Anti-cariogenic Characteristics of Rubusoside.

Streptococcus mutans plays an important role in the development of dental caries in humans by synthesizing adhesive insoluble glucans from sucrose by mutansucrase activity. To explore the anti-cariogenic characteristics of rubusoside (Ru), a natural sweetener component in Rubus suavissimus S. Lee (Rosaceae), we investigated the inhibitory effect of Ru against the activity of mutansucrase and the growth of Streptococcus mutans. Ru (50 mM) showed 97% inhibitory activity against 0.1 U/mL mutansucrase of S. mutans with 500 mM sucrose. It showed competitive inhibition with a K i value of 1.1 ± 0.2 mM and IC50 of 2.3 mM. Its inhibition activity was due to hydrophobic and hydrogen bonding interactions based on molecular docking analysis. Ru inhibited the growth of S. mutans as a bacteriostatic agent, with MIC and MBC values of 6 mM and 8 mM, respectively. In addition, Ru showed synergistic anti-bacterial activity when it was combined with curcumin. Therefore, Ru is a natural anti-cariogenic agent with anti-mutansucrase activity and antimicrobial activity against S. mutans. ELECTRONIC SUPPLEMENTARY MATERIAL ESM: The online version of this article (doi: 10.1007/s12257-018-0408-0) contains supplementary material, which is available to authorized users.

The use of fermented buckwheat to produce L-carnitine enriched oyster mushroom.

L-Carnitine is an essential compound that shuttles long chain fatty acids into mitochondria. The objective of this study was to produce L-carnitine enriched oyster mushroom (Pleurotus ostreatus) using common buckwheat fermented by Rhizopus oligosporus. Mushroom grown on common buckwheat medium contained 9.9-23.9% higher L-carnitine (186.3 mg/kg) than those grown on basal medium without any buckwheat addition. Those grown on fermented common buckwheat medium contained the highest L-carnitine content (201.2 mg/kg). Size index and lightness of mushroom pileus (L*) were also the highest (100.7 and 50.6, respectively) for those grown in medium added with fermented common buckwheat (20%, w/w). Antioxidant activities of both mushroom extracts (1.5 mg/mL) showed the same level as 38.7% for mushroom grown in media added with common buckwheat or fermented common buckwheat. At the treatment concentration of 300 µg/mL, viabilities of murine macrophage cell line Raw 264.7 cells treated with ethanol extract of oyster mushroom grown on buckwheat medium ranged from 58.9 to 67.8%. The oyster mushroom grown on buckwheat and fermented buckwheat medium can be used as one of the substitutes for meat based diets.