Chemical and biological investigations of essential oils from Juniperus genus

Objective ln the context of problem solving of environmental damages caused by synthetic pesticides, the objectives of this work were 1 ) to determine the chemical composition of essential oils ffom fresh leaves and branches of common juniper (J##7.per£ts comm#77j.s L.), rocky mountain juniper (J!t#z.per#s scop#/or#;7] Sarg.), and creeping juniper (/3t#z.per#s ¢or7.zo#/cz/z.s Moench.) from Bighom Mountains (Wyoming); 2) to evaluate thier antimicrobial activity against four phytopathogenic fiingi (A4lo#z./z.7zz.c7 //.itc/j.co/o [G. Winter] Honey, Aspergillus niger van Tìeghern, Penicillium expansum Link ànd Botrytis cinerea Pers.), aLgz\±rLst two Grarnpositive (G+ve), Bc7cz.//#s megc7/erz.#m de Bary (ITM100) and C/czvz.bczc/cr m7.c¢z.gcr#e#sz.s Smith and three Gram-negative (G-ve) bacterial strains, Pse#c7omo#cLs /#oresce7?s Flùgge (Migula), P. s}jrz.#gcre pv. p¢c#eo/7.co/cr Van Hall and .Ycr77/Àomowc7s cczmpes/rz.s Pammel; 3) to assay their antioxidant capability. Methods The essential oils were obtained by steam distillation ffom leaves and branches of the three species ofJ3t77jpera4§ and were characterized by GC-MS. The possible fimgicidal activity of the EOs was evaluated at two different doses and fimgitoxicity was expressed as percentage of mycelium growth compared to the negative control. The antibacterial test was carried out following the disc diffi]sion method by measuring the diameter of inhibition hyaline zone (mm) around each treated disc compared to the positive control one. Also cell membrane permeability (CMP) was determined by measuring the potential of electrical current transport through water as molar conductivity or electrolytic conductivity (EC) and the results were expressed as increasing percantage of EC value. The antioxidant activity was also detemined using the stable l ,1 -diphenyl-2-picrylhydrazyl radical method (DPPH) and EC50 value was defined as the dose of sample which reduced the initial DPPH of 50%. Results The assays used for the evaluation of some biological activities of the tested EOs showed variable results. The major component of J. comm##z.§ was oi-pinene; sabinene was the main constituent of /. scop2//oratm and J. ¢orz.zo#/cz/z.s. The three tested EOs have antifimgal activity against A4 /"cf7.co/c7 and P. expc!#sc4m and effective antibacterial activity against P. s);rz.#gcre pv. pÀc7§eo/z.co/c7 and 8. megcz/erz.atm. The results of antioxidant activity showed comparable EC5o value between all three evaluated juniper EOs: after 45 minutes of experimental time the EC50 values are 487.1 Hg/ml for J. commct77z.s, 527.4 Hg/ml for /. scope//or£/m, 533 .3 Hg/ml for J. s'copat/orc/m. Conclusions The outfindings of this research showed promising antimicrobial effects against the majority of the tested phytopathogens: these data, conoborated also ffom the antioxidant capability shown by the three essential oils, highlighted potential for a their possible utilize them as natural altematives to synthetic drugs, cause of global environmental problems, pathogen resistance and difficulty to control many post-harvest plant diseases.