Abstract

This study investigated the effect of seasonal variation on the chemical composition, antioxidant and antidiabetic activities of essential oil from leaves of Eucalyptus globulus. Pulverized leaves (500 g) of E. globulus from dry and rainy season harvests afforded 0.54 and 0.43 % (w/w) of essential oils respectively when subjected to hydrodistillation. GC and GC/MS analyses revealed the presence of forty-five and thirty-three compounds that represented 95.4 and 98.4 % of the oils obtained from leaves harvested during the dry and rainy seasons. The principal constituents of the essential oils were; D-limonene, m-cymene, o-cymene, 6-camphenol, terpinen-4-ol, globulol, diosphenol and spathulenol. The oils showed scavenging activity for DPPH radical with IC₅₀ of 20.15 (dry) and 11.23 μL/mL (rainy). The essential oils showed significant reducing powers of 356.46±0.88 (dry) and 394.34±0.95 (rainy) FRAP equivalent. The oils inhibited the activity of α-amylase with IC₅₀ of 8.37 (dry) and 6.78 (rainy) μg/mL. The IC₅₀ for the α-glucosidase inhibition of the oils were 6.19 (dry) and 7.20 (rainy) μg/mL. The antioxidant and antidiabetic activities of the oils compared favourably with the standards used for the study. Hence, the essential oils can serve as an alternative to synthetic drugs to ameliorate oxidative stress and management of type 2 diabetes.

摘要

这项研究调查了季节性变化对桉树叶精油化学成分，抗氧化剂和抗糖尿病活性的影响。干燥和雨季收获时得到的球状大肠杆菌的粉状叶子（500克）经加氢蒸馏后分别得到0.54％和0.43％（w / w）的精油。GC和GC / MS分析表明，有45种和33种化合物的存在，分别占干燥季节和雨季收获的叶片中油的95.4％和98.4％。精油的主要成分是；D-柠檬烯，间异丙苯，邻-异丙苯，6-香豆酚，萜品烯-4-醇，球蛋白，二酚和七绿烯酚。这些油显示出对DPPH自由基的清除活性，IC ₅₀为20.15（干）和11.23μL/ mL（雨）。精油显示出显着的356.46±0.88（干）和394.34±0.95（雨）FRAP当量的还原能力。这些油抑制了α-淀粉酶的活性，IC ₅₀为8.37（干）和6.78（雨）μg/ mL。抑制油中α-葡萄糖苷酶的IC ₅₀为6.19（干）和7.20（雨）μg/ mL。这些油的抗氧化和抗糖尿病活性优于用于研究的标准。因此，精油可作为合成药物的替代品，以减轻氧化应激和控制2型糖尿病。