In Vitro and In Vivo Antimelanogenesis Effects of Leaf Essential Oil from Agathis dammara.

Agathis species are widely distributed around Southeast Asia, Australasia, South Pacific islands, and etc. Traditionally, Agathis species have been used as the folk medicines, the common ethnopharmacological uses of Agathis genus are the treatments of headache and myalgia. This study aims to investigate the chemical composition of Agathis dammara (Lamb.) Rich. leaf essential oil and to explore its antimelanogenesis effect. The chemical constituents of leaf essential oil are analyzed using gas chromatography-mass spectrometry (GC-MS), the major constituents of leaf essential oil are sesquiterpenoids. The major constituents are δ-cadinene (16.12%), followed by γ-gurjunene (15.57%), 16-kaurene (12.43%), ß-caryophyllene (8.58%), germacrene D (8.53%), and γ-cadinene (5.33%). As for the in vitro antityrosinase activity, leaf essential oil inhibit the tyrosinase activity of mushroom when the substrate is 3,4-dihydroxyphenylalanine (L-DOPA). Leaf essential oil prevents tyrosinase from acting as diphenolase and catalyzing L-DOPA to dopaquinone, and converting into dark melanin pigments. A. dammara leaf essential oil also exhibits the in vivo antimelanogenesis effect, leaf essential oil reduces 43.48% of melanin formation in zebrafish embryos at the concentration of 50 µg/mL. Results reveal A. dammara leaf essential oil has the potential for developing the skin whitening drug and depigmentation ingredient for hyperpigmentary disorders.

Xanthine Oxidase Inhibitory Activity and Chemical Composition of Pistacia chinensis Leaf Essential Oil.

Gout is a common metabolic disease caused by abnormal purine metabolism that promotes the formation and deposition of monosodium urate crystals within joints that causes acute arthritis and can seriously affect the daily life of patients. Pistacia chinensis is one of the traditional medicinal plants of the Anacardiaceae family, and there have been many studies on its biological activity, including anti-inflammatory, antidepressant, antibacterial, antioxidant, and hypoglycemic activities. The aim of this study was to evaluate the antigout effect of P. chinensis leaf essential oil and its constituents through xanthine oxidase inhibition. Leaf essential oil showed good xanthine oxidase inhibitory activity for both substrates, hypoxanthine and xanthine. Six fractions were obtained from open column chromatography, and fraction E1 exhibited the best activity. The constituents of leaf essential oil and fraction E1 were analyzed by GC-MS. The main constituents of both leaf essential oil and fraction E1 were limonene and 3-carene; limonene showed a higher inhibitory effect on xanthine oxidase. Based on the enzyme kinetic investigation, limonene was the mixed-type inhibitor against xanthine oxidase. The results revealed that Pistacia chinensis leaf essential oil and limonene have the potential to act as natural remedies for the treatment of gout.

Evaluation of Motor Coordination and Antidepressant Activities of Cinnamomum osmophloeum ct. Linalool Leaf Oil in Rodent Model.

Cinnamomum plants (Lauraceae) are a woody species native to South and Southeast Asia forests, and are widely used as food flavors and traditional medicines. This study aims to evaluate the chemical constituents of Cinnamomum osmophloeum ct. linalool leaf oil, and its antidepressant and motor coordination activities and the other behavioral evaluations in a rodent animal model. The major component of leaf oil is linalool, confirmed by GC-MS analysis. Leaf oil would not induce the extra body weight gain compared to the control mice at the examined doses after 6 weeks of oral administration. The present results provide the first evidence for motor coordination and antidepressant effects present in leaf oil. According to hypnotic, locomotor behavioral, and motor coordination evaluations, leaf oil would not cause side effects, including weight gain, drowsiness and a diminishment in the motor functions, at the examined doses. In summary, these results revealed C. osmophloeum ct. linalool leaf essential oil is of high potential as a therapeutic supplement for minor/medium depressive syndromes.

Thermal Degradation of Linalool-Chemotype Cinnamomum osmophloeum Leaf Essential Oil and Its Stabilization by Microencapsulation with ß-Cyclodextrin.

The thermal degradation of linalool-chemotype Cinnamomum osmophloeum leaf essential oil and the stability effect of microencapsulation of leaf essential oil with ß-cyclodextrin were studied. After thermal degradation of linalool-chemotype leaf essential oil, degraded compounds including ß-myrcene, cis-ocimene and trans-ocimene, were formed through the dehydroxylation of linalool; and ene cyclization also occurs to linalool and its dehydroxylated products to form the compounds such as limonene, terpinolene and α-terpinene. The optimal microencapsulation conditions of leaf essential oil microcapsules were at a leaf essential oil to the ß-cyclodextrin ratio of 15:85 and with a solvent ratio (ethanol to water) of 1:5. The maximum yield of leaf essential oil microencapsulated with ß-cyclodextrin was 96.5%. According to results from the accelerated dry-heat aging test, ß-cyclodextrin was fairly stable at 105 °C, and microencapsulation with ß-cyclodextrin can efficiently slow down the emission of linalool-chemotype C. osmophloeum leaf essential oil.

