Biological activities, antioxidant properties and phytoconstituents of essential oil from sweet basil (Ocimum basilicum L.) leaves

This study investigated the biological activities of essential oil from sweet basil leaves via its effect on α-amylase, α-glucosidase and angiotensin-I-converting enzyme (ACE) activities, inhibition of Fe²⁺ and sodium nitroprusside (SNP)-induced lipid peroxidation in rats’ pancreas and heart homogenates. The phytoconstituents of the oil were analysed using gas chromatography (GC). The essential oil exhibited a dose-dependent inhibition of α-amylase (IC₅₀ = 3.21 mg/mL), α-glucosidase (IC₅₀ = 3.06 mg/mL) and ACE (IC₅₀ = 0.89 mg/mL) activities in vitro. The oil also inhibited both Fe²⁺- and SNP-induced lipid peroxidation in rats’ pancreas and heart. The GC analysis revealed the presence of about 28 phytoconstituents, with limonene (47.40 %), borneol (8.66 %), geranial (6.93 %), neral (5.71 %), myrcene (4.68 %), β-caryophyllene (4.68 %), α-terpineol (4.60 %), 1,8-cineole (4.17 %), linalool (3.53 %), β-elemene (3.05 %), germacrene D (2.68 %), and terpinen-4-ol (2.21 %) being the most prominent. Thus, the antioxidant and enzyme inhibitory effects of the essential oil could be attributed to the presence of these phytochemicals, which could be the principle responsible for the antidiabetic and antihypertensive properties of the essential oil. This study therefore, could provide the possible rationale for the application of essential oil from sweet basil leaves as functional foods and nutraceutical ingredient in the management of type 2 diabetes and hypertension.