Evaluation of Antioxidant, Alpha-Glucosidase Enzyme Inhibitory and Antimicrobial Activities of Anthraquinone and Aloe-emodin

Background and Objectives: Aloe-vera is one of the most valuable medicinal plants in the world. The aim of this study was to evaluate the antioxidant, alpha-glucosidase inhibitory and antimicrobial properties of aloe-vera derivatives including aloe-emodin and anthraquinone.  Materials & Methods: Antioxidant activity of aloe-emodin and anthraquinone was determined using ABTS method. Antimicrobial activity of aloe-emodine and anthraquinone was evaluated against Bacillus cereus, Klebsiella pneumoniae, Candida albicans, and Pseudomonas aeruginosa. To determine the inhibition of alpha-glucosidase enzyme, pNPG)p-nitrophenyl-α-D-glucopyranoside)bwas used as substrate. Enzymatic activity was determined by measuring the absorption of para-nitrophenol produced in the solution. Results: The results showed that aloe-emodin and anthraquinone do not have an antioxidant effect at 0.05­mg/mL concentration. The results of the alpha-glucosidase enzyme inhibitory test for aloe-emodin and anthraquinone aloe vera also showed a positive and significant correlation between the sample’s concentration and its alpha-glucosidase inhibitory activity (p˂0.05). At concentrations of 0.18 ­and 0.05­mg/mL aloe-emodin and anthraquinone had a 50% inhibitory effect on the alpha-glucosidase enzyme. Therefore, the inhibitory effect of anthraquinone was higher than that of aloe-emodin. In microbial test, the diameter of the non-growth zone indicated that aloe-emodin had the highest effect on Bacillus cereus and the least effect on Pseudomonas aeruginosa (p˂0.05). Alsot anthraquinone had the highest effect on Candida albicans and Klebsiella pneumoniae and the least effect on Pseudomonas aeruginosa (p˂0.05). According to the results of alpha-glucosidase inhibitor test, anthraquinone is a potent inhibitor, and the antimicrobial activity of anthraquinone is higher than that of aloe-emodin. Conclusion: Considering the favorable antimicrobial and inhibitory properties of alpha-glucosidase, it is recommended to use it as a natural additive in food industry.