Synthesis and Antimicrobial Activity of N-(6-Carboxyl Cyclohex-3-ene Carbonyl) Chitosan with Different Degrees of Substitution

Mohamed E I Badawy,Entsar I Rabea

doi:10.1155/2016/6046232

Abstract

Five products of N-(6-carboxyl cyclohex-3-ene carbonyl) chitosan as antimicrobial agents were prepared by reaction of chitosan with tetrahydrophthalic anhydride (THPA) at different degrees of substitution (DS). The antimicrobial activity was evaluated against four plant bacteria and eight fungi. The results proved that the inhibitory property and water solubility of the synthesized chitosan derivatives, with increase of the DS, exhibited a remarkable improvement over chitosan. The product with a DS of 0.40 was the most active one with MIC of 510, 735, 240, and 385 mg/L against Erwinia carotovora, Ralstonia solanacearum, Rhodococcus fascians, and Rhizobium radiobacter, respectively, and also in mycelial growth inhibition against Alternaria alternata (EC50 = 683 mg/L), Botrytis cinerea (EC50 = 774 mg/L), Botryodiplodia theobromae (EC50 = 501 mg/L), Fusarium oxysporum (EC50 = 500 mg/L), F. solani (EC50 = 260 mg/L), Penicillium digitatum (EC50 = 417 mg/L), Phytophthora infestans (EC50 = 298 mg/L), and Sclerotinia sclerotiorum (EC50 = 763 mg/L). These compounds based on a biodegradable and biocompatible chitosan could be used as potentially antimicrobial agents in crop protection instead of hazardous synthetic pesticides.

Highlights

Chitosan is a linear biopolymer consists of higher than 70% of β-(1-4)-2-deoxy-β-D-glucopyranose (GlcN) and lower than 30% of β-(1-4)-2-acetamido-2-deoxy-β-D-glucose (GlcNAc) units linked by β-1,4-glucosidic bonds
Based on the current state of research and progress in corresponding areas, this article aims at preparing water-soluble N-(6-carboxyl cyclohex-3-ene carbonyl) chitosan derivatives to enhance the antimicrobial activity of chitosan molecule against plant pathogenic bacteria Erwinia carotovora, Ralstonia solanacearum, Rhodococcus fascians, and Rhizobium radiobacter
Chitosan products were obtained at a range of degrees of substitution (DS) 0.09–0.40 when five mole ratios (0.1, 0.3, 0.5, 0.8, and 1.0 mole) of tetrahydrophthalic anhydride (THPA) per glucose amine were tested

Summary

Introduction

Chitosan is a linear biopolymer consists of higher than 70% of β-(1-4)-2-deoxy-β-D-glucopyranose (GlcN) and lower than 30% of β-(1-4)-2-acetamido-2-deoxy-β-D-glucose (GlcNAc) units linked by β-1,4-glucosidic bonds. It can be obtained through a deacetylation process of purified chitin, a naturally abundant polysaccharide, and the supporting material of crustaceans, insects, and fungi [1,2,3]. All of the chemical modifications have been performed on the primary amino group (at C-2) or the two hydroxyl groups (at C-3 and C6) of the chitosan molecule such as N-reductive amination, quaternization, hydroxyalkylation, N,O-carboxymethylation, International Journal of Carbohydrate Chemistry

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