[Investigation of the in vitro effects of Melissa officinalis L., Mentha x piperita L. and Ocimum basilicum L. (Lamiaceae) essential oils on the cysts and trophozoites of Acanthamoeba castellani]. / Melissa officinalis L., Mentha x piperita L. ve Ocimum basilicum L. (Lamiaceae) uçucu yaglarinin Acanthamoeba castellani kist ve trofozoitleri üzerine in vitro etkisinin arastirilmasi.

Acanthamoeba species are free living amoeba found widely all over the world. They are responsible for Acanthamoeba keratitis (AK), an infection which is especially seen in contact lens users and after minor corneal traumas, that may lead blindness. At present, antifungals and antiseptics are used for the treatment of AK cases, however, some problems such as long treatment periods and the occurrence of side effects, resistance of cyst forms against drugs, emphasize the need for new drugs. There are some published studies that pointed out the effectiveness of plant extracts and essential oils on Acanthamoeba spp. The aim of this study was to investigate the in vitro effects of essential oils of Mentha x piperita L. (peppermint), Melissa officinalis L. (lemon balm) and Ocimum basilicum L. (basil) belonging to Lamiaceae family, on the cysts and trophozoites of Acanthamoeba castellanii. The strain used in our study, namely A. castellanii T4 genotype, is the most frequently isolated amoeba from environment and also the causative agent of AK and granulomatous amebic encephalitis. For the determination of amebicidal activity, essential oils obtained from Mentha x priperita L., Melissa officinalis L. and Ocimum basilicum L. by Neo-Clevenger type of distillation apparatus have been used. In vitro experiments were performed by using 96-well microplates. Cyst and trophozoite solutions were added on the essential oil dilutions to obtain the last concentrations of 40, 20, 10, 5, 2.5 and 1.25 µg/ml for the cysts, and 10, 5, 2.5, 1.25, 0.625 and 0.313 µg/ml for the trophozoites. After the incubation of microplates at 30oC for 1, 6, 24, 48 and 72 hours, the viability of parasitic forms were evaluated under the light microscope followed by staining trypan blue. It was found that, each essential oil showed amebicidal effect on A.castellani cysts and trophozoites dependent on dosage and time, when compared with the control group, The maximum lethal effect occured with Melissa officinalis followed by Mentha x piperita and Ocimum basilicum, respectively. In our study, susceptibility of A.castellanii trophozoites to essential oils were more than the cysts, as expected. The essential oils of Melissa officinalis and Mentha x piperita showed 100% lethal effect at their highest concentrations whereas the essential oil of Ocimum basilicum showed only 63.3% lethal effect on cysts after 72 hours at the highest concentration (40 µg/mL). The results of this first study investigating the activities of essential oils extracted from Mentha x piperita, Melissa officinalis and Ocimum basilicum against Acanthamoeba spp. cysts and trophozoites, have suggested that, these essential oils could be potential novel and alternative natural products for the treatment of Acanthamoeba spp. infections.

Antimicrobial, insecticidal and phytotoxic activities of Cotinus coggyria Scop. essential oil (Anacardiaceae).

The essential oil of Cotinus coggyria Scop.' leaves was found to be rich in α-pinene (43.1%), limonene (21.3%) and ß-myrcene (8.5%). In the antimicrobial screening, essential oil was notably active on Staphylococcus aureus ATCC 29213, S. aureus ATCC BAA-977, Candida albicans ATCC 14053 and C. parapsilosis ATCC 22019 using the disc diffusion and volatilisation assays. The fumigant assay of the essential oil caused 70% and 100% mortality on the two pest adults of Acanthoscelides obtectus and Tribolium castaneum at 80 µL L⁻¹ air concentration at 96 h, respectively. In the toxicity assay on weeds, a dose-dependent decrease was observed in the germination and seedling growth of Silybum marianum and Portulaca oleracea. The present results indicated that oil could be suggested as an effective biocontrol agent in various fields.

Flavonoids in Helichrysum pamphylicum inhibit mammalian type I DNA topoisomerase.

DNA topoisomerases are important targets for cancer chemotherapy. We investigated the effects of a methanolic extract of Helichrysum pamphylicum on mammalian DNA topoisomerase I via in vitro plasmid supercoil relaxation assays. The extracts manifested a considerable inhibition of the enzyme's activity in a dose-dependent manner. We also performed a HPLC analysis to identify the flavonoid content of the H. pamphylicum extract and tested the identified flavonoids; luteolin, luteolin-4-glucoside, naringenin, helichrysinA and isoquercitrin, on DNA topoisomerase I activity. The measurement of the total antioxidant capacity of the flavonoid standards suggested that the topoisomerase inhibition might be correlated with the antioxidant capacity of the plant.

Essential oil composition and antioxidant activity of endemic Ziziphora taurica subsp. cleonioides.

The essential oil of Turkish endemic Ziziphora taurica subsp. cleonioides aerial parts was found to contain (+)-pulegone (81.86%), limonene (4.48%) and piperitenone (2.30%) activity. The essential oil showed relevant antioxidant activity.

Hypericum triquetrifolium Turra. Extract exhibits antiinflammatory activity in the rat.

The aim of the present study was to explore the probable antiinflammatory effect of Hypericum triquetrifolium Turra. in a rat model of carrageenan induced inflammation. Male Wistar rats were treated intraperitoneally with 0.4% dimethylsulphoxide (DMSO) (as control group) and H. triquetrifolium extract (25, 50, 60 mg/kg), 30 min before 0.1 ml 1% carrageenan injection. Paw volume was measured before and 1, 2, 3, 4, 5 and 6 h after the injection of carrageenan. The results are expressed as the mean+/-s.e. mean and the statistical significance of differences between groups was analyzed by One Way Analysis of Variance (ANOVA). The intraplantar injection of carrageenan caused a time-dependent paw edema in the rat although saline injection caused no swelling. Intraperitoneal administration of H. triquetrifolium extract (25, 50, 60 mg/kg) inhibited paw swelling dose-dependently at 2, 3, 4, 5 and 6 h after carrageenan injection (P<0.05). We can conclude that H. triquetrifolium extract may exert an antiinflammatory effect in rats.