Pelargonium quercetorum is a medicinal plant traditionally used for treating intestinal worms. In the present study, the chemical composition and bio-pharmacological properties of P. quercetorum extracts were investigated. Enzyme inhibition and scavenging/reducing properties of water, methanol, and ethyl acetate extracts were assayed. The extracts were also studied in an ex vivo experimental model of colon inflammation, and in this context the gene expression of cyclooxygenase-2 (COX-2) and tumor necrosis factor α (TNFα) were assayed. Additionally, in colon cancer HCT116 cells, the gene expression of transient receptor potential cation channel subfamily M (melastatin) member 8 (TRPM8), possibly involved in colon carcinogenesis, was conducted as well. The extracts showed a different qualitative and quantitative content of phytochemicals, with water and methanol extracts being richer in total phenols and flavonoids, among which are flavonol glycosides and hydroxycinnamic acids. This could explain, at least in part, the higher antioxidant effects shown by methanol and water extracts, compared with ethyl acetate extract. By contrast, the ethyl acetate was more effective as cytotoxic agent against colon cancer cells, and this could be related, albeit partially, to the content of thymol and to its putative ability to downregulate TRPM8 gene expression. Additionally, the ethyl acetate extract was effective in inhibiting the gene expression of COX-2 and TNFα in isolated colon tissue exposed to LPS. Overall, the present results support future studies for investigating protective effects against gut inflammatory diseases.

In the present study, chemical compositions of essential oils from seeds and leaves of laurel (Laurus nobilis L.) were evaluated using GC-GC/MS system. Sixty nine different compounds were identified constituting 86.7% of the total oil from the seed, while 76 compounds were determined, constituting 95.8% of the total oil extracted from the leaves. The major compounds of essential oil from laurel seeds included eucalyptol (17.2%), α-terpinyl acetate (9.0%), caryophyllene oxide (6.1%), spathulenol (5.0%) and methyl eugenol (4.2%), constituting 41.5% of the total oil. However, eucalyptol (18.0%), α-terpinyl acetate (13.1%), sabinene (7.8%), α-pinene (4.5%), 2 (4-methoxyphenyl)-N,N,2-trimethyl-1-pyrroline (4.4%) were identified as the major compounds in the oil from laurel leaves, constituting 47.8% of the total oil. Eucalyptol and α- terpinyl acetate, belonging to monoterpenoids, were determined in the highest concentrations within both oils. However, the other principle compounds differ between the two volatile oils.

The chemical composition, antimicrobial and antioxidant properties of the essential oils from the leaves of endemic Thymus leucostomus naturally grown in Turkey were investigated and chemical differences were discussed by means of chemotaxonomy. Twenty-six components were identified representing 98.8% of the oils. The main compounds in the essential oil of T. leucostomus were: o-cymene (30.6%), carvacrol (9.6%), thymol methyl ether (7.2%), limonene (6.8%). Essential oil was screened for their antimicrobial activities against 7 bacteria and 2 yeast species by using disc-diffusion and MIC procedure. The essential oil showed higher effectiveness against all the tested bacteria and yeast. The extract was observed to be much more effective in Gram-positive bacteria (especially, S. aureus ATCC 6538). In vitro antioxidant activity based on the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical was evaluated for the essential oil, and it was found that the essential oil had good antioxidant activity in the range of the IC50= 5.42 ±0.8 μg/ml.

The chemical composition, antimicrobial and antioxidant properties of the essential oil (EO), obtained from the leaves of Vaccinium myrtillus naturally grown in the northernmost of Turkey were determined by GC and GC-MS and chemical differences were discussed with the help of chemotaxonomy. The leaves of the plant samples were hydro-distilled to produce oil in the yields of 1%. Nineteen components were identified representing 96.4% of the oil. The main compounds in the EO of V. myrtillus were; 1,8-cineole (38.6%), α- pinene (21%), linalool (19.5%), α-terpineol (5.8%). The EO extract was screened for their antimicrobial activities against the 9 bacteria and 3 yeast species by using disc-diffusion and MIC procedure. The EO extract displayed more effective against all the tested bacteria (especially, S. aureus ATCC 6538 and MRSA) and yeast (only C. krusei). The MIC values of sample against tested microorganisms were found to be in the range of 320 to ≥1280 μg/ml. The most effective MIC values were observed against the S. aureus and MRSA (320 μg/ml). In vitro the antioxidant activity based on the 1,1-diphenly-2-picrylhydrazyl (DPPH) free radical was evaluated for the EO extract, and it was found that the extract had good antioxidant activity in the range of the IC50 = 583.4 ±11 μg ml. Antibacterial and antioxidant activities of the EO from the leaves of V. myrtillus has been reported for the first time.

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