Comparative evaluation of the antimicrobial activity of <i>Citrullus colocynthis</i> immature fruit and seed organic extracts

Abstract

Gastrointestinal problems, dermatological, gynaecological and pulmonary infections produced by micro-organisms are widespread in the entire globe. The treatment of these infections is mainly based on the use of synthetic drugs which have lost, in recent years, their effectiveness, due to the development of resistant strains and the rise of opportunistic fungal infections. Tunisian traditional medicine is a potential source of new remedies namely, Citrullus colocynthis Schrad. (Cucurbitaceae). Lyophilized aqueous and organic extracts from immature fruits and seeds were screened for activity against gram-negative (Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Vibrio parahaemolyticus and Vibrio alginolyticus) and gram-positive (Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, Listeria monocytogenes and Micrococcus luteus) bacteria and various Candida spp. (Candida glabrata, Candida albicans, Candida parapsilosis and Candida kreusei). Minimal inhibition concentrations (MICs) and minimal bactericidal/fungicidal  concentrations (MBCs/MFCs) were used to investigate the antimicrobial activity. Extracts from the two C. colocynthis Schrad. organs, at immature state, inhibited the growth of all the tested strains. The highest antibacterial effects were obtained against E. coli (MIC = 0.006 mg/ml) with the fruit methanol and the seed petroleum extracts. Regarding the anticandidal activity assessment, seed extracts showed the lowest results. This study demonstrated the broad spectrum antimicrobial activity of C. colocynthis immature fruit and seed extracts.

Key words: Citrullus colocynthis Schrad, fruits, seeds, organic extracts, antibacterial, anticandidal.