seco-Pregnane Glycosides from Australian Caustic Vine (Cynanchum viminale subsp. australe).

Cynanchum viminale subsp. australe, more commonly known as caustic vine, is a leafless succulent that grows in the northern arid zone of Australia. Toxicity toward livestock has been reported for this species, along with use in traditional medicine and its potential anticancer activity. Disclosed herein are novel seco-pregnane aglycones cynavimigenin A (5) and cynaviminoside A (6), together with new pregnane glycosides cynaviminoside B (7) and cynavimigenin B (8). Cynavimigenin B (8) contains an unprecedented 7-oxobicyclo[2.2.1]heptane moiety in the seco-pregnane series, likely arising from a pinacol-type rearrangement. Interestingly, these isolates displayed only limited cytotoxicity in cancer and normal human cell lines, in addition to low activity against acetylcholinesterase and Sarcoptes scabiei bioassays, suggesting that 5-8 are not associated with the reported toxicity of this plant species.

Glycosylated coumarins, flavonoids, lignans and phenylpropanoids from Wikstroemia nutans and their biological activities.

Wikstroemia nutans Champ. ex Benth., a traditional herbal medicine collected at the Lingnan region of China, was chemically investigated. A new biscoumarin glucoside, wikstronutin (1), along with three known bis- and tricoumarin glucosides (2-4), two flavonoid glycosides (5-6), and eleven lignan glucosides (7-17) were isolated from the stems and roots of W. nutans. The new structure including its absolute configuration was elucidated based on a combination of 1D and 2D NMR, UV, IR, HRESIMS spectroscopic data, as well as chemical transformation. Compounds 1-17 were first isolated from the plant species W. nutans, while compounds 1-3, 8, and 11 were reported from the genus Wikstroemia for the first time. All co-isolates were evaluated for their in vitro inhibitory effects on nitric oxide (NO) production induced by lipopolysaccharide (LPS) in murine RAW264.7 macrophage cells. The antibacterial activity of the selected compounds was also tested. Our work enriches the structure diversity of the secondary metabolites from the genus Wikstroemia.

Regioisomers Salviprolin A and B, Unprecedented Rosmarinic Acid Conjugated Dinorditerpenoids from Salvia przewalskii Maxim.

Salvia przewalskii Maxim is a perennial plant from the genus Salvia (family Lamiaceae). The roots of S. przewalskii were long used as a traditional herb to treat blood circulation related illnesses in China. As part of our continuing interest in polycyclic natural products from medicinal plants, two unprecedented adducts comprised of a dinor-diterpenoid and a 9'-nor-rosmarinic acid derivative, linked by a 1,4-benzodioxane motif (1 and 2), were isolated from the roots of S. przewalskii. Their structures were established by extensive spectroscopic approaches including 1D, 2D NMR, and HRFABMS. Their cytotoxic activities against five human tumor cell lines were evaluated.

Przewalcyrones A-F, epoxychromene-containing polycyclic polyprenylated acylphloroglucinols with immunosuppressive activity from Hypericum przewalskii Maxim.

Chemical investigation of the extracts of the aerial parts of Hypericum przewalskii Maxim. resulted in the isolation and identification of six new epoxychromene-containing polycyclic polyprenylated acylphloroglucinols (PPAPs), named przewalcyrones A-F (1-6), and one known analogue (7). All of the structures were determined based on extensive spectroscopic analyses, X-ray crystallographic analysis, modified Mosher's method, [Rh2(OCOCF3)4]-induced ECD, and electronic circular dichroism (ECD) comparison. Structurally, przewalcyrones A-F represent the first examples of PPAPs containing an unexpected 8,8-dimethyl-3,9-epoxychromene moiety. All these compounds were evaluated for the immunosuppressive activity in anti-CD3/anti-CD28 monoclonal antibody (mAb)-stimulated human T cells. Among them, przewalcyrones C and D exhibited potential in vitro immunosuppressive activity, with IC50 values of (5.01 ± 0.52) µM and (5.26 ± 0.56) µM, respectively, highlighting those compounds as a promising starting point for the development of new immunosuppressive agents.

Hyperforatins L-U: Prenylated acylphloroglucinols with a terminal double bond from Hypericum perforatum L. (St John's Wort).

