In this study, various parts of cucurbitacin rich plantCitrullus colocynthisextracts were assayed the biological activities like antimicrobial, cytotoxicity inAllium sativumroot tips,MTT assay with MDA-MD-231cancer cells and DNA cleavage. Antimicrobial activity, high concentration of root extract was found to be more effective on both gram-positive and gram-negative bacteria, almost similar results to low concentration of standard cucurbitacin E, whereas other extracts showed a moderate effect. Cytotoxicity was observed inAllium sativumroot tips with all extracts in both durations (4 hrs and 24 hrs) with increasing duration of treatment. More chromosomal aberrations in mitotic cell division were observed with root and fruit pulp extracts. At higher concentrations, root extract showed positive results in MTT assay, whereas no effect of other extracts was observed. Most effective DNA cleavage was recorded with root extracts in both concentrations. The cumulative biological effect was observed by root extract while comparing with other extracts.