Phytochemical Investigation of Root Extracts of Three Sudanese Citrus Species

Abstract

ABSTRACT The root extracts of Citrus sinensis; Cparadisi and Caurantium of the family Rutaceae were subjected to phytochemical investigation in addition to antimicrobial and antioxidant assessment of activities. The root samples of the three species were collected in Khartoum province and extracted with petroleum ether (40-60°C). chloroform and methanol. Antibacterial and antifungal activities were assessed by the agar disk diffusion method. Observations on the antimicrobial activity showed that Staphylococcus aureus was the most sensitive (30mm inhibition zone). followed by Bacillus subtilis (25mm inhibition zone) against Cparadfsi methanolic extract. The chlorofonn root extracts of the three species were active against Candida albicans (15-20mm inhibition zone). The methanolic root extract of Csinensis was devoid of antifungal activity but it showed the highest antioxidant activity (80°/oi-0.02) amongst the tested root methanolic extracts of the three citrus species, which was done by using the (DPPH) method to assess the antioxidant activity. Phytochemical screening of the prepared pet. ether (40-60°C). chloroform and methanol root extracts revealed the presence of different secondary metabolites such as terpenoids: phenolics. lactones. saponins, alkaloids, tannins and carbohydrates. Based on phytochemical. antimicrobial and antioxidant assessment, the root methanolic extract was subjected to detailed chromatographic and spectroscopic investigations. The total phenolic and flavonoid contents were determined in addition to toxicity against the brine shrimp. and observed that it‘s totally free of toxicity. Column chromatographic fractionation of the active methanolic root extract on silica gel packed column and fractionation with n-hexane. chloroform and methanol ended up with three most active fractions. The three active fractions were further investigated by UV- and lR- spectroscopy and finally with GC-MS method to identify their components qualitatively and quantitatively. The GC-MS analysis lead to the identification of 64 compounds of different classes of organic compounds. Seven main compounds were characterized among these classes in the three active fractions and were identified as: Compound (1): 3-(2.5-dimethoxyphenyl)propionic acid; Compound (2): Hedycaryol; Compound (3): 4-((1E)-3-hydroxy-l-propenyl)-2-methoxyphenol; Compound (4): Limonin; Compound (5): Tetracosanol. Compound (6): 2'.3'-dihydroxydihydrosuberosin and Compound (7): 2.5-Dimethoxybenzyl acetate. The results of the present study could be assessed as a new addition to the global data base on the chemical composition of Csinensis root and its antimicrobial and antioxidant activities. It is noteworthy to report that several compounds of the root extracts were reported for the first time in the current literature.