Spectroscopic studies on a withanolide from Withania coagulans

The structure of a new withanolide was elucidated as 3β,14α,2Oα_F,27-tetrahydroxy-1-oxo-20R,22R-witha-5,24-dienolide using chemical and spectroscopic methods. The structure was corroborated by comparative studies with known closely related withanolides. Sitosterol-β-d-glucoside was identified through chemical and spectroscopic means.     

Aerobic degradation of highly chlorinated polychlorobiphenyls by a marine bacterium, Pseudomonas CH07

Hitherto, aerobic degradation of polychlorinated biphenyls (PCBs) has been reported to be limited to the less chlorinated biphenyls. We report here a marine mercury-resistant bacterium, Pseudomonas CH07 (NRRL B-30604) which was capable of degrading a variety of highly chlorinated congeners of PCBs from the technical mixture Clophen A-50. Of the two most toxic coplanar PCBs present in Clophen A-50, one coplanar pentachloro congener CB-126 and one toxic sterically hindered heptachloro congener CB-181 were found to be degraded completely and the other coplanar tetrachloro congener CB-77 was degraded by more than 40% within 40 h by this microorganism. The apparent absence of bphC in this bacterium leads to the proposal of a different mechanism for degradation of PCBs.     

Influence of hydrophilic polymers on celecoxib complexation with hydroxypropyl β-cyclodextrin

Complexation of celecoxib with hydroxypropyl β-cyclodextrin (HPβCD) in the presence and absence of 3 hydrophilic polymers—polyvinyl pyrrolidone (PVP), hydroxypropyl methylcellulose (HPMC), and polyethylene glycol (PEG)—was investigated with an objective of evaluating the effect of hydrophilic polymers on the complexation and solubilizing efficiencies of HPβCD and on the dissolution rate of celecoxib from the HPβCD complexes. The phase solubility studies indicated the formation of celecoxib-HPβCD inclusion complexes at a 1∶1M ratio in solution in both the presence and the absence of hydrophilic polymers. The complexes formed were quite stable. Addition of hydrophilic polymers markedly enhanced the complexation and solubilizing efficiencies of HPβCD. Solid inclusion complexes of celecoxib-HPβCD were prepared in 1∶1 and 1∶2 ratios by the kneading method, with and without the addition of hydrophilic polymers. The solubility and dissolution rate of celecoxib were significantly improved by complexation with HPβCD. The celecoxib-HPβCD (1∶2) inclusion complex yielded a 36.57-fold increase in the dissolution rate of celecoxib. The addition of hydrophilic polymers also markedly enhanced the dissolution rate of celecoxib from HPβCD complexes: a 72.60-, 61.25-, and 39.15-fold increase was observed with PVP, HPMC, and PEG, respectively. Differential scanning calorimetry and X-ray diffractometry indicated stronger drug amorphization and entrapment in HPβCD because of the combined action of HPβCD and the hydrophilic polymers. Published: September 29, 2006     

Syntheses of α-tocopheryl glycosides by glucosidases

Enzymatic syntheses of water-soluble alpha-tocopheryl glycosides were carried out in di-isopropyl ether using amyloglucosidase from Rhizopus mold or beta-glucosidase isolated from sweet almond. Optimum conditions for the amyloglucosidase were: alpha-tocopherol 0.5 mmol, D-glucose 0.5 mmol, 400 activity unit (AU) amyloglucosidase, 0.2 mM pH 7 phosphate buffer and 72 h; and for the beta-glucosidase: alpha-tocopherol 0.5 mmol, D: -glucose 0.5 mmol, 110 AU beta-glucosidase, 0.1 mM pH 6 phosphate buffer and 72 h. Out of 11 carbohydrates employed, amyloglucosidase reacted only with D-glucose to give 50% of 6-O-(alpha-D-glucopyranosyl)alpha-tocopherol. However, the beta-glucosidase gave 6-O-(beta-D-glucopyranosyl)alpha-tocopherol, 6-O-(alpha-D-galactopyranosyl)alpha-tocopherol, 6-O-(beta-D-galactopyranosyl)alpha-tocopherol, 6-O-(alpha-D-mannopyranosyl)alpha-tocopherol and 6-O-(beta-D-mannopyranosyl)alpha-tocopherol in yields ranging from 10-25%. Water solubility of 6-O-(alpha-D-glucopyranosyl)alpha-tocopherol was 26 g/l at 25 degrees C. alpha-Tocopheryl glycosides showed antioxidant activities with IC(50) values from 0.5 to 1 mM and angiotensin-converting enzyme (ACE) inhibitory activity with IC(50) values from 1.3 to 2.6 mM.     

Long-term variations in abundance and distribution of sewage pollution indicator and human pathogenic bacteria along the central west coast of India

Safe water quality criteria on the load and types of microbial populations are important for human use from fishery, tourism and navigational viewpoints. To understand the variations in sewage pollution indicator and certain human pathogenic bacteria, data collected from various locations along central west coast of India during 2002–2007 were analyzed. Water and sediment samples were examined for total viable counts (TVC), pollution indicator bacteria (total coliforms – TC, fecal coliforms – FC and Escherichia coli – EC) and potential pathogens (Vibrio cholerae – VC, Shigella – SH, and Salmonella spp. – SA). In both Mandovi and Zuari estuaries, where fishing and tourist-related activities are sizable and long-term data collection was regular, we observed high counts of TC, FC, VC, SH and SA in particular during monsoon due to increased land runoff. Further, the abundance of TC and FC has increased significantly over the years in the water column to much above either USEPA or India permissible limits. The concentrations of Vibrio cholerae, and Shigella correlated with those of coliforms. Pathogenic bacteria were detected even 20 km and/or 25 km offshore mainly due to dumping of raw or improperly treated sewage effluents either from land, fishing trawlers and/or ships in the anchorage. Higher concentrations of fecal coliforms and pathogenic bacteria in neretic waters signify threats to environmental and human health.     

Competitive substrate inhibition of amyloglucosidase from Rhizopus sp. by vanillin and curcumin

Kinetic studies of two glucosylation reactions catalyzed by an amyloglucosidase from Rhizopus sp. leading to the synthesis of vanillin-α/β-D-glucoside from D-glucose and vanillin and curcumin-bis-α-D-glucoside from D-glucose and curcumin were investigated in detail. Initial reaction rates were determined from kinetic runs involving different concentrations of D-glucose and vanillin (5?mM to 0.1?M) or D-glucose and curcumin (5?mM to 0.1?M). Graphical double reciprocal plots showed that the kinetics of the two enzyme catalyzed reactions exhibited Ping-Pong Bi-Bi mechanism where competitive substrate inhibition by vanillin/curcumin led to dead-end amyloglucosidase–vanillin/curcumin complexes at higher concentrations of vanillin/curcumin. An attempt to obtain the best fit of this kinetic model through computer simulation yielded in good approximation, the values of four important kinetic parameters, vanillin-α/β-D-glucoside: k_cat=35.0±3.2 10^?5M?h^?1·mg, K_i=10.5±1.1?mM, K_mD-glucose=60.0±6.2?mM, K_mvanillin=50.0±4.8?mM; curcumin-bis-α-D-glucoside: k_cat=6.07±0.58 10^?5M?h^?1·mg, K_i=3.0±0.28?mM, K_mD-glucose=10.0±0.9?mM, K_mcurcumin=4.6±0.5?mM.