Preparation, identification and α-glucosidase inhibitory activity of a high-methoxyl HG-type pectin from Liangping pomelo (Citrus maxima cv. Liangpin Yu) peel.

Abstract

The peel from Liangping pomelo (Citrus maxima cv. Liangpin Yu) is generally discarded as waste during post-harvest handling and process, resulting in environmental pollution and waste. Pectin is the major component in pomelo peels and yields significant economic advantages. Thus, developing pomelo peel pectin (PPs) might be a feasible strategy to reduce environmental pollution caused by pomelo peel. The optimized PPs yield was 156.5 ± 2.5 g kg-1 under the inoculum size of 100 mg g-1, liquid-solid ratio of 31 mL g-1, fermentation time of 64 h, and fermentation temperature of 39 °C. PPs-6Aa, a pectin fraction from PPs purified with DEAE-52 cellulose, Sephadex G-100 and Sephadex G-75 column chromatography, showed higher α-glucosidase inhibitory activity, with an IC50 of 0.12 ± 0.03 mg mL-1. It was a high-methoxyl HG-type pectin of 42.8 kDa, and its repeat unit was →4)-α-GalpA-6-OMe-(1→4)-α-GalpA-6-OMe-(1→. Additionally, its α-glucosidase inhibitory activity might be related to hydrogen bonds formed with Lys-156, Glu-277, His-280, Asp-307, Arg-315, Asn-350, Asp-352 and Glu-411, and to hydrophobic interactions formed with Ser-157, Tyr-158, Asp-233, Gln-239, Ser-240, Phe-303, Thr-306, Leu-313, Phe-314, Gln-353 and Arg-442. These findings provide structural and bioactivity information on pectin from Liangping pomelo peel, which could be beneficial for the development of functional foods and pharmaceuticals. © 2024 Society of Chemical Industry.