RESUMEN
The acaricidal activities of compounds derived from Thymus vulgaris (thyme) oil against Tyrophagus putrescentiae were assessed using an impregnated fabric disk bioassay, and were compared with those of the synthetic acaricides, benzyl benzoate and N,N-diethyl-m-toluamide. The observed responses differed according to dosage and chemical components. The 50% lethal dose (LD50) value of the T. vulgaris oil against T. putrescentiae was 10.2 microg/cm2. Biologically active constituents derived from T. vulgaris oil were purified by using silica gel chromatography and high-performance liquid chromatography. The structures of acaricidal components were analyzed by gas chromatography-mass spectrometry, 1H nuclear magnetic resonance (NMR), 13C NMR, 1H-13C COSY-NMR, and DEPT-NMR spectra, and were subsequently identified as carvacrol and thymol. Carvacrol was the most toxic compound with LD50 values (4.5 microg/cm2) significantly different from thymol (11.1 microg/cm2), benzyl benzoate (11.3 microg/cm2), and N,N-diethyl-m-toluamide (13.9 microg/cm2). Linalool was as toxic as was N,N-diethyl-m-toluamide. The lower LD50 of carvacrol indicates that it may be the major contributor of the toxicity of T. vulagaris oil against the stored food mite, although it only constitutes 14.2% of the oil. From this point of view, carvacrol and thymol can be very useful as potential control agents against stored food mite.
Asunto(s)
Conservación de Alimentos/métodos , Insecticidas/farmacología , Ácaros/efectos de los fármacos , Aceites de Plantas/farmacología , Thymus (Planta)/química , Animales , Bioensayo , Cromatografía en Gel , Cromatografía Líquida de Alta Presión , Cimenos , Relación Dosis-Respuesta a Droga , Microbiología de Alimentos , Cromatografía de Gases y Espectrometría de Masas , Dosificación Letal Mediana , Monoterpenos/farmacología , Control Biológico de Vectores/métodos , Timol/farmacologíaRESUMEN
The growth-inhibitory activity of materials derived from the fruit of Terminalia chebula was evaluated against six intestinal bacteria by means of an impregnated paper disk agar diffusion method. The butanol fraction of T. chebula extract had profound growth-inhibitory activity at a concentration of 5 mg per disk. The biologically active component isolated from the T. chebula fruits was identified with a variety of spectroscopic analyses as ethanedioic acid. The growth responses varied in accordance with the bacterial strain, chemical, and dosage tested. In a test with concentrations of 2 and 1 mg per disk, ethanedioic acid had strong and moderate inhibitory activity against Clostridium perfringens and Escherichia coli, respectively, with no associated adverse effects on the growth of the four tested lactic acid-producing bacteria. Ellagic acid derived from T. chebula fruits exerted a potent inhibitory effect against C. perfringens and E. coli, but little or no inhibition was observed with treatments of behenic acid, P-caryophyllene, eugenol, isoquercitrin, oleic acid, ca-phellandrene, 3-sitosterol, stearic acid, a-terpinene, terpinen-4-ol, terpinolene, or triacontanoic acid. These results may be an indication of at least one of the pharmacological properties of T. chebula fruits.