Bioorganic & Medicinal Chemistry - BIOORGAN MED CHEM, 2010
Bioassay guided fractionation of the EtOAc fraction of the sponge Callyspongia aerizusa yielded s... more Bioassay guided fractionation of the EtOAc fraction of the sponge Callyspongia aerizusa yielded seven new cytotoxic cyclic peptides callyaerins A–F (1–6) and H (8). Their structures were determined using extensive 1D (1H, 13C and DEPT) and 2D (COSY, HMQC, HMBC, TOCSY, and ROESY) NMR and mass spectral (ESI and HRESI-TOF) data. All compounds were cyclic peptides containing ring systems of 5–9 amino acids and side chains of 2–5 amino acids in length. An unusual (Z)-2,3-diaminoacrylic acid unit provided the template for ring closure and afforded the linkage to the peptidic side chain which was always initiated with a proline moiety. All peptides contained three or more proline residues and the remaining residues were predominantly hydrophobic residues with all amino acids present in the l form. Callyaerins A–F (1–6) and H (8) showed biological activity in antibacterial assays and in various cytotoxicity assays employing different tumour cell-lines (L5178Y, HeLa, and PC12). Callyaerins E...
... kappa B Inhibitors and Antitrypanosomal Metabolites from Endophytic Fungus Penicillium sp. Is... more ... kappa B Inhibitors and Antitrypanosomal Metabolites from Endophytic Fungus Penicillium sp. Isolated from Limonium tubiflorum. Amal H Aly, Abdessamad Debbab, Carol Clements, et al. (2010). Bioorganic Medicinal Chemistry. ...
Zeitschrift für Naturforschung. C, Journal of biosciences
Specimens of the spongivorous Mediterranean opisthobranch Tylodina perversa that had been collect... more Specimens of the spongivorous Mediterranean opisthobranch Tylodina perversa that had been collected while feeding on Aplysina acerophoba were shown to sequester the brominated isoxazoline alkaloids of their prey. Alkaloids were stored in the hepatopancreas, mantle tissues, and egg masses in an organ-specific manner. Surprisingly, the known sponge alkaloid aerothionin which is found only in A. cavernicola but not in A. aerophoba was also among the metabolites identified in wild caught specimens of T. perversa as well as in opisthobranchs with a documented feeding history on A. aerophoba. Mollusc derived aerothionin is postulated to be derived from a previous feeding encounter with A. cavernicola as T. perversa was found to freely feed on both Aplysina sponges in aquarium bioassays. The possible ecological significance of alkaloid sequestration by T. perversa is still unknown.
Bioassay-guided fractionation of an extract obtained from roots of Aglaia duperreana led to the i... more Bioassay-guided fractionation of an extract obtained from roots of Aglaia duperreana led to the isolation of 17 1H-cyclopenta[b]benzofurans of the rocaglamide type. Of the compounds isolated, four rocaglamide derivatives (2, 6, 11, and 16) were obtained as new natural products, and their structure elucidation was conducted by spectral methods. For bioassay-guided fractionation and determination of LC 50 and EC 50 values, neonate larvae of Spodoptera littoralis were employed. The results of chronic feeding assays have shown new aspects of the structure-activity relationship of rocaglamide derivatives. The substitution of a hydroxyl group at C-8b by a methoxyl substituent leads to a loss of insecticidal activity in a manner not previously documented in this compound class.
