Abstract
In this study, the oil constituents of Lippia gracilis were identified by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The antioxidant and antifungal activities were also evaluated. The leaf oil showed a yield of 3.7% and its main constituents were thymol (70.3%), p-cymene (9.2%), thymol methyl ether (5.4%) and p-methoxythymol (2.7%). The thin stem oil showed a yield of 0.4% and its major components were thymol (70.1%), thymol methyl ether (4.4%), p-methoxythymol (4.0%), p-cymene (3.8%), α-humulene (2.4%) and (E)-caryophyllene (2.1%). The aromatic monoterpenes found in the oils showed an average of 88%. The scavenging activity of the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) for the leaf oil, expressed as half maximal effective concentration (EC50), was 35.7±3.3 µg/ml, indicating high antioxidant activity. The evaluation of fungicide activity for the leaf oil, using direct bioautography, showed also a significant value for lethal concentration (LC50 5.0 μg/ml) against Cladosporium sphaerospermum and C. cladosporioides fungi. Key words: Essential oil composition, thymol and carvacrol, DPPH radical scavenging and bioautography
Highlights
Lippia (Verbenaceae) comprises nearly 200 species of herbs, shrubs and small trees spread wide in South and Central America and Tropical Africa
L. gracilis occurring in Northeast Brazil have shown
From the Brazilian Amazon showed significant amounts of thymol, carvacrol, p-cymene, 1,8-cineole, -terpinene, (E)-caryophyllene, citral, carvone and terpinen-4-ol (Zoghbi et al, 1998; Zoghbi et al, 2001; Maia et al, 2005; Morais et al, 1972; Silva et al, 2009; Damasceno et al, 2011). This way, one must consider that these chemical types of L. gracilis may result from the polymorphism of the plant, taking into account, mainly, the season time and site collection
Summary
Lippia (Verbenaceae) comprises nearly 200 species of herbs, shrubs and small trees spread wide in South and Central America and Tropical Africa. The oil produced in Ceará state showed thymol (30.6%), carvacrol (11.8%) and p-cymene (10.7%) as main compounds (Lemos et al, 1992). The oil analyzed in Sergipe state was dominated by thymol (24.0%), p-cymene (15.9%), methylthymol (11.7%) and γ-terpinene (10.9%) (Teles et al, 2010). The main volatile constituents frequently found in the oils of Lippia species are thymol, carvacrol, p-cymene methylthymol, methylcarvacrol, γ-terpinene, 1,8-cineole and (E)-caryophyllene. The aim of this study was to analyze the oil composition of leaves and thin stems of L. gracilis that occur in the eastern Brazilian Amazon, as well as to evaluate their antioxidant and antifungal and activities
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