Antioxidant Activity andα-Amylase Inhibitory Effect of Polyphenolic-Rich Extract fromOriganum GlandulosumDesf

Abstract

The polyphenolic-rich extract of Tunisian Origanum glandulosum Desf. was investigated for its phenolic composition, antioxidant activity and potential to contribute to the dietary management of type II diabetes. By mean of an ultraperformance liquid chromatography-electrospray ionization-mass spectrometry (UPLC-PDA-ESI-MS) 16 phenolics were characterized. The major detected compounds are caffeic acid, luteloin glucoside, xanthomicrol and carvacrol. The polyphenolic-rich extract presented a notable antioxidant activity similar to that of the synthetic antioxidant Trolox. It was found to inhibit, in a concentration dependent manner, the a-amylase activity with an IC 50 value (8.22 mg/mL) comparable to that of Acarbose (6.12 mg/mL).Overall, our findings suggest that O. glandulosum could be considered as a valuable source of high-value phytochemicals with pharmaceutical and functional food additive applications. PRACTICAL APPLICATIONSOriganum glandulosum Desf., a North African endemic species, is one of the most used plants in folk medicine against whooping cough, fever, bronchitis and diabetes. In the present work, the ability of O. glandulosum to inhibit pancreatic a-amylase in vitro as well as to act as antioxidant food was investigated. The results suggest that O. glandulosum could be considered as a valuable source of phytochemicals with a potent a-amylase inhibition property and antioxidant capacity. Further animal and clinical studies were needed to confirm the potential use of O. glandulosum for the management of type II diabetes.

Understanding glycaemic control and current approaches for screening antidiabetic natural products from evidence-based medicinal plants

“…Both the activity of α -amylase and α -glucosidase can be monitored by colorimetric methods. A colorimetric assay based on the colour change of dinitrosalicylic acid has been used to screen various medicinal plants [170–172], herbs and spices [121, 173]. The α -glucosidase inhibition assay uses p -nitrophenyl- α - d -glucopyranoside (PNPG) as the substrate.…”

“…Sixteen compounds including caffeic acid, luteolin glucoside, xanthomicrol, carvacrol, and luteolin were putatively identified from an Origanum glandulosum extract via LC–MS. Although the compounds were not evaluated individually, the extract showed dose-dependent α -amylase inhibitory potential similar to acarbose, and antioxidant activity comparable to trolox (an antioxidant analogue of vitamin E, used as a control in antioxidant assays) [170].…”

Flavonoids and Phenolic Acids from Oregano: Occurrence, Biological Activity and Health Benefits

“…Regarding Origanum glandulosum (syn. Origanum compactum ), Béjaoui et al [ 73 ] measured the antioxidant capacity of the methanolic extract, presenting an IC 50 value of 0.6 mg/mL for DPPH, attributed principally to the presence of caffeic acid, which has been reported as a potent antioxidant [ 74 ]. Another widely studied oregano species regarding antioxidant capacity is Origanum majorana , characterized by the high content of rosmarinic acid.…”

Phytochemical and bioactive compounds identification of Ocimum tenuiflorum leaves of methanol extract and its fraction with an anti-diabetic potential

“…[32] The α-amylase inhibition property and antioxidant capacity of the major detected compounds such as caffeic acid, luteolin glucoside, xanthomicrol, and carvacrol from Origanum glandulosum were reported as a pharmacological effect. [33] In previous reports, researchers were reported that 3,.4,.5-trimethoxycinnamic acid as flavones showed antioxidant, anti-proliferative, antitumour, antimicrobial, oestrogenic, acetylcholinesterase, and anti-inflammatory activities, and was also used in treating cancer, cardiovascular disease, neurodegenerative disorders, etc., but we could not find any report on antidiabetic activity. [34] Phthalates (di(ethylhexyl) phthalate) are widely used as a plasticizer and are considered as a typical endocrine-disrupting chemical.…”