Hyperforatins L-U, ten undescribed polycyclic polyprenylated acylphloroglucinols (PPAPs) bearing a terminal double bond, together with a known compound hypericumoxide J, were isolated from the aerial parts of Hypericum perforatum L. Their structures were elucidated by spectroscopic methods, including HRESIMS, IR, UV, and NMR (1H, 13C, DEPT, HSQC, HMBC, 1H-1H COSY, and NOESY experiments). Their absolute configurations were determined by comprehensive analyses of their experimental ECD spectra in conjunction with a modified Mosher's method. Evaluation of their neuroprotective activities highlighted hyperforatin L, which displayed mild activity at a concentration of 10 µM.

Anti-Inflammatory Activities of Leaf Oil from Cinnamomum subavenium In Vitro and In Vivo.

The study determined the chemical constituents and anti-inflammatory effects of leaf oil from Cinnamomum subavenium (CS-LO) that has been used in folk medicine to treat various symptoms including inflammation. The anti-inflammatory effects of the oil were evaluated by LPS-stimulated RAW264.7 cells and the Carr-induced hind mouse paw edema model, respectively. In vitro, nitric oxide (NO), prostaglandin E2 (PGE2), TNF-α, IL-6, and IL-1ß were significantly decreased by CS-LO, and the expression of nuclear factor-κB (NF-κB) protein was blocked as well. In in vivo, the malondialdehyde (MDA) and paw edema levels were decreased by CS-LO, and the same result came up on the NO and tumor necrosis factor (TNF-a) of serum at the 5th h after Carr injection. In addition, iNOS and COX-2 immunoreactive cells of the paw tissue were decreased significantly by CS-LO (200 mg/kg) in histological examination. The present findings indicated that CS-LO have anti-inflammatory properties, and the effects might be caused through inhibiting iNOS, COX-2, TNF-α, IL-1ß, and IL-6 expression via affecting NF-κB pathway, which will provide a power scientific basis for CS-LO to be used as the treatment of inflammatory diseases.

Bioactive polycyclic polyprenylated acylphloroglucinols from Hypericum perforatum.

Fifteen new polycyclic polyprenylated acylphloroglucinols (PPAPs), hyperforatones A-O (1-15), along with 3 structurally related analogues (16-18), were isolated from the stems and leaves of Hypericum perforatum. Their structures and absolute configurations were established by a combination of NMR spectroscopic analyses, experimental and calculated electronic circular dichroism (ECD), modified Mosher's methods, Rh2(OCOCF3)4- and [Mo2(OAc)4]-induced ECD, X-ray crystallography, and the assistance of quantum chemical predictions (QCP) of 13C NMR chemical shifts. Compound 5 was found to be the first PPAP decorated by a rare 2,2,4,4,5-(pentamethyltetrahydrofuran-3-yl)methanol moiety and an oxepane ring. Furthermore, the isolates were screened for their acetylcholinesterase (AChE) and ß-site amyloid precursor protein cleaving enzyme 1 (BACE1) inhibitory activities. Compounds 5, 10, 11, and 15 showed desirable AChE inhibitory activities (IC50 6.9-9.2 µM) and simultaneously inhibited BACE1 (at a concentration of 5 µM) with inhibition rates of 50.3%, 34.3%, 47.2%, and 34.6%, respectively. Interestingly, compound 5 showed the most balanced inhibitory activities against both AChE and BACE1 of all the tested compounds, which means that 5 could serve as the first valuable dual-targeted PPAP for the treatment of Alzheimer's disease. Preliminary molecular docking studies of 5 with BACE1 and AChE were also performed.

Polyketide and Prenylxanthone Derivatives from the Endophytic Fungus Aspergillus sp. TJ23.

Eight secondary metabolites, including a new polyketide, named asperetide (1) and a new prenylxanthone derivative, called asperanthone (4), and six known compounds, (S)-3-butyl-7-methoxyphthalide (2), ruguloxanthone C (3), tajixanthone hydrate (5), tajixanthone methanoate (6), salimyxin B (7), and ergosterol (8), were isolated and identified from the medicinal plant-derived fungus, Aspergillus sp. TJ23. The new structures and their absolute configurations were elucidated via multiple methods, including 1D- and 2D-NMR, HR-ESI-MS, UV, IR, and the electronic circular dichroism (ECD) calculations. All of the isolates were characterized from the strain for the first time. The in vitro bioassay showed that compounds 3-5 and 8 exerted inhibitory activities against five cancer cell lines (B16, MDA-MB-231, 4T1, HepG2, and LLC) with IC50 values ranging from 5.13 to 36.8 µm.

