Synergistic effects and antityrosinase mechanism of four plant polyphenols from Morus and Hulless Barley.

Sanggenone C, oxyresveratrol, catechin and l-epicatechin exist in Morus and Hulless Barley as natural polyphenols with antityrosinase activity. Little research on their synergistic and structure-function relationships of them has been reported in recent years. In this paper, the inhibition mechanisms of these four plant polyphenols were investigated by enzyme kinetics, HPLC, fluorescence spectra, and molecular docking methods. The results showed that oxyresveratrol (IC50 = 1.096 ± 0.048 µg/mL), sanggenone C (IC50 = 13.360 ± 1.029 µg/mL), l-epicatechin (IC50 = 55.730 ± 1.762 µg/mL), and catechin (IC50 = 148.500 ± 3.355 µg/mL) exhibited tyrosinase inhibition activity. When sangenone C (14 µg/mL) was mixed with l-epicatechin (56 µg/mL) at 4:1 (40 µL + 10 µL), the highest tyrosinase inhibition was achieved. Molecular docking showed that the number and position of phenolic hydroxyls of polyphenols were the key for tyrosinase inhibition activity. This study provided new ideas for the application of these four plant polyphenols from Hulless Barley and Morus as tyrosinase inhibitors in food preservation.

Monoterpenoid Indole Alkaloids from Kopsia officinalis and the Immunosuppressive Activity of Rhazinilam.

Six new monoterpenoid indole alkaloids, kopsinidines C-E (1-3), 11,12-methylenedioxychanofruticosinic acid (4), 12-methoxychanofruticosinic acid (5), and N(4)-methylkopsininate (7), as well as chanofruticosinic acid (6, as a natural product) and 23 known alkaloids, were obtained from the twigs and leaves of Kopsia officinalis. Their structures were characterized by physical data analysis. All isolated compounds were evaluated for their immunosuppressive activity on human T cell proliferation. Rhazinilam (29) significantly inhibited human T cell proliferation activated by anti-CD3/anti-CD28 antibodies (IC50 = 1.0 µM) and alloantigen stimulation (IC50 = 1.1 µM) without obvious cytotoxicity for naïve human T cells and peripheral blood mononuclear cells (0-320 µM). Although it did not affect T cell activation, it induced T cell cycle arrest in the G2/M phase and inhibited proinflammatory cytokine production in activated T cells.

[A new cytotoxic isocoumarin from endophytic fungus Aspergillus versicolor].

A new isocoumarin, along with five known ones,were isolated from the fermentation products of an endophytic fungus Aspergillus versicolorby using various chromatographic techniques.Their structures were elucidated on the basis of extensivespectroscopic analysis, including 1D-and 2D-NMR techniques. Compound 1 was evaluated for cytotoxicity against five human tumor cell lines. The results showed that 1 exhibited weak cytotoxicityagainst NB4, SHSY5Y and MCF7 cells with IC50 values of 6.8, 4.3,8.8 µmol•L⁻¹, respectively.

[Phenylpropanoids and phenylethanol from flowers of Rosa rugosa].

A new phenylpropanoid (1), together with seven known ones (2-8), has been isolated from the flowers of Rosa rugosa collected from Shanxi province by using various chromatographic techniques. Compound 1 is a new compound, and it displayed cytotoxicity against NB4, SH-SY5Y, PC3, A549 and MCF7 cell lines with IC50 values of 8.2, 6.2, 4.3, 2.8, and 9.6 µmol · L⁻¹ respectively.

[A new flavone from stems of Garcinia bracteata and its anti-TMV activity].

A phytochemical investigation on the stems of Garcinia bracteata collected from Xishuangbanna resulted in the isolation of a new flavone. By analysis of the HRESIMS, IR, UV, 1D and 2D NMR spectra, the structure of the new compound was determined as 7-methoxy-4',6-dihydroxy-8-isobutyryl-flavone(1). Compound 1 was also tested for its anti-tobacco mosaic virus(TMV) activity. Results suggested the 1 possessed remarkable anti-TMV activity, with an inhibition rate of 28.2%.

7,8-Secolignans from the fruits of Schisandra neglecta.

