The most commonly used spices in Thai traditional medicine: in vitro evaluation of anti-hyperglycemic, antioxidant, polyphenol content, and nitric oxide production inhibitory activities

Abstract

Background and purpose: Diabetes mellitus is a persistent hyperglycemic condition. Thai cuisine and medicine incorporate spices: nutmeg, mace, clove buds, cardamom, cinnamon, and coriander. The in vitro impacts of these spices on anti-diabetic, antioxidant, anti-inflammatory, and total phenolic and flavonoid content were assessed. Experimental approach: Alpha-amylase and alpha-glucosidase inhibition assays were conducted. Antioxidant potential was measured through DPPH and ABTS assays. Anti-inflammatory activity was determined by inhibiting nitric oxide generation in RAW 264.7 cells. Total phenolic content was quantified using the Folin Ciocalteu method, while total flavonoid content was estimated via the aluminum chloride colorimetric method. Findings/Results: Ethanolic and aqueous extracts of a blend of spices (Siam cardamom, nutmeg, mace, and clove buds), denoted as 4-GlurE and 4-GlurA, displayed concentration-dependent inhibition of alpha-glucosidase, with IC50 values of 0.373 and 0.435 mg/mL, respectively. 4-GlurE and 4-GlurA exhibited antioxidant activity, by ABTS·+ radical and DPPH scavenging capabilities. 4-GlurE demonstrated anti-inflammatory potential by reducing nitric oxide generation (IC50: 43.95 ± 2.47 μg/mL). 4-GlurE and 4-GlurA possessed total phenolic content (TPC) of 122.47 ± 1.12 and 148.72 ± 0.14 mg GAE/g, respectively. 4-GlurE exhibited a higher total flavonoid content (TFC) compared to the aqueous extract (340.33 ± 4.77 and 94.17 ± 3.36 mg QE/g). Cinnamon and clove aqueous extracts were more potent than acarbose in alpha-glucosidase inhibition with the highest antioxidant activity. Polyphenol levels (TPC and TFC) exhibited strong correlations with antioxidant capacity. Conclusions and implications: Findings are consistent with the traditional use of 4-Glur, with cinnamon, for diabetes prevention and treatment.