抄録
Objective: Glycation is a non-enzymatic reaction in which reducing sugars and derived aldehydes bind to amino groups of proteins, leading to the formation of advanced glycation end products (AGEs). AGEs accumulate in tissues with aging, causing inflammation, discoloration, and functional deterioration, and are associated with the onset and progression of lifestyle-related diseases. This study investigated the glycative stress-alleviating effects of black soybeans.
Methods: Seven commercially available black soybean varieties, one yellow soybean variety, 12 isoflavones, and cyanidin-3-glucoside (C3G) were used. Beans were hot-water-extracted at 80°C for 1 hour as whole-bean samples or separated into seed coats and cotyledons prior to extraction. Glycation inhibitory effects were evaluated using a human serum albumin (HSA)–glucose glycation model by measuring suppression of fluorescent AGE formation. Antioxidant activity was assessed by the DPPH method. Isoflavone and C3G contents were quantified by reversed-phase HPLC. In addition, α-glucosidase inhibitory activity and the effect of black bean intake on postprandial blood glucose levels were examined.
Results: All soybean extracts inhibited fluorescent AGE formation, with black soybeans showing stronger effects than yellow soybeans. Among black soybeans, Kurosengoku exhibited the highest inhibition rate (85.3 ± 2.5%). Seed coat extracts showed significantly stronger anti-glycation activity than cotyledon extracts, with inhibition rates of up to 99.7 ± 0.28%. All black soybean varieties demonstrated antioxidant activity, with a maximum of 286.1 µmol Trolox equivalents /L (7.5 mg/mL solids). Isoflavones were more abundant in seed coats than cotyledons, while C3G was detected only in seed coats.
Conclusion: Black soybeans exhibit both anti-glycation and antioxidant properties, suggesting their potential as a dietary strategy to alleviate glycative stress.
