Gold-Catalyzed Reactions of Enynals with Alkenes for Synthesis Binaphthyl Derivatives.

A PPh3Au[B(C6F5)4]-catalyzed reaction of enynals and alkenes for the construction of binaphthyl derivatives was described. This transformation was achieved through o-Quinodimethane (o-QDM) intermediate's extended conjugated addition process. The reaction has the advantages of wide substrate scopes, mild reaction conditions, high efficiency, and good scalability.

New Iridoids and Acyclic Monoterpenoids from the Roots and Rhizomes of Valeriana officinalis var. latifolia.

Five new iridoids, valeralides A-E (1-5), two new acyclic monoterpenoids, valeralides F (6) and G (7), together with two known iridoids (8 and 9), were isolated from the roots and rhizomes of Valeriana officinalis var. latifolia. Their structures were elucidated based on 1D and 2D NMR, as well as HR-ESI-MS spectroscopic data. The absolute configuration of compounds 1-4 were elucidated based on electronic circular dichroism (ECD) calculation. In addition, all the isolates were evaluated for their inhibition on nitric oxide production, cytotoxicity and anti-influenza A virus activity.

Flavonoids From the Aerial Parts of Sophora tonkinensis and Their Potential Anti-Inflammatory Activities.

Four undescribed prenylated flavonoids, sophoratones A-D (1-4), and 17 known flavonoids, were obtained from the aerial parts of Sophora tonkinensis. Their structures with absolute configurations were elucidated by detailed interpretation of NMR spectroscopy, mass spectrometry, and ECD calculations. Meanwhile, the ability of these compounds to inhibit the release of nitric oxide (NO) by a lipopolysaccharide induced mouse in RAW 264.7 cells was assayed. The results indicated that some compounds exhibited clear inhibitory effects, with IC50 ranging from 19.91±1.08 to 35.72±2.92 µM. These results suggest that prenylated flavonoids from the aerial parts of S. tonkinensis could potentially be used as a latent source of anti-inflammatory agents.

Flavonoids from the Roots of Sophora flavescens and Their Potential Anti-Inflammatory and Antiproliferative Activities.

The phytochemical investigation of the roots of the traditional Chinese medicinal plant Sophora flavescens led to the isolation of two novel prenylflavonoids with an unusual cyclohexyl substituent instead of the common aromatic ring B, named 4',4'-dimethoxy-sophvein (17) and sophvein-4'-one (18), and 34 known compounds (1-16, 19-36). The structures of these chemical compounds were determined by spectroscopic techniques, including 1D-, 2D-NMR, and HRESIMS data. Furthermore, evaluations of nitric oxide (NO) production inhibitory activity against lipopolysaccharide (LPS)-treated RAW264.7 cells indicated that some compounds exhibited obvious inhibition effects, with IC50 ranged from 4.6 ± 1.1 to 14.4 ± 0.4 µM. Moreover, additional research demonstrated that some compounds inhibited the growth of HepG2 cells, with an IC50 ranging from 0.46 ± 0.1 to 48.6 ± 0.8 µM. These results suggest that flavonoid derivatives from the roots of S. flavescens can be used as a latent source of antiproliferative or anti-inflammatory agents.

Iridoids and sesquiterpenoids from Valeriana jatamansi and their anti-influenza virus activities.

Twenty-one new iridoids, jatamansidoids A-U (1-12, 21-26, 32, 35 and 36), two new natural ones, jatamansidoids V (37) and W (38), eighteen known ones (13-20, 27-31, 33 and 34), together with three patchoulol-type sesquiterpenoids (39-41), were isolated from the roots and rhizomes of Valeriana jatamansi. Structurally, compounds 1-7 were the first examples of iridoids from V. jatamansi with unique α, ß, γ, δ-unsaturated aldehyde fragment between C-11, C-4, C-5, C-9 and C-8; compound 8 was an unprecedented iridoid derivative with a methyl group (Me-10) at C-1, rather than C-8, and its plausible biogenetic pathway was proposed in this paper; compounds 22 and 23 were the first examples of Δ4(5)-iridoids simultaneously replaced by oxygen-containing groups at C-3, C-6 and C-7; compound 24 was the first iridoid with both 6,7- and 1,10-epoxy fragments. The structures and absolute configurations of new compounds were elucidated based on extensive spectroscopic techniques and quantum chemical calculation. Furthermore, compounds 13-15 and 39-41 exhibited potent anti-influenza virus activities with H1N1 and H3N2 strains, with IC50 values of 0.21-1.48 µM.

