Chemometric evaluation of functional components and anti-quorum sensing activity of mulberry leaves from Indian cultivars: a potential contribution to the food industry.

BACKGROUND: Potential use of many native, easily available vegetal materials for human consumption and value addition is not well recognized. Mulberry, being a traditional industrial crop rich in nutrients and nutraceuticals can be of great importance for the food industry. However, mulberry leaves are mainly being utilized in sericulture and are not exploited for their functional components. Thus, the selection of promising mulberry cultivars, rich in bioactive compounds, like resveratrol and 1-deoxynojirimycin, increase their potential use in functional foods. RESULTS: Chlorogenic acid, myricetin and kaempferol were the major polyphenols present in the nine selected cultivars, in the range 0.001-0.086, 0.003-0.079 and 0.003-0.163 g kg-1 fresh weight (FW), respectively. Protocatechuic acid, epicatechin and rutin were predominantly present in cultivars V-1, G-2 and ML (0.103, 0.080 and 0.121 g kg-1 FW, respectively). Similarly, resveratrol and 1-deoxynojirimycin were highest in cultivars ML and K-2 (0.078 and 0.079 g kg-1 FW, respectively). Leaf extracts of cultivars G-2 and ML were able to effectively inhibit the violacein production with 64.08% and 70.04%, respectively at the concentration of 6 mg mL-1 presumably due to a higher content of polyphenols. Chemometric evaluation of chromatographic data showed the intraspecific variability and secondary metabolite co-existence in different cultivars. CONCLUSIONS: Considering phytoconstituents, cultivars G-2, ML, K-2 and V-1 could contribute efficiently to the rational utilization of mulberry in agro-food industries. Furthermore, cultivars G-2 and ML leaves can be a new source of quorum sensing inhibitory agents. © 2021 Society of Chemical Industry.

Suppression of N-glycan processing enzymes by deoxynojirimycin in tomato (Solanum lycopersicum) fruit.

The present study investigated the potential of a small molecule inhibitor, 1-deoxynojirimycin (DNJ), to extend the shelf life of tomatoes. The optimum concentration of DNJ and the proper ripening stage for treatment were standardized using response surface methodology, following a central composite design. The concentration of DNJ used for the analysis was 0.15 mM, and 0.30 mM and the ripening stages of the tomato fruit analysed were immature green, mature green, breaker, ripen and over-ripen. Analysis of the influence of the DNJ treatment of the fruit using quadratic multiple regression models considering the factors colour, texture, and free sugars revealed significant responses. A DNJ concentration of 0.30 mM and fruit-ripening stage of mature green was found to be optimal for the treatment. DNJ-treatment maintained fruit firmness throughout ripening with a significant reduction in reducing sugar formation. Enzyme activity of the N-glycan processing enzymes involved in cell wall softening, α-mannosidase and ß-d-N-acetylhexosaminidase revealed a significant reduction in their activity by 2 and 3.5-fold, respectively. Down-regulation of expression of important ripening-related and softening process-associated genes, aminocyclopropane carboxylic synthase-4, aminocyclopropane carboxylic oxidase, polygalacturonase and pectin methylesterases at 4, 5, 6 and 5-fold, respectively, was also observed. The present results showed that the treatment of mature green tomato fruit with DNJ at a concentration of 0.30 mM can delay the ripening of the tomato fruit by inhibiting cell wall and N-glycan processing enzymes.