Extraction, Purification and Characterization of Exopolysaccharide from Lactiplantibacillus plantarum B7 with Potential Antioxidant, Antitumor and Anti-Inflammatory Activities

In recent years, exopolysaccharides (EPSs) have emerged as significant substances due to their impressive biological properties. This research intends to analyze the EPS extracted from probiotic bacteria and assess its various biological activities. The promising probiotic bacteria isolated from human breast milk was isolated and identified as Lactiplantibacillus plantarum B7 by 16S rRNA sequencing. The EPS yield of this strain was quantified as 5.2 g/L. The crude extract (EPSc) was subjected to purification by chromatography on DEAE-cellulose and Sephadex G-100 columns, giving two main fractions named EPSF1 and EPSF2. Structural features were investigated by HPLC, FTIR, GPC and 1HNMR. Chromatographic analysis indicated that EPSF1 and EPSF2 were composed of mannuronic acid, mannose and glucose in a molar ratio of 2.6:2.15:1.00 and 3.92:2.65:1.00 with a molecular weight of 4.36 x 104 and 5.27 x 105, respectively. Multiple in vitro assays of EPSc, EPSF1 and EPSF2 showed potent radical scavenging activity on DPPH, ABTS, hydroxyl radical scavenging activity (HRS) and superoxide scavenging activity. Also, they showed reducing power of 0.69, 0.61 and 0.58, respectively, at 1000 mu g/mL. EPSc, EPSF1 and EPSF2 displayed negligible toxicity against WI-38 human normal lung cells but had cytotoxic effects against human colon cancer (Caco-2), (IC50 = 122.13 +/- 0.01, 72.5 +/- 0.12 and 81.6 +/- 0.1 mu g/mL), HepG2 liver cancer (IC50 = 112.5 +/- 0.01, 60.3 +/- 0.1 and 62.0 +/- 0.03 mu g/mL) and human prostate cancer (PC3) (IC50 = 109.6 +/- 0.03, 65.7 +/- 0.01 and 70.3 +/- 0.04 mu g/mL). While anti-inflammatory as hemolysis inhibition was 79.3 +/- 0.05, 93.5 +/- 0.05 and 87.9 0.03% at 500 mu g/mL, respectively. The results indicate that EPSF1 showed promising antioxidant, antitumor and anti-inflammatory activities.