Kuang-Hway Yih

Dual Bioactivities of Essential Oil Extracted from the Leaves of Artemisia argyi as an Antimelanogenic versus Antioxidant Agent and Chemical Composition Analysis by GC/MS

The study was aimed at investigating the antimelanogenic and antioxidant properties of essential oil when extracted from the leaves of Artemisia argyi, then analyzing the chemical composition of the essential oil. The inhibitory effect of the essential oil on melanogenesis was evaluated by a mushroom tyrosinase activity assay and B16F10 melanoma cell model. The antioxidant capacity of the essential oil was assayed by spectrophotometric analysis, and the volatile chemical composition of the essential oil was analyzed with gas chromatography-mass spectrometry (GC/MS). The results revealed that the essential oil significantly inhibits mushroom tyrosinase activity (IC50 = 19.16 mg/mL), down-regulates B16F10 intracellular tyrosinase activity and decreases the amount of melanin content in a dose-dependent pattern. Furthermore, the essential oil significantly scavenged 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzthiazoline- 6-sulphonic acid) ABTS radicals, showed an apparent reduction power as compared with metal-ion chelating activities. The chemicals constituents in the essential oil are ether (23.66%), alcohols (16.72%), sesquiterpenes (15.21%), esters (11.78%), monoterpenes (11.63%), ketones (6.09%), aromatic compounds (5.01%), and account for a 90.10% analysis of its chemical composition. It is predicted that eucalyptol and the other constituents, except for alcohols, in the essential oil may contribute to its antioxidant activities. The results indicated that essential oil extracted from A. argyi leaves decreased melanin production in B16F10 cells and showed potent antioxidant activity. The essential oil can thereby be applied as an inhibitor of melanogenesis and could also act as a natural antioxidant in skin care products.

Inhibition of Melanogenesis Versus Antioxidant Properties of Essential Oil Extracted from Leaves of Vitex negundo Linn and Chemical Composition Analysis by GC-MS

This study was aimed at investigating the antimelanogenic and antioxidative properties of the essential oil extracted from leaves of V. negundo Linn and the analysis of the chemical composition of this essential oil. The efficacy of the essential oil was evaluated spectrophotometrically, whereas the volatile chemical compounds in the essential oil were analyzed by gas chromatography-mass spectrometry (GC-MS). The results revealed that the essential oil effectively suppresses murine B16F10 tyrosinase activity and decreases the amount of melanin in a dose-dependent manner. Additionally, the essential oil significantly scavenged 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radicals, and showed potent reducing power versus metal-ion chelating properties in a dose-dependent pattern. The chemical constituents in the essential oil are sesquiterpenes (44.41%), monoterpenes (19.25%), esters (14.77%), alcohols (8.53%), aromatic compound (5.90%), ketone (4.96%), ethers (0.4%) that together account for 98.22% of its chemical composition. It is predicted that the aromatic compound in the essential oil may contribute to its antioxidant activities. The results indicated that essential oil extracted from V. negundo Linn leaves decreased melanin production in B16F10 melanoma cells and showed potent antioxidant activities. The essential oil can thereby serve as an inhibitor of melanin synthesis and could also act as a natural antioxidant.

The Dual Antimelanogenic and Antioxidant Activities of the Essential Oil Extracted from the Leaves of Acorus macrospadiceus (Yamamoto) F. N. Wei et Y. K. Li

The antimelanogenic and antioxidant activities of the essential oil extracted from the leaves of Acorus macrospadiceus (Yamamoto) F. N. Wei et Y. K. Li have never been explored. The essential oil effectively inhibited mushroom tyrosinase activity (EC50 = 1.57u2009mg/mL) and B16F10 tyrosinase activity (IC50 = 1.01u2009mg/mL), decreased the melanin content (EC50 = 1.04u2009mg/mL), and depleted the cellular level of the reactive oxygen species (ROS) (EC50 = 1.87u2009mg/mL). The essential oil effectively scavenged 2,2-diphenyl-1-picryl-hydrazyl (DPPH) (EC50 = 0.121u2009mg/mL) and 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) ABTS+ radicals (EC50 = 0.122u2009mg/mL). It also exhibited an apparent reducing power (EC50 = 0.021u2009mg/mL) and metal-ion chelating activity (EC50 = 0.029u2009mg/mL). The chemical constituents of the essential oil are ethers (55.73%), ketones (19.57%), monoterpenes (7.82%), alcohols (3.85%), esters (3.77%), sesquiterpenes (3.72%), and aromatic compounds (2.85%). The results confirm that A. macrospadiceus essential oil is a natural antioxidant and inhibitor of melanogenesis.

