Diarylpentanoids from Diplomorpha canescens and Diplomorpha ganpi

Two new α-hydroxy ketone type diarylpentanoids, diplomorphanone A, 2(S)-hydroxy-1-(4-hydroxyphenyl)-5-phenyl-1-pentanone (1) and diplomorphanone B, 2(R)-hydroxy-1,5-diphenyl-1-pentanone (2) were isolated from aerial parts of Diplomorpha canescens (Meisn.) C.A. Meyer and roots of Diplomorpha ganpi (Sieb. et Zucc.) Nakai, respectively. Nine known compounds including diarylpentanoids (3–6), phenylpropanoid derivatives (7–9), (+)-afzelechin (10) and apiosylskimmin (11) were also isolated for the first time from D. ganpi. Structures of these compounds were elucidated on the basis of spectroscopic data.     

Two novel saponins from Cephalaria davisiana (Dipsacaceae)

Two novel hederagenin type triterpene saponins, namely davisianoside A (1) and davisianoside B (2) together with ten known compounds (3–12) were isolated from the aerial parts of Cephalaria davisiana (Dipsacaceae). One new prosapogenin (1a) was also obtained after the alkaline hydrolysis of compound 1. The chemical structures of all compounds were established mainly by 1D-, 2D-NMR and HR-ESI/MS analysis as well as chemical methods.The antibacterial and antifungal effects of compounds 1–2 were evaluated against Gram-positive, Gram-negative bacteria and unicellular yeast C. albicans by MIC method.     

Triterpenoid saponins from Echinopsis macrogona (Cactaceae)

Triterpene saponins, pachanosides C1, E1, F1 and G1 (1-4), and bridgesides A1, C1, C2, D1, D2, E1 and E2 (5-11) were isolated from Echinopsis macrogona. Compounds 1-4 were saponins with pachanane type triterpene saponins, while the others (5-11) were oleanane type triterpene saponins. While the aglycones of 2-4 and 8-11 were hitherto unknown, the structure of pachanol C was revised in this paper. Their structures were elucidated on the basis of chemical and physicochemical evidence.     

Bioactive constituents of Morus wittiorum

From the stem bark of Morus wittiorum, one new Diels–Alder type adduct wittiorumin G (1) and three new 2-arylbenzofuran derivatives wittifurans P–R (2–4) along with five known Diels–Alder type adducts albafuran C, sorocein A, mulberrofuran E, mulberrofuran F and mulberrofuran O were isolated. Their structures were determined on the basis of spectroscopic analysis. Compounds 2–4 and two known compounds sorocein A and mulberrofuran F were evaluated for their antioxidant activity in a Fe²⁺/cysteine-induced microsomal lipid peroxidation assay and cytotoxicity against five human cancer cell lines respectively.     

Three new iridoid glycosides isolated from the traditional herb Siphonostegia chinensis with NF-κB inhibitory activity

Siphonoids A–C (1–3), among which siphonoids A-B (1–2) are rare (E)-p-coumaroyl iridoids, were isolated from Siphonostegia chinensis along with ten known iridoids (4–13) and four lignans (14–17). The structures of the compounds were established by 1D- and 2D-NMR spectroscopy and mass spectrometry. Most of the iridoids isolated from S. chinensis were found to possess (E)-p-coumaroyl iridoid subtype skeletons. Hence, this type of iridoid could be regarded as a chemotaxonomic marker of S. chinensis. The inhibition activities for the NF-κB pathway of iridoids (1–6) were detected. The present results showed that compounds 1–2 and 4–6 processed moderate activity towards the inhibition of NF-κB.     

Antidiabetic potential of phytochemicals isolated from the stem bark of Myristica fatua Houtt. var. magnifica (Bedd.) Sinclair

Phytochemical investigation of the stem bark of Myristica fatua Houtt. led to the isolation of a new compound 1 (3-tridecanoylbenzoic acid), along with six known acylphenols (2–7). All the compounds displayed moderate inhibitory activity on α-amylase and significant activity on α-glucosidase; however malabaricone B (6) and C (7) were identified as potent α-glucosidase inhibitors with IC₅₀ values of 63.70?±?0.546, and 43.61?±?0.620?µM respectively. Acylphenols (compounds 3–7) also showed significant antiglycation property. The molecular docking and dynamics simulation studies confirmed the efficient binding of malabaricone C with C-terminus of human maltase-glucoamylase (2QMJ). Malabaricone B also enhanced the 2-NBDG [2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxy glucose] uptake in L6 myotubes. These findings demonstrate that acylphenols isolated from Myristica fatua Houtt. can be considered as a lead scaffold for the treatment of type II diabetes mellitus.     