Valeridoids G - Q, Eleven seco-Iridoids from Valeriana jatamansi and Their Bioactivites.

Eleven new seco-iridoids, valeridoids G-Q (1-6 and 8-12), along with four known products, 9-epi-valtral C (7), desacylbaldrinal (13), 11-methoxyviburtinal (14) and baldrinal (15), were obtained from Valeriana jatamansi. Among them, the new compounds were identified by their NMR, HR-ESI-MS spectroscopic data and ECD calculation. Moreover, valeridoid N and O were a pair of C3 epimers, whose ether bonds between C-1 and C-3 opened, and new ether bonds formed between C-3 and C-6. Valeridoid Q belonged to the C-1 degradation of seco-iridoids. As a result, 9-epi-valtral C displayed significant inhibition on Streptococcus agalactiae, Staphylococcus aureus, Staphylococcus argenteus, Shigella flexneri and Klebsiella pneumoniae, and valeridoid Q exhibited the most significant inhibition against Salmonella enteritidis. 9-Epi-valtral C and baldrinal selectively inhibited the growth of human glioma stem cells. Valeridoid Q exhibited significant anti-influenza activity, while valeridoid O inhibited nitric oxide production.

Synthesis, characterization and antitumor mechanism investigation of ruthenium(II) polypyridyl complexes with artesunate moiety.

Six artesunate (ART) conjugated ruthenium(II) complexes (Ru(II)-ART conjugates) with the formula [Ru(N^N)2bpy(4-CH3-4'-CH2OART)](PF6)2 (Ru-ART-1-3) and [Ru(N^N)2bpy(4-CH2OART-4'-CH2OART)](PF6)2 (Ru-ART-4-6) (N^N = 2,2'-bipyridine (bpy, in Ru-ART-1 and Ru-ART-4), 1,10-phenanthroline (phen, in Ru-ART-2 and Ru-ART-5) and 4,7-diphenyl-1,10-phenanthroline (DIP, in Ru-ART-3 and Ru-ART-6)), were synthesized and characterized. Among them, Ru-ART-1-3 and Ru-ART-4-6 carry one and two ART moieties, respectively. Ru-ART-3 and Ru-ART-6 exhibit better cytotoxicity among six Ru(II)-ART conjugates. These two complexes can be effectively taken up by human cervical carcinoma (HeLa) cells. In addition, they selectively kill cancer cell lines while mildly affect normal cells. Mechanism studies have shown that HeLa cells treated with Ru-ART-3 and Ru-ART-6 show typical apoptotic characteristics (morphology changes, mitochondrial dysfunction, caspase cascade, etc.). On the other hand, the up regulation of Beclin-1 and conversion of LC3-I to LC3-II note the appearance of autophagy. As a result, Ru-ART-3 and Ru-ART-6 induce autophagy-dependent cell apoptosis via mitochondrial dysfunction and reactive oxygen species (ROS) accumulation. In this work, six artesunate (ART) conjugated ruthenium(II) complexes (Ru(II)-ART conjugates) have been synthesized and characterized. Among them, Ru-ART-3 and Ru-ART-6 exhibit better cytotoxicity. Mechanism studies have shown that HeLa cells treated with Ru-ART-3 and Ru-ART-6 show typical apoptotic characteristics (morphology changes, mitochondrial dysfunction, caspase cascade, etc.). On the other hand, the up regulation of Beclin-1 and conversion of LC3-I to LC3-II note the appearance of autophagy.

Aerobic Copper-Catalyzed Intramolecular Cascade Oxidative Isomerization/[4+4] Cyclization of 2,2'-Disubstituted Stilbenes.

