Antidiabetic, anti-Alzheimer, general toxicity, and antioxidant activities of Salvia syriaca were evaluated. Phytochemical composition of the essential oil and methanolic extract of the plant were identified using gas chromatography-mass spectrometry and reverse-phase high-performance liquid chromatography-diode array detector techniques, respectively. Essential oil of S. syriaca exhibited strong cytotoxicity, antioxidant, α-amylase, and α-glucosidase inhibitory activities. Gas chromatography-mass spectrometry analysis showed that spathulenol (87.4%), isospathulenol (7.6%), and bornyl acetate (2.7%) are the major compounds in essential oil. High-performance liquid chromatography analysis indicated that rutin, quercetin, apigenin, rosmarinic acid, and ferulic acid are the most abundant phenolic components. S. syriaca could be considered as a valuable source of bioactive natural compounds for functional foods, medical, and pharmaceutical applications.

Background and the purpose of the study: The early stage of diabetes mellitus type 2 is associated with postprandial hyperglycemia. Hyperglycemia is believed to increase the production of free radicals and reactive oxygen species, leading to oxidative tissue damage. In an effort of identifying herbal drugs which may become useful in the prevention or mitigation of diabetes, biochemical activities of Polygonum hyrcanicum and its constituents were studied. Methods: Hexane, ethylacetate and methanol extracts of P. hyrcanicum were tested for α-glucosidase inhibitory, antioxidant and radical scavenging properties. Active constituents were isolated and identified from the methanolic extract in an activity guided approach. Results: A methanolic extract from flowering aerial parts of the plant showed notable α-glucosidase inhibitory activity (IC₅₀ = 15 μg/ml). Thirteen phenolic compounds involving a cinnamoylphenethyl amide, two flavans, and ten flavonols and flavonol 3-O-glycosides were subsequently isolated from the extract. All constituents showed inhibitory activities while compounds 3, 8 and 11 (IC₅₀ = 0.3, 1.0, and 0.6 μM, respectively) were the most potent ones. The methanol extract also showed antioxidant activities in DPPH (IC₅₀ = 76 μg/ml) and FRAP assays (1.4 mmol ferrous ion equivalent/g extract). A total phenol content of 130 mg/g of the extract was determined by Folin-Ciocalteu reagent. Conclusion: This study shows that P. hyrcanicum contains phenolic compounds with in vitro activity that can be useful in the context of preventing or mitigating cellular damages linked to diabetic conditions.