Isolation of Lactiplantibacillus sp. from Korean salted and fermented seafoods for effective fermentation of strawberry leaf extract: enhanced anti-inflammatory activity

Berries are rich in bioactive phytochemicals and phenolic compounds. In the present study, strawberry leaves obtained from Nangsan-myeon, Jeollabuk-do, Korea in 2019 were fermented using Lactiplantibacillus plantarum B1-4 and studied for antioxidant and anti-inflammatory properties. Comparative testing of active ingredients in the raw and fermented extract showed an increase in total polyphenol content and total flavonoid content from 92.0 mg GAE/g and 40.4 mg QE/g, respectively, to 116.1 mg GAE/g and 49.5 mg QE/g, respectively, in fermented extracts. Similarly, catechin content in fermented extract was increased by 26.5% and epicatechin content was decreased by 9.3%. Total and reducing sugar contents in the fermented extract were decreased by 58.4% and 50.4%. DPPH radical scavenging activity of the extracts before and after fermentation increased by about 10.7% from 35.6 to 46.3% at 250 µg/mL and ABTS by about 6.0% from 48.6 to 54.6% at 500 µg/mL. Cytotoxicity assay confirmed that fermented extract caused no harm to chromatid structure of RAW 264.7 cells up to 500 µg/mL concentration. Fermented extracts (400 µg/mL) reduced nitric oxide production (9.7%) and the levels of TNF-α (18.1%) and IL-6 (11.8%), making them ideal for integration into skin care products. The significant functional groups present in raw and fermented extracts were identified using FTIR. Thus, this study adds to the notion of using fermented extracts in functional foods due to their anti-inflammatory properties.