Biofunctional molecules from Citrullus colocynthis: An HPLC/MS analysis in correlation to antimicrobial and anticancer activities

Abstract

Background: Citrullus colocynthis belongs to Family Cucurbitaceae. It grows widely in Egypt and Sudan and it has been used in folk medicine of Sudan and many other African countries as anti inflammatory, anti diabetic, and antioxidant agent. Objectives: To evaluate the antibacterial, antifungal, antiviral, anticancer activities of ethanolic crude extracts of the fruits, leaves, seeds and roots of this plant, as well as identifying them HPLC/MS. Materials and Methods: Dried fruits, seeds, leaves and roots of C. colocynthis were powdered and passed through a 40- mesh, then, the powders were extracted with 95% ethanol in a soxhlet apparatus. The residues were dried under reduced pressure in rotary evaporator. Crude extract from different plant parts were evaluated biologically and phytochemically. Results: All extracts showed good antifungal activities with inhibition zone ranges between 15.1 ± 0.32 to 25.6 ± 0.16 mm. In terms of plant organ, fruits were the most active. In term of fungal strain Aspergillus fumigatus and Geotricum candidum were the most sensitive. Against tested Gram +ve, all extracts showed good activities except roots, while antibacterial activity against Gram –ve showed that the fruits extract have good activity as it was the sole extract with activity against Pseudomonas aeruginosa. Test for antiviral activities showed moderate to weak inhibitions of cytopathic effect (CPE). Anticancer activities of different crude extracts showed that fruits had significant antitumor activities against all tested cell lines, the IC₅₀ values were 24.6, 16, 18.5 and 19.7 µg /ml for HCT-116, MCF-7, Hep-G2 and Caco-2 respectively. Seeds extract was only active on HCT-116 and Hep G2 with IC50 =21.2 µg/ml for HCT-116 and 22.4 µg/ml for Hep G2. Leaves extract was only active against Hep G2 cancer cell line with IC₅₀ 19.7 µg/ml. Roots extract show weak antitumor activity on tested cell lines (IC₅₀ values > 30µg/ml). HPLC/MS qualitative and quantitative analysis of different organs extracts revealed the presence of 21 compounds identified as fourteen cucurbitacins, three flavonoids, three tannins, and one sterol. The presence of cucurbitacins can explain most of the biological activities. Conclusion: The biological activities of colocynth different parts are due to the presence of secondary metabolites mainly cucurbitacins in addition to flavonoids and tannins.  These activities prove the use of this plant in folk medicine and deserve much more future exploration targeting their discovery in unexplored sources and their derivatives for improving their anticancer and antimicrobial abilities.

Keywords: Citrullus colocynthis, crude extracts, antifungal, antibacterial, antiviral, anticancer, HPLC/MS