ABSTRACT
Objective:To determine the chemical composition, as well as the antioxidant, antityrosinase and antibacterial activities of essential oils obtained from some Apiaceous and Lamiaceous plants collected in Thailand.Methods:The essential oils of the specified spices and aromatic herbs were obtained by hydro-distillation, and their chemical constituents were analyzed by gas chromatography/mass spectrometry. Antioxidant assays were based on the scavenging effects of 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2’-Azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) free radicals as well as the lipid oxidation inhibition of ß-carotene bleaching by linoleic acid. Tyrosinase enzyme inhibition was evaluated by the dopachrome method. Broth microdilution technique was performed for the purposes of studying microbial growth inhibition against the isolated bacterial strains.Results:The essential oils of Elsholtzia stachyodes, Coleus amboinicus (I) and Trachyspermum ammi presented a high degree of potency in DPPH, ABTS and ß-carotene bleaching assays. The Trachyspermum ammi oil, which mainly contained thymol (49.04%) and p-cymene (22.06%), proved to be the most effective in terms of antibacterial activity. The major compositions of Coleus amboinicus (I) were carvacrol (51.57%), y-terpinene (18.04%) and p-cymene (7.81%); while thymol (43.76%) and y-terpinene (24.61%) were identified as the major components of Elsholtzia stachyodes oil, with p-cymene (6.73%) being identified as a minor constituent. Moreover, Cuminum cyminum oil containing cuminaldehyde (49.07%) and Elsholtzia communis oil composed with geranial (44.74%) and neral (35.27%) as the major components displayed a specific ability for the inhibition of the mushroom tyrosinase enzyme.Conclusions:The results indicated that these bioactive essential oils obtained from indigenous herbs are of significant interest as alternative raw materials in food, cosmetic and medicinal products.
ABSTRACT
Objective: To determine the chemical composition, as well as the antioxidant, antityrosinase and antibacterial activities of essential oils obtained from some Apiaceous and Lamiaceous plants collected in Thailand. Methods: The essential oils of the specified spices and aromatic herbs were obtained by hydro-distillation, and their chemical constituents were analyzed by gas chromatography/mass spectrometry. Antioxidant assays were based on the scavenging effects of 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) free radicals as well as the lipid oxidation inhibition of ß-carotene bleaching by linoleic acid. Tyrosinase enzyme inhibition was evaluated by the dopachrome method. Broth microdilution technique was performed for the purposes of studying microbial growth inhibition against the isolated bacterial strains. Results: The essential oils of Elsholtzia stachyodes, Coleus amboinicus (I) and Trachyspermum ammi presented a high degree of potency in DPPH, ABTS and ß-carotene bleaching assays. The Trachyspermum ammi oil, which mainly contained thymol (49.04%) and p-cymene (22.06%), proved to be the most effective in terms of antibacterial activity. The major compositions of Coleus amboinicus (I) were carvacrol (51.57%), y-terpinene (18.04%) and p-cymene (7.81%); while thymol (43.76%) and y-terpinene (24.61%) were identified as the major components of Elsholtzia stachyodes oil, with p-cymene (6.73%) being identified as a minor constituent. Moreover, Cuminum cyminum oil containing cuminaldehyde (49.07%) and Elsholtzia communis oil composed with geranial (44.74%) and neral (35.27%) as the major components displayed a specific ability for the inhibition of the mushroom tyrosinase enzyme. Conclusions: The results indicated that these bioactive essential oils obtained from indigenous herbs are of significant interest as alternative raw materials in food, cosmetic and medicinal products.
ABSTRACT
The flowers of African marigold [Tagetes erecta L], a medicinal plant widely cultivated in Thailand, were subjected to evaluation for total phenolics, DPPH scavenging and thiobarbituric acid-reactive substance [TBARs] assays as well as tyrosinase inhibitory activity. In preliminary studies, the ethyl acetate [EA] extract obtained by continuous extraction showed the highest activities with highest phenolic content among all extracts. Bioassay-guided fractionation of EA extract led to isolation of a flavonoid identified as quercetagetin. Interestingly, it was found that quercetagetin exhibited potent DPPH scavenging activity with IC50 of 3.70 Micro g/ml which is about 2-3 times higher activity than standard quercetin [IC50 5.07 Micro g/ml] and trolox [IC50 9.93 Micro g/ml]. Moreover, it exhibited tyrosinase inhibitory activity on L-tyrosine [IC50 89.31 Micro g/ml], higher than Alpha - and Beta -arbutins [IC50 157.77 and 222.35 Micro g/ml] and slightly higher [IC50 128.41 Micro g/ml] than ellagic acid [IC50 151.1 Micro g/ml] when using L-DOPA as substrate. Testing with skin fibroblasts, all the extracts and quercetagetin demonstrated no toxic effect. These finding strongly indicate that African marigold flower is a promising source of natural antioxidative and tyrosinase inhibitory substances with safe to skin