Isolation and characterization of the acid and base degradation products of andrographolide.

Andrographolide was subjected to degradation under acidic and basic conditions. Three degradation products including two novel compounds, 8,9-didehydroandrographolide (AG-A) and 15-seco-andrographolide (AG-B2), and a known product, 14-deoxy-11,12-didehydroandrographolide (AG-B1), were isolated by chromatography and identified on the basis of their NMR and MS data. The degradation product, AG-A, may result from the isomerization of andrographolide under acidic conditions whereas the base degradation products, AG-B1 and AG-B2, were formed most likely due to the dehydration of allyl alcohol and the hydrolysis of andrographolide at the lactone ring, respectively.

Effects of Curcuma spp. on P-glycoprotein function.

The effects of Curcuma longa (khamin chan) and Curcuma sp. "khamin-oi" (khamin-oi), as well as isolated major curcuminoids on intestinal P-gp functions were evaluated in vitro. The accumulation of R123 in Caco-2 cells was increased and the R123 efflux ratios were significantly decreased by both Curcuma longa and Curcuma sp.

Weed growth inhibitors from Aspergillus fischeri TISTR 3272.

Chloroform and ethyl acetate extracts of Aspergillus fischeri TISTR 3272 showed good growth inhibitory activity on Mimosa pigra and Echinochloa crus-galli. Bioassay-directed fractionation of the active extracts led to the isolation of five known compounds, (+)-terrein (1), (-)-6-hydroxymellein (2), two diketopiperazines (cyclo-(S-Pro-S-Leu) (3) and cyclo-(S-Pro-S-Val) (4)) and butyrolactone I (5). Compounds 2-5 were reported for the first time in this fungus.

Mucosal uptake of gabapentin (neurontin) vs. pregabalin in the small intestine.

Purpose: To compare the mucosal membrane transport of gabapentin and pregabalin in animal small intestine.

Methods: Uptake of the two drugs by brush-border membrane vesicles (BBMV) from rat and rabbit small intestine was studied as a function of temperature, uptake-medium sodium content, and intestinal region. Amino acid inhibition studies were conducted with pregabalin.

Cimetidine absorption and elimination in rat small intestine.

The purpose of this study was to determine the characteristics of intestinal absorption and metabolism of cimetidine. The initial finding of the appearance of cimetidine sulfoxide in rat and human jejunum from cimetidine perfusions had prompted an isolation of mucosal membrane transport and enterocyte metabolism contributions in earlier membrane vesicle and microsomal studies, respectively. In this report, perfusion studies in rat small intestine detail regional differences in intestinal elimination.