Antimicrobial spiroketal macrolides and dichloro-diketopiperazine from Micromonospora sp. FIMYZ51.

Four compounds (1-4) featuring with an L-rhodinose and spiroketal, possess uncommon continuous hydroxy groups in the macrolide skeleton, and a dichloro-diketopiperazine (5) were isolated from a marine derived Micromonospora sp. FIMYZ51. The determination of the relative and absolute configurations of all isolates was achieved by extensive spectroscopic analyses, single-crystal X-ray diffraction analysis, and ECD calculations. According to structural characteristic and genomic sequences, a plausible biosynthetic pathway for compound 1-4 was proposed and a spirocyclase was inferred to be responsible for the formation of the rare spirocyclic moiety. Compounds 1-4 exhibited potent antifungal activities which is equal to itraconazole against Aspergillus niger. Compounds 1-5 exhibited different degree of inhibitory activities against opportunistic pathogenic bacteria of endocarditis (Micrococcus luteus) with MIC values ranging from 0.0625 µg/mL to 32 µg/mL. Compounds 2 and 3 showed moderate cytotoxicity against drug-resistant tumor cell lines (Namalwa and U266). The result not only provides active lead-compounds, but also reveal the potential of the spirocyclase gene resources from Micromonospora sp., which highlights the promising potential of the strain for biomedical applications.

Natural spirocyclic alkaloids and polyphenols as multi target dementia leads.

The U rhynchophylla, U tomentosa, Isatis indigotica Fortune, Voacanga Africana, herbal constituents, fungal extracts from Aspergillus duricaulis culture media, include spirooxindoles, polyphenols or bridged spirocyclic alkaloids. Their constituents exhibit specific and synergistic multiple neuroprotective properties including inhibiting of Aß fibril induced cytotoxicity, NMDA receptor inhibition in mice models of Alzheimer's disease (AD). The pioneering research from Woodward to Waldmann has advanced the synthesis of spirocyclic alkaloids. Furthermore, the elucidation of the genetic analysis, biochemical pathways that links strictosidine to the alkaloids akuammicine, stemmadenine, tabersonine, catharanthine, will now enable the biotechnological generation, also stimulate synthesis of related bridged spirocyclic alkaloids for medicinal investigations. From the value of spirocyclic structures as multi target dementia leads, we hypothesise that simpler Lipinski-like natural/synthetic alkaloid analogues may likewise be discovered that provide neurocognitive enhancing activities against dementia and AD.

Benzannulated 5,5-spiroketal sesquiterpenes from the roots of Angelica Pubescens.

Two new tetrahydrobenzannulated 5,5-spiroketal sesquiterpenes (1 and 2) and three novel benzannulated 5,5-spiroketal sesquiterpenes (3-5) namely angepubesins A-E, together with a new heliannane-type benzannulated sesquiterpene namely angepubesin F (6) and two known monoterpenes (7 and 8), were isolated from the roots of Angelica Pubescens. Their structures were identified by various spectroscopic analyses (NMR, MS, UV, IR), in combination with 13C NMR calculation as well as MAE, CMAE, DP4 + and MAEΔΔδ values analyses. The absolute configurations of 1-6 were determined by modified Mosher's method, ECD calculation and single-crystal X-ray diffraction (Cu Kα). Furthermore, the inhibitory activities of these isolated compounds against nitric oxide (NO) production induced by lipopolysaccharide (LPS) in RAW264.7 macrophage cells were evaluated. The results showed that compounds 2-4, 6 and 7, especially 6, displayed markedly inhibitory effects on NO production in a concentration-dependent manner. Mechanical study revealed that compound 6 could significantly inhibit the expression of nitric oxide synthase (iNOS) protein at a concentration of 10 µM. In addition, compound 6 suppressed the activation of JAK-STAT and NF-κB pathways.

Two new compounds, Talaromycin A and B, isolated from an endophytic fungus, Talaromyces aurantiacus.

