Fruit juice mediated multicomponent reaction for the synthesis of substituted isoxazoles and their in vitro bio evaluation

Abstract A simple, efficient and eco-friendly procedure for the synthesis of isoxazoles derivatives (4a-4h) using one-pot three components reaction between substituted aldehydes (1a), methyl acetoacetate (2a) and hydroxylamine hydrochloride (3a) has been achieved in presence of Cocos nucifera L. juice, Solanum lycopersicum L. juice and Citrus limetta juice respectively. This protocol is natural acid catalysed multicomponent reaction for the synthesis of potentially bioactive isoxazole derivatives. The homogeneity of synthesized compounds was confirmed by melting point and thin layer chromatography. The synthesized compounds were characterized by using 1HNMR, FTIR and CHN spectral analysis and evaluated for in vitro herbicidal activity against Raphanus sativus L. (Radish seeds). The compounds (4a-4h) were also screened for their fungicidal activity against Rhizoctonia solani and Colletotrichum gloeosporioides by poisoned food techniques. Antibacterial activity was also tested against Erwinia carotovora and Xanthomonas citri by inhibition zone method. From bio evaluation data, it was found that compound 4b was most active against Raphanus sativus L. (root) and Raphanus sativus L. (shoot) respectively. Compound 4b was also found most active against both the fungus viz. R. solani and C. gloeosporioides showing maximum percentage growth inhibition i.e. 90.00 against R. solani and 82.45 against C. gloeosporioides at 2000 µg/mL concentration. Compound 4h has shown maximum inhibition zone i.e. 3.00-9.60 mm against Erwinia carotovora at 2000 µg/mL concentration. Maximum Xanthomonas citri growth was also inhibited by compound 4h showing inhibition zone 1.00-5.00 mm at highest concentration. Less reaction time, high yields of desired products, mild reaction conditions, simple work-up, cost effectiveness and no need of column chromatography are some beauties of present methodology.