Terrusnolides A-D, new butenolides with anti-inflammatory activities from an endophytic Aspergillus from Tripterygium wilfordii.

Terrusnolides A-D (1-4), four butenolides were isolated from an endophytic Aspergillus from Tripterygium wilfordii. The structures of 1-4 were established by comprehensive spectroscopic analyses and electronic circular dichroism (ECD) calculation. It is interesting that 1 was a butenolide derived by a triple decarboxylation, while 2-4 were the metabolites with 4-benzyl-3-phenyl-5H-furan-2-one motif possessing an isopentene group fused to the benzene ring. In vitro anti-inflammatory effects of these isolates were evaluated in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. 1-4 exhibited excellent inhibitory effects on the production of interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α), and nitric oxide (NO) in LPS-induced macrophages, comparable with the positive control (indomethacin). Those results indicated that, terrusnolides A-D might serve as new potential natural remedies for the treatment of inflammation.

Phenylacetylene-bearing 3,4-seco-cleistanthane diterpenoids from the roots of Phyllanthus glaucus.

Three new cleistanthane diterpenoids, phyllanglins A-C (1-3), a new natural product, 4-acetyl-bergenin (4), and three known compounds (5-7) were isolated from the roots of Phyllanthus glaucus. Their structures were elucidated by extensive spectroscopic data analyses and single-crystal X-ray diffraction. Phyllanglins A-C were unusual cleistanthane diterpenoids with phenylacetylene moieties, and a plausible biogenetic pathway was proposed to discuss the origins of them. All of the isolates were evaluated for their anti-inflammatory activities.

Protoilludane, Illudalane, and Botryane Sesquiterpenoids from the Endophytic Fungus Phomopsis sp. TJ507A.

To explore the chemical diversity of metabolites from endophytic fungi, the strain Phomopsis sp. TJ507A, isolated from the medicinal plant Phyllanthus glaucus, was investigated. A 2,3- seco-protoilludane-type sesquiterpenoid (1), eight protoilludane-type sesquiterpenoids (2-9), four illudalane-type sesquiterpenoids (10a/10b, 11, and 12), and a botryane-type sesquiterpenoid (13) in addition to seven known sesquiterpenoids (14-20) were identified from the liquid culture of the fungus. Structures of the isolated compounds, including their absolute configurations, were elucidated based on extensive spectroscopic analyses, a modified Mosher analysis, electronic circular dichroism (ECD) calculations, and [Rh2(OCOCF3)4]-induced ECD spectra as well as X-ray crystallographic analyses. Compound 1 represents the first example of a naturally occurring sesquiterpenoid containing the unusual 2,3- seco-protoilludane scaffold. Compounds 1 ( p < 0.001); 2-6, 15, and 18 ( p < 0.01); and 7, 9, and 20 ( p < 0.05) displayed ß-site amyloid precursor protein cleaving enzyme 1 (BACE1) inhibitory activities ranging from 19.4% to 43.8% at the concentration of 40 µM. LY2811376 was used as the positive control with an inhibitory activity of 38.6% ( p < 0.01). Furthermore, none of these compounds showed obvious hepatotoxicity at concentration of 40 µM.

Hyperjaponol H, A New Bioactive Filicinic Acid-Based Meroterpenoid from Hypericum japonicum Thunb. ex Murray.

Hyperjaponol H (1), a new filicinic acid-based meroterpenoid, with a 6/6/10 ring system trans-fused by hetero-Diels-Alder cycloaddition between a germacrane sesquiterpenoid and a filicinic acid moiety, was isolated from aerial parts of Hypericum japonicum. The elucidation of its structure and absolute configuration were accomplished by the analyses of extensive spectroscopic data and the comparison of Cotton effects of electron circular dichroism (ECD) with previously reported ones. The bioactivity assay showed that hyperjaponol H exhibited a moderate inhibitory efficacy on lytic Epstein-Barr virus (EBV) DNA replication in B95-8 cells.

Hyperattenins L and M, two new polyprenylated acylphloroglucinols with adamantyl and homoadamantyl core structures from Hypericum attenuatum.