Two new 7,8-secolignans, neglectahenols E and F (1 and 2), together with four known 7,8-secolignans (3-6), were isolated from the fruits of Schisandra neglecta. The structures were elucidated by spectroscopic methods, including extensive 1D and 2D NMR techniques. Compounds 1-6 were tested for their anti-tobacco mosaic virus (anti-TMV) activities at the concentration of 20 µM. Compounds 1 and 6 showed high anti-TMV activities with inhibition rates of 38.2% and 32.7%, respectively. These rates are higher than that of a positive control. Compounds 2-5 also showed modest anti-TMV activities with inhibition rates in the range of 22.8-28.7%. These rates are close to that of a positive control.

Calophyline A, a new rearranged monoterpenoid indole alkaloid from Winchia calophylla.

Calophyline A (1), a novel unprecedented rearranged monoterpenoid indole alkaloid, along with a new natural product N-methyl aspidodasycarpine (2) and six known analogues, was isolated from the trunk barks of Winchia calophylla. The structure of compound 1 was elucidated on the basis of spectroscopic data and then confirmed by a single-crystal X-ray crystallographic analysis. A hypothetical biogenetic pathway for compound 1 was proposed. All isolated compounds were evaluated for their in vitro cytotoxicity against a small panel of human cancer cell lines.

19-oxygenated ent-kaurane diterpenoids from Isodon pharicus.

Eight new 19-oxygenated ENT-kaurane diterpenoids were isolated from the aerial parts of Isodon pharicus. Their structures were determined by means of extensive spectroscopic techniques including interpretation of 1D and 2D NMR spectra. Selected compounds were evaluated for their cytotoxicity against NB4, A549, PC-3, MCF-7, and SH-SY5Y cell lines.

ent-Abietane diterpenoids from Isodon xerophilus.

Three new ent-abietanoids, named xerophilusins XIV-XVI, and four known analogues, as well as four known chemical constituents were isolated from the leaves of Isodon xerophilus. Their structures were elucidated by extensive spectroscopic studies, and comparison with literature data. In addition, the cytotoxic activity of the ent-abietanoids against chronic myelogenous leukemia (K562), stomach adenocarcinoma (MKN45), and hepatocellular carcinoma (HepG2) human cell lines was investigated and no activities were observed.

ent-Kaurane and cembrane diterpenoids from Isodon sculponeatus and their cytotoxicity.

Nine new ent-kauranoids, sculponins D-L (1-9), and 14 known diterpenoids (10-23) were isolated from the aerial parts of Isodon sculponeatus. The structures of the new diterpenoids were determined by detailed interpretation of their 1D and 2D NMR spectra and HRESIMS. The isolated compounds were evaluated for their cytotoxic activities against a small panel of human cancer cell lines.

Cytotoxic ent-kaurane diterpenoids from Isodon henryi.

Chromatographic fractionation of the extract of Isodon henryi resulted in the isolation of seven new ENT-kaurane diterpenoids, named minheryins A-G (1-7), together with the six known ENT-kaurane diterpenoids leukamenin F (8), excisoidesin (9), leukamenin E (10), wangzaozin A (11), pseurata A (12), and racemosin A (13), which were elucidated by spectroscopic analysis. Compounds 7-13 were tested for their cytotoxicity against K562 and HepG2 cell lines, and they all exhibited significant activities with IC50 values<0.50 microg/mL. Isolates 1-5 were evaluated against the K562 cell line, and only 3 showed weak activity.

Three new compounds from Kadsura longipedunculata.

Two new tetrahydrofuran lignans, kadlongirins A and B (1, 2), a new cadinane-type sesquiterpenoid, 2,7-dihydroxy-11,12-dehydrocalamenene (3), together with seven known lignans, grandisin, fragransin B1, vladirol F, kadsuralignan C, otobaphenol, isoanwulignan, and 4-[4-(3,4-dimethoxyphenyl)-2,3-dimethylbutyl]-2-methoxy-phenol, were isolated from the leaves and stems of Kadsura longipedunculata. The structures of these new compounds were elucidated by spectroscopic methods. Compound 2 exhibited weak anti-human immunodeficiency virus-1 activity with an EC50 value of 16.0 microg/ml, and therapeutic index (TI) value of 6.7.

ent-Kaurane Diterpenoids from Isodon nervosus.

