Substituent activity relationship studies on new azolo benzoxazepinyl oxazolidinones.

In an effort to discover potent antibacterials based on the entropically favored 'bioactive conformation' approach, a series of novel tricyclic molecules mimicking the conformationally constrained structure of Linezolid is reported. Based on the initial tricyclic molecule 1, the benzazepine derivative 2 was designed where the tricyclic structure had more flexibility around C-N bond compared to 1. While, the molecule 2 was less active, the molecule 3 showed promising antibacterial activity presumably after having obtained rigidity due to pyrrole ring. The syntheses, SAR studies, and evaluation of 3 as a lead compound are reported.

A rapid technique for screening of lovastatin-producing strains of Aspergillus terreus by agar plug and Neurospora crassa bioassay.

The success of strain improvement programme depends on the number of isolates that can be screened after mutagenic treatment. A technique to rapidly screen large number of high-yielding isolates was developed. The 'agar plug' method that utilizes the anti-fungal property of lovastatin to produce a zone of inhibition against Neurospora crassa was not only economical but also less labour-intensive. We were able to isolate a high-yielding strain, the productivity of which increased by 138% as compared to the parent strain in the submerged fermentation process.

Novel quinolone derivatives as potent antibacterials.

Several 7-(3R,4R-N,N'-dialkyl diaminopyrrolidinyl)-substituted quinolones were synthesized and evaluated for antibacterial activities. 5-Amino-7-(3R,4R-N,N'-dimethyldiamino-6,8-difluoro-1,4-dihydro-1-c yclopropyl -4-oxoquinoline-3-carboxylic acid was found to have potent antibacterial activity against gram +ve organisms.