Two new compounds Talaromycin A (1) and Talaromycin B (2) were isolated from a liquid culture of Talaromyces aurantiacus. The structures of 1 and 2 were elucidated by IR, MS, 1D and 2D NMR spectra and comparison of the experimental and calculated electronic circular dichroism spectra. Additional known compounds (3-6) were also isolated. These compounds were tested for monoamine oxidase, acetylcholinesterase and PI3K inhibitory activity, but showed only weak activity.

The Spirocyclic Imine from a Marine Benthic Dinoflagellate, Portimine, Is a Potent Anti-Human Immunodeficiency Virus Type 1 Therapeutic Lead Compound.

In this study, we aimed to find chemicals from lower sea animals with defensive effects against human immunodeficiency virus type 1 (HIV-1). A library of marine natural products consisting of 80 compounds was screened for activity against HIV-1 infection using a luciferase-encoding HIV-1 vector. We identified five compounds that decreased luciferase activity in the vector-inoculated cells. In particular, portimine, isolated from the benthic dinoflagellate Vulcanodinium rugosum, exhibited significant anti-HIV-1 activity. Portimine inhibited viral infection with an 50% inhibitory concentration (IC50) value of 4.1 nM and had no cytotoxic effect on the host cells at concentrations less than 200 nM. Portimine also inhibited vesicular stomatitis virus glycoprotein (VSV-G)-pseudotyped HIV-1 vector infection. This result suggested that portimine mainly targeted HIV-1 Gag or Pol protein. To analyse which replication steps portimine affects, luciferase sequences were amplified by semi-quantitative PCR in total DNA. This analysis revealed that portimine inhibits HIV-1 vector infection before or at the reverse transcription step. Portimine has also been shown to have a direct effect on reverse transcriptase using an in vitro reverse transcriptase assay. Portimine efficiently inhibited HIV-1 replication and is a potent lead compound for developing novel therapeutic drugs against HIV-1-induced diseases.

Two spiroketal derivatives with an unprecedented amino group and their cytotoxicity evaluation from the endophytic fungus Pestalotiopsis flavidula.

Two new spiroketal derivatives with an unprecedented amino group, 2'-aminodechloromaldoxin (1) and 2'-aminodechlorogeodoxin (2), along with one known analogue dechloromaldoxin (3), were isolated from the plant endophytic fungus Pestalotiopsis flavidula. Their structures were elucidated on the basis of extensive spectroscopic analysis. The purification was cytotoxicity-guided which indicated the extract, fractions and compounds were evaluated in vitro for anti-proliferative activity against a panel of human cancer cell lines. The results showed compounds 1 and 2 with moderate cytotoxicity while 3 was inactive, which suggested -NH2 group might play a very important role for their cytotoxicity. This is the first study for P. flavidula and the first time to report the spiroketal derivatives as alkaloids from the Pestalotiopsis genus.

Hyperpatulols A-I, spirocyclic acylphloroglucinol derivatives with anti-migration activities from the flowers of Hypericum patulum.

Nine new spirocyclic acylphloroglucinol derivatives, hyperpatulols A-I (1-9), were characterized from the flowers of Hypericum patulum. Their structures were elucidated by the basic analysis of the obtained spectroscopic data, and their absolute configurations were assigned by both the electronic circular dichroism (ECD) exciton chirality method and ECD calculation. The evaluation of their anti-migration effects on U2-OS human osteosarcoma cells showed that compound 4 exhibited moderate inhibitory activity in a dose-dependent manner. Further pharmacological studies revealed that 4 could regulate the expression of the proteins Vimentin and E-cadherin.

An LC-ESI-MS/MS method for the simultaneous determination of pronuciferine and roemerine in some Papaver species.

