In vitro inhibition of CYP2B1 monooxygenase by beta-myrcene and other monoterpenoid compounds.
ABSTRACT beta-myrcene (MYR) is an acyclic monoterpene found in the essential oils of several useful plants such as lemongrass (Cymbopogon citratus), hop, bay, verbena and others. Recently it has been reported that MYR as well as lemongrass oil blocked the metabolic activation of some promutagens (e.g., cyclophosphamide and aflatoxin B1) in in vitro genotoxicity assays. The present study was performed to evaluate the inhibitory effects of MYR and some other monoterpenoid compounds on microsomal enzymes involved in the activation of genotoxic substances. The effects of MYR and other monoterpenes on the activity of pentoxyresorufin-O-depenthylase (PROD), a selective marker for CYP2B1, was determined in a pool of liver microsomes prepared from phenobarbital-treated rats. The effect of MYR on the activity of ethoxyresorufin-O-deethylase (EROD), a marker for CYP4501A1, was investigated in liver microsomes of untreated rats. Results revealed that MYR had almost no effect on EROD (IC50 > 50 microM), but produced a concentration-dependent inhibition of PROD activity (IC50 =0.14 microM). The analysis of alterations produced by MYR on PROD kinetic parameters (Lineweaver-Burk plot) suggested that inhibition is competitive (Ki = 0.14 microM). The inhibitory effects of seven other monoterpenes on PROD activity (pentoxyresorufin 5 microM) were also studied and the IC50 were as follows: (-)-alpha-pinene, 0.087 microM; (+)-alpha-pinene, 0.089 microM; d-limonene, 0.19 microM; alpha-terpinene, 0.76 microM; citral, 1.19 microM; citronellal, 1.56 microM, and (+/-) camphor, 7.89 microM. The potent inhibitory effects on CYP4502B1 suggest that MYR, and other monoterpenes, interfere with the metabolism of xenobiotics which are substrates for this isoenzyme.
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ABSTRACT: The essential oils (EOs) from the Brazilian species Croton zehntneri, Pterodon emarginatus and Schinopsis brasiliensis were examined for their chemical constituents, and antioxidant and antimicrobial activities. The composition of EOs was determined by using gas chromatography coupled with mass spectrometry analysis, while the antioxidant activity was evaluated through the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and oxygen radical absorbance capacity (ORAC) assays. Furthermore, the antimicrobial activity was investigated against Escherichia coli and Pseudomonas aeruginosa (both Gram-negative), Staphylococcus aureus (Gram-positive) and Candida parapsilosis (fungus). The main components of C. zehntneri, P. emarginatus and S. brasiliensis were identified as estragole, trans-anethole, b-caryophyllene and myrcene. Among the EOs, P. emarginatus showed the highest antioxidant activity, with an IC50 of 7.36 mg/mL and a Trolox equivalent antioxidant capacity of 3748mmol/g determined by DPPH and ORAC assays, respectively. All EOs showed low activities against the bacterial strains tested, whereas the C. zehntneri oil and its main constituent estragole exhibited an appreciable antifungal activity against C. parapsilosis. Keywords: Brazilian plants; essential oils; DPPH; ORAC; Candida parapsilosis
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ABSTRACT: The present investigation was aimed to analyse the chemical composition of essential oil isolated from Heracleum persicum Desf. ex Fischer and assess its lethal and sub-lethal effects against Tribolium castaneum (Herbst). Essential oil from hydro-distilled seeds of H. persicum was analyzed by gas chromatography-mass spectrometry (GC-MS), and hexyl butyrate (50.58%), octyl acetate (9.80%) and hexyl hexanoate (8.75%) were found as principal constituents. Repellent activity, contact and fumigant toxicity and antifeedant effects of this oil were assessed against the adults of T. castaneum. The essential oil strongly repelled T. castaneum adults even at the lowest concentration (0.035 μL cm–2). Complete repellency 100%) occurred when the highest concentration (0.212 μL cm–2) was applied for 8 h. T. castaneum was very susceptible to H. persicum oil at both contact and fumigant bioassays. In the fumigant toxicity, essential oil killed the larvae, pupae and adults and significantly decreased larvae emerged from treated eggs. LC10 to LC40 values of fumigation adult’s bioassay as sub-lethal concentrations were used to evaluate the antifeedant effects. H. persicum essential oil has significant antifeedant effects on T. castaneum adults and decrease of feeding happened when oil concentrations increased. The results of the present study indicate that essential oil of H. persicum, with wide bio-effects on T. castaneum, is a source of biologically active agents which may potentially prove to be efficient insecticides.SPANISH JOURNAL OF AGRICULTURAL RESEARCH 12/2014; 12(4):1166-1174. DOI:10.5424/sjar/2014124-6527 · 0.51 Impact Factor
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ABSTRACT: Pimpinella brachycarp is a widely distributed vegetable with known antibacterial, antitumor, antioxidant, antithrombotic, and anti-inflammatory effects. In the present study, a cocktail probe assay and LC-MS/MS were used to investigate the modulating effect of the ethanolic extract of P. brachycarp on CYP enzymes in human liver microsomes. The extract significantly inhibited CYP 1A2, 2B6, and 3A4 by mix-mode inhibition and CYP2C19 and 2D6 by competitive inhibition.Journal of the Korean Society for Applied Biological Chemistry 02/2014; 57(1):113-116. DOI:10.1007/s13765-013-4206-2 · 0.54 Impact Factor