Goniothalamus macrocalyx leaf extracts: A study on phenolics, antioxidant activity, and antidiabetic potential

Abstract

Goniothalamus macrocalyx Bân is an endemic plant species of Vietnam with limited data regarding its phenolic composition and potential health-promoting properties. This study evaluated the phenolic content, antioxidant capacity, and antidiabetic potential (via inhibition of α-amylase and α-glucosidase) of leaf extracts. HPLC-DAD analysis identified eight phenolic compounds, with catechins being the most abundant. The ethanol extract yielded the highest total phenolic content (59.79 ± 1.40 mg GAE/g) and demonstrated the strongest antioxidant activity in both DPPH (IC₅₀ = 0.78 ± 0.08 mg/mL) and ABTS (IC₅₀ = 0.81 ± 0.06 mg/mL) assays. Notably, it also exhibited strong α-glucosidase inhibitory activity (IC₅₀ = 32.75 ± 1.24 μg/mL), outperforming acarbose. While all extracts showed relatively weak α-amylase inhibition compared to acarbose, the acetone extract was the most effective (IC₅₀ = 449.33 ± 12.66 μg/mL). These findings highlight the bioactive potential of G. macrocalyx leaf extracts, particularly as a source of natural α-glucosidase inhibitors.

KEY WORDS: Catechin, Liquid chromatography, Antioxidant, α-Glucosidase inhibition

Bull. Chem. Soc. Ethiop. 2026, 40(11), 2361-2370

DOI: https://dx.doi.org/10.4314/bcse.v40i11.6