Papaver species, well known for their alkaloids, have been used for the treatment of several diseases, such as inflammation, diarrhea, depression, and sleep disorders in certain parts of Anatolia. In this study, four Papaver species (P. lacerum, P. syriacum, P. glaucum and P. rhoeas) were collected from different localities of Turkey. Methanolic extracts were prepared from the aerial parts of the plants. A rapid analytical method was developed for the simultaneously quantitative analysis of two alkaloids, pronuciferine and roemerine, using liquid chromatography tandem mass spectrometry. Multiple reaction monitoring in the positive ionization mode was used for detection. Pronuciferine and roemerine were analyzed on a C18 column (2.1 × 50 mm, 3 µm) with the mobile phase run in the gradient mode with 0.1% formic acid in water (A) and 0.1% formic acid in acetonitrile at a flow rate of 0.3 mL/min. The transitions 312.1→283.1 m/z and 280.0→249.0 m/z were used to monitor pronuciferine and roemerine, respectively. The assay was linear in the concentration range of 0.01 µg/mL to 1 µg/mL (r = 0.996 for roemerine, r = 0.998 for pronuciferine). The validation studies revealed that the method was linear, sensitive, accurate, precise, selective, repeatable, robust, and rugged. Finally, the developed method was applied to quantify pronuciferine and roemerine in the selected species. The amounts of pronuciferine and roemerine were respectively found as 8.5 to 48 µg/g and 4.4 to 43,000 µg/g.

A new phenylspirodrimane dimer from the fungus Stachybotrys chartarum.

A new phenylspirodrimane dimer, named stachartarin A (1), was isolated from cultures of the tin mine tailings-associated fungus Stachybotrys chartarum. Its structures were elucidated by means of spectroscopic methods. At the same time, the compound was tested for its cytotoxicity against HL-60, SMMC-7721, A-549, MCF-7, and SW480 cells.

Enantioselective Organocatalytic Synthesis of a Secoyohimbane-Inspired Compound Collection with Neuritogenic Activity.

Natural products provide evolutionary validated core structures to inspire the synthesis of new compound collections endowed with neurite growth-promoting activity. Rhynchophylline is the major component of Uncaria species, and has been used to treat neurological diseases in Chinese traditional medicine. Based on the structure of this spirocyclic secoyohimbane alkaloid, we developed a highly enantioselective and efficient organocatalyzed synthesis method to provide a tetracyclic secoyohimbane scaffold incorporating a quaternary and three tertiary stereogenic centers, in a one-pot multistep reaction sequence. A compound collection of derived secoyohimbanes was synthesized and expanded by decorating the periphery of the basic scaffold with additional substituents to increase the diversity. Evaluation of the different subcollections of secoyohimbanes for modulation of neurite outgrowth in the SH-SY5Y human cell line led to the discovery of new compounds that promote neurite outgrowth.

Bioactive spirans and other constituents from the leaves of Cannabis sativa f. sativa.

In this paper, 17 compounds (1-17) were isolated from the leaves of Hemp (Cannabis sativa f. sativa). Among the isolates, two were determined to be new spirans: cannabispirketal (1), and α-cannabispiranol 4'-O-ß-D-glucopyranose (2) by 1D and 2D NMR spectroscopy, LC-MS, and HRESIMS. The known compounds 7, 8, 10, 13, 15, and 16 were isolated from Hemp (C. sativa f. sativa) for the first time. Furthermore, compounds 8 and 13 were isolated from the nature for the first time. All isolated compounds were evaluated for cytotoxicity on different tissue-derived passage cancer cell lines through cell viability and apoptosis assay. Among these compounds, compounds 5, 9 and 16 exhibited a broad-spectrum antitumor effect via inhibiting cell proliferation and promoting apoptosis. These results obtained have provided valuable clues to the understanding of the cytotoxic profile for these isolated compounds from Hemp (C. sativa f. sativa).

Rhodomentones A and B, novel meroterpenoids with unique NMR characteristics from Rhodomyrtus tomentosa.

Two novel meroterpenoids, rhodomentones A and B bearing an unprecedented caryophyllene-conjugated oxa-spiro[5.8] tetradecadiene skeleton, were isolated from the leaves of Rhodomyrtus tomentosa. Their structures with unique NMR characteristics were determined by extensive spectroscopic analysis, single-crystal X-ray diffraction, quantum molecular calculation, chemical transformation as well as total synthesis.

A novel α-glucosidase inhibitory constituent from Uncaria gambir.

