khulekani."

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Identification of alpha-glucosidase inhibitors in indigenous plants used for diabetes.
(2024) Ngcobo, Nkosinathi Khulekani.; van Heerden, Fanie Retief.; Rasalanavho, Muvhango.
Diabetes, a global health concern, is a metabolic disorder with a broad range of micro and macro complications. There is still a need to develop new diabetic therapies. Hence, there is a resurging interest in isolating bioactive compounds with antidiabetic activity. One of the therapeutic therapies is the inhibition of α-glucosidase, an enzyme located in the digestive tract that facilitates the hydrolysation of carbohydrates into glucose. Plant-derived compounds and their derivatives have played a significant role in developing numerous drugs, such as the antidiabetic drug metformin. With the intention to advance and explore new plant-derived compounds that can potentially be developed into new biologically active drugs that will be used to treat diabetes, several Indigenous South African species traditionally used to treat diabetes were selected for investigation. These plants were Bulbine frutescens (L.) Willd., Carpobrotus dimidiatus (Haw.) L.Bolus, Cassia abbreviata Oliv. subsp. beareana (Holmes) Brenan, Gomphocarpus tomentosus Burch. subsp. tomentosus, Maerua angolensis DC. subsp. angolensis, Merwilla plumbea (Lindl.) Speta, Pappea capensis Eckl. & Zeyh, Sclerocarya birrea (A.Rich.) Hochst. subsp. caffra (Sond.) Kokwaro, Senegalia mellifera (Vahl) Seigel & Ebinger subsp. detinens (Burch.) Kyal. & Boatwr., Senna italica Mill. subsp. arachoides (Burch.) Lock, Tabernaemontana elegans Stapf, and Ziziphus mucronata Willd. subsp. mucronata. Lead-like extracts were prepared for all the plant species, and the extracts were subjected to in vitro enzyme inhibition studies. The extract of S. birrea was selected for further investigation since it demonstrated the highest inhibitory activity against α-glucosidase. An active fraction of S. birrea stem bark was subjected to LC-MS analysis, and five compounds were identified in the extracts. Preparative chromatography was used to isolate four compounds: catechin, β-sitosterol, β-sitosterol glucopyranoside, and stigmasterol. Of the isolated compounds, only catechin showed reasonable inhibition of α-glucosidase.