Carbonic Anhydrase-II, α-Glucosidase, and Chemical Composition of Essential Oils from Stem and Leaves of Zygophyllum qatarense

The essential oils (EOs) of the stem (SEO) and leaves (LEO) of Zygophyllum qatarense were analysed by GC/MS. Seventeen compounds comprising 94.0% of the total oil composition were identified in the essential oil leaves (LEO), while eleven compounds accounting 100% of the total oil composition were detected in the essential oil stem (SEO). The main constituents identified in the LEO were methyl-8-pimaren-18-oate (33.09%), methyl palmitate (10.55%), methyl linolenate (7.67%), 6,6-dimethylhept-1-en-4-yne (7.45%) and caryophyllene (6.14%). The SEO was found rich in urs-12-en-28-ol (21.81%), followed by 15-bromopentadecan-1-ol (13.67%), 8,8-diheptylpentadecane (10.35%), α-pinene (8.92%), octadecanamide (8.92%), 2,6,10,14-tetramethylheptadecane (8.87%), hentriacontane (8.52), and caryophyllene (7.15%). Both the EOs were further screened for carbonic anhydrase II (CA II), and α-glucosidase inhibitions. Essential oil leaves of Z. qatarense exhibited significant CA-II activity (IC50 = 68.4 ± 2.3 µg/mL) than stem (IC50 = 76.9 ± 1.32 µg/mL) compared to standard (acetazolamide, IC50 = 18.2 ± 1.2 µM). Similarly, stem oil presented significant α-glucosidase (IC50 = 10.18 ± 0.39 µg/mL) inhibition than leaves (IC50 = 19.9 ± 1.17 µg/mL) in comparison with standard Acarbose (377.7 ± 1.34 µg/mL). From the results, it can be concluded that EOs of both parts of the study plant might have potential to be used for treatment of diabetes mellitus and CA II related diseases. In addition to that, up to the best of our knowledge, this is the first report on the GC/MS analysis, α-glucosidase, and CA-II enzyme inhibition of the essential oils isolated from stem and leaves of Z. qatarense.