Characterisation of Bioactive Compounds and Antidiabetic Properties of Extracts from Bitter Leaf (Vernonia amygdalina) Consumed in Cross River State

Vernonia amygdalina, commonly known as bitter leaf, is widely consumed as a food ingredient and traditional medicine across South South Nigeria, including Cross River State. Emerging evidence suggests it possesses bioactive compounds with antidiabetic potential, yet systematic characterisation of these compounds in samples from Cross River State has not been reported. This study characterised the bioactive compounds and evaluated the antidiabetic properties of aqueous and ethanolic leaf extracts of Vernonia amygdalina obtained from three agroecological zones of Cross River State. Phytochemical screening, high performance liquid chromatography-diode array detection analysis for phenolic profiling, and quantification of total alkaloids, flavonoids, saponins, and terpenoids were performed. Antidiabetic potential was assessed by alpha-amylase and alpha-glucosidase inhibitory activity assays in vitro, with acarbose as reference standard. Results identified luteolin, quercetin, kaempferol, and chlorogenic acid as major phenolic compounds. Ethanolic extracts demonstrated significantly higher total phenolic content (184.2 mg GAE per gram) and flavonoid content compared to aqueous extracts. Alpha-glucosidase inhibitory activity IC50 was 0.38 mg per ml for ethanolic extract, compared to 0.22 mg per ml for acarbose, indicating significant inhibitory potency. Saponin fractions also contributed to enzyme inhibitory activity. The study provides phytochemical evidence supporting the antidiabetic properties of Vernonia amygdalina and recommends further in vivo validation studies. Keywords: Vernonia amygdalina, bioactive compounds, antidiabetic, alpha-glucosidase, Cross River.