Chalcone glycosides isolated from aerial parts of Brassica rapa L. ‘hidabeni’ suppress antigen-stimulated degranulation in rat basophilic leukemia RBL-2H3 cells

We isolated three chalcone glycosides along with other glycoside constituents from the aerial parts of Brassica rapa L. ‘hidabeni’ and examined the effects of these compounds on the antigen-stimulated degranulation in rat basophilic leukemia RBL-2H3 cells. Treatments with both 4′-O-β-d-glucopyranosyl-4-hydroxy-3′-methoxychalcone (C1) and 4′-O-β-d-glucopyranosyl-3′,4-dimethoxychalcone (C2) markedly inhibited antigen (Ag)-stimulated degranulation. To gain further insight into the inhibitory mechanisms by C1 and C2, we examined early intracellular signaling events, Ca²⁺ mobilization and intracellular reactive oxygen species (ROS) production. Both C1 and C2 did not affect early intracellular signaling events but exhibited the suppression of intracellular ROS production through NADPH oxidase (NOX) inactivation. From these results, we proposed that the inhibitory effects of C1 and C2 on Ag-stimulated degranulation were mainly due to suppression of intracellular Ca²⁺ elevation by suppression of intracellular ROS production through NOX inactivation. Our findings suggest that C1 and C2 would be beneficial to alleviate symptoms of type I allergy.     

Four analogues of spiroleptosphol isolated from Leptosphaeria doliolum

Spiroleptosphol B (2), spiroleptosphol C (3), norleptosphol C (4) and hydroleptosphol (5) were isolated from ascomycete Leptosphaeria doliolum. Detailed ¹H and ¹³C NMR spectral analyses revealed these were structural analogues of spiroleptosphol (1) which we have recently isolated from the same fungi. Spiroleptosphol B (2) carried an unprecedent 5,3-dioxatricyclo[4.4.0.1^1.4]undecane framework in place of the spirobicyclo ring system of 1. Spiroleptosphol C (3) was a 17-(R)-hydroxy derivative of 1. Norleptosphol C (4) was deduced to be the monocyclic structure biosynthetically resulted by decarboxylation from 3. Although 5 gave broaden ¹H NMR spectrum, it was gradually transformed to 2 which suggested being a hydrolysate of 1.     

Chevalierinoside B and C: Two new isoflavonoid glycosides from the stem bark of Antidesma laciniatum Muell. Arg (syn. Antidesma chevalieri Beille)

Chevalierinosides B (1) and C (2), two new isoflavonoid glycosides, characterized as biochanin A 7-O-[β-d-apiofuranosyl-(1→2)-β-d-glucopyranoside] and genistein 7-O-[β-d-apiofuranosyl-(1→2)-β-d-glucopyranoside], together with the known isoflavonoids, chevalierinoside A (3) and genistein 7-O-β-d-glucopyranoside (4), kaempferol 3-O-β-d-glucopyranoside (5) and triterpenes, friedelin (6), betulinic acid (7), 30-oxobetulinic acid (8), 30-hydroxybetulinic acid (9), were isolated from the stem bark of Antidesma laciniatum Muell. Arg. (syn. Antidesma chevalieri Beille). Their structures were established by direct interpretation of their spectral data, mainly HR-TOFESIMS, 1D-NMR (¹H, ¹³C and DEPT) and 2D-NMR (COSY, NOESY, TOCSY, HSQC and HMBC), and by comparison with the literature.     

