Volatile Constituents of Cistanche tubulosa and Their Antioxidant and Antimicrobial Potentials

The hydrodistilled volatile constituents of Cistanche tubulosa (commonly known as Desert Ginseng) have been chemically and biologically investigated. Based on the retention times and mass fragmentation of the obtained GC-MS chromatogram, 106 individual components which representing≈ 99.29% of the total volatile constituents have been identified. The major compounds (66.57% of the total composition) were identified as hexanal (15.98%), trans-sabinyl acetate (12.22%), allo-aromadendrene (9.30%), nonanoic acid (6.66%), 3Z-hexeny-2-methyl butanoate (6.09%), valeranone (5.25%),(E, E)-α-Farnesene (3.18%), α-pinene (3.06%), linalool isovalerate (3.03%) and α-humulene (1.8%). Estimation of the antioxidant activity of EO showed promising effect at 80 μg/mL concentration, it exerted 62.40, 863.29 and 62.72% inhibition compared to TBHQ that showed 78.62, 77.56 and 79.23% inhibition using DPPH, ABTS and β-carotene/Linoleic acid, respectively. The antioxidant activity was pronounced at 80 μg/mL than other concentrations. The volatile constituents showed inhibitory activity against gram positive bacteria ranged from 2.23 mg/100 mL (for staphylococcus aureus), and 15.68 mg/100 mL (for Bacillus cereus) compared to ciprofloxacin which showed inhibitory activity 0.185, and 0.182 mg/100 mL, respectively. Moreover, the MIC of volatiles towards gram negative bacteria are ranged from 18.35 (Escherichia coli) to 31.61 mg/100 mL (Klebsiella pneumonia) compared to ciprofloxacin with 0.184 to 0.188 mg/mL respectively. Additionally, the antifungal activity against candida albicans was rather promising (4.36 mg/mL).