Conversion of Flavonols Kaempferol and Quercetin in Mulberry (Morus Alba L.) Leaf Using Plant-Fermenting Lactobacillus Plantarum

The aim of this study was to examine the levels of flavonols in mulberry leaf fermented by Lactobacillus plantarum isolated from a traditional Korean soybean-fermented food. Flavonol kaempferol and quercetin contents were markedly higher in fermentates of mulberry leave (FML) extracts than in unfermented mulberry leave (UFML) extracts (kaempferol and quercetin: 30.43 ± 1.83 mg/100 g and 49.96 ± 2.74 mg/100 g equivalent weight of dry in FML versus 0.54 ± 0.11 mg/100 g and 0.58 ± 0.15 mg/100 g equivalent weight of dry in UFML). In addition, total phenolic and flavonoid contents in FML extract were 1,183.28 ± 2.99 mg/100 g equivalent weight of dry and 425.61 ± 9.73 mg/100 g equivalent weight of dry, respectively, which were considerably higher than those of the control UFML extract. Practical Applications Flavonols kaempferol and quercetin with antioxidant and anti-inflammatory properties have been implicated in the prevention and development of therapies for cancers, cardiovascular disease, neurological and metabolic disorders, and bone diseases and so on. These results suggest that Lactobacillus plantarum isolated from a traditional Korean soybean-fermented food could be used as a starter strain for improvement of biologically beneficial flavonol compounds in plant-derived food materials.