Evolvosides C–E,flavonol-4-O-triglycosides from Evolvulus alsinoides and their anti-stress activity

Phytochemical investigation of the n-butanol fraction of Evolvulus alsinoides (Linn.) led to the isolation of three new phenolic glycosides, evolvosides C, D and E (1–3) along with six known compounds (4–9). The structures of the compounds were elucidated on the basis of spectroscopic analysis, viz. 1D and 2D NMR experiments, chemical study, and comparison with literature data. Evolvoside C (1) was characterized as kaempferol 4′-O-β-d-glucopyranosyl-(1→2)-α-l-rhamnopyranosyl-(1→6)-β-d-glucopyranoside, whereas evolvosides D and E (2–3) were found to be mono and di-O-methyl derivatives of 1. The new compounds (1–3) represent rare triglycoside derivatives of flavonol at C-4′. The isolated compounds (1–6) were screened for acute stress-induced biochemical changes in male Sprague–Dawley rats at a dose of 40 mg/kg body weight. Compounds 1 and 2 displayed anti-stress effects by normalizing hyperglycemia, plasma corticosterone, plasma creatine kinase, and adrenal hypertrophy. Compounds 3 and 6 were also found to be effective in normalizing most of these stress parameters, whereas compounds 4 and 5 were ineffective in normalizing most of these effects.     

Cytotoxic pterosins from Pteris multifida roots against HCT116 human colon cancer cells

Two new pterosin glycosides, (2S,3S)-pterosin C 3-O-β-d-(4′-(E)-caffeoyl)-glucopyranoside (1) and (2S,3S)-pterosin C 3-O-β-d-(6′-(E)-p-coumaroyl)-glucopyranoside (2), were isolated from Pteris multifida (Pteridaceae) roots along with ten known pterosin compounds (3–12). The chemical structures of the isolated compounds were elucidated by extensive analysis of the 1D, 2D NMR, HRESIMS, and CD spectroscopic data. The cytotoxicities of 1–12 against HCT116 human colorectal cancer cell line were evaluated. Among the isolates, compound 1 showed moderate antiproliferative activity in HCT116 cells with an IC₅₀ value of 8.0 ± 1.7 μM. Additionally, 1 induced the upregulation of the caspase-9 and procaspase-9 levels in Western blots and increased the annexin V/propidium iodide (PI)-positive cell population in flow cytometry.     

Nitric oxide inhibitory constituents from Siegesbeckia pubescens

Two new sesquiterpenoids (1 and 2) and a new ent-pimarane type diterpenoid (3), together with eighteen known compounds (4–21), were isolated from the whole plants of Siegesbeckia pubescens. The structures of the new compounds were determined on the basis of 1D-, 2D NMR and HRESIMS data. All compounds were evaluated for their inhibitory effects on LPS-induced nitric oxide production in RAW 264.7 macrophages. Of these, highly oxygenated germacrane type sesquiterpenoids (1–2 and 13–14) showed significant inhibitory effects with IC₅₀ values ranging from 3.9 to 16.8 μM.     

Chemical constituents from Cistanche sinensis (Orobanchaceae)

Phytochemical investigation of 70% aqueous EtOH extract of Cistanche sinensis led to the isolation of fifteen compounds (1–15), including nine phenylethanoid glycosides (PhGs, 1–9), five iridoid glycosides (10–14), and one lignan glycoside (15). Their structures were determined on the basis of 1D- and 2D-NMR experiments and by comparison with physical data of known compounds. Among the isolated compounds, 1 was identified as a new compound, three compounds (9, 14, and 15) were firstly reported from the genus Cistanche, and seven compounds (2–6, 11, and 12) were isolated from C. sinensis for the first time. PhGs with a 6′-O-rhamnosyl moiety such as cistansinenside B (1), poliumoside (7), and 2′-O-acetylpoliumoside (9) could serve as chemotaxonomic markers to differentiate C. sinensis from other species of Cistanche.     

Furanoterpenes,new types of protein tyrosine phosphatase 1B inhibitors,from two Indonesian marine sponges,Ircinia and Spongia spp.