Hyperattenins L (1) and M (2), two new benzoylated polyprenylated phloroglucinol derivatives possessing unusual adamantyl and homoadamantyl core structures, were isolated from the aerial parts of Hypericum attenuatum. Their structures were determined by extensive NMR spectroscopic methods. Compound 1 possesses an unusual tetracyclo[6.3.1.11,10.01,5]tridecane skeleton, representing the second report of natural product with this carbon skeleton. Compound 2 features an unexpected 2,3,13-trioxapentacyclo[7.5.3.17,11.05,16.012,16]octodecane ring system formed by the fusion of 2,3,8-trioxabicyclo[4.3.1]decane moiety to the tricycle[4.3.1.13,8]undecane core. Both compounds were evaluated for their cytotoxic activities against five human cancer cell lines and compound 1 showed excellent inhibitory activities against HL-60, A-549, and MCF-7 cell lines with IC50 values of 3.86, 4.34, and 5.78µM, respectively.

Discovery of acylphloroglucinol-based meroterpenoid enantiomers as KSHV inhibitors from Hypericum japonicum.

Kaposi's sarcoma associated herpesvirus (KSHV) has gained considerable attention as a type of carcinogenic pathogen. Recent research suggests that KSHV has participated in the pathogenesis of Kaposi's sarcoma-related malignant neoplastic diseases. Viral lytic infection might be pivotal for the etiopathogenesis of KSHV-induced diseases; however, most clinical KSHV lytic replication inhibitors like ganciclovir, nelfinavir, or cidofovir do not restrain virus replication effectively enough to achieve clinical efficacy. In our continued pharmaceutical studies on Chinese herbal medicines, new acylphloroglucinol-based meroterpenoid enantiomers have been discovered from Hypericum japonicum. Most of these metabolites have potential inhibitory activities that target KSHV lytic replication. Amongst these analogues, compounds 1a and 1b possess an unreported ring system cyclopenta[b]chromene. Compounds 1a with 4a exhibit stronger inhibitory activities towards the lytic replication of KSHV in Vero cells. In addition, 1a and 4a have IC50 values of 8.30 and 4.90 µM and selectivity indexes of 23.49 and 25.70, respectively. Qualitative and quantitative SAR and molecular docking studies for acylphloroglucinol-based meroterpenoids with regard to anti-KSHV activity were conducted. An explanation for the variation in the activity and selectivity indexes was proposed in accordance with the predicted binding pose found with molecular docking to a putative target, thymidylate synthase (kTS). Compounds 1a and 4a have potential for further development and optimization of their anti-KSHV activities which could lead to new candidate drugs.

Azacoccones A-E, five new aza-epicoccone derivatives from Aspergillus flavipes.

Azacoccones A-E (1-5), five new aza-epicoccone derivatives, were isolated from the culture of Aspergillus flavipes. Their structures were determined by extensive NMR spectroscopic analyses and the absolute configuration of 5 was determined by electronic circular dichroism (ECD) calculation. Compounds 1-5 are proposed to be generated via a Pictet-Spengler reaction-based biosynthetic route starting from the precursor flavipin. Pictet-Spengler reaction is rarely found in the fungal kingdom, which indicated the distinctive nature of 1-5. Compounds 3 and 5 exhibit significant free radical scavenging activities with IC50 values of 4.0 and 2.4µg/mL, respectively, which are better than the positive control trolox (4.55µg/mL).

Atrichodermones A-C, three new secondary metabolites from the solid culture of an endophytic fungal strain, Trichoderma atroviride.

An endophytic fungal strain named Trichoderma atroviride was isolated from the bulb of Lycoris radiata. Following cultivation on rice medium, a novel 3-amino-5-hydroxy-5-vinyl-2-cyclopenten-1-one dimer, atrichodermone A (1), a new cyclopentenone derivative, atrichodermone B (2), and a new sesquiterpene, atrichodermone C (3), together with three known cyclopentenone derivatives (4-6) were isolated. Their structures were elucidated by extensive spectroscopic (UV, IR, ECD, HRESIMS, and NMR) data analyses, and absolute configurations of the new compounds were determined by comparing their experimental ECD spectra with structurally similar compounds and computational analyses of their electronic circular dichroism (ECD) spectra. Compounds 1-3 were evaluated for their cytotoxicity against HL60 and U937 cell lines, as well as anti-inflammatory effect against the production of the pro-inflammatory cytokines TNF-α and IL-1ß.

Tricyclic Polyprenylated Acylphloroglucinols from St John's Wort, Hypericum perforatum.

