Direct biological fixation provides a freshwater sink for NO.

Nitrous oxide (NO) is a potent climate gas, with its strong warming potential and ozone-depleting properties both focusing research on NO sources. Although a sink for NO through biological fixation has been observed in the Pacific, the regulation of NO-fixation compared to canonical N-fixation is unknown. Here we show that both NO and N can be fixed by freshwater communities but with distinct seasonalities and temperature dependencies.

Isolation, characterization, and xanthine oxidase inhibitory activities of flavonoids from the leaves of .

Phytochemical investigation of the water extract from the leaves of (Lamiaceae) led to the isolation of a new flavanone, a new chalcone, and a new aurone, namely, (2)-5,7-dimethoxy-8,4'-dihydroxyflavanone (), 2',4'-dimethoxy-4,5',6'-trihydroxychalcone (), and ()-4,6-dimethoxy-7,4'-dihydroxyaurone (), respectively. The structures were unambiguously elucidated on the basis of spectroscopic data. And the absolute configuration of was determined by analysis of electronic circular dichroism spectrum.

Capsaicinoids from hot pepper ( L.) and their phytotoxic effect on seedling growth of lettuce ( L.).

One new capsaicinoid, -vanillyl-4,6-dien-8-methylnonanamide (), along with nine known capsaicinoids, capsaicin (), dihydrocapsaicin (), -vanillyloctanamide (), nordihydrocapsaicin (), -vanillyldecanamide (), homocapsaicin (), -vanillyl-4,8-dimethylnonanamide (), homodihydrocapsaicin II (), and homodihydrocapsaicin I () were isolated from the fruits of using semi-preparative high-performance liquid chromatography. The structural characterizations of the isolated compounds were elucidated by spectroscopic data and comparison with the literatures. Bioassays showed that the isolated capsaicinoids significantly reduced the radical length of seedling, this inhibition being dose-dependent.

Isolation of Tricin as a Xanthine Oxidase Inhibitor from Sweet White Clover () and Its Distribution in Selected Gramineae Species.

Xanthine oxidase, an enzyme present in significant levels in the intestine and liver, metabolizes hypoxanthine to xanthine and xanthine to uric acid in the purine catabolic pathway. An inhibitory compound acting against xanthine oxidase was isolated from sweet white clover () by bioassay and high-performance liquid chromatography guided separation. It was identified as tricin by spectroscopic analysis.