Abelmoschus enbeepeegearense sp. nov. (Malvaceae), an endemic species of okra from Western Ghats,India

Abelmoschus enbeepeegearense J. John et al. is a new species occurring at low elevations in the Western Ghats of India, comprising Kerala, Karnataka and Tamil Nadu. The taxon is morphologically allied to A. moschatus subsp. moschatus, A. moschatus subsp. tuberosus and A. crinitus, but easily distinguishable by virtue of its orthotropic branching, 3–5‐angled leaves, glandular hairy plant body with whitish waxy secretions, glandular non‐setose epiclayx segmens which is more than eight in number and ovate hirsute fruits with a short mucro at the apex. It can be crossed with all three taxa with varying degree of success, but the hybrids are sterile. The material belonging to it was earlier identified as and placed under A. moschatus Medik. The taxon is described and illustrated with notes on its phenology, ecology and distribution. In additions, a key to all Abelmoschus taxa occurring in India is provided.     

Purification and characterization of laccase secreted by Phellinus linteus MTCC-1175 and its role in the selective oxidation of aromatic methyl group

A laccase from the culture filtrate of Phellinus linteus MTCC-1175 has been purified to homogeneity. The method involved concentration of the culture filtrate by ammonium sulphate precipitation and an anion exchange chromatography on DEAE-cellulose. The SDS-PAGE and native-PAGE gave single protein band indicating that the enzyme preparation was pure. The molecular mass of the enzyme determined from SDS-PAGE analysis was 70 kDa. Using 2.6-dimethoxyphenol, 2.2′[azino-bis-(3-ethylbonzthiazoline-6-sulphonic acid) diammonium salt] (ABTS) and 4-hydroxy-3,5-dimethoxybenzaldehyde azine as the substrates, the K _m, k _cat and k _cat/K _m values of the laccase were found to be 160 μM, 6.85 s^?1, 4.28 × 10⁴ M^?1 s^?1, 42 μM, 6.85 s^?1, 16.3 × 10⁴ M^?1 s^?1 and 92 μM, 6.85 s^?1, 7.44 × 10⁴ M^?1 s^?1, respectively. The pH and the temperature optima of the P. linteus MTCC-1175 laccase were 5.0 and 45°C, respectively. The activation energy for thermal denaturation of the enzyme was 38.20 kJ/mole/K. The enzyme was the most stable at pH 5.0 after 1 h reaction. In the presence of ABTS as the mediator, the enzyme transformed toluene, 3-nitrotoluene and 4-chlorotoluene to benzaldehyde, 3-nitrobenzaldehyde and 4-chlorobenzaldehyde, respectively.     

Purification and characterization of pectin lyase secreted by Aspergillus flavus MTCC 10938

An indigenously isolated fungal strain Aspergillus flavus MTCC 10938 was subjected to pectin lyase (PNL) production under submerged fermentation conditions. The enzyme was purified to homogeneity from the culture filtrate of the fungus involving concentration by ultrafiltration, anion exchange chromatography on DEAE cellulose and gel filtration chromatography on Sephadex G-100. The purified PNL gave a single protein band in SDS-PAGE analysis with a relative molecular mass corresponding to 50 kDa. Using citrus pectin as the substrate the K _m and k _cat values of the enzyme were obtained as 1.7 mg/ml and 66 s^?1, respectively. The optimum pH of the purified PNL from A. flavus MTCC 10938 was 8.0 and up to 90% of its activity retained in the pH range from 3.0 to 11.0 after 24 h incubation. The optimum temperature of the purified enzyme was revealed at 55°C and it was completely stable up to 40°C when exposed for 30 min. The purified A. flavus MTCC 10938 PNL showed efficient retting of Crotalaria juncea fibres.     

Synthesis of (R)-norbgugaine and its potential as quorum sensing inhibitor against Pseudomonas aeruginosa

(R)-Bgugaine is a natural pyrrolidine alkaloid from Arisarum vulgare, which shows antifungal and antibacterial activity. In this Letter, we have accomplished the simple synthesis of norbgugaine (demethylated form of natural bgugaine) employing Wittig olefination and cat. hydrogenation as the key steps and its biological studies are reported for the first time. The synthesized norbgugaine was evaluated for inhibition of quorum sensing mediated virulence factors (motility, biofilm formation, pyocyanin pigmentation, rhamnolipid production and LasA protease) in Pseudomonas aeruginosa wherein swarming motility is reduced by 95%, and biofilm formation by 83%.