Citrullus colocynthis L. is one of the most important medicinal plants mainly used in folk medicines. It is widely used for the remedy of cancer, tumours, and abdominal disorders. Owing to medicinal importance of Citrullus colocynthis, the current work is concentrated to explore its proximate, metals analysis and antibacterial activity. Phytochemical screening of the roots, stem and leaves extracts showed various secondary metabolites such as Alkaloids, Tannins, Saponin, Flavonoids, Terpenoids and Glycosides. Elemental analysis of the roots, stem and leaves extracts showed variable concentration of eight (08) different heavy metals such as Iron (Fe), Copper (Cu), Zinc (Zn), Manganese (Mn), Nickel (Ni), Tin (Sb), Cobalt (Co) and Lead (Pb). Various plant parts were tested against pathogenic bacterial strains. Roots and Fruit Ethanolic extract of the plant showed significant anti-bacterial activity upto 19 mm against MDR human pathogenic Gram-positive strain Bacillus subtilis while it was comparatively effective against E. coli and other bacilli with average 17mm zone of inhibition, while levofloxacin was used as standard antibiotics.

Key words: Citrullus colocynthis, metals analysis, antibacterial activity, zone of inhibition, Bacillus subtilis