Evaluation of Corn Cob (Zea mays L.) Extract and Fractions as Inhibitors of α- and β-Glucosidase

Abstract

Corn cob (Zea mays L.), a common agricultural waste, may act as a natural inhibitor of the α/β-glucosidase enzymes, which are crucial for blood glucose regulation and carbohydrate metabolism. This potential arises from secondary metabolites in corn cob, including phenolics, flavonoids, polysaccharides, and steroids, which have been reported to exhibit α/β-glucosidase inhibitory activity. Despite its abundance, corn cob has been largely underexplored as a source of dual α-/β-glucosidase inhibitors, particularly through fraction-based bioactivity profiling. This study aims to assess the potential of the methanol extract and fractions (n-hexane, ethyl acetate, and butanol) of corn cob as α- and β-glucosidase inhibitors. The methodology includes drying and grinding corn cob, followed by maceration and fractionation. The inhibitory activities of the extract and fractions against α- and β-glucosidase were evaluated in vitro using spectrophotometry with a microplate reader and thin-layer chromatography (TLC) bioautography. Furthermore, the secondary metabolite content of the bioactive fraction was determined via liquid chromatography-tandem mass spectrometry (LC-MS/MS). The corn cob extract and fractions exhibited inhibitory activity against α- and β-glucosidase, with the n-hexane fraction showing the lowest observed IC₅₀ values (IC₅₀=22.11±1.07 µg/mL for α-glucosidase and IC₅₀=77.28±0.29 µg/mL for β-glucosidase). LC-MS/MS profiling of the n-hexane fraction led to the detection of 21 compounds; of these, 10 were putatively identified as fatty acids, steroids, terpenoids, and flavonoids, which act as active inhibitors of α- and β-glucosidase. These findings highlight the novel potential of corn cob waste as a dual enzyme inhibitor and a promising natural therapeutic candidate for managing diabetes and hyperglycemia.