The new polyprenylated acylphloroglucinol derivatives 1-15 and the known furohyperforin (16) were isolated from the stems and leaves of Hypericum perforatum. Their structures were determined by analyses of NMR and HRESIMS data. Their absolute configurations were elucidated by a combination of electronic circular dichroism (ECD) and Rh2(OCOCF3)4-induced ECD, as well as X-ray diffraction crystallography. The new hyperforatin F (9) contains a unique acetyl functionality at C-1 of the bicyclo[3.3.1]nonane core. Hyperforatins G (10) and H (11) are similarly the first examples of naturally occurring [3.3.1]-type polycyclic prenylated acylphloroglucinols possessing a carbonyl functionality at C-32. The compounds were tested for their acetylcholinesterase (AChE) inhibitory activities and cytotoxic activities against a panel of human tumor cell lines. Compounds 3, 5, 6, 8, and 9 exerted moderate inhibitory activities (IC50 3.98-9.13 µM) against AChE.

Diterpenoids of the Cassane Type from Caesalpinia decapetala.

Eighteen compounds, including eight new cassane-type furanoditerpenoids, 3ß-hydroxyphanginin H (1), 3ß-acetoxyphanginin H (2), 7ß-acetoxyphanginin H (3), 7ß-hydroxyphanginin H (4), 4-epi-3ß-hydroxycaesalpinilinn (5), 4-epi-3ß-acetoxycaesalpinilinn (6), 20-acetoxytaepeenin D (7), and tomocin E (8), along with 10 known compounds (9-18) were isolated from the roots of Caesalpinia decapetala. Compounds 1-13 were isolated from C. decapetala for the first time. The new compounds with their absolute configurations were determined by extensive spectroscopic analysis, single-crystal X-ray diffraction, and electronic circular dichroism calculations. Compounds 1, 4, 5, 7, and 11 exhibited inhibitory activities against the SW1990 human pancreatic cancer cell line with IC50 values ranging from 2.9 to 8.9 µM.

6,8-Di-C-methyl-flavonoids with neuroprotective activities from Rhododendron fortunei.

Six 6,8-di-C-methyl-flavonoids, (2R,3R)-6,8-di-C-methyl-5,7,4'-trihydroxyflavanonol 7-O-ß-d-gluco-pyranoside (1), (2R,3R)-6,8-di-C-methyl-5,7,4'-trihydroxyflavanonol 7-O-ß-d-xylopyranosyl(1→6)-ß-d-glucopyranoside (2), 6,8-di-C-methylkaempferol 7-O-ß-d-glucopyranoside (3), (2R)-farrerol (4a), (2R/2S)-farrerol 7-O-ß-d-glucopyranoside (5), and (2R/2S)-farrerol 7-O-ß-d-xylopyranosyl(1→6)-ß-d-glucopyranoside (6), and four known analogues, farrerol (4b), (2R,3R)-6,8-di-C-methyldihydrokae-mpferol (7), 6,8-di-C-methylkaempferol 7-O-ß-d-glucopyranoside (8), and 6,8-di-C-methylkaempferol (9), were isolated from the twigs and leaves of Rhododendron fortunei. The structures of compounds 1-9 were determined by spectroscopic analyses (HRESIMS, 1D and 2D NMR, and CD) and chemical methods. Compounds 1-9 were evaluated for their neuroprotective effects on the human neuroblastoma SH-SY5Y cells apoptosis induced by hydrogen peroxide (H2O2) and amyloid ß peptide (Aß), respectively. Compounds 1-3 and 5-9 exhibited significant neuroprotective effects against H2O2-induced SH-SY5Y cell apoptosis, and compound 8 exhibited the strongest activity with a improvement of cell viability by about 30% at the concentration of 10µM. Compounds 1-9 showed significant neuroprotective effects against Aß-induced SH-SY5Y cell apoptosis.

(±)-Japonones A and B, two pairs of new enantiomers with anti-KSHV activities from Hypericum japonicum.

Two pairs of new enantiomers with unusual 5,5-spiroketal cores, termed (±)-japonones A and B [(±)-1 and (±)-2], were obtained from Hypericum japonicum Thunb. The absolute configurations of (±)-1 and (±)-2 were characterized by extensive analyses of spectroscopic data and calculated electronic circular dichroism (ECD) spectra, the application of modified Mosher's methods, and the assistance of quantum chemical predictions (QCP) of (13)C NMR chemical shifts. Among these metabolites, (+)-1 exhibited some inhibitory activity on Kaposi's sarcoma associated herpesvirus (KSHV). Virtual screening of (±)-1 and (±)-2 were conducted using the Surflex-Dock module in the Sybyl software, and (+)-1 exhibited ability to bind with ERK to form key interactions with residues Lys52, Pro56, Ile101, Asp165, Gly167 and Val99.