Anti-oxidant activity and major chemical component analyses of twenty-six commercially available essential oils

This study analyzed 26 commercially available essential oils and their major chemical components to determine their antioxidant activity levels by measuring their total phenolic content (TPC), reducing power (RP), β-carotene bleaching (BCB) activity, trolox equivalent antioxidant capacity (TEAC), and 1,1-diphenyl-2-picrylhydrazyl free radical scavenging (DFRS) ability. The clove bud and thyme borneol essential oils had the highest RP, BCB activity levels, and TPC values among the 26 commercial essential oils. Furthermore, of the 26 essential oils, the clove bud and ylang ylang complete essential oils had the highest TEAC values, and the clove bud and jasmine absolute essential oils had the highest DFRS ability. At a concentration of 2.5xa0mg/mL, the clove bud and thyme borneol essential oils had RP and BCB activity levels of 94.56%xa0±xa00.06% and 24.64%xa0±xa00.03% and 94.58%xa0±xa00.01% and 89.33%xa0±xa00.09%, respectively. At a concentration of 1xa0mg/mL, the clove bud and thyme borneol essential oils showed TPC values of 220.00xa0±xa00.01 and 69.05xa0±xa00.01xa0mg/g relative to gallic acid equivalents, respectively, and the clove bud and ylang ylang complete essential oils had TEAC values of 809.00xa0±xa00.01 and 432.33xa0±xa00.01xa0μM, respectively. The clove bud and jasmine absolute essential oils showed DFRS abilities of 94.13%xa0±xa00.01% and 78.62%xa0±xa00.01%, respectively. Phenolic compounds of the clove bud, thyme borneol and jasmine absolute essential oils were eugenol (76.08%), thymol (14.36%) and carvacrol (12.33%), and eugenol (0.87%), respectively. The phenolic compounds in essential oils were positively correlated with the RP, BCB activity, TPC, TEAC, and DFRS ability.

Dicarbonyl­chlorido(phen­oxy­thio­carbonyl-κ2C,S)bis­(triphenyl­phosphane-κP)molybdenum(II)

In the title complex, [Mo(C7H5OS)Cl(C18H15P)2(CO)2], the geometry around the metal atom is a capped octahedron. The phenoxythiocarbonyl ligand coordinates the MoII atom through the C and S atoms. A one-dimensional structure is formed by π–π intermolecular interactions and a supramolecular aggregation is determined by intermolecular C—H⋯O, C—H⋯Cl, C—H⋯π(arene) hydrogen bonds and CO⋯π(arene) interactions [O⋯centroid distances = 3.485u2005(4) and 3.722u2005(3)u2005Å].

Bis(carbonyl-κC)(N,N-dimethyl­thio­carbamoyl-κ2C,S)(pyridine-2-thiol­ato-κ2N,S)(triphenyl­phosphine-κP)molybdenum(II)

There are two independent molecules with similar configurations in the title complex, [Mo(C3H6NS)(C5H4NS)(C18H15P)(CO)2]. The geometry around the metal atom is that of a capped octahedron. The thiocabamoyl and pyridine-2-thiolate ligands coordinate to the molybdenum metal center through the C and S atoms, and N and S atoms, respectively. NMR, IR and MS analyses are in agreement with the structure of the title compound.

trans-Bromido(pyrimidinyl-κC2)bis­(triphenyl­phosphane-κP)palladium(II)

There are two independent molecules with similar configurations in the asymmetric unit of the title complex, [Pd(C4H3N2)I(C18H15P)2]. In each molecule, the geometry around the Pd atom is distorted square-planar, with the Pd atom displaced by 0.0549u2005(12) and 0.0734u2005(13)u2005Å from the least-squares plane of the I—P—P—C atoms. The PPh3 ligands are in trans positions, with P—Pd—P angles of 173.12u2005(4) and 170.29u2005(4)°, while the pyrazinyl ligands and I atoms, also trans to each other, form C—Pd—I angles of 179.38u2005(12) and 178.44u2005(12)°. In the crystal, C—H⋯π interactions occur, resulting in a three-dimensional supramolecular architecture.

[(Pyrrolidin-1-yl)carbothio­ylsulfan­yl]methyl pyrrolidine-1-carbodithio­ate

The title compound, C11H18N2S4, was unexpectedly obtained during studies on the reactivity of the complex tris(acac-κ2 O,O′)gallium(III) (acac is acetylacetonate) with C4H8NCS2H in dichloromethane. The title compound shows disordered two pyrrolidine rings with major and minor occupancies of 0.546u2005(4) and 0.454u2005(4). Two (pyrrolidin-1-yl)carbothioylsulfanyl units are linked together through a methylene C atom and weak C—H⋯S interactions are found.

trans-Bromido(pyrimidinyl-κC)bis-(triphenyl-phosphane-κP)palladium(II).

In the title complex, [PdBr(C4H3N2)(C18H15P)2], the geometry around the PdII atom is distorted square-planar with the PdII atom displaced by 0.0150u2005(5)u2005Å from the least-squares BrP2C plane. Two PPh3 ligands are in trans positions [P—Pd—P = 176.743u2005(17)°], while the pyrimidinyl ligand and Br atom are trans to one another [C—Pd—Br = 176.56u2005(5)°]. Structural parameters from NMR, IR and mass spectra are in agreement with the crystal structure of the title compound.

Novel palladium and platinum carbene-complexes containing dithiocarbonate ligand [M(PPh3){?2(S,S)-S2CO]{C(SR)(NMe2)}] formed via alkyl migration of O-alkyldithiocarbonate to thiocarbamoyl ligandElectronic supplementary information (ESI) available: 1H and 13C{1H} NMR spectra of 3 and the 1H NMR spectrum of the mixtures of 4 and 5. See http://www.rsc.org/suppdata/dt/b3/b305374a/

The first example of alkyl migration of O-alkyldithiocarbonate to thiocarbamoyl ligand results in carbene-complexes [M(PPh3){η2(S,S)-S2CO]{C(SR)(NMe2)}] n(M = Pd, Pt; R = Me, Et) from the reactions of [M(η2-SCNMe2)(PPh3)2][PF6] with KS2COR in MeOH.