Xanthine Oxidase Inhibitory Activity and Thermostability of Cinnamaldehyde-Chemotype Leaf Oil of Cinnamomum osmophloeum Microencapsulated with ß-Cyclodextrin.

The xanthine oxidase inhibitory activity and thermostability of Cinnamomum osmophloeum leaf oil microencapsulated with ß-cyclodextrin were evaluated in this study. The yield of leaf oil microcapsules was 86.3% using the optimal reaction conditions at the leaf oil to ß-cyclodextrin ratio of 15:85 and ethanol to water ratio ranging from 1:3 to 1:5. Based on the FTIR analysis, the characteristic absorption bands of major constituent, trans-cinnamaldehyde, were confirmed in the spectra of leaf oil microcapsules. According to the dry-heat aging test, ß-cyclodextrin was thermostable under the high temperature conditions, and it was beneficial to reduce the emission of C. osmophloeum leaf oil. Leaf oil microcapsules exhibited high xanthine oxidase inhibitory activity, with an IC50 value of 83.3 µg/mL. It is concluded that the lifetime of C. osmophloeum leaf oil can be effectively improved by microencapsulation, and leaf oil microcapsules possess superior xanthine oxidase inhibitory activity.

Regeneration of ß-Carotene from Radical Cation by Eugenol, Isoeugenol, and Clove Oil in the Marcus Theory Inverted Region for Electron Transfer.

The rate of regeneration of ß-carotene by eugenol from the ß-carotene radical cation, an initial bleaching product of ß-carotene, was found by laser flash photolysis and transient absorption spectroscopy to be close to the diffusion limit in chloroform/methanol (9:1, v/v), with a second-order rate constant (k2) of 4.3 × 109 L mol-1 s-1 at 23 °C. Isoeugenol, more reducing with a standard reduction potential of 100 mV lower than eugenol, was slower, with k2 = 7.2 × 108 L mol-1 s-1. Regeneration of ß-carotene following photobleaching was found 50% more efficient by eugenol, indicating that, for the more reducing isoeugenol, the driving force exceeds the reorganization energy for electron transfer significantly in the Marcus theory inverted region. For eugenol/isoeugenol mixtures and clove oil, kinetic control by the faster eugenol determines the regeneration, with a thermodynamic backup of reduction equivalent through eugenol regeneration by the more reducing isoeugenol for the mixture. Clove oil, accordingly, is a potential protector of provitamin A for use in red palm oils.

The constituents of Michelia compressa var. formosana and their bioactivities.

Phytochemical investigation of the heartwood of Michelia compressa afforded forty-four compounds, which were identified by comparison of experimental and literature analytical and spectroscopic data. Some compounds were evaluated for their anti-inflammatory and anticancer bioactivities. The result showed that soemerine (1) and cyathisterol (2) exhibited significant nitric oxide (NO) inhibition, with IC50 values of 8.5±0.3 and 9.6±0.5 µg/mL, respectively. In addition, liriodenine (3) and oliveroline (4) exhibited cytotoxicity to human nasopharyngeal carcinoma (NPC-TW01), non-small cell lung carcinoma (NCI-H226), T cell leukemia (Jurkat), renal carcinoma (A498), lung carcinoma (A549) and fibrosarcoma (HT1080) cell lines with IC50 values in the range of 15.7-3.68 µM.

Insecticidal activities of leaf and twig essential oils from Clausena excavata against Aedes aegypti and Aedes albopictus larvae.

BACKGROUND: The current study investigates, for the first time, the mosquito larvicidal activities of leaf and twig essential oils from Clausena excavata Burm. f. and their individual constituents against Aedes aegypti L. and Aedes albopictus Skuse larvae. The yields of essential oils obtained from hydrodistillation were compared, and their constituents were determined by GC-MS analyses. RESULTS: The LC(50) values of leaf and twig essential oils against fourth-instar larvae of Ae. aegypti and Ae. albopictus were 37.1-40.1 microg mL(-1) and 41.1-41.2 microg mL(-1) respectively. This study demonstrated that C. excavata leaf and twig essential oils possess mosquito larvicidal activity, inhibiting the growth of mosquito larvae for both species at a low concentration. In addition, results of larvicidal assays showed that the effective constituents in leaf and twig essential oils were limonene, gamma-terpinene, terpinolene, beta-myrcene, 3-carene and p-cymene. The LC(50) values of these constituents against both mosquito larvae were below 50 microg mL(-1). Among these effective constituents, limonene had the best mosquito larvicidal activity, with LC(50) of 19.4 microg mL(-1) and 15.0 microg mL(-1) against Ae. aegypti and Ae. albopictus larvae respectively. CONCLUSION: The findings suggested that the essential oils from Clausena excavata leaf and twig and their effective constituents may be explored as a potential natural larvicide.