Organic extracts of the twigs and leaves of Aglaia odorata yielded eight insecticidal cyclopentat... more Organic extracts of the twigs and leaves of Aglaia odorata yielded eight insecticidal cyclopentatetrahydrobenzofuran rocaglamide derivatives including three congeners which proved to be new natural products. Moreover, four new cyclopentatetrahydrobenzopyran aglain derivatives, as well as the known aminopyrrolidine odorine and odorinol, syringaresinol and¯avonoid derivatives were also isolated. Structure elucidation of the new compounds is described and a rationale of the biosynthesis of the rocaglamide and aglain congeners is considered. The isolated rocaglamide derivatives exhibited strong insecticidal activity towards neonate larvae of the polyphagous pest insect Spodoptera littoralis when incorporated into arti®cial diet with LC 50 values varying from 1.0±8.0 ppm. The most active compounds showed LC 50 values between 1.0 and 1.1 ppm, comparable to those of the insecticide azadirachtin, which was used as a positive control. The remaining compounds isolated from A. odorata were inactive with regard to insecticidal activity. #
An undescribed fungus of the genus Microsphaeropsis, isolated from the Mediterranean sponge Aplys... more An undescribed fungus of the genus Microsphaeropsis, isolated from the Mediterranean sponge Aplysina aerophoba, produces two new betaenone derivatives (1, 2) and three new 1,3,6,8-tetrahydroxyanthraquinone congeners (5-7). The structures of the compounds were established on the basis of NMR spectroscopic and mass spectrometric data and by CD spectroscopy. This is the first report wherein the 1 H and 13 C NMR data of the betaenone congeners are fully and unambiguously assigned on the basis of two-dimensional NMR spectroscopy. Furthermore, we describe the first elucidation of the absolute configuration of 1-(2′-anthraquinonyl)ethanols such as 5 and 6, by quantum chemical calculation of their circular dichroism (CD) and comparison with experimentally measured spectra. Moreover, it was shown that compounds 1, 5, 6, and 7 are inhibitors of PKC-, CDK4, and EGF receptor tyrosine kinases.
Bioorganic & medicinal chemistry letters, Jan 15, 2014
Bioassay-guided fractionation of the fermentation broth of Arctic Streptomyces nitrosporeus YBH10... more Bioassay-guided fractionation of the fermentation broth of Arctic Streptomyces nitrosporeus YBH10-5 resulted in the isolation of seven new compounds named nitrosporeunols A-G (1-7), together with seven known analogues (8-14). Their structures were determined based on extensive spectroscopic analysis. Compounds 1-14 were evaluated for the lowering lipid effects, while two compounds (10 and 12) remarkably decreased lipid levels including total cholesterol (TC) and triglycerides (TG) in HepG2 cells. Quantitative realtime PCR and Western blot indicated that farnesylquinone (12) increased the expression of the key proteins including peroxisome proliferator-activated receptor-α (PPARα), peroxisome proliferator-activated receptor-γ, and coactivator 1α (PGC-1α), as well as their downstream genes carnitine palmitoyltransterase-1 (CPT-1), acyl-coenzyme A oxidase 1 (ACOX), malonyl CoA decarboxylase 1 (MCD1), pyruvate dehydrogenase kinase 4 (PDK4), and cholesterol 7α -hydroxylase (CYP7A1). Luci...
Nine new isomalabaricane-type triterpenoids namely globostelletins were isolated from the marine ... more Nine new isomalabaricane-type triterpenoids namely globostelletins were isolated from the marine sponge Rhabdastrella globostellata. Their structures were established on the basis of extensive spectroscopic data analysis including IR, MS, 1D and 2D NMR, and CD spectra. Globostelletins J–R are characterized by the presence of an unusual cyclopentane unit linked at different positions of sidechains. These unprecedented structures enriched a number
European journal of medicinal chemistry, Jan 7, 2015
A class of prenylated indole diketopiperazine alkaloids including 15 new compounds namely rubruml... more A class of prenylated indole diketopiperazine alkaloids including 15 new compounds namely rubrumlines A-O obtained from marine-derived fungus Eurotium rubrum, were tested against influenza A/WSN/33 virus. Neoechinulin B (18) exerted potent inhibition against H1N1 virus infected in MDCK cells, and is able to inhibit a panel of influenza virus strains including amantadine- and oseltamivir-resistant clinical isolates. Mechanism of action studies indicated that neoechinulin B binds to influenza envelope hemagglutinin, disrupting its interaction with the sialic acid receptor and the attachment of viruses to host cells. In addition, neoechinulin B was still efficient in inhibiting influenza A/WSN/33 virus propagation even after a fifth passage. The high potency and broad-spectrum activities against influenza viruses with less drug resistance make neoechinulin B as a new lead for the development of potential inhibitor of influenza viruses.
Two new triterpenoids, olean-18-en-3beta-O-E-coumaroyl ester (1) and olean-18-en-3beta-O-Z-coumar... more Two new triterpenoids, olean-18-en-3beta-O-E-coumaroyl ester (1) and olean-18-en-3beta-O-Z-coumaroyl ester (2), were isolated from the stem bark of marine mangrove plant Barringtonia racemosa, along with five known compounds, germanicol, germanicone, betulinic acid, lupeol, and taraxerol. Their structures were determined mainly by spectroscopic methods.
