Antioxidant,antiproliferative and antimicotoxigenic activity of Citrullus colocynthis L. Schrader organic extracts

Citrullus colocynthis L. Schrader is an annual plant, belonging to the Cucurbitaceae family, which grows in arid and semi-arid regions. Native to tropical Asia and Africa, is also widely distributed in the desert areas of the Mediterranean basin. Many pharmacological properties (anti-inflammatory, anti-diabetic, analgesic, anti-epileptic) are ascribed to different organs of this plant; extracts and derivatives of C. colocynthis are used in folk Berber medicine for the treatment of numerous diseases from rheumatism arthritis, hypertension bronchitis, from mastitis and, even, to cancer. We developed a combined approach aimed at investigating biological activities of leaf and root organic extracts, including: i) classic antioxidant activity in vitro tests (DPPH assay; Reducing power determination; β-Carotene/linoleic acid bleaching assay); ii) antiproliferative and antioxidant evaluation on the human colon adenocarcinoma cell line HT29; iii) high-throughput fluorescence-based procedure to determinate the inhibitory effect on aflatoxin production and spores germination in Aspergillus flavus. Extracts showed a high antioxidant capacity in vitro. Regarding the human cell line HT29, the greater antiproliferative activity was observed with the leaf chloroform extract (IC50 = 160μg/ml), that also proved to be capable of significantly reducing the oxidative damage to DNA induced by hydrogen peroxide. This antioxidant activity is similar to that obtained with ascorbic acid 1mM. Furthermore, the results achieved showed that some extract were able to interfere with aflatoxin metabolism in A. flavus, that can be used as a model system to detect the antioxidant potential of compounds (either pure or in mixture) or plant complex extracts.