Antifungal properties of ethanolic extract and its active compounds from Calocedrus macrolepis var. formosana (Florin) heartwood.

The ethanolic extract of Calocedrus macrolepis var. formosana heartwood was screened for antifungal compounds by agar dilution assay and liquid chromatography. Two compounds, beta-thujaplicin and gamma-thujaplicin, responsible for the antifungal property of C. macrolepis var. formosana heartwood were isolated by high performance liquid chromatography (HPLC), and identified by 1H NMR and 13C NMR. The antifungal activities of these two compounds were further evaluated against total 15 fungi, including wood decay fungi, tree pathogenic fungi and molds. The hexane soluble fraction showed the strongest antifungal activities among all fractions. beta-Thujaplicin and gamma-thujaplicin exhibited not only very strong antifungal activity, but also broad antifungal spectrum. The MIC values of beta-thujaplicin and gamma-thujaplicin were in the range of 5.0-50.0 microg/ml. In addition, scanning electron microscopy (SEM) was carried out to study the structural change of fungal hyphae induced by beta-thujaplicin. Strong cell wall shrinkage indicated the fungicidal effect could be attributed to the combined actions of metal chelating and cytoplasm leakage. It also suggests that the role of metal chelating is indispensable in the design of environmental-friendly fungicides.

Anti-termitic activities of essential oils from coniferous trees against Coptotermes formosanus.

In this study, the anti-termitic activities of 11 essential oils from three species of coniferous tree against Coptotermes formosanus Shiraki were investigated using direct contact application. Results demonstrated that at the dosage of 10 mg/g, the heartwood and sapwood essential oils of Calocedrus macrolepis var. formosana and Cryptomeria japonica and the leaf essential oil of Chamaecyparis obtusa var. formosana had 100% mortality after 5 d of test. Among the tested essential oils, the heartwood essential oil of C. macrolepis var. formosana killed all termites after 1 d of test, with an LC(50) value of 2.6 mg/g, exhibiting the strongest termiticidal property. The termiticidal effect of heartwood essential oil was due to its toxicity and its repellent action.

Evaluation of antifungal properties of octyl gallate and its synergy with cinnamaldehyde.

The objective of this study was to investigate the possibility of using octyl gallate alone or with organic biocides as a preservative against wood decay fungi. Antifungal activities of three antioxidants, propyl gallate, octyl gallate and butylated hydroxyltoluene (BHT) were tested against four wood decay fungi, Lenzites betulina, Trametes versicolor, Gloeophyllum trabeum and Laetiporus sulphureus. Octyl gallate was found to be the only active compound with IC50 values of 0.47, 0.16, 0.24 and 0.04 mM against L. betulina, T. versicolor, G. trabeum and L. sulphureus, respectively. A synergistic effect was also found when octyl gallate was combined with cinnamaldehyde. Results obtained herein demonstrated that octyl gallate by itself exhibited an excellent antifungal property and enhanced protection was further observed by combining it with cinnamaldehyde.

Antitermitic and antifungal activities of essential oil of Calocedrus formosana leaf and its composition.

Calocedrus formosana Florin (Cupressaceae) is an endemic tree species in Taiwan; its timber is recognized for natural decay resistance. To examine the antitermitic and antifungal activities of leaf essential oil and its main constituents, C. formosana leaves were extracted and the essential oils analyzed by GC-MS. Bioactivity tests against the termite Coptotermes formosanus demonstrate that the LC50 value of leaf essential oil is 27.6 mg/g. Furthermore, exposure to T-muurolol caused 100% mortality at a dosage of 5 mg/g after 14 d. Leaf oil constituents displayed activity against four fungi, Lenzites betulina, Pycnoporus coccineus, Trametes versicolor, and Laetiporus sulphureus. Two compounds, alpha-cadinol and T-muurolol, exhibited the strongest antifungal activity. The LC50 values of alpha-cadinol against L. sulphureus, L. betulina, and T. versicolor are 9.9, 28.6, and 30.4 microg/ml, respectively.

Bioactivity of selected plant essential oils against the yellow fever mosquito Aedes aegypti larvae.

The bioactivity of 14 essential oils from five plants has been studied using the brine shrimp lethality test and the Aedes aegypti larvicidal assay. All essential oils screened had LC50 values smaller than 200 microg/ml, showing significant lethality against brine shrimp. In addition, nine of the 14 essential oils tested showed toxicity against the fourth-instar A. aegypti larvae in 24 h (LC50<100 microg/ml). Of these, the leaf and bark essential oils of Cryptomeria japonica demonstrated high larvicidal activity, the most active being the leaf essential oil of C. japonica, with a LC50=37.6 microg/ml (LC90=71.9 microg/ml), followed by the bark essential oil of C. japonica also showing high activity against A. aegypti larvae, with a LC50=48.1 microg/ml (LC90=130.3 microg/ml). The results obtained from this study suggest that the leaf and bark essential oils of C. japonica are promising as larvicides against A. aegypti larvae and could be useful in the search for new natural larvicidal compounds.