An aerobic copper-catalyzed cascade oxidative isomerization/[4+4] cyclization of 2,2'-disubstituted stilbenes is described. Under the mild CuCl/DBED/air catalytic system, various 5,10-heteroatom-containing tetrahydroindeno[2,1-a]indenes were efficiently prepared through the difunctionalizations of alkenes in a highly atom economic manner. Mechanistic investigations suggested the bicyclic product was likely formed through a sequence of rapid single-electron oxidation/[4+4] cyclization from 2,2'-disubstituted stilbene. The antarafacial manner of the thermally allowed [4+4] cyclization was further proven by series of control experiments and density functional theory calculations. Our findings provide an important addition to the aerobic copper-catalyzed oxidative cyclization.

Structurally diversified ent-kaurane and abietane diterpenoids from the stems of Tripterygium wilfordii and their anti-inflammatory activity.

Four undescribed ent-kaurane diterpenoids, wilkaunoids A - D (1-4), and three undescribed abietane diterpenoids, wilabinoids A - C (13-15), along with thirteen known ones (5-12 and 16-20), were isolated from Tripterygium wilfordii. Their structures were elucidated by extensive spectroscopic methods, electroniccirculardichroism calculation, and X-ray diffraction analysis. Compounds 1 and 2 were a pair of C-19 epimers of ent-kaurane diterpenoids, featuring a rare 19,20-epoxy-19,20-dimethoxy-kaurane fragment. Compound 3 possessed a rare naturally occurring 1,3-dioxacyclohexane moiety. Compounds 13 and 15 represented the first example of abietane diterpenoids with an isovalerate substitution from the genus of Tripterygium. The possible biosynthetic pathways of 1-3 were postulated. The effect of 1-20 on nitric oxide production was examined in lipopolysaccharide-stimulated RAW 264.7 cells. Abietane diterpenoid quinones 7-13 (IC50: 1.9-10.2 µM) exhibited the significant activity to inhibit nitric oxide production versus positive control (NG-monomethyl-l-arginine acetate salt, IC50 = 24.9 µM). The structure activity relationship of 7-13 in inhibiting nitric oxide production was then discussed. The most potent 7 and 8 were found to significantly suppress the expression of cyclooxygenase-2 and inducible nitric oxide synthase proteins, showing a good anti-inflammatory potential. The findings provided some valuable insights for the discovery and structural modification of abietane diterpenoids towards anti-inflammatory lead compounds.

Quinolizidine alkaloids from Sophora alopecuroides with anti-inflammatory and anti-tumor properties.

Forty-three quinolizidine alkaloids (1-43), including twelve new matrine-type ones, sophalodes A-L (1-7, 17, 19 and 28-30), were isolated from the seeds of Sophora alopecuroides. Structurally, compounds 1-4 were the first examples of C-11 oxidized matrine-type alkaloids from Sophora plants. The structures and absolute configurations of new compounds were elucidated by extensive spectroscopic techniques, X-ray diffraction analysis, and quantum chemical calculation. In addition, the NMR data and absolute configuration of compound 18 was reported for the first time. All the isolates were evaluated for their inhibition on nitric oxide production induced by lipopolysaccharide in RAW 264.7 macrophages, among them, compounds 29, 38 and 42 exhibited the most significant activity with IC50 values of 29.19, 25.86 and 33.30 µM, respectively. Further research about new compound 29 showed that it also suppressed the protein levels of iNOS and COX-2, which revealed its anti-inflammatory potential. Moreover, additional research showed that compound 16 exhibited marginal cytotoxicity against HeLa cell lines, with an IC50 value of 24.27 µM.

Matrine-Type Alkaloids from the Seeds of Sophora alopecuroides and Their Potential Anti-inflammatory Activities.

Three new matrine-type alkaloids, 8ß-hydroxyoxysophoridine (1), 9ß-hydroxysophoridine (2), 9ß-hydroxyisosophocarpine (3), together with one known analog, 11,12-dehydromatrine (4), were isolated from the seeds of Sophora alopecuroides L. The structures of new compounds were elucidated using extensive spectroscopic techniques including the experimental and calculated ECD data. The anti-inflammatory activities of all the isolates on NO production in RAW 264.7 cells stimulated by lipopolysaccharide were evaluated. Among them, 8ß-hydroxyoxysophoridine (1) showed a significant inhibitory effect with an IC50 value of 18.26 µM.

