Background and the purpose of the studyThe 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.MethodsHexane, 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.ResultsA 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.ConclusionThis 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.

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The present study investigated the chemical composition of the essential oil (EO) from aerial parts (flowering stage) of Pulicaria vulgaris Gaertn. by GC-MS. Also, the antimicrobial activity of the EO against Gram-positive bacteria (Bacillus cereus and Staphylococcus aureus), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and fungi (Aspergillus niger and Candida albicans) was tested. In total, 23 compounds were recognized, accounting for 98.08 % of the EO. The main compounds in the EO were thymol (50.22%), p-menth-6-en-2-one (carvotanacetone, 20.2%), thymol isobutyrate (16.88%), menthan-2-one (4.31%), 1-methyl-1,2-propanedione (4.13%), 2,5-dimethoxy-p-cymene (4.01%), myrtenol (1.22%), linalool (1.1%), and β-myrcene (1.9%). Results of antibacterial test of P. vulgaris essential oil showed that all assayed concentrations significantly inhibited the growth of B. cereus, S. aureus, E. coli, and P. aeruginosa at P < 0.05. MIC for B. cereus, S. aureus, E. coli, P. aeruginosa was 17.5, 25.2, 19.4 and 33.2 µg/mL respectively; antifungal screening of the essential oil of P. vulgaris showed that the oil significantly inhibited the growth of A. niger and C. albicans (MIC = 15.5 and 9.9 µg/mL, respectively). Results of cytotoxicity assay showed that the essential oil exhibited a significant cytotoxic activity against both cell lines. In case of MCF-7 and Hep-G2 cell lines, IC 50 of the essential oil were 5.36 and 7.16 μg/ml, respectively. The potent antimicrobial and cytotoxic activities of the EO may be attributed to its high contents of thymol, carvotanacetone and thymol isobutyrate. Antimicrobial and antitumor chemotherapies are showing diminishing effectiveness because of emergence of drug-resistance. Hence, using efficient natural chemotherapeutic agents such as Pulicaria vulgaris essential oil with fewer side effects is an encouraging approach to fight cancer and infectious diseases in medicine, agriculture, food science and related fields.

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