Abordagem Química e Farmacológica do Estoraque (Ocimum micranthum Willd)

Abstract

The species Ocimum micranthum Willd (Lamiaceae) is known in the Amazon region as estoraque. Probably of Asian origin, it occurs predominantly in the northern and northeastern regions of Brazil, and is popularly used in folk medicine, in religious baths and rituals, and in cooking. Previous study of the species revealed a high yield of essential oil, rich in methyl (E)-cinnamate. In order to expand the scientific knowledge about the species, we analyzed the subacute toxicity of the storax essential oil (OEOm) in mice, and its antinociceptive effect through the use of differentiated nociceptive test models using the acetic acid and hot plate (55 ± 1°C) tests. The Dl.; of OEOm was obtained at a dose of 4000mglKg. OEOm, orally, showed antinociceptive effect at a dose of 250 mg/kg, probably due to inhibition of prostaglandin synthesis, a mechanism of action common to all non-steroidal anti-inflammatory drugs. In the hot plate test, OEOm showed an antinociceptive effect at a dose of 500 mg/kg, suggesting a central analgesic mechanism. The favorable chemical and biological characteristics of the essential oil of o. micranthum have raised the interest for propagation studies, and the necessity of using a micro technique for extraction of its volatile components for chemical monitoring of genotypes of the species in propagation experiments. This motivated the realization of an experiment to verify the effectiveness of the extraction of volatiles using simultaneous distillation-extraction (DES) comparing the results with those obtained by hydrodistillation, and determining the minimum amount of sample for extraction. Samples of 1000, 500, 100, 70, 50 and lOmg were used, in a Chrompack system, and pentane (3mL) as solvent. The components were identified by CGIEM, using DB-5MS column (30m x 0.25mm; 0.25mm), and helium as carrier gas, the injector and detector temperature was 250-C and temperature program 60-C-240-C (rClmin). The data obtained indicated the effectiveness of extraction using DES for o. micranthum, where 56.3% of the components showed 0.1 correlation factor, including the principal components, except for limonene. The lowest amount of 23 ro +"'" Cl) eo Cl) Cl) ro u ro o C ro +"'" 24 sample used in the experiment was 10mg, which still allowed the major components to be monitored. The results presented suggest a peripheral and central analgesic activity, and a low toxicity for OEOm, which lead to suggest a good therapeutic index for OEOm, and that the DES technique is a strong tool for studies of the chemical composition of the essential oil of O. micranthum in experiments where the sample amount is reduced