Along with five known 30-norlanostane-type saponins, sarasinosides A 1 (5A), A 3 (6A), I 1 (7), I... more Along with five known 30-norlanostane-type saponins, sarasinosides A 1 (5A), A 3 (6A), I 1 (7), I 2 (8), and H 2 (9), four new triterpenoidal saponin congeners, sarasinosides J (1), K (2), L (3), and M (4), were isolated from the Indonesian sponge Melophlus sarassinorum. Sarasinosides J (1) and K (2) are the 24,25hydrogenated congeners of the previously described sarasinosides A 1 and H 2 , respectively. The carbon skeleton of sarasinoside M (4) possesses a rearranged 8R, 9R-epoxy-8,9-seconorlanosta-8(14),9(11),24-triene system, which is novel and unprecedented in nature. The structures of the new compounds were confirmed by spectral analyses, chemical derivatization, and GC analyses. Compounds 1 and 5A exhibited antimicrobial activity toward Bacillus subtilis and Saccharomyces cerevisiae.
ABSTRACT A detailed chemical investigation of the minor metabolites produced by the endophytic fu... more ABSTRACT A detailed chemical investigation of the minor metabolites produced by the endophytic fungus Pestalotiopsis sp. isolated from the Chinese mangrove Rhizophora mucronata afforded sixteen new compounds of polyketide origin, including pestalotiopyrones A–H (1–8), pestalotiopisorin A (10), pestalotiollides A–B (11–12), pestalotiopin A (13), and four amides pestalotiopamides A–D (14–17), along with three known compounds, nigrosporapyrone D (9), 2-anhydromevalonic acid (18), and p-hydroxy benzaldehyde (19). The structures of all compounds were unambiguously established from their spectroscopic data that included HR-ESIMS and 1- and 2-dimensional NMR spectroscopy, and by comparison with the literature.
The Micronesian sponge Oceanapia sp. has an unusual growth form that consists of an irregular tur... more The Micronesian sponge Oceanapia sp. has an unusual growth form that consists of an irregular turnip-shaped base, which is buried in the substrate. One to several fistules, which protrude through the sand, are attached to the base of the sponge. On top of each fistule is a small fragile capitum. We examined whether this conspicuous red-colored sponge was chemically defended
Chemical investigation of the sponge Leucetta chagosensis collected in Indonesia afforded five ne... more Chemical investigation of the sponge Leucetta chagosensis collected in Indonesia afforded five new imidazole alkaloids, naamine F (2), naamine G (3), kealiinine A (6), kealiinine B (7), and kealiinine C (8), in addition to the known compound naamine A (1). Naamine G (3) exhibited strong antifungal activity against the phytopathogenic fungus Cladosporium herbarum and also showed mild cytotoxicity against mouse lymphoma (L5178Y) and human cervix carcinoma (HeLa) cell lines. In the brine shrimp assay, kealiinine A (6) was more active than naamine G (3). The structures of the new compounds were unambiguously established by 1D and 2D NMR and MS data.
Thirteen new metabolites, melophlins C-O (1-13), were identified from the marine sponge Melophlus... more Thirteen new metabolites, melophlins C-O (1-13), were identified from the marine sponge Melophlus sarassinorum. Compounds 1-13 represent tetramic acid derivatives that differ with regard to the nature of their alkyl side chains. The structures of the new compounds were elucidated on the basis of comprehensive spectral analysis (1H, 13C, 1H-1H COSY, HMQC, and HMBC NMR, as well as low- and high-resolution ESIMS and EIMS). The absolute configurations of 1, 8, 10, 11, 12, and 13 were determined by ESI LC/MS analysis of chiral derivatives obtained upon oxidation and hydrolysis of the respective parent compounds. Melophlin C (1) displayed pronounced antibacterial activity against Bacillus subtilisand Staphylococcus aureus, together with antifungal activity against Candida albicans.