Bioactivity-guided fractionation of an aqueous methanolic extract of manufactured gambir product from Uncaria gambir with in vitro α-glucosidase inhibitory activity was performed to isolate a novel prenyl resorcinol derivative (1) together with seven known compounds, including two flavone glycosides (2, 3), three catechin analogues (4-6), and two simple phenolics (7, 8). Structures of the isolated compounds were determined by analysis of physical and spectroscopic data (NMR, UV, [α]D, and MS). All isolates were evaluated for in vitro α-glucosidase inhibitory activity. Among the compounds, novel compound 1, possessing an unprecedented spirocyclopropane ring in the molecule, showed the most potent α-glucosidase inhibitory activity in this assay. On the other hand, compounds 4 and 7 showed less potent inhibitory effects in this same bioassay, with half-maximal inhibitory concentration values of 17.3 ± 1.0 µM and 27.0 ± 0.9 µM, respectively.

Yuccalides A-C, three new phenolic compounds with spiro-structures from the roots of Yucca gloriosa.

Three new phenolic compounds, yuccalides A-C (1-3), were isolated from the roots of Yucca gloriosa L., along with four known compounds (4-7). The structures of the new compounds were established by extensive NMR spectroscopic analyses. Inducible nitric oxide synthase (iNOS) mRNA levels induced by lipopolysaccharide (LPS) in mouse macrophage-like RAW 264.7 cells were effectively suppressed by compounds 2, 4, and 6, all of which had the (2R*, 3R*)-configuration. IL-1ß and IL-6 mRNA levels induced by LPS were significantly attenuated by compounds 4, 5, and 6, but not by 2.

Cipacinoids A-D, Four Limonoids with Spirocyclic Skeletons from Cipadessa cinerascens.

Four limonoids, cipacinoids A-D (1-4), with spirocyclic skeletons were isolated from Cipadessa cinerascens. It is particularly notable that compounds 1-3 had a 17S-configuration for the first time in the limonoid family. Their structures with absolute configurations were assigned by spectroscopic data, X-ray crystallography, and CD analysis. Compound 1 showed moderate protein tyrosine phosphatase 1B (PTP1B) inhibition.

Isolation, characterization, and anthelminthic activities of a novel dichapetalin and other constituents of Dichapetalum filicaule.

CONTEXT: Dichapetalum filicaule Breteler (Dichapetalaceae) is a rare species occurring only in Côte d'Ivoire and Ghana. Although research on several species of the genus has produced interesting bioactive compounds, particularly the Dichapetalins, a novel class of triterpenoids with antineoplastic properties, there is virtually no information on the ethnobotanical uses and chemical constituents of D. filicaule. OBJECTIVE: The phytochemical and anthelminthic activities of the constituents of D. filicaule were investigated. MATERIALS AND METHODS: Chemical constituents of the petroleum ether, chloroform-acetone, and methanol root extracts of D. filicaule were isolated by column chromatography and characterized by their physico-chemical properties, 1-D and 2-D NMR spectroscopy and mass spectrometry. In vitro anthelminthic activity of the extracts and compounds against the human hookworm, Necator americanus, Stiles 1902 (Nematoda: Ancylostomatidae) was determined within a concentration range of 2500-250 µg/ml using the Egg Hatch Inhibition (EHI) Assay. The hookworm species were identified using a published polymerase chain reaction (PCR) method. RESULTS: A new dichapetalin, dichapetalin X (1), together with the known dichapetalin A (2), pomolic acid (3), glycerol monostearate (4), D:A-friedooleanan-3ß-ol (5), and D:A-friedooleanan-3-one (6) were isolated. Compounds 1, 2, and 4 exhibited EHI with IC50 values of 523.2, 162.4, and 306.0 µg/ml, respectively, against the hookworm. The positive control albendazole gave an IC50 value of 93.27 µg/ml. DISCUSSION AND CONCLUSION: This is the first report of the phytochemical investigation of D. filicaule. The study has yielded a new dichapetalin and also demonstrated the potential anthelminthic properties of the constituents.

Larvicidal spirobisnaphthalenes from the endophytic fungus Berkleasmium sp. against Aedes albopictus.

BACKGROUND: In our screening programme for new agrochemicals from endophytic fungi, the ethyl acetate extract of an endophytic Berkleasmium sp. isolated from the medicinal plant Dioscorea zingiberensis was found to possess strong larvicidal activity against the Asian tiger mosquito, Aedes albopictus. RESULTS: Bioassay-guided fractionation of the fungal extract has led to the isolation of seven spirobisnaphthalenes, including palmarumycins C8, C12, C15 and B6 and diepoxins γ, δ and ζ. Among them, palmarumycins C8 and B6 showed strong larvicidal activity against the fourth-instar larvae of A. albopictus, with LC50 values of 8.83 and 11.51 µg mL(-1) respectively. Interestingly, only spirobisnaphthalenes with a chlorine substituent possessed strong larvicidal activity. CONCLUSION: The results indicated that the spirobisnaphthalenes derived from the endophytic fungus Berkleasmium sp. could be promising leads for the development of new larvicides against A. albopictus.

Dimeric Octaketide Spiroketals from the Jellyfish-Derived Fungus Paecilomyces variotii J08NF-1.

Paeciloketals (1-3), new benzannulated spiroketal derivatives, were isolated from the marine fungus Paecilomyces variotii derived from the giant jellyfish Nemopilema nomurai. Compound 1 was present as a racemate and was resolved into enantiopure 1a and 1b by chiral-phase separation on a cellulose column. Compounds 2 and 3, possessing a novel benzannulated spiroketal skeleton, were rapidly interconvertible and yielded an equilibrium mixture on standing at room temperature. The relative and absolute configurations of compounds 2 and 3 were determined by NOESY analysis and ECD calculations. Compound 1 showed modest antibacterial activity against the marine pathogen Vibrio ichthyoenteri.

Nepetaefuran and leonotinin isolated from Leonotis nepetaefolia R. Br. potently inhibit the LPS signaling pathway by suppressing the transactivation of NF-κB.

Leonotis nepetaefolia R. Br., also known as Klip Dagga or Lion's Ear, has traditionally been used as a folk medicine to treat inflammatory diseases such as rheumatism, bronchitis, and asthma; however, the components that exhibit its anti-inflammatory activity have not yet been identified. In the present study, we investigated the effects of three types of diterpenoids, nepetaefuran, leonotinin, and leonotin, which were isolated from L. nepetaefolia R. Br., on the LPS signaling pathway in order to elucidate the anti-inflammatory mechanism involved. Nepetaefuran more potently inhibited the LPS-induced production of NO and CCL2 than leonotinin by suppressing the expression of iNOS mRNA and CCL2 mRNA. On the other hand, leonotin failed to inhibit the production of NO and CCL2 induced by LPS. Although nepetaefuran and leonotinin had no effect on the LPS-induced degradation of IκBα or nuclear translocation of NF-κB p65, they markedly inhibited the transcriptional activity of NF-κB. Nepetaefuran and leonotinin also inhibited the transcriptional activity of the GAL4-NF-κB p65 fusion protein. On the other hand, nepetaefuran, leonotinin and leonotin did not affect the LPS-induced activation of MAP kinase family members such as ERK, p38, and JNK. In addition, inhibitory effect of nepetaefuran and leonotinin on NF-κB activation is well correlated with their ability to induce activation of Nrf2 and ER stress. Taken together, these results demonstrated that nepetaefuran and leonotinin could be the components responsible for the anti-inflammatory activity of L. nepetaefolia R. Br. by specifically inhibiting the LPS-induced activation of NF-κB.

Spiroalkaloids from Shensong Yangxin capsule.

Four spiroalkaloids, including a new compound shensongine A (1), were isolated from the anti-arrhythmic TCM formula Shensong Yangxin capsule. Their structures were determined on the basis of spectroscopic analysis. Compounds 1 and 3 displayed cardiovascular activities by shortened APD in rat myocardial cells. These compounds were possibly generated from precursors in different composed herbal medicines during the processing of the TCM formula.