Development of anti-influenza agents from natural products.

The influenza pandemic continues to threaten public health due to its high morbidity and mortality rates, despite some successes in antiviral research. Natural drugs are important alternative therapies in the treatment of and recovery from influenza and have been the subjects of intense investigation during the last few decades. Many reports have shown that the development of novel bioactive chemicals extracted from natural drugs has significant advantages. Oseltamivir is a successful case of an anti-influenza drug synthesized using two natural products, quinic acid, and shikimic acid, as starting materials. In China, traditional Chinese medicine (TCM) plays an important role in the treatment of influenza. TCM herbal extracts and prescriptions or their isolated bioactive constituents have shown significant therapeutic and preventive effects against influenza. For example, the roots of Isatis indigotica (Banlangen) fight viral infection by targeting both the virus and the host and have significantly different effects than those of synthetic chemicals. Lianhuaqingwen capsule exerts its anti-influenza activity by regulating the immune response to interfere with both viral and host reactions and might well be an alternative therapeutic option to treat influenza virus infection. This paper reviews the chemical ingredients, crude extracts, and TCM prescriptions with anti-influenza activity reported during the period of 2010-September 2019. We hope that this comprehensive review will not only fuel research on anti-influenza active natural products and TCM research but also provide a promising alternative candidate for further anti-influenza drug development.

Diterpenoids from Euphorbia neriifolia and Their Related Anti-HIV and Cytotoxic Activity.

Fifteen diterpenoids (1-15), including three undescribed ones with ent-atisane skeleton, eupnerias G-I (1-3), were obtained from Euphorbia neriifolia. Compounds 1-3 were established through comprehensive spectroscopic analysis. Compounds 4 and 5 exhibited obvious anti-HIV-1 effect, and their EC50 were 6.6±3.2 and 6.4±2.5 µg mL-1 , respectively. Compound 6 exhibited moderate cytotoxicity on HepG2 and HepG2/Adr cells with IC50 at 13.70 and 15.57 µm, respectively. In addition, compound 15 exhibited significant cytotoxicity on HepG2 cell lines (IC50 =0.01 µm), while it did not show any cytotoxicity against HepG2/Adr cell lines.

Bioactive 3,8-Epoxy Iridoids from Valeriana jatamansi.

Twelve 3,8-epoxy iridoids, including four new compounds, jatamanins R-U (1-4), and eight known compounds (5-12), were obtained from the roots and rhizomes of Valeriana jatamansi. The structures were elucidated from analysis of spectroscopic data. The absolute configurations of 1-4 were determined by comparison of experimental and literature ECD spectra. Moreover, the compounds were evaluated for cytotoxic effects against glioma stem cells, inhibition of NO production, activity against influenza A virus and reversal of multidrug resistance of HepG2/ADR cells. Compounds 9 and 12 showed significant cytotoxic potency against GSC-18# (IC50 =1.351 and 4.439 µg ml-1 , respectively) and GSC-3# (IC50 =10.88 and 6.348 µg ml-1 , respectively) glioma stem cells, while compound 12 was also slightly less potent against GSC-12# (IC50 =13.45 µg ml-1 ) glioma stem cell growth. In addition, compounds 9 and 12 displayed obvious inhibition of NO production (IC50 =4.6 and 15.8 µm, respectively).

Five New Cucurbitane-Type Triterpenoid Glycosides from the Rhizomes of Hemsleya penxianensis with Cytotoxic Activities.

