Among the microorganisms employed in the study, Aspergillus niger (GUFCC5443), Escherichia coli (ATCC9637), Streptomyces halstedii (CKM-2), Pseudomonas putida (NCIB9494), Cunninghamella elegans (NCIM689) and Sphingomonas paucimobilis (NCTC11030) were capable for the enantioselective conversion of racemic Carvedilol. Immobilization technique enhanced the enantioselectivity of microorganisms and thus increased the enantiomeric purity of the drug. Excellent enantiomeric ratios (E) were found in reactions catalyzed by immobilized A. niger and E. coli with values 174.44 and 104.26, respectively. Triacylglycerol lipase from Aspergillus niger was also employed in this study as a biocatalyst which resulted in the product with 83.35% enantiomeric excess (ee) and E of 11.34 while the enzyme on immobilization has yielded 99.08% ee and 216.39 E. The conversion yield (C%) of the drug by free-enzyme was 57.42%, which was enhanced by immobilization to 90.51%. Hence, our results suggest that immobilized triacylglycerol lipase from A. niger (Lipase AP6) could be an efficient biocatalyst for the enantioselective resolution of racemic Carvedilol to (S)-(−)-Carvedilol with high enantiomeric purity followed by immobilized cultures of A. niger and E. coli.

Isradipine (ID), is an antihypertensive drug, having low oral bioavailability (15-24%) due to poor aqueous solubility (0.01 mg/mL) and also hepatic first-pass metabolism. Among various approaches, Solid lipid nanoparticles (SLNs) were developed using stearic acid, glyceryl monostearate as lipid matrices for improving the oral bioavailability of ID. ID-SLNs were prepared by using hot homogenization followed by ultrasonication. The prepared SLNs were characterized for size, PDI, zeta potential (ZP), entrapment efficiency (EE) and drug content. release studies were performed in 0.1NHCl and pH 6.8 phosphate buffer of by open tube method. Physical stability of the SLNs was observed at refrigerated temperature and room temperature for 90 days. Further, pharmacodynamic study was conducted in wistar rats. SLNs prepared with GMS having size of 188.6±3.6 nm, PDI of 0.273±0.052, ZP of - 21.8±2.7 mV with 86.86±0.75% EE were optimized. Differential scanning calorimetric (DSC) study revealed that no interaction between drug and lipid. release studies showed that more cumulative release of ID in pH 6.8 phosphate buffer than in 0.1NHCl during 24 h. The lyophilized SLN formulation was used in knowing morphology of SLNs, and was found to have spherical shape with increased polydispersity by Scanning electron microscopy. Pharmacodynamic study of SLNs in fructose induced hypertensive rats showed a decrease in systolic blood pressure for 36 h, when compared to suspension, which showed a decrease in systolic blood pressure for only 2 h. Thus, the results conclusively demonstrated the role of SLNs for a significant enhancement in pharmacodynamic effect of ID.

Aldose reductase is the first enzyme in the polyol pathway and catalyzes the reduction of glucose to sorbitol by coupling with the oxidation of NADPH to NADP(+) . This sorbitol accumulation leads to various diabetic complications, including neuropathy, nephropathy, cataracts, and retinopathy. In the present study, aldose reductase inhibitory (ARI) activity of the methanolic as well as standardized extracts of Andrographis paniculata (Burm. f.) Wall. ex Nees (Acanthaceae) and its chief constituent, andrographolide, were studied using in vitro and in vivo methods. In the in vitro method, rat lens as well as kidney homogenates were used for the preparation of enzyme, whereas the effect of these test samples on the galactitol level in the eye lens was studied in a galactosemic rat model in vivo. The results of the study revealed that both extracts of the plant and its major compound, andrographolide, possess ARI activity in vitro. They were also found to significantly decrease galactitol accumulation in vivo.

A simple chiral HPLC method was developed and validated for quantification of S(-)-Carvedilol in Active Pharmaceutical Ingredient (API) and marketed tablet formulation of racemic Carvedilol. Chiral resolution of enantiomers of Carvedilol was achieved on Phenomenex Lux-cellulose-4 (250 mm × 4.6 mm; 5 µ particle size) chiral column by using a mobile phase, Isopropanol and n-Heptane (60:40 v/v), at a flow rate of 1.0 ml/min and by employing UV detection at 254 nm wavelength. The method was validated according to the ICH guidelines and was proved to be specific, linear, precise and accurate for the analysis of S(-)-Carvedilol.

Most pharmaceutical compounds have asymmetric nature and are optically active. Compounds with one asymmetric centre (chiral centre) would exhibit two enantiomeric forms and among them one is pharmacologically active (eutomer) while the other one contributed side effects or toxic effects or totally inert (distomer) [1] . Hence, current interest is towards development and administration of eutomer instead of its racemic mixture to improve therapeutic efficacy and reduce the unwanted effects due to the distomer [2] . Biocatalysts have excellent selectivity under mild reaction conditions [2] and hence in this study various whole-cell microorganisms like Bacillus subtilis [3] , Escherichia coli [4] , Pseudomonas putida [5] , Sphingomonas paucimobilis [6] , Rhodococcus erythropolis [7] , Streptomyces halstedii [8] , Aspergillus niger [9] , Candida parapsilosis [10] , Geotrichum candida [11] , Rhizopus oryzae [12] , Cunninghamella elegans [13] and Cunninghamella blakesleeana [14] were employed as biocatalysts for the stereo inversion of racemic sotalol to its active enantiomer. However, a limitation for using whole-cell microorganisms as biocatalysts is reduced stereo selectivity due to competition between multiple enzymes of the microorganism for the same substrate [15] . The use of isolated pure enzymes with suitable cofactors as biocatalysts would help overcome this limitation of using whole-cell microorganisms [16] and the reactions catalysed by pure enzymes also serves some other advantages like they are highly selective under mild conditions, more catalytic in nature and environmentally benign [2] . Lipases have great versatility in catalysing different reactions like aminolysis, esterification, transesterification and interesterification. The means followed by lipases to catalyse these reactions can be described as a ping-pong bi-bi mechanism. Accordingly, first step involves nucleophilic attack on the carbonyl group of a drug, which results in acyl-