Abstract
Background and Objective: Importance of traditional medicines cannot be over emphasized, as they are not only widely used in Saudi Arabia but worldwide. This study was designed to determine phenolic acids contents, antitumor, antioxidant and antimicrobial activities of traditional medicinal plants Coleus forskohlii (C. forskohlii) and Plectranthus barbatus (P. barbatus) in Saudi Arabia. Materials and Methods: Phenolic acids were detected by HPLC, antioxidant activity determined by 2,2-Diphenyl-1 -picrylhydrazyl (DPPH) scavenging system. Antitumor activity performed on HCT-116 cell line by antioxidant enzymes catalase, polyhenoloxidase and peroxidase enzymes were estimated in plant extracts. Poisoned food technique and disc diffusion method for antifungal and antibacterial assay were used respectively. Results: The HPLC analysis of the Coleus forskolii and Plactranthus barbatus extracts indicated the presence of different types of phenolic acids. Ferulic acid and gallic acids were detected in highest concentrations among the other phenolic acid, where the concentration of ferulic acid in C. forskolii and P. barbatus was 27.55 and 23.26 mu g g(-1), respectively, while gallic acid concentration in C. forskolii and P. barbatus was 25.42 and 22.58 mu g g(-1), respectively. Coleus forskolii and P. barbatus species have different antioxidant enzymes which include catalase, polyhenoloxidase and peroxidase enzymes. The IC50 value of the antioxidant activity of C. forskolii was lower than in P. barbatus. Coleus forskolii and P. barbatus have promising effect in tumor activities that appeared in its ability in inhibiting cell proliferation of HCT-116 cell line. Coleus forskohlii but not P. barbatus has antibacterial activities against S. aureus, E. coli and S. typhi while weak antifungal activity was observed with using C. forskohlii and P. barbatus extracts. Conclusion: Plectranthus barbatus has potential antioxident activity then C. forskohli whereas, C. forskohli has antimicrobial properties which are not shown by other plant so, current comparative results support the folk use of this medicinal plants.