Isolation and characterization of antioxidative monoterpenes from Cynanchum atratum roots.

One novel monoterpene rhamnoside (1) and 7 known monoterpenes (2-8) were isolated from the ethanol extract of Cynanchum atratum for the first time. Their structures were identified by comprehensive spectroscopic data analysis such as nuclear magnetic resonance, high-resolution electrospray ionization mass spectra, optical rotatory dispersion, and acid hydrolysis. In the subsequent antioxidant assay, compound 8 exhibited obvious 2,2-diphenyl-2-picrylhydrazyl hydrate radical scavenging activity.

Synthesis of cinnamoyl glucoside derivatives and their antiproliferation activities against murine melanoma B16-F10 cell line.

Twelve cinnamoyl glucoside derivatives were prepared by glycosylation of glucosyl trichloroacetimidate and cinnamic acid derivatives, followed by dechloroacetylation with a pyridine/H2O mixture. Their structures were characterized by 1H and 13C NMR, as well as mass analysis. All the products were tested for their antiproliferation activities against murine melanoma B16-F10 cell line. Compounds 4e-4j were able to inhibit the proliferation of murine melanoma B16-F10 cell line with IC50 values of 17.38 ± 0.07, 9.87 ± 0.09, 9.69 ± 0.12, 29.42 ± 0.04, 32.95 ± 0.08, 25.68 ± 0.09 µM, respectively.

Two new iridoid glycosides from Gardeniae Fructus.

Two new iridoid glycosides, genipin 1,10-di-O-α-l-rhamnoside (1) and genipin 1,10-di-O-ß-d-xylopyranoside (2), along with thirteen known compounds (3-15) were isolated from Gardeniae Fructus. Their structures were elucidated by physical data analyses such as NMR, UV, IR, HR-ESI-MS, as well as chemical hydrolysis. All compounds were tested for their tyrosinase inhibitory and antioxidant activities. At a concentration of 25 µM, compound 13 showed obvious mushroom tyrosinase inhibition activity with % inhibition value of 36.52 ± 1.98%, with kojic acid used as the positive control (46.09 ± 1.29%). At a concentration of 1 mM, compounds 8 and 9 exhibited considerable DPPH radical scavenging activities, with radical scavenging rates of 48.54 ± 0.47%, 58.59 ± 0.39%, respectively, with l-ascorbic acid used as the positive control (59.02 ± 0.77%).

Two new phenylethanoid glycosides from Ginkgo biloba leaves and their tyrosinase inhibitory activities.

Two undescribed phenylethanoid glycosides, Ginkgoside C (1) and D (2), together with ten known glycosides (3-12) were isolated from Ginkgo biloba leaves. Their structures were characterized by physical data analyses such as NMR, HRESIMS, as well as chemical hydrolysis. All compounds were tested for their tyrosinase inhibitory activities. At a concentration of 25 µM, compounds 2, 4, 5, 6, and 11 showed obvious mushroom tyrosinase inhibition activities, with %inhibition values of 19.12 ± 2.59%, 25.79 ± 1.83%, 16.07 ± 1.07%, 24.46 ± 1.10%, 18.64 ± 3.62%, respectively, with kojic acid used as the positive control (27.50 ± 2.72%).

Chemical constituents from Ginkgo biloba leaves and their cytotoxicity activity.

One novel neoligan glucoside, Ginkgoside B (1), and one new glucose ester, 6-O-(4-hydroxyhydrocinnamoyl)-D-glucopyranose (2), along with nine known compounds (3-11) were isolated from the ethanol extract of Ginkgo biloba leaves. Their structures were elucidated by combination of spectroscopic analyses and alkaline methanolysis. The absolute configuration of compound 1 was determined by single-crystal X-ray diffraction. All the isolated compounds were evaluated for their cytotoxicity activities, and compound 11 exhibited IC50 values of 36.20 and 58.95 µM against 5637 and HeLa cell lines, respectively.

Isolation, structure elucidation, tyrosinase inhibitory, and antioxidant evaluation of the constituents from Angelica dahurica roots.

Two undescribed phenolic compounds, angelicols A (1) and B (2) and one undescribed coumarin rhamnoside, angelicoside A (3), together with 17 known compounds (4-20) were isolated from the roots of Angelica dahurica. Their structures were characterized by physical data analyses such as NMR, HRESIMS, and X-ray diffraction. Compounds 2, 3, 5, 6 and L-ascorbic acid (positive control) exhibited obvious DPPH radical scavenging activities with IC50 values of 0.36 mM, 0.43 mM, 0.39 mM, 0.44 mM, 0.25 mM, respectively. At a concentration of 25 µM, all compounds showed weaker tyrosinase inhibition activities (%inhibition < 5%) than kojic acid (26.00 ± 0.67%, IC50 = 44.29 ± 0.06 µM).

Neolignans with a Rare 2-Oxaspiro[4.5]deca-6,9-dien-8-one Motif from the Stem Bark of Cinnamomum subavenium.

Two pairs of racemic spirodienone neolignans with a rare 2-oxaspiro[4.5]deca-6,9-dien-8-one motif, named (±)-subaveniumins A (1) and B (2), were isolated from the bark of Cinnamomum subavenium. The chiral separation of the (+)-1, (-)-1, (+)-2, and (-)-2 enantiomers was accomplished via high-performance liquid chromatography on a chiral column. Their structures were elucidated using single-crystal X-ray diffraction and spectroscopic analyses (UV, IR, HRESIMS, and 1D and 2D NMR). The absolute configurations of the enantiomers were determined by comparing the experimental and calculated electronic circular dichroic spectra. The (+)-1, (-)-1, (+)-2, and (-)-2 enantiomers exhibited moderate inhibitory effects against NO production in RAW264.7 mouse macrophages induced by lipopolysaccharide, with IC50 values of 17.9, 5.6, 15.1, and 4.3 µM, respectively.

Wilsonols A-L, megastigmane sesquiterpenoids from the leaves of Cinnamomum wilsonii.

Twelve new megastigmane sesquiterpenoids, wilsonols A-L (1-12), were isolated from the leaves of Cinnamomum wilsonii, along with seven known analogues (13-19). The structures of compounds 1-12 were established by spectroscopic analyses. The absolute configurations of 1-5 were determined by single-crystal X-ray diffraction analysis with Cu Kα irradiation, and the absolute configurations of 6-12 were determined by the modified Mosher's method. Compounds 1-9 and 13-19 were evaluated for in vitro cytotoxicity against five human cancer cell lines, HL-60, SMMC-7721, A-549, MCF-7, and SW-480, and compared against the Beas-2B immortalized (noncancerous) human bronchial epithelial cell line. Compound 13 exhibited IC50 values ranging from 2.5 to 12 µM and selectivity indices of >10 against SMMC-7721, A-549, and MCF-7 cell lines. Selected compounds were evaluated for in vitro immunomodulatory activity.