Protein tyrosine phosphatase (PTP) 1B negatively regulates the insulin and leptin signaling pathways, and, thus, the clinical application of PTP1B inhibitors to the prevention and treatment of type 2 diabetes and obesity is expected. During our studies on PTP1B inhibitors, two furanosesterterpenes and a C21 furanoterpene were obtained as new types of PTP1B inhibitors from two Indonesian marine sponges. (7E, 12E, 20Z, 18S)-Variabilin (1) and (12E, 20Z, 18S)-8-hydroxyvariabilin (2) from Ircinia sp. and furospongin-1 (3) from Spongia sp. inhibited PTP1B activity with IC₅₀ values of 1.5, 7.1, and 9.9 μM, respectively. The inhibitory activity of compound 1 against T-cell PTP (TCPTP) was approximately 2-fold that against PTP1B, whereas the vaccinia H-1-related phosphatase (VHR) inhibitory effects of 1 were 4-fold weaker than that of its PTP1B inhibitory activity. Compounds 1–3 at 50 μM did not show cytotoxicity against two human cancer cell lines, hepatoma Huh-7 and bladder carcinoma EJ-1. Compound 1 did not enhance the phosphorylation level of Akt, a key downstream effector of the cascade, in Huh-7 cells.     

New potent P-glycoprotein modulators with the cucurbitane scaffold and their synergistic interaction with doxorubicin on resistant cancer cells

The novel cucurbitacins, balsaminagenin A and B (1–2) and balsaminoside A (3) and the know cucurbitacin karavelagenin C (4), together with five new mono or diacylated derivatives (5–9) of karavelagenin C were evaluated for multidrug resistance reversing activity on human MDR1 gene transfected mouse lymphoma cells. Compounds 2–6 exhibited a strong activity compared with that of the positive control, verapamil. Structure–activity relationships are discussed. Moreover, in the checkerboard model of combination chemotherapy, the interaction between doxorubicin and compounds 2–5 synergistically enhanced the effect of the anticancer drug. Compounds 1–4 were isolated from the aerial parts of Momordica balsamina L. The structures of the compounds were established on the basis of spectroscopic methods including 2D NMR experiments (COSY, HMQC, HMBC and NOESY).     

An antibacterial cytochalasin derivative from the marine-derived fungus Diaporthaceae sp. PSU-SP2/4

A new pentacyclic cytochalasin (diaporthalasin, 1) and a new ethyl trihydroxytridecatrienoate (diaporthacol, 2) together with five known compounds, R-mevalonolactone (4), dothiorelone C (5), (4S,7S,13S)-4,7-dihydroxy-1,3-tetradeca-1,5-dienolide (6), 4β-acetoxy-9β,10β,15α-trihydroxyprobotrydial (7) and O-methyldihydrobotrydial (8) were isolated from the marine-derived fungus Diaporthaceae sp. PSU-SP2/4. The structures were established by spectroscopic techniques. Compound 1 displayed significant antibacterial activity against both Staphylococcus aureus and methicillin-resistant S. aureus with equal MIC values of 2 μg/mL.     

A new triterpenic diester from the aerial parts of Chrysanthemum macrocarpum

A new triterpenic diester, 3,21-dipalmitoyloxy-16β,21α-dihydroxy-β-amyrine (1), along with two natural cyclitols, conduritol C (2) and viburnitol (3), four known triterpenes (4–7), and seven known flavonoids (8–14) were isolated from the aerial parts of Chrysanthemum macrocarpum. Their structures were established on the basis of extensive 1D and 2D NMR (¹H, ¹³C, COSY, HMBC, HSQC, and ROESY) and ESIMS studies. The chloroform fraction, taraxasterol (4) and β-sitosterol (7) were investigated for their antibacterial activity against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae. The chloroform fraction and taraxasterol (4) showed a weak antibacterial activity and were evaluated for their cytotoxic activity against human colon cancer HT-29 cells and human prostate carcinoma PC3 cells. The results indicated that both the chloroform fraction and taraxasterol (4) inhibited cell proliferation of both PC3 and HT-29 cells.     

Five-coordinate zinc(II) complexes with optically active Schiff bases derived from (1R,2R)-(−)cyclohexanediamine: X-ray structure and CP MAS NMR characterization of [cyclohexylenebis(5-chlorosalicylideneiminato)zinc(II)pyridine] and [cyclohexylenebis(5-bromosalicylideneiminato)zinc(II)pyridine]