Three new meliacarpin derivatives\ namely 0\2!dicinnamoyl!00!hydroxymeliacarpin\ 0!cinnamoyl!2!me... more Three new meliacarpin derivatives\ namely 0\2!dicinnamoyl!00!hydroxymeliacarpin\ 0!cinnamoyl!2!methacrylyl!00!hydroxy! meliacarpin and 0!cinnamoyl!2!acetyl!00!hydroxymeliacarpin\ were isolated as the principal insecticidal and growth disrupting constituents of Melia azedarach leaves[ Their structures were unambiguously established on the basis of MS spectrometric and NMR spectroscopic data " 0 H\ 02 C\ COSY\ 0 H!detected direct and long!range 02 CÐ 0 H correlations# and by comparison with known compounds[ The insecticidal properties of the new meliacarpin derivatives were examined using larvae of the polyphagous pest insect Spodoptera littoralis[ When incorporated into arti_cial diet and o}ered to larvae in a chronic feeding bioassay\ 0!cinnamoyl!2!acetyl! 00!hydroxymeliacarpin exhibited an EC 49 of 9[16 ppm and a LC 49 of 9[37 ppm and is thus comparable with regard to insecticidal activity to the well known natural insecticide azadirachtin[ Furthermore\ all three meliacarpin derivatives had a pronounced detrimental in~uence on larval metamorphosis[ Þ 0888 Elsevier Science Ltd[ All rights reserved[ Keywords] Melia azedarach^Meliaceae^Structure elucidation^Insecticidal activity^C!seco limonoid^New meliacarpin derivatives^AzadirachtinŜ podoptera littoralis
Endophytes are microorganisms that inhabit the interior of a healthy plants. They offer great-unt... more Endophytes are microorganisms that inhabit the interior of a healthy plants. They offer great-untapped potentials, which can be exploited to maintain healthy crops. Many cultivated and wild type plants have been investigated for endophytic fungal metabolites which include guanidine and pyrrolizidine alkaloids, indole derivatives, sesquiterpenes, isocoumarin derivatives. These metabolites show beneficial effects to crop plants and many of them also
Investigation of the tropical sponges Axinella damicornis and Stylissa flabelliformis, family Axi... more Investigation of the tropical sponges Axinella damicornis and Stylissa flabelliformis, family Axinillidae, afforded five new bromopyrrole alkaloids (1-5) and thirteen known compounds (6-18). Semi synthesis of 5 was carried out in order to confirm its structure. The structures of the isolated compounds were elucidated using 1D-and 2D-NMR spectroscopy and mass spectrometry. The cytotoxicity, antimicrobial and protein-kinase inhibition activities were tested for the isolated compounds.
Bioorganic & Medicinal Chemistry - BIOORGAN MED CHEM, 2010
Bioassay guided fractionation of the EtOAc fraction of the sponge Callyspongia aerizusa yielded s... more Bioassay guided fractionation of the EtOAc fraction of the sponge Callyspongia aerizusa yielded seven new cytotoxic cyclic peptides callyaerins A–F (1–6) and H (8). Their structures were determined using extensive 1D (1H, 13C and DEPT) and 2D (COSY, HMQC, HMBC, TOCSY, and ROESY) NMR and mass spectral (ESI and HRESI-TOF) data. All compounds were cyclic peptides containing ring systems of 5–9 amino acids and side chains of 2–5 amino acids in length. An unusual (Z)-2,3-diaminoacrylic acid unit provided the template for ring closure and afforded the linkage to the peptidic side chain which was always initiated with a proline moiety. All peptides contained three or more proline residues and the remaining residues were predominantly hydrophobic residues with all amino acids present in the l form. Callyaerins A–F (1–6) and H (8) showed biological activity in antibacterial assays and in various cytotoxicity assays employing different tumour cell-lines (L5178Y, HeLa, and PC12). Callyaerins E...
... kappa B Inhibitors and Antitrypanosomal Metabolites from Endophytic Fungus Penicillium sp. Is... more ... kappa B Inhibitors and Antitrypanosomal Metabolites from Endophytic Fungus Penicillium sp. Isolated from Limonium tubiflorum. Amal H Aly, Abdessamad Debbab, Carol Clements, et al. (2010). Bioorganic Medicinal Chemistry. ...
Zeitschrift für Naturforschung. C, Journal of biosciences
Specimens of the spongivorous Mediterranean opisthobranch Tylodina perversa that had been collect... more Specimens of the spongivorous Mediterranean opisthobranch Tylodina perversa that had been collected while feeding on Aplysina acerophoba were shown to sequester the brominated isoxazoline alkaloids of their prey. Alkaloids were stored in the hepatopancreas, mantle tissues, and egg masses in an organ-specific manner. Surprisingly, the known sponge alkaloid aerothionin which is found only in A. cavernicola but not in A. aerophoba was also among the metabolites identified in wild caught specimens of T. perversa as well as in opisthobranchs with a documented feeding history on A. aerophoba. Mollusc derived aerothionin is postulated to be derived from a previous feeding encounter with A. cavernicola as T. perversa was found to freely feed on both Aplysina sponges in aquarium bioassays. The possible ecological significance of alkaloid sequestration by T. perversa is still unknown.
