Variation in chemical composition and antibacterial activity of the essential oil of wild populations of Phlomis olivieri

Various species of the genus Phlomis have been reported to produce metabolites demonstrating significant pharmacological efficiency. In this study, the essential oils from 12 populations of Phlomis olivieri collected from natural habitats were investigated for their chemical components. The hydrodistillated essential oil analyzed by GC-FID and GC-MS. Analyses revealed 27 compounds, constituting 90.52-98.51% of the essential oils. Results indicated that the major components of the essential oils from various populations of P. olivieri were germacrene D (26.54 to 56.41%), bicyclogermacrene (6.38 to 30.55%), β-caryophyllene (5.32 to 24.52%) and α-pinene (1.29 to 15.53%). Principal component analyses (PCA) was used to identify any geographical variations in essential oil composition. Notably, three groups of Iranian P. olivieri populations were determined according to the major compounds. Results of the in vitro antibacterial activity indicated that P. olivieri essential oils showed good inhibitory activities against bacteria, especially Bacillus subtilis. The results of this study gave new insights for cultivation and industrial uses of P. olivieri in Iran

Quali-quantitative variation of essential oil from Iranian rosemary (Rosmarinus officinalis L.) accessions according to environmental factors

The aim of this study was to assess the effects of environmental factors on quality and quantity of essential oil in Iranian rosemary. Chemical components were identified by GC-FID and GC-MS analyses. Results showed that essential oil yields exhibited significant variation among accessions. The highest contents were recorded for the Bo2 and Bo3 accessions (2.6 and 2.3 ml/100 g, respectively). In these areas the soil samples were richer in nitrogen. The major essential oil constituents were 1,8-cineole (5.32 to 28.29%), camphor (1.58 to 25.32%) and α-pinene (14.19 to 21.43%). The Iranian accessions also exhibited chemical variability for other major compounds such as borneol, piperitone, camphene, bornyl acetate, verbenone and trans-pinocamphone. Multivariate analyses including CA, HCA, DCA and PCA were also used to analyze the collected data. According to multivariate analysis, the Iranian rosemary accessions belonged to two main chemotypes (I camphor type, including Bo1–3, Ke1–3 populations, and II α-pinene/1,8- cineole/camphor type, including Bi1–3, Do1–3, Jo1–3, Kh1–3 and Ma1–3 populations). Results of CA and DCA were similar and both of them were in agreement with the results of PCA. Furthermore, there were positive and negative correlations between the major rosemary constituents and environmental factors in collection localities

Antioxidant and antibacterial activities of the essential oils obtained from seven Iranian populations of Rosmarinus officinalis

Rosemary (Rosmarinus officinalis) is an aromatic shrub belonging to the Lamiaceae family and widely used as herbal remedy and spices. In this work, the leaf essential oil from seven populations of rosemary growing in Western Iran was obtained by hydrodistillation and analyzed by GC-FID and GC-MS. The major chemical groups occurring in the essential oils were monoterpene ketones (14.55 to 37.31%), hydrocarbons (28.36 to 36.81%) and oxygen-containing compounds (9.05 to 27.60%). The major constituents of the essential oils were 1,8-cineole (5.63 to 26.89%), camphor (1.66 to 24.82%) and α-pinene (14.69 to 20.81%). The essential oils were screened for antibacterial and antioxidant activities. The antibacterial activity of the essential oils was evaluated on two gram-positive and two gram-negative strains, namely Streptococcus agalactiae, Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae by the agar disc diffusion method. Results of antibacterial test indicated that the largest inhibition (inhibition zone of 18.51 mm) was achieved with essential oil from Ma population against E. coli. This sample showed high level of 1,8-cineole. Antioxidant activity of the essential oils was evaluated using the DPPH radical inhibition assay (at 0.4, 0.8, 1.6 and 3.2 mg/ml). Overall, the essential oils from the seven populations, at 3.2 mg/ml, exhibited high antioxidant activity (more than 50% radical inhibition). Statistical analysis revealed a significant correlation between some essential oil components and biological activity displayed

Microemulsions for delivery of Apiaceae essential oils – towards highly effective and eco-friendly mosquito larvicides?

The development of effective and eco-friendly pesticides to manage mosquito vector larvae is a timely and crucial challenge nowadays. Insecticide resistance is on the rise, therefore plant-borne insecticides may represent promising candidates to control insect vectors. In the present work, we encapsulated selected essential oils (EOs) from Pimpinella anisum, Trachyspermum ammi and Crithmum maritimum into highly stable microemulsions (MEs) with the aim to develop effective and eco-friendly larvicidal formulations. MEs made with both single EOs and their mixtures were tested against 3rd instar larvae of Culex quinquefasciatus, assessing acute and chronic toxicity, emergence of adults, and their impact on non-target invertebrates, i.e., Daphnia magna, Tubifex tubifex and Eisenia fetida. All MEs were able to exert toxicity against mosquito larvae, with LC50 values in the ranges 1.45-4.01 ml.L-1, along with high larval mortality and low percentage of hatched adults following short-term exposure to sublethal concentrations. Low or none mortality was observed on D. magna and E. fetida. Taken together, these results give new insights for the exploitation of plant-borne EOs as active ingredients of novel and reliable larvicidal products