Schiff bases obtained from (1R,2R)-(−)-cyclohexanediamine and 5-chloro- (1) or 5-bromosalicylaldehyde (2) are used as ligands for Zn(II) resulting in [(1R,2R)-cyclohexylenebis(5-chlorosalicylideneiminato)]zinc(II) (1a) and (1R,2R)-[cyclohexylenebis-(5-bromosalicylideneiminato)]zinc(II) (2a). In the presence of pyridine, 1a and 2a turned out into (1R,2R)-[cyclohexylenebis(5-chlorosalicylideneiminato)pyridine]zinc(II) (1b) and (1R,2R)-[cyclohexylenebis(5-bromosalicylideneiminato)pyridine]zinc(II) (2b). Coordination sphere of Zn(II) atoms in both pyridine adducts is a slightly distorted square pyramid, with N₂O₂ chromophore units and axially bonded pyridine as it is evident from single crystal X-ray analyzes of 1b and 2b. The asymmetric unit of 1b and 2b contains two molecules of complexes. The observed distances of Zn-O in both molecules indicate the rigidity of the tetradentate ligand as a main factor influencing the geometry of coordination sphere. Obtained complexes were characterized by ¹H NMR in solution and ¹³C CP MAS NMR. NOE differential experiments revealed significant steric interactions between C(6)-H in the phenyl ring, cyclohexyl C(1)-H and imine hydrogen. Significant coordination shifts of carbons in the closest proximity to the coordination center were noted as well.     

Design,synthesis, and X-ray crystal structures of 2,4-diaminofuro[2,3-d]pyrimidines as multireceptor tyrosine kinase and dihydrofolate reductase inhibitors

To optimize dual receptor tyrosine kinase (RTK) and dihydrofolate reductase (DHFR) inhibition, the E- and Z-isomers of 5-[2-(2-methoxyphenyl)prop-1-en-1-yl]furo[2,3-d]pyrimidine-2,4-diamines (1a and 1b) were separated by HPLC and the X-ray crystal structures (2.0 and 1.4 Å, respectively) with mouse DHFR and NADPH as well as 1b with human DHFR (1.5 Å) were determined. The E- and Z-isomers adopt different binding modes when bound to mouse DHFR. A series of 2,4-diaminofuro[2,3-d]pyrimidines 2–13 were designed and synthesized using the X-ray crystal structures of 1a and 1b with DHFR to increase their DHFR inhibitory activity. Wittig reactions of appropriate 2-methoxyphenyl ketones with 2,4-diamino-6-chloromethyl furo[2,3-d]pyrimidine afforded the C8–C9 unsaturated compounds 2–7 and catalytic reduction gave the saturated 8–13. Homologation of the C9-methyl analog maintains DHFR inhibitory activity. In addition, inhibition of EGFR and PDGFR-β were discovered for saturated C9-homologated analogs 9 and 10 that were absent in the saturated C9-methyl analogs.     

Generation of methylated violapyrones with improved anti-influenza A virus activity by heterologous expression of a type III PKS gene in a marine Streptomyces strain

Heterologous expression of the type III polyketide synthase (PKS) gene vioA in marine-derived Streptomyces youssoufiensis OUC6819 led to production of six violapyrones (VLPs), including four novel compounds VLPs Q–T (1–4) and two known compounds VLPs B and I (5 and 6). The structures of 1–4 were elucidated by a combination of spectroscopic analyses, including HR-ESIMS and 1D and 2D NMR data, demonstrating that 1–4 are novel VLPs which are methylated at 4-OH with their corresponding non-methylated counterparts to be VLP A, 5 and 6 and VLP C, respectively. Anti-influenza A [H1N1 (A/Virginia/ATCC1/2009) and H3N2 (A/Aichi/2/1968)] virus activity of compounds 1–6 as well as VLPs A and C were then evaluated using ribavirin as a positive control (IC₅₀?=?66.7 and 99.6?μM). The results revealed that these VLPs showed considerable anti-H1N1 and anti-H3N2 activities with IC₅₀ values of 30.6–132.4?μM and 45.3–150.0?μM, respectively. Notably, all the methylated VLPs displayed better anti-virus activity than their non-methylated counterparts, among which compound 3 (VLP S) exhibited the best activities. Interestingly, methylation at 4-OH has negative effect on the anti-MRSA (methicillin-resistant Staphylococcus aureus) activity instead, with methylated VLPs displaying decreased (2) or abolished (3 and 4) activities in comparison with each of their non-methylated counterparts.