Background Danggui Buxue Tang (DBT), an ancient Chinese herbal decoction containing Astragali Radix and Angelicae Sinensis Radix at a ratio of 5: 1, is prescribed for menopausal women. Flavonoids and its flavonoid glycosides are considered as the major active ingredients within the herbal decoction; however, their amount is not controllable during the preparation. Besides, the aglycons within DBT are believed to have better gut absorption and pharmacological efficacy. Methods The herbal extract of DBT was fermented with Lactobacillus plantarum. The amounts of flavonoid glucosides and its aglycones in the fermented product were analyzed by using UPLC-MS/MS. In addition, in vitro assays were employed to evaluate the efficacy of the fermented DBT in regulating the activities of α-glucosidase, α-amylase and lipase, as well as their antioxidant capacity (DPPH and T-AOC assays) and anti-glycation property (BSA-methylglyoxal, BSA-fructose, and arginine-methylglyoxal models). Results The fermentation of DBT with L. plantarum drove a completed conversion of calycosin-7-O-β-D-glucoside and ononin to calycosin and formononetin, respectively. The chemical transformation could be probably mediated by β-glycosidase within the fermented product. Several in vitro assays corresponding to anti-diabetic functions were compared between parental DBT against its fermented product, which included the activities against α-glucosidase, α-amylase and lipase, as well as anti-oxidation and anti-glycation. The fermented DBT showed increased activities in inhibiting α-glycosidase, suppressing DPPH radical-scavenging and anti-glycation, as compared to the original herbal product. Conclusion These results suggested that DBT being fermented with the probiotic L. plantarum could pave a new direction for fermentation of herbal extract, as to strengthen its pharmacological properties in providing health benefits.

Background Danggui Buxue Tang (DBT), an ancient Chinese herbal decoction containing Astragali Radix and Angelicae Sinensis Radix at a ratio of 5: 1, is prescribed for menopausal women. Flavonoids and its flavonoid glycosides are considered as the major active ingredients within the herbal decoction; however, their amount is not controllable during the preparation. Besides, the aglycons within DBT are believed to have better gut absorption and pharmacological efficacy. Methods In order to enhance the therapeutic efficacy of DBT, the herbal extract was fermented together with Lactobacillus plantarum, a Gram-positive Lactobacillus commonly found in fermented food products. Results The fermentation of DBT with L. plantarum drove a completed conversion of calycosin-7-O-β-D-glucoside and ononin to calycosin and formononetin, respectively, as determined by UPLC-MS/MS analysis. The chemical transformation could be probably mediated by β-glycosidase within the fermented product. Several in vitro assays corresponding to anti-diabetic functions were compared between parental DBT against its fermented product, which included the activities against α-glucosidase, α-amylase and lipase, as well as anti-oxidation (e.g. DPPH radical-scavenging and total antioxidant capacities) and anti-glycation (e.g. BSA-methylglyoxal, BSA-fructose and arginine-methylglyoxal models). The fermented DBT showed increased activities in inhibiting α-glycosidase, suppressing DPPH radical-scavenging and anti-glycation, as compared to the original herbal product. Conclusion The results supported the possible application of L. plantarum or other Lactobacillus in fermenting herbal extract, as such to increase the yield and efficacy of the final products.