Chemical composition and biological activities of essential oils and solvent extracts of Origanum vulgare subsp. glandulosum Desf. from Tunisia

This study aimed to quantify the active biological compounds in Origanum vulgare subsp. glandulosum Desf. Analysis of the chemical composition essential oil from Tunisia was carried out using gas chromatography-mass spectral (GC-MS). The antioxidant capacities of essential oil and extracts were evaluated using free radical scavenging, ferric reducing antioxidant power assay and metal chelating effects. The antidiabetic activity was screened using α-amylase. The oil was dominated by carvacrol (61.20 to 74.03), p-cymene (5.89 to 12.60), and γ γ γ γ-terpinene (1.13 to 6.88). 1,1-diphenyl-2picrylhydrazyl (DPPH) and ferric reducing antioxidant power assay (FRAP) assays showed that leaves of O. vulgare have a potent antioxidant activities which was comparable to Trolox. The methanol extract have the highest ion chelating ability at around 76.98 mg equivalent ethylenediaminetetraacetic acid (EDTA)/g dry matter (DM). The amounts of chlorophylls A and B were higher than that of lycopene and β-carotene. Essential oils and extracts, screened for α-amylase inhibitory effect, showed a strong capacity to inhibit the degradation of starch by pancreatic and salivary α-amylase. Extracts and essential oils of O. vulgare showed substantial antioxidant activity, and detectible inhibitory effect on α-amylase activity, therefore it could be used as a natural preservative ingredient in food and/or pharmaceutical industries.