Pharmacokinetics and Metabolism Study of Deep-Sea-Derived Butyrolactone I in Rats by UHPLC–MS/MS and UHPLC–Q-TOF-MS

Butyrolactone I (BTL-I) is a butanolide isolated from the deep-sea-derived fungus, Aspergillus sp. It provides a potential new target for the prevention and treatment of food allergies. This study aimed to investigate the metabolic and pharmacokinetic profile of BTL-I in rats. The metabolic profiles were obtained by UHPLC–Q-TOF-MS. As a result, eleven metabolites were structurally identified, and the proposed metabolic pathways of BTL-I were characterized. The main metabolites were the oxidative and glucuronidative metabolites. In addition, a sensitive UHPLC–MS/MS method was established for the quantitation of BTL-I in rat plasma (LOQ = 2 ng/mL). The method was fully validated and successfully applied to the pharmacokinetic study of BTL-I in rats after oral administration or intravenous administration. The oral bioavailability was calculated as 6.29%, and the maximum plasma concentrations were 9.85 ± 1.54 ng/mL and 17.97 ± 1.36 ng/mL for intravenous and intragastric dosing groups, respectively.

Urea Utilization by Cattle as Influenced by Casein

THE influence of casein on urea-nitrogen utilization by cattle was investigated in two studies. In a fattening study, the inclusion of casein to a soybean meal (SBM) or urea-supplemented ration depressed both average daily gain (ADG) and average daily feed intake (P<.05}. Casein addition, on the other hand, significantly (P <.05 increased rumen :ammonia concentration. The second and metabolism study involved the use of identical rations as in the fattening study. Cattle fed rations with casein did not show any significant decrease in nitrogen retention as compared to cattle fed rations without casein. However, there was a non-significant drop in nitrogen retention, and an increase in urinary nitrogen excretion attributable to casein. Ruminal histamine observed for steers on the fattening study was higher than that noted for steers on the metabolism study. Part of the poor performance of steers on the casein diets could be attributed to the higher urinary nitrogen excreted and the elevated ruminal histamine levels observed.