PHYTOCHEMICAL SCREENING, ANTIOXIDANT PROPERTIES AND ANTIMICROBIAL ACTIVITIES OF GINGER AND SWEET ORANGE PEELS ESSENTIAL OILS.

Abstract

Essential oils are highly concentrated substances obtained from vegetable raw materials and are complex mixtures whose composition may include hydrocarbons, alcohols, esters and aldehydes. These oils are often used for their flavour and their therapeutic or odiferous properties. The study was carried out to determine the phytochemical constituents, antioxidant properties and antimicrobial activities of essential oil from Ginger (Zingiber officinale) and sweet orange (Citrus sinenesis) peels. Fresh ginger rhizomes and sweet orange peels were hydro-distilled to get the essential oils which were screened for the presence of phytochemicals and their effect on 1,1-Diphenyl-2-picryl-hydrazyl radical (DPPH) was used to determine their free radical scavenging activity. Total alkaloids and total terpenoids were quantitatively estimated. The oils were also evaluated for antimicrobial activity against fish pathogenic bacteria by disc diffusion method. Antibacterial activity was determined against four di?erent fish pathogens Vibrio sp, Escherichia coli, Pseudomonas aeruginosa and Bacillus sp. Bacillus sp. Phytochemical screening of the ginger and sweet orange peel essential oils showed the presence of alkaloids, terpenoids, cardiac glycosides, coumarin, anthraquinones and vitamin C which are useful substances that have medicinal and physiological activities. They did not contain saponin, tannins, steroids, phenols and flavonoids. Concentrations of the essential oil required for 50% inhibition of the DPPH radical scavenging effect (IC50) were recorded as 200 µg/ml, 400 µg/ml, 600 µg/ml, 800 µg/ml and 1000µg/ml for ginger and sweet orange peel essential oil. Antioxidant screening of the ginger and sweet orange peels essential oils DPPH was positive indicating the presence of free radical scavenging molecules and antioxidant potency of the essential oils. The disc di?usion results indicated that essential oil of Zingiber officinale and Citrus sinensis peel significantly inhibited the growth of Vibrio sp, Escherichia coli, Pseudomonas aeruginosa, and Bacillus sp. The inhibition of the test isolates was dependent on the concentration of the solvent used. The phytochemical analysis of ginger and sweet orange peel essential oil revealed the presence of phytochemical constituents which conferred antimicrobial property on the oils.