Azo Dye Degradation by Chlorella vulgaris: Optimization and Kinetics

11 June, 2026

Background and Objective: Azo dyes are most widely used in various industries due to their ease of synthesis and chemical stability. But many azo dyes and their breakdown derivatives have been suggested to be toxic to life. Biological treatments of dyes with microorganisms are relatively cost effective and eco-friendly due to lower sludge production. In this study, the microalgae Chlorella vulgaris was examined for its degrading ability of azo dyes viz., Reactive Black 5, Direct Blue 71 and Disperse Red 1. Materials and Methods: The experiments included dye decolorization experiments and factors affecting decolorization such as initial dye concentration, pH and temperature. Further, azoreductase enzyme specific activity and its kinetics were determined. Results: The results revealed that azo degradation based on the initial dye concentration varied among the dyes tested and the same was reflected for pH. In specific, 200 mg L^–¹ was found optimum for Reactive Black 71 and Direct Blue 71 whereas 300 mg L^–¹ was for Disperse Red 1. The optimum pH for decolorization of RB5, DB71 and DR1 was 5, 8 and 8, respectively. The optimum temperature for degradation of all the dyes was found as 40°C. Maximum azoreductase activity of 0.127 U mg^–¹ protein was observed for DR1 and the enzyme activity was not pH dependent but substrate specific. Conclusion: The results revealed the azo dye degrading potential of Chlorella vulgaris and the decolorizing conditions were optimized for the microalgae.

Effect of Vitamin C Alone and in Combination with Loperamide on Castor Oil-induced Diarrhea

11 June, 2026

Background and Objective: Diarrhea is a killer disease especially amongst children. Oxidative stress is one of the causes of diarrhea. This study investigated the effect of an antioxidant (vitamin C) when administered alone and in combination with loperamide, an antidiarrheal drug, in castor oil-induced diarrhea. Materials and Methods: Adult albino rats were administered 25-150 mg kg^–¹ b.wt. vitamin C alone and in combination with 3 mg kg^–¹ b.wt. loperamide. The antidiarrheal activity was assessed using standard procedures. The concentration of malondialdehyde (MDA) and Na⁺-K⁺ ATPase activity in small intestine homogenates were also evaluated. Antioxidant enzymes activity and MDA concentration in rat small intestinal homogenates after 5 days co-administration of 50, 100 and 200 mg kg^–¹ b.wt. of vitamin C with 3 mg kg^–¹ b.wt. loperamide was evaluated and compared with loperamide alone and normal rats. Results: There was a significant decrease (p<0.05) in the number of wet stools at 100 and 150 mg kg^–¹ b.wt. Vitamin C alone and in combination with loperamide. The weight and volume of intestinal fluids as well as the small intestinal MDA concentration of rats administered 50 mg kg^–¹ b.wt. vitamin C and loperamide significantly decreased when compared to other treatments. Administration of 50-200 mg kg^–¹ b.wt. vitamin C and loperamide for 5 days significantly decreased catalase and glutathione peroxidase activities and the concentration of MDA when compared with loperamide alone. Conclusion: These findings indicate that vitamin C when combined with loperamide has better antidiarrheal activity and reverses oxidative stress caused by prolonged usage of loperamide.

International Journal of Biological Chemistry - Current Issue

Azo Dye Degradation by Chlorella vulgaris: Optimization and Kinetics

Effect of Vitamin C Alone and in Combination with Loperamide on Castor Oil-induced Diarrhea