Bioassay-guided fractionation of an extract obtained from roots of Aglaia duperreana led to the i... more Bioassay-guided fractionation of an extract obtained from roots of Aglaia duperreana led to the isolation of 17 1H-cyclopenta[b]benzofurans of the rocaglamide type. Of the compounds isolated, four rocaglamide derivatives (2, 6, 11, and 16) were obtained as new natural products, and their structure elucidation was conducted by spectral methods. For bioassay-guided fractionation and determination of LC 50 and EC 50 values, neonate larvae of Spodoptera littoralis were employed. The results of chronic feeding assays have shown new aspects of the structure-activity relationship of rocaglamide derivatives. The substitution of a hydroxyl group at C-8b by a methoxyl substituent leads to a loss of insecticidal activity in a manner not previously documented in this compound class.
Organic extracts of the twigs and leaves of Aglaia odorata yielded eight insecticidal cyclopentat... more Organic extracts of the twigs and leaves of Aglaia odorata yielded eight insecticidal cyclopentatetrahydrobenzofuran rocaglamide derivatives including three congeners which proved to be new natural products. Moreover, four new cyclopentatetrahydrobenzopyran aglain derivatives, as well as the known aminopyrrolidine odorine and odorinol, syringaresinol and¯avonoid derivatives were also isolated. Structure elucidation of the new compounds is described and a rationale of the biosynthesis of the rocaglamide and aglain congeners is considered. The isolated rocaglamide derivatives exhibited strong insecticidal activity towards neonate larvae of the polyphagous pest insect Spodoptera littoralis when incorporated into arti®cial diet with LC 50 values varying from 1.0±8.0 ppm. The most active compounds showed LC 50 values between 1.0 and 1.1 ppm, comparable to those of the insecticide azadirachtin, which was used as a positive control. The remaining compounds isolated from A. odorata were inactive with regard to insecticidal activity. #
An undescribed fungus of the genus Microsphaeropsis, isolated from the Mediterranean sponge Aplys... more An undescribed fungus of the genus Microsphaeropsis, isolated from the Mediterranean sponge Aplysina aerophoba, produces two new betaenone derivatives (1, 2) and three new 1,3,6,8-tetrahydroxyanthraquinone congeners (5-7). The structures of the compounds were established on the basis of NMR spectroscopic and mass spectrometric data and by CD spectroscopy. This is the first report wherein the 1 H and 13 C NMR data of the betaenone congeners are fully and unambiguously assigned on the basis of two-dimensional NMR spectroscopy. Furthermore, we describe the first elucidation of the absolute configuration of 1-(2′-anthraquinonyl)ethanols such as 5 and 6, by quantum chemical calculation of their circular dichroism (CD) and comparison with experimentally measured spectra. Moreover, it was shown that compounds 1, 5, 6, and 7 are inhibitors of PKC-, CDK4, and EGF receptor tyrosine kinases.
Bioorganic & medicinal chemistry letters, Jan 15, 2014
Bioassay-guided fractionation of the fermentation broth of Arctic Streptomyces nitrosporeus YBH10... more Bioassay-guided fractionation of the fermentation broth of Arctic Streptomyces nitrosporeus YBH10-5 resulted in the isolation of seven new compounds named nitrosporeunols A-G (1-7), together with seven known analogues (8-14). Their structures were determined based on extensive spectroscopic analysis. Compounds 1-14 were evaluated for the lowering lipid effects, while two compounds (10 and 12) remarkably decreased lipid levels including total cholesterol (TC) and triglycerides (TG) in HepG2 cells. Quantitative realtime PCR and Western blot indicated that farnesylquinone (12) increased the expression of the key proteins including peroxisome proliferator-activated receptor-α (PPARα), peroxisome proliferator-activated receptor-γ, and coactivator 1α (PGC-1α), as well as their downstream genes carnitine palmitoyltransterase-1 (CPT-1), acyl-coenzyme A oxidase 1 (ACOX), malonyl CoA decarboxylase 1 (MCD1), pyruvate dehydrogenase kinase 4 (PDK4), and cholesterol 7α -hydroxylase (CYP7A1). Luci...
