Suppressive components in rice husk against mutagens-induced SOS response usingSalmonella typhimuriumTA1535/pSK1002umutest

Abstract

The EtOAc extract from rice (Oriza sativa cv. Hinohikari) husk showed a suppressive effect on umu gene expression of the SOS response in Salmonella typhimurium TA1535/pSK1002 against the mutagen, Trp-P-1, which requires liver metabolizing enzyme. To obtain the suppressive compound, the EtOAc extract was fractionated by SiO(2) column chromatography using umu test as a bioassay guide. Suppressive compound was isolated and identified as momilactone A (1) by EIMS, IR, (1)H- and (13)C-NMR spectroscopy. Compound 1 inhibited of the SOS-inducing activity of Trp-P-1 in the umu test. Gene expression was suppressed by 32.6% at less than 0.60 mM. Compound 1 was assayed with activated Trp-P-1. The suppressive effect of Compound 1 was decreased compared with that of Trp-P-1. Furthermore, 1 was assayed with another mutagens, such as MeIQ, activated MeIQ, furylfuramide (AF-2), MNNG, and UV-irradiation. Compound 1 showed greater suppressive effect on AF-2-inducing SOS response than other mutagens.

Ameliorative Capacity of Rice Husk Extract on Codeine-induced Testicular Dysfunction in Male Wistar Albino Rats

“…According to Mckim [24], a methanol extract of japonica rice husk ( MEJRH) inhibited human colon cancer cell proliferation in dimethylhydrazine-induced rats. Okuno and Miyazawa [25] reported that momilactone-A from an ethyl acetate extract of rice husk ( AERH) suppressed the SOS-inducing activity of Trp-P-1 in the Salmonella antimicrobial usage ( Amu) test. A dichloromethane extract of purple rice husk strongly inhibited aflatoxin B1 ( AFB1) and MeIQ-( amino-imidazo-quinolines denoted IQ compounds), induced mutagenesis in the Ames test and decreased the number of micronuclei in the liver of diethylnitrosamine-induced rats [20].…”