Dissertação
Composição química e atividades biológicas de Ocimum gratissimum L.
Fecha
2009-03-31Registro en:
SILVA, Lenise de Lima. Chemical composition and biological activities of Ocimum gratissimum L.. 2009. 165 f. Dissertação (Mestrado em Farmácia) - Universidade Federal de Santa Maria, Santa Maria, 2009.
Autor
Silva, Lenise de Lima
Institución
Resumen
Ocimum gratissimum L. (Lamiaceae), known as alfavaca, is widely distributed in tropical and
warm-temperature regions. It is used as a food flavoring and for medicinal purposes against
infectious diseases. Its biological properties are attributed to the presence of thymol or
eugenol-rich essential oils. This study describes qualitative and quantitative variations in
essential oils from stems, inflorescences and leaves of O. gratissimum L. grown in southern
Brazil, in two harvest periods. The evaluation of eugenol content, antibacterial activity and
toxicity of the different ethanolic extracts from dried aerial parts of O. gratissimum were
studied. Afterwards, the essential oil from fresh inflorescences had its antibacterial activity,
toxicity and chemical composition determined. The essential oils were obtained by
hydrodistillation and analyzed by GC/MS. The extracts were obtained by maceration, soxhlet,
ultrasonic cleaning bath, ultrasonic horn and microwave-assisted extractions. Eugenol content
was determined by GC-FID using the pure compound isolated from aerial parts of the plant as
reference. Antibacterial activity was assayed by microdilution method as established by
CLSI/NCCLS. Toxicity was verified by brine shrimp (Artemia salina L.) lethality test. The
major compounds of all essential oils were eugenol (52.6 - 89.2 %) and γ-muurolene (6.2
35.3 %). The harvest season influenced only the yields of inflorescence and stem essential
oils. The low seasonal variation of eugenol in the essential oil of the leaves indicated that
these are the best source to obtain this compound. Inflorescences essential oil was
bacteriostatic (MIC between 0.5-2 mg/mL) and bactericidal (MBC between 1-4 mg/mL)
against all strains tested. Significant differences (P<0.05) among the extractive methods used
to the obtention of ethanolic extracts were observed in all analyses. Higher antimicrobial
activity was verified to extracts compared to the essential oil tested against S. aureus ATCC
25923 and clinical isolate of B. cereus, MRSA (MIC of 0.66 mg/mL), ESBL and Shigella
flexneri (MIC of 1.32 mg/mL). Bactericidal activity of the extracts was verified in Grampositive
bacteria. Eugenol content did not explain all differences obtained among the
antimicrobial activities of the tested extracts. The results suggest synergistic action among
phyto-constituents. Maceration was considered the best extraction process considering the
biological activities of all extracts. The antimicrobial avaliation results confirmed the brine
shrimp lethality test as predictive method for this activity.