Nine new isomalabaricane-type triterpenoids namely globostelletins were isolated from the marine ... more Nine new isomalabaricane-type triterpenoids namely globostelletins were isolated from the marine sponge Rhabdastrella globostellata. Their structures were established on the basis of extensive spectroscopic data analysis including IR, MS, 1D and 2D NMR, and CD spectra. Globostelletins J–R are characterized by the presence of an unusual cyclopentane unit linked at different positions of sidechains. These unprecedented structures enriched a number
European journal of medicinal chemistry, Jan 7, 2015
A class of prenylated indole diketopiperazine alkaloids including 15 new compounds namely rubruml... more A class of prenylated indole diketopiperazine alkaloids including 15 new compounds namely rubrumlines A-O obtained from marine-derived fungus Eurotium rubrum, were tested against influenza A/WSN/33 virus. Neoechinulin B (18) exerted potent inhibition against H1N1 virus infected in MDCK cells, and is able to inhibit a panel of influenza virus strains including amantadine- and oseltamivir-resistant clinical isolates. Mechanism of action studies indicated that neoechinulin B binds to influenza envelope hemagglutinin, disrupting its interaction with the sialic acid receptor and the attachment of viruses to host cells. In addition, neoechinulin B was still efficient in inhibiting influenza A/WSN/33 virus propagation even after a fifth passage. The high potency and broad-spectrum activities against influenza viruses with less drug resistance make neoechinulin B as a new lead for the development of potential inhibitor of influenza viruses.
Two new triterpenoids, olean-18-en-3beta-O-E-coumaroyl ester (1) and olean-18-en-3beta-O-Z-coumar... more Two new triterpenoids, olean-18-en-3beta-O-E-coumaroyl ester (1) and olean-18-en-3beta-O-Z-coumaroyl ester (2), were isolated from the stem bark of marine mangrove plant Barringtonia racemosa, along with five known compounds, germanicol, germanicone, betulinic acid, lupeol, and taraxerol. Their structures were determined mainly by spectroscopic methods.
Along with five known 30-norlanostane-type saponins, sarasinosides A 1 (5A), A 3 (6A), I 1 (7), I... more Along with five known 30-norlanostane-type saponins, sarasinosides A 1 (5A), A 3 (6A), I 1 (7), I 2 (8), and H 2 (9), four new triterpenoidal saponin congeners, sarasinosides J (1), K (2), L (3), and M (4), were isolated from the Indonesian sponge Melophlus sarassinorum. Sarasinosides J (1) and K (2) are the 24,25hydrogenated congeners of the previously described sarasinosides A 1 and H 2 , respectively. The carbon skeleton of sarasinoside M (4) possesses a rearranged 8R, 9R-epoxy-8,9-seconorlanosta-8(14),9(11),24-triene system, which is novel and unprecedented in nature. The structures of the new compounds were confirmed by spectral analyses, chemical derivatization, and GC analyses. Compounds 1 and 5A exhibited antimicrobial activity toward Bacillus subtilis and Saccharomyces cerevisiae.
ABSTRACT A detailed chemical investigation of the minor metabolites produced by the endophytic fu... more ABSTRACT A detailed chemical investigation of the minor metabolites produced by the endophytic fungus Pestalotiopsis sp. isolated from the Chinese mangrove Rhizophora mucronata afforded sixteen new compounds of polyketide origin, including pestalotiopyrones A–H (1–8), pestalotiopisorin A (10), pestalotiollides A–B (11–12), pestalotiopin A (13), and four amides pestalotiopamides A–D (14–17), along with three known compounds, nigrosporapyrone D (9), 2-anhydromevalonic acid (18), and p-hydroxy benzaldehyde (19). The structures of all compounds were unambiguously established from their spectroscopic data that included HR-ESIMS and 1- and 2-dimensional NMR spectroscopy, and by comparison with the literature.
