Evaluation of antioxidant enzyme content, phenolic content, and antibacterial activity of Commiphora gileadensis grown in Saudi Arabia

Commiphora gileadensis is commonly used in Saudi Arabia for oral hygiene. A lack of data about its biological activity encouraged us to evaluate the antioxidant and antibacterial activities of its leaf and stem extracts. Ethanol, methanol, acetone and deionized water were tested as extraction solvents. 80% methanol gave the highest extracted concentrations of phenolic and flavonoid substances. The leaf and stem extracts were respectively evaluated for their radical scavenging activity with DPPH (EC50 = 3.39, and 1.06), ABTS (EC50 = 0.690, and 0.55), and peroxide scavenging activity (EC50 = 2.43, and 1.28). GC-MS identified a wide range of compounds that may be responsible for these activities of the results observed. The highest levels of chlorophyll, carotenoids, and lycopene were found in the leaf extract while level of proanthocyanidins was found in the stem peels extract. The peroxidase and catalase activities of stem peel extract were higher than those of the leaf extract. The findings showed that the leaf and stem peel extracts of C. gileadensis exhibited significant antibacterial activity against the test organisms. The minimum inhibitory concentrations for the plant extracts were compared with the standard reference drug Augmentin but the time-kill curves for the C. gileadensis extracts showed that they were less effective than Augmentin. Moreover, the stem peel extract exhibited stronger antibacterial activity than the leaf extract. In conclusion, C. gileadensis can be an important source of natural antioxidants, used as a healthy chewing stick for teeth brushing and oral hygiene purposes.