Gas chromatography-mass spectrometry (GC-MS) analysis and <i>in vitro</i> evaluation of antioxidant and antimicrobial activities of various solvent extracts from <i>Citrullus colocynthis</i> (L.) roots to control pathogen and spoilage bacteria

Abstract

Citrullus colocynthis (L.) schrad is an important medicinal plant belonging to the family of Cucurbitaceae. In the present study we evaluated in vitro the antimicrobial and the antioxidant properties of various solvent extracts from C. colocynthis roots as well as the latter phytochemical characterisation. Total phenolic and flavonoid contents were determined. The highest content of total phenolic was found in extracts obtained with ethyl acetate (205 mg GAE/g) followed by methanol (85 mg GAE/g). The major phenolic compounds in ethyl acetate extract were identified by gas chromatography-mass spectrometry (GC-MS). A total of 12 compounds were characterized including oleic acid, linoleic acid, caffeic acid, hexadecanoic acid and octadecanoic acids. The antioxidant activities were evaluated using 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) and lipid peroxidation methods. These tests showed that the ethyl acetate extract exhibited the best performance. The different extracts were also tested against a panel of pathogen, food-borne and spoilage bacteria and fungi in order to evaluate the antimicrobial properties of this plant. Among the tested extracts, only the ethyl acetate extract exhibited bactericidal and fungicidal activities. To our knowledge, this is the first report on the chemical composition, antioxidant and antimicrobial activities of phenolic extracts from C. colocynthis roots. The results of the present work indicate that C. colocynthis extracts could be used as natural antioxidant and antimicrobial agents in the food preservation and human health.

Key words: Citrullus colocynthis, antibacterial activity, antifungal activity, antioxidant activity, phenolics composition.