Phytochemical standardization and biological activities of certain desert plants growing in Saudi Arabia.

The phytochemical screening, antimicrobial and antitumor activities of Calendula tripterocarpa, Centarea sinaica, Centaurea pseudosinaica, Koelpinia linearis, Plectranthus arabicus, Plectranthus asirensis and Tripleurospermum auriculatum determined. The best antibacterial activity; 41.8 ± 0.23 mm, 39.7 ± 0.25 mm, 35.8 ± 0.58 mm, 34.7 ± 0.51 mm and 32.7 ± 0.25 mm was obtained by Plectranthus arabicus against Klebsiella pneumonia, Tripleurospermum auriculatum against Bacillus subtilis, Centaurea pseudosinaica against Bacillus subtilis, Centaurea pseudosinaica against Stroptococcus pyogenes and Plectranthus arabicus against Staphylococcus epidermidis, respectively. While the highest antifungal activity; 35.9 ± 1.15 mm, 34.6 ± 0.34, 30.6 ± 0.26 mm and 29.9 ± 0.63 mm was obtained by Tripleurospermum auriculatum against Geotricum candidum, Candida albicans, C. tropicalis and Aspergillus fumigatus, respectively. The antitumor activity (IC50) obtained by Centarea sinaica; 3.1 ± 6.9 µg/ml, 14.3 ± 3.1 µg/ml and 22.7 ± 4.1 µg/ml was better than activity of vinblastine sulphate; 5.9 ± 0.4 µg/ml, 59.7 ± 2.1 µg/ml and 30.3 ± 1.4 µg/ml against breast carcinoma (MCF-7), cervical carcinoma (Hela) and colorectal carcinoma (CACO), respectively. Plectranthus arabicus alcoholic extract showed higher antitumor activity; 15.3 ± 5.3 µg/ml, 28.6 ± 3.6 µg/ml and 24.3 ± 4.1 µg/ml than vinblastine; 21.2 ± 0.9 µg/ml, 59.7 ± 2.1 µg/ml and 30.3 ± 1.4 µg/ml against prostate carcinoma (Pc3), cervical carcinoma (Hela) and colorectal carcinoma (CACO), respectively. Also, the antitumor activity of Plectranthus asirensis against cervical carcinoma (Hela) (37.1 ± 2.6 µg/ml) was potent than vinblastine sulphate (59.7 ± 2.1 µg/ml). The obtained results of LD50 and sub-chronic toxicity revealed that the plants have no toxicity.