Five new cucurbitane-typetriterpenoid glycosides, named Xuedanoside F-J (1-5), were obtained from the rhizomes of Hemsleya penxianensis (Xue dan), which belongs to the family of Cucurbitaceae. These new compounds were elucidated byspectroscopic analysis, including 1D, 2D NMR, and HR-ESI-MS spectra. Additionally, all the isolates were evaluated for cytotoxicity against three human cancer cell lines (Hela, MCF-7, and A-549) with the IC50 ranging from 2.25 to 49.44 µM in vitro with treatment 48 h and showed low cytotoxicity in human normal liver L-02 cells (IC50 > 50 µM). Compound 5 showed the most significant cytotoxic activity with the IC50 value of 2.25, 4.72, and 5.33 µM in 48 h, respectively.

Terpenes from Euphorbia antiquorum and Their in Vitro Anti-HIV Activity.

Three new compounds (1 - 3), including two euphane type triterpenes, 24,24-dimethoxy-25,26,27-trinoreuphan-3ß-ol (1) and (24S)-24-hydroperoxyeupha-8,25-dien-3ß-ol (2), and an ent-atisine diterpene, ent-atisane-3α,16α,17-triol (3), were isolated from an acetone extract of the stems of Euphorbia antiquorum, together with eight known diterpenes (4 - 11). The structures of compounds (1 - 11) were elucidated using NMR and MS spectroscopic methods. Compound 7 showed moderate activity against HIV-1 replication in vitro (EC50 = 1.38 µm).

New Naphthalene Derivatives from the Bulbs of Eleutherine americana with Their Protective Effect on the Injury of HUVECs.

Five new naphthalene derivatives, named Eleutherols A⁻C (1⁻3) and Eleuthinones B⁻C (4,5), together with three known compounds were isolated from the bulbs of Eleutherine americana. Their structures were elucidated on the basis of spectroscopic analysis including HR-ESI-MS, 1D and 2D NMR techniques. These compounds exhibited a potent effect against the injury of human umbilical vein endothelial cell (HUVECs) induced by high concentrations of glucose in vitro.

[A new naphthalene derivative from bulbs of Eleutherine americana].

A new naphthalene derivative and three known compounds were isolated from the petroleum ether extract of the bulbs of Eleutherine americana by using various chromatographic techniques, such as column chromatography over silica gel and semi-preparative HPLC. Their structures were elucidated by spectroscopic date (MS, UV, IR, NMR), which were identified as eleutherol B (1), 4,8-dihydroxy-3-methoxy-1-methylanthraquinone-2-carboxylic acid methyl ester (2), 8-hydroxy-3,4-dimethoxy-1-methylanthraquinone-2-carboxylic acid methyl ester (3), and isoeleutherine (4). Compound 1 is a new compound. The diastolic blood vessels activity of compound 1 and 2 were potent, reaching 82.5% and 85.3% at the concentration of 10 µmol·L⁻¹, which were basically the same as that of the positive drug tanshinone ⅡA.

Naphthoquinones from Onosma paniculatum with Potential Anti-inflammatory Activity.

Four new naphthoquinones (1-4), including a dimeric one, shikometabolin G (1), together with six known ones (6-10), were isolated from the methanol extract of Onosma paniculatum. Their structures were established based on the analysis of NMR and MS spectroscopic data. All of the compounds were evaluated for inhibitory effects on NO production in murine macrophage RAW 264.7 cells. Compounds 2, 3, 5, 6, 7, 8, and 10 displayed good activity on the inhibition of NO production (IC50 = 0.4-16.5 µM), suggesting the potential property of anti-inflammation.

Anti-inflammatory and Anti-HIV Compounds from Swertia bimaculata.

Three new compounds (1 - 3), including a sesterterpenoid, aspterpenacid C (1), with an unusual 5/3/7/6/5 pentacyclic skeleton, together with seven known ones (4 - 10), were isolated from the ethanol extract of the traditional Chinese medicinal plant Swertia bimaculata. Their structures were elucidated on the basis of the methods of spectroscopic NMR, MS, and computational chemistry. The structure of 1 was further confirmed by single-crystal X-ray diffraction analysis. Compounds 1 - 10 were tested for activities on the inhibition of nitric oxide production and HIV-1 replication in vitro. Compound 1 exhibited moderate activity in inhibiting nitric oxide production (IC50 = 16.1 µM) and HIV-1 replication (EC50 = 1.35 µM).