Comparative study of biological activities of methanol and aqueous leaves extracts of five Juniperus L. (Cupressaceae) species growing in Turkey

Numerous Juniperus L. (Cupressaceae) species, particularly those under the Juniperus section, are frequently employed in Turkish folk medicine to treat several diseases. Since ancient times, Juniperus L. female cones and leaves have been utilized as an antihelmintic, diuretic, stimulant, wound-healing, and antiseptic [1]. In continuation of our studies on Juniperus L. species under Juniperus section growing in Turkey, this work was designed to define and compare the antioxidant and antimicrobial properties of methanol and aqueous leaves extracts of five Juniperus species: J. communis L. var. communis (Jcc), J. communis L. var. saxatilis Pall. (Jcs), J. drupacea Labill. (Jd), J. oxycedrus L. ssp. oxycedrus (Joo), J. oxycedrus L. ssp. macrocarpa (Sibth. & Sm.) Ball. (Jom). MATERIALS AND METHODS The total polyphenol content (TPC) of Juniperus L. spp. leaves extracts was determined spectrophotometrically by the Folin-Ciocalteau reagent. The antioxidant properties were examined in vitro by DPPH test, reducing power assay, and TBA assay. In addition, the antioxidant activity of the extracts was correlated to the TPC. The Artemia salina Leach (brine shrimp) lethality bioassay was employed to predict the potential cytotoxic activity of the extracts. Further, the antimicrobial potential of Juniperus L. spp. extracts against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, and Aspergillus niger ATCC strains was evaluated by standard methods [2]. RESULTS AND DISCUSSION The TPC of Juniperus L. spp. leaves methanol extracts ranged from 71.76 ± 0.13 mgGAE/g (Jcc) to 133.28 ± 1.74 mgGAE/g (Joo); the TPC of water extracts ranged from 70.08 ± 2.51 mgGAE/g (Jcc) to 176.05 ± 1.15 mgGAE/g (Joo). Both in the DPPH test and in the reducing power assay, Joo methanol extract was found to be the most active (IC50 = 0.092 ± 0.006 mg/mL and ASE/mL = 2.56 ± 0.06, respectively). A strong positive correlation between primary antioxidant activity and TPC was found. In the TBA assay, Jcs methanol extract exhibited the highest activity (IC50 = 4.39 ± 0.47 μg/mL). A positive correlation between TPC and anti-lipid peroxidation activity was highlighted for aqueous extracts, whilst no correlation with methanol extracts was found. All the extracts resulted potentially non-toxic against Artemia salina (LC50 > 1000 μg/mL). The MIC values obtained from the antimicrobial tests indicated that Juniperus L. spp. leaves extracts display bacteriostatic activity versus S. aureus, whereas they are not effective against the Gram-negative bacteria and the yeasts tested in the study. CONCLUSIONS The results of our investigation give a scientific basis to the ethnopharmacological use of these Turkish Juniperus L. species, also demonstrating the potential of their leaves as sources of natural antioxidant and antimicrobial compounds. REFERENCES 1. Tumen, I.; Süntar, I.; Keleş, H.; Akkol, E.K., A therapeutic approach for wound healing by using essential oils of Cupressus and Juniperus species growing in Turkey. Evid Based Complement Altern Med 2012, 1-7. 2. Miceli, N.; Trovato, A.; Marino, A.; Bellinghieri, V.; Melchini, A.; Dugo, P.; Cacciola, F.; Donato, P.; Mondello, L.; Güvenç, A.; De Pasquale, R.; Taviano, M.F., Phenolic composition and biological activities of Juniperus drupacea Labill. berries from Turkey. Food Chem Toxicol 2011, 49 (10), 2600-2608.