A pentacyclic ent-kauranoid, nervonin A ( 1), with an unprecedented cyclobutane moiety in the structure, and nine other new ent-kaurane diterpenoids, nervonins B-J ( 2- 10), along with 10 known ones ( 11- 20), were isolated from Isodon nervosus. Their structures were elucidated by detailed spectroscopic analysis. All diterpenoids were assayed for their cytotoxicity against K562, A549, and HepG2 human cell lines. Compounds 2, 11, 16, 17, and 20 showed significant cytotoxicity.

Negative electrospray ionization tandem mass spectrometric investigation of ent-kaurane diterpenoids from the genus Isodon.

ent-Kaurane diterpenoids are a class of natural compounds isolated from genus Isodon, which have been found to have important bioactivities. Negative electrospray ionization tandem mass spectrometry ((-)ESI-MS(n)) was used to investigate the fragmentation pattern of C-20-nonoxygenated ent-kauranes and two subtypes of C-20-oxygenated ent-kauranes by using an ion trap instrument and accurate mass measurement on an ESI-Q-time-of-flight (TOF) mass spectrometer. The analysis revealed that loss of CH(2)O or CO(2) is the predominant process for 7, 20-epoxy and 7, 20 : 14, 20-diepoxy subgroup of C-20-oxygenated ent-kauranes. In addition, compounds of C-20-nonoxygenated ent-kauranes with a conserved core structure but different substituent groups, such as a hydroxyl, aldehyde, carboxyl, and acetyl moiety, resulted in diagnostic product ions through losses of H(2)O, CO, CO(2), and AcOH, respectively. This work clearly demonstrates the utility of tandem mass spectrometry for studies on the rationalization of the diagnostic fragmentation of a series of compounds from two main types of the ent-kaurane diterpenoids.

Isolation and structure elucidation of kadlongilactones C-F from Kadsura longipedunculata by NMR spectroscopy and DFT computational methods.

Four new triterpenoids, kadlongilactones C-F (2-5), containing a consecutive hexacyclic [7,7,5,6,6,6] ring system, were isolated from the leaves and stems of Kadsura longipedunculata. In comparison with the NMR data of kadlongilactones A (1) and D (3), a significant phenomena was discovered that ring D of 3 inverted from a half-chair in 1 to a half-boat conformation when the HO-16 group changed from alpha- to beta-orientation. The structures of 2-5 were established on the basis of detailed spectroscopic analysis, and DFT computational methods were applied in the structural validation of compounds 3 and 5. Compounds 1-4 showed significant cytotoxicity against A549, HT-29, and K562 cell lines with IC50 values of 0.49-3.61 microM in vitro.

Structural characterization of schintrilactone, a new class of nortriterpenoids from Schisandra chinensis.

Two new nortriterpenoids, designated as schintrilactones A (1) and B (2), with modified five-membered D ring and delta-lactone E ring, were isolated from Schisandra chinensis. Their structures were determined to have a unique carbon skeleton by elucidation of spectroscopic evidence and density functional theory calculations of circular dichroism. Schintrilactones A and B occur as a pair of configurationally unstable and thus slowly interconverting diastereomers.

Cytotoxic ent-kauranoids from the medicinal plant Isodon xerophilus.

Bioassay-directed fractionation of the leaves of the medicinal plant Isodon xerophilus led to the isolation of a series of potential antitumor molecules. Thirteen new (1-13) and 23 (14-36) known diterpenoids were isolated and identified, representing ent-kauranoids of several structural types. The structures of 1-13 were determined by means of spectroscopic studies. The absolute configurations of the new compounds were clarified by CD spectroscopic studies or were postulated on biogenetic grounds. All compounds obtained were evaluated for their cytotoxic activity against the K562, MKN45, and HepG2 cell lines. Compounds 1, 2, 11, 16-19, 23, 26-28, 30, and 32 demonstrated significant cytotoxic activity for one or more cell lines.