ß-Carboline-Based pH Fluorescent Probe and Its Application for Monitoring Enzymatic Ester Hydrolysis.

A novel pH-activatable fluorescent probe, 1-(propan-2-yl)-9H-pyrido[3,4-b]indole-3-carboxylic acid (L-1), based on ß-carboline derivatives, has been developed, which displays significant fluorescent response toward pH variation with high selectivity, good photo-stability and favorable pKa value. Moreover, L-1 can dynamically monitor the release of protons during ester hydrolysis reaction in consistent with enzymatic kinetics manner.

Trichothecrotocins D-L, Antifungal Agents from a Potato-Associated Trichothecium crotocinigenum.

Seven new merosesquiterpenoids, trichothecrotocins D-J (1-7), two new trichothecene sesquiterpenoids, trichothecrotocins K (12) and L (13), and six known compounds (8-11, 14, and 15), were isolated from a potato-associated fungus, Trichothecium crotocinigenum. Compounds 5 and 6 were racemates which were further separated as pure enantiomers. Structures together with absolute configurations were established by extensive spectroscopic analysis, as well as quantum chemistry calculations on ECD and optical rotations. Compounds 1-4 are rare meroterpenoids featuring a seco-phenyl group, while 1 and 2 possessed a novel 6-6/5 fused ring system. Compounds 1-4, 8, 11, and 12 showed antifungal activity against four plant pathogens with MIC values of 8-128 µg/mL. It is suggested that the meroterpenoids produced by T. crotocinigenum may play an important role in the antifungal property of the fungus, thereby protecting the host plant, i.e., potato.

Associative effects of supplementing rice straw-based diet with cornstarch on intake, digestion, rumen microbes and growth performance of Huzhou lambs.

Thirty-six male Hu lambs consuming a rice straw-based diet were used in a 60-day trial to study the associative effects of cornstarch supplementation on intake, digestion, ruminal microbial population and growth performance. All animals were fed rice straw ad libitum together with 160 g/day of rapeseed meal and supplemented with cornstarch at levels of 0 (control), 60, 120 or 180 g/day, respectively. Increment of supplementary cornstarch showed little influence on rice straw intake. Optimal growth performance and highest apparent digestibility of organic matter was achieved in the 120 g/day cornstarch group (P < 0.05), while the digestibilities of neutral detergent fiber and crude protein were significantly decreased by 180 g/day cornstarch (P < 0.05). Similar results were observed for carboxymethyl cellulose activity and relative populations of cellulolytic bacteria (Ruminococcus albus, Ruminococcus flavefaciens and Fibrobacter succinogene). Blood urea nitrogen was reduced by supplementary cornstarch, indicating enhanced protein utilization efficiency. Carcass traits were all significantly improved by supplementary cornstarch. These results suggested that proper amounts of starch supplementation (within 0.5% BW) has little adverse effect on forage utilization, but could effectively improve growth performance. High levels of cornstarch, however, would decrease cellulase activity and populations of cellulolytic bacteria, and hence the digestibility of forage.