Metabolites of Cercospora. Taiwapyrone,an α-pyrone of unusual structure from Cercospora taiwanensis

(+)-Mellein (1), cis-3S,4S-4-hydroxymellein (3), and taiwapyrone (4), a new α-pyrone, have been isolated from the mycelium of Cercospora taiwanensis, grown on potato-agar. The structure and absolute configuration of (3) and (4) have been elucidated.     

A click chemistry approach for the synthesis of cyclic ureido tethered coumarinyl and 1-aza coumarinyl 1,2,3-triazoles as inhibitors of Mycobacterium tuberculosis H37Rv and their in silico studies

Nucleoside bases like uracil, pharmacophoric triazoles and benzimidazolones have been used during the present study to design molecular matrices for antitubercular activity, employing Click Chemistry. Click triazoles 4/7/10 have been obtained by the reaction of 4-(Azidomethyl)-2H-chromen-2-ones/quinolin-2(1H)-ones 3 and propargyl ethers 2/6/9 derived from theophylline/6-methyl uracil/2-benzimidazolone respectively. In addition to spectral data structures have been confirmed by single crystal X-ray diffraction studies in case of uracil bis alkyne (6) and theophylline mono triazole (4c). Theophylline linked mono triazoles, 4(a-d) and 6-methyl uracil linked bis triazoles, 7(a-e) have been found to inhibit Mycobacterium tuberculosis H37Rv with MIC values in the range 55.62–115.62 μM. Benzimidazolone bis triazoles, 10(a-n) showed better activity with MIC in the range 2.33–18.34 μM. Molecular modeling studies using Surflex-Dock algorithm supported our results.     

The synthesis of some methy 4,6-O-Benzylidene-α-D-erythro-Hexopyranosid-2,3-Diulose derivatives

Methyl 4,6-O-benzylidene-3-deoxy-3-phenylazo-α-D-glucopyranoside (1) has been oxidised with the Pfitzner—Moffat reagent to the 2,3-diulose 3-phenylhydrazone derivative (2) which has been characterised as the phenylosazone (3) and oxime (4). An unstable 2-imino derivative (10) of the same diulose has been produced by base-catalysed elimination of nitrogen from methyl 2-azido-4,6-O-benzylidene-2-deoxy-α-D-ribo-hexopyranosid-3-ulose (8). The imino intermediate was trapped as a quinoxaline derivative (9). The base-catalysed reactions of certain other hydrazone derivatives of methyl hexosiduloses have also been examined.     

Design,synthesis and antibacterial activities of thiouracil derivatives containing acyl thiourea as SecA inhibitors

A series of novel thiouracil derivatives containing an acyl thiourea moiety (7a–7x) have been synthesized by structural modification of a lead SecA inhibitor, 2. All the compounds have been evaluated for their antibacterial activities against Bacillus amyloliquefaciens, Staphylococcus aureus, and Bacillus subtilis. Compounds 7c, 7m, 7u, 7v exhibited promising activities against above bacteria. Such four compounds were further tested for their inhibitory activity against SecA ATPase, and the results showed that compounds 7c and 7u had higher inhibitory activities than that of compound 2. Molecular docking work suggests that compound 7u might bind at a pocket close to the ATPase ATP-binding domain.     

Eudistomidin G,a new β-carboline alkaloid from the Okinawan marine tunicate Eudistoma glaucus and structure revision of eudistomidin B

A new β-carboline alkaloid, eudistomidin G (1), has been isolated from the Okinawan marine tunicate Eudistoma glaucus, and the structure was elucidated from spectroscopic data. Furthermore, the structure of eudistomidin B (2), which has been isolated from the same tunicate, was revised from 2a to 2b by detailed analyses of spectroscopic data. Asymmetric synthesis of the revised structure (2b) of eudistomidin B (2) and its (1S,10S)-diastereomer (2c) has been accomplished with the Noyori catalytic asymmetric hydrogen-transfer reaction. The absolute configuration of eudistomidin B (2) was confirmed to be 2b possessing (1R,10S)-configuration, from comparison of the ¹H NMR data, CD spectra, [α]_D values, and HPLC analysis of 2b, 2c, and natural eudistomidin B.     

Analyzing the role of cannabinoids as modulators of Wnt/β-catenin signaling pathway for their use in the management of neuropathic pain

Neuropathic pain is a debilitating form of treatment-resistant chronic pain caused by damage to the nervous system. Cannabinoids have been known for suppressing neuropathic pain by modulating the endo cannabinoid system. Since the canonical Wnt/β-catenin signaling has recently been implicated in pain sensation, we investigated the impact of major cannabinoids (1–6) from the leaves of Cannabis sativa and an epoxy derivative of compound 2, here upon referred to as 2a, on modulating Wnt/β-catenin signaling pathway. The results presented in this study show that compound 1, 2 and 2a exhibited potent inhibitory activity against Wnt/β-catenin pathway in a dose-dependent manner. Compound 2a was seen to inhibit this pathway at slightly lower concentrations than its parent molecule 2, under similar conditions. Taken together, compound 1, 2 and 2a, by virtue of their inhibition of Wnt/β-catenin signaling pathway, could be developed as effective neuroprotective agents for the management of neuropathic pain.     

Amino acids and low-molecular-weight carbohydrates of some marine red algae

Amino acids and low-MW carbohydrates of 18 red algae have been analyzed. Several non-protein amino acids have been identified, including pyrrolidine-2,5-dicarboxylic acid (3c) and N-methylmethionine sulfoxide (5), new natural products, and 13 known compounds, citrulline, β-alanine, γ-aminobutyric acid, baikiain (1), pipecolic acid (2), domoic acid (3a), kainic acid (3b), azetidine-2-carboxylic acid (4), methionine sulfoxide taurine, N-methyltaurine, N,N-dimethyltaurine and N,N