New pyran derivative with antioxidant and anticancer properties isolated from the probiotic Lactobacillus plantarum H24 strain.

This work was aimed to prepare, isolate and identify antioxidant and cytotoxic compound from the culture filtrate of a probiotic lactobacillus strain. New compound, plantarone (1), together with two known compounds, kojic acid (2) and methyl dodecanoate (3), were isolated from the ethyl acetate extract of the culture filtrate of probiotic Lactobacillus plantarum H24. Their structures were elucidated using spectroscopic methods including 2 D NMR, HRMS analyses. Isolated compounds were screened for antioxidant and cytotoxic activities against Caco-2 colon cancer cells. Compounds 1 and 2 showed lowers DPPH radical scavenging activities (p < 0.05) with IC50 values of 66.3 ± 0.34 µM and 50.2 ± 0.28 µM respectively, compared to standard butylated hydroxyanisole (BHA: IC50 = 44.2 ± 0.24 µM). Whereas only compound 1 showed a good cytotoxicity activity with inhibition value of 60.72 ± 3.55%. Accordingly, L. plantarum H24 could be used to prevent oxidative stress and its injuries, improving human health.

Viability and Stress Response of Putative Probiotic Lactobacillus plantarum Strains in Honey Environment.

Due to problem of preservation of dairy products which serve as a matrix for probiotics, it is challenging to use these probiotics as food supplements in many developing countries. To determine the suitability of the Lactobacillus strains for exploitation as probiotics in honey, we investigated the effect of their storage on the viability, functionality, and the mechanism associated with their protective effect. Three isolates obtained from our laboratory collection were identified through amplification of the 16S rRNA gene. The viability of the strains in honey at different storage conditions was studied. Three genes (hdc, gtf, and clpL) responsible for the resistance of bacteria in acidic environments were screened. SDS-PAGE analysis of total protein was performed to observe protein profile changes of the strains after exposure to honey. All the three isolates, namely, GGU, GLA51, and GLP56, were identified as Lactobacillus plantarum strains. After 28 days of storage in honey at 4 °C, viable cell concentrations of the three strains were higher than 2.04 × 106 CFU/ml. During the same period at room temperature, only the Lactobacillus plantarum GLP56 strain remained viable with a cell concentration of 1.86 × 104 CFU/ml. The clpL gene coding for ATPase was detected in all the three strains. The protein of molecular weight ~ 50 kDa was absent in the protein profile of Lactobacillus plantarum GGU after 60 days of storage in honey at 4 °C. The Lactobacillus plantarum GLP56, Lactobacillus plantarum GLA51, and Lactobacillus plantarum GGU strains exposed to honey can withstand acidic environmental stress but their viability declines over time.