Developing a new antibacterial drug by using (Z/E)-4-(4-substituted-benzylidene)-2-isoquinoline-1,3(2H,4H)-diones (5a-h) via DNA gyrase inhibition mechanism is the main aim of this study. DNA gyrase inhibition assay was executed to confirm the DNA gyrase inhibition potentials of 5a-h. DNA gyrase inhibitory potentials were further validated through molecular docking. Docking study was also intended to get more insight into the binding mode of 5a-h into the active site of DNA gyrase A. Agar well diffusion method antimicrobial activity on Gram bacteria Escherichia coli (MTCC 443), Pseudomonas aeruginosa (MTCC 424), and Gram bacteria (Staphylococcus aureus (MTCC 96) and Streptococcus pyogenes (MTCC 442) was evaluated. Excellent DNA gyrase inhibition was exhibited by the compound 5c, IC 0.55±0.12 μM; 5d, IC 0.65±0.075 μg/mL; 5e, IC 0.45±0.035 μM; 5f, IC 0.58±0.025 μM; 5h, IC 0.25±0.015 μM while Clorobiocin (standard) showed IC 0.5±0.05 μM. Apart from all the in vitro studies, a plausible mechanism of DNA gyrase inhibition was also proposed through the in silico validations that are including molecular docking, predicted SAR, functional group availability, pharmacokinetic, and ADMET properties. These predictions are well supported to confirm the druggability possibility of the most potent compounds among (Z/E)-4-(4-substituted-benzylidene)-2-isoquinoline-1,3(2H,4H) -diones (5a-h).

Microalgae are photosynthetic microorganisms which have the ability to transform carbon source into biochemicals that can be utilized as biofuels, food, feed and high value bioactive compounds. This study was carried out to evaluate the diversity of phytoplankton including diatoms, microalgae and cyanobacteria in water from two different locations in Salem district of Tamil Nadu, India. In the present study ten water samples were collected from these two sites and their phytoplankton diversity was studied using microscopy. Nearly four cyanobacteria, nine green algae and twenty four diatoms were observed. From them thirteen microalgae and cyanobacteria were isolated and grown in laboratory conditions, nine were able to sustain growth. Algal isolates viz., Chlorella sp. (88 mg/l), Chlorococcum sp. (67 mg/l), Oscillatoria sp. (53 mg/l) and Phormidium sp. (72 mg/l) were selected based on biomass productivity. Higher biochemical profile was found in two microalgae and one cyanobacterium. These three algae were optimized by box benkhen analysis of response surface methodology using varying sources such as carbon, nitrogen, phosphate, pH and temperature. The results revealed that these algae showed maximum biomass production in optimized conditions. The obtained biomass may be used for extraction of bioactive compounds, probiotics, biofuels and other value added products.