Molecular and cellular approach in the study of antioxidant/pro-oxidant properties ofMicromeria croatica(Pers.) Schott

Antihyperglycemic Activity of Micromeria graeca Aqueous Extract in Streptozotocin-Induced Diabetic Rats

AIM

This study aimed to investigate the effect of Micromeria graeca on blood glucose levels and lipid parameters in an experimental model of diabetes.

BACKGROUND

Micromeria graeca (L.) Benth. ex Rchb is a medicinal plant used in Morocco for the treatment of several pathologies including diabetes.

OBJECTIVE

This study aimed to evaluate the antihyperglycemic and antihyperlipidemic effects of the aqueous extract of Micromeria graeca (M. graeca) aerial parts (AEMG) under physiological (normal rats) and pathological (STZ-induced diabetic rats) conditions. Additionally, we analyzed the phytochemical composition and antioxidant capacity.

METHODS

The effects of the acute and sub-chronic administration of AEMG (20 mg/kg) on blood glucose levels and lipid profiles were evaluated in normal and streptozotocin-induced diabetic rats. Moreover, the phytochemical analysis was carried with standard tests and estimation of total phenolics compounds by Folin-Ciocalteu reagent. The antioxidant activity was realized by the DPPH method.

RESULTS

Single oral administration of M. graeca aqueous extract decreased blood glucose levels 4 and 6 hours (p<0.01) after treatment in diabetic rats. In accordance, the repeated oral administration of M. graeca showed a significant reduction in blood glucose levels in diabetic rats since the second day to the end of the period experiment (p<0.0001). In addition, two weeks of treatment with M. graeca reduced total cholesterol levels (p<0.05) with a significant increase of HDL-c level (p<0.01) in diabetic rats. Moreover, M. graeca scavenged DPPH radical in a dose-dependent manner (IC50=0.48 mg/ml), whereas IC50 was 0.55 mg/ml for BHT. Phytochemical analysis showed the richness of Micromeria graeca on polyphenols (281.94±4.61 mg GAE/1 g), flavonoids, tannins, glycosides, saponins, sterols, sesquiterpenes, and terpenoids.

CONCLUSION

AEMG exhibits antihyperglycemic and antihyperlipidemic activities in STZ-induced diabetic rats and a potent antioxidant capacity.

Antioxidant activity and phenolic compounds identification of Micromeria inodora (Desf.) Benth. from Western Algeria

Micromeria inodora (Desf.) Benth. is most studied for the antimicrobial activity of their essential oils; nevertheless there are no reports on the phenolic compounds of this species and their antioxidant activity. In this study, aqueous and organic extracts were assayed for their antioxidant activity. The polyphenol and total flavonoid content, varied between 175.50 and 332.62 mg GAE/g extract and 65.38-86.30 mg catechin equivalent/g extract, respectively. The results of antioxidant activity have shown that all extracts reported an important activity and the ethyl acetate extract showed the stronger effect, higher than some standards molecules. Its IC₅₀ value of scavenging DPPH is 1.5 ± 0.001 μg/mL; β-Carotene Bleaching assay (BCB) IC₅₀ = 28.1 ± 0.001 μg/mL and the Ferric Reducing Antioxidant Power (FRAP) IC₅₀ = 6.96 ± 0.05 μg/mL. RP-HPLCPDA analysis of phenolic compounds revealed the presence of phenolic acids and flavonoids as: gallic acid, quercetin, rutin, vanillin and naringenin.