Abstract
Previously, five strains of Lactiplantibacillus plantarum (L. plantarum) isolated from various algerian fruits: white mulberries (Morus alba L.), prickly pears (Opuntia ficus-indica), dates (Phoenix dactylifera L.) and figs (Ficus carica) have been shown to possess probiotic potential. In this study, we demonstrate their capacity to produce exopolysaccharides (EPS). Initially, physicochemical properties (moisture, ash, fat, carbohydrate and protein) of EPS were determined. Then, monosaccharide composition of this EPS was determined by Thin-Layer Chromatography (TLC) and High-Performance Liquid Chromatography (HPLC). Results showed that the EPS was a polymer of glucose. Characterization of the structure and functional groups of the EPS was conducted via Fourier Transform Infrared Spectroscopy (FT-IR). Results revealed the presence of characteristic absorption peaks of most of the polysaccharides. The UV-absorption also showed a lack of any absorption in the range of 250 and 280 nm. The antioxidant activities were also studied. The 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity of EPS was found to be 87.285 ± 2.815% at 10 mg/ml for EPS-FB23. While the maximum scavenging percentage of EPS-F8 was about 77.43 ± 2.07% at 10 mg/ml for the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS). For the reducing power analysis, EPS-F8 reached a maximum absorbance of 0.903 ± 0.074 at 20 mg/ml. Our findings proved that EPS from L. plantarum F8 and L. plantarum FB23 strains exhibit strong antioxidant activities, suggesting their potential use as natural antioxidants in health-promoting applications. The entire methodology is summarized in a graphical abstract.