The Micronesian sponge Oceanapia sp. has an unusual growth form that consists of an irregular tur... more The Micronesian sponge Oceanapia sp. has an unusual growth form that consists of an irregular turnip-shaped base, which is buried in the substrate. One to several fistules, which protrude through the sand, are attached to the base of the sponge. On top of each fistule is a small fragile capitum. We examined whether this conspicuous red-colored sponge was chemically defended
Chemical investigation of the sponge Leucetta chagosensis collected in Indonesia afforded five ne... more Chemical investigation of the sponge Leucetta chagosensis collected in Indonesia afforded five new imidazole alkaloids, naamine F (2), naamine G (3), kealiinine A (6), kealiinine B (7), and kealiinine C (8), in addition to the known compound naamine A (1). Naamine G (3) exhibited strong antifungal activity against the phytopathogenic fungus Cladosporium herbarum and also showed mild cytotoxicity against mouse lymphoma (L5178Y) and human cervix carcinoma (HeLa) cell lines. In the brine shrimp assay, kealiinine A (6) was more active than naamine G (3). The structures of the new compounds were unambiguously established by 1D and 2D NMR and MS data.
Thirteen new metabolites, melophlins C-O (1-13), were identified from the marine sponge Melophlus... more Thirteen new metabolites, melophlins C-O (1-13), were identified from the marine sponge Melophlus sarassinorum. Compounds 1-13 represent tetramic acid derivatives that differ with regard to the nature of their alkyl side chains. The structures of the new compounds were elucidated on the basis of comprehensive spectral analysis (1H, 13C, 1H-1H COSY, HMQC, and HMBC NMR, as well as low- and high-resolution ESIMS and EIMS). The absolute configurations of 1, 8, 10, 11, 12, and 13 were determined by ESI LC/MS analysis of chiral derivatives obtained upon oxidation and hydrolysis of the respective parent compounds. Melophlin C (1) displayed pronounced antibacterial activity against Bacillus subtilisand Staphylococcus aureus, together with antifungal activity against Candida albicans.
Three new meliacarpin derivatives\ namely 0\2!dicinnamoyl!00!hydroxymeliacarpin\ 0!cinnamoyl!2!me... more Three new meliacarpin derivatives\ namely 0\2!dicinnamoyl!00!hydroxymeliacarpin\ 0!cinnamoyl!2!methacrylyl!00!hydroxy! meliacarpin and 0!cinnamoyl!2!acetyl!00!hydroxymeliacarpin\ were isolated as the principal insecticidal and growth disrupting constituents of Melia azedarach leaves[ Their structures were unambiguously established on the basis of MS spectrometric and NMR spectroscopic data " 0 H\ 02 C\ COSY\ 0 H!detected direct and long!range 02 CÐ 0 H correlations# and by comparison with known compounds[ The insecticidal properties of the new meliacarpin derivatives were examined using larvae of the polyphagous pest insect Spodoptera littoralis[ When incorporated into arti_cial diet and o}ered to larvae in a chronic feeding bioassay\ 0!cinnamoyl!2!acetyl! 00!hydroxymeliacarpin exhibited an EC 49 of 9[16 ppm and a LC 49 of 9[37 ppm and is thus comparable with regard to insecticidal activity to the well known natural insecticide azadirachtin[ Furthermore\ all three meliacarpin derivatives had a pronounced detrimental in~uence on larval metamorphosis[ Þ 0888 Elsevier Science Ltd[ All rights reserved[ Keywords] Melia azedarach^Meliaceae^Structure elucidation^Insecticidal activity^C!seco limonoid^New meliacarpin derivatives^AzadirachtinŜ podoptera littoralis
Endophytes are microorganisms that inhabit the interior of a healthy plants. They offer great-unt... more Endophytes are microorganisms that inhabit the interior of a healthy plants. They offer great-untapped potentials, which can be exploited to maintain healthy crops. Many cultivated and wild type plants have been investigated for endophytic fungal metabolites which include guanidine and pyrrolizidine alkaloids, indole derivatives, sesquiterpenes, isocoumarin derivatives. These metabolites show beneficial effects to crop plants and many of them also
Investigation of the tropical sponges Axinella damicornis and Stylissa flabelliformis, family Axi... more Investigation of the tropical sponges Axinella damicornis and Stylissa flabelliformis, family Axinillidae, afforded five new bromopyrrole alkaloids (1-5) and thirteen known compounds (6-18). Semi synthesis of 5 was carried out in order to confirm its structure. The structures of the isolated compounds were elucidated using 1D-and 2D-NMR spectroscopy and mass spectrometry. The cytotoxicity, antimicrobial and protein-kinase inhibition activities were tested for the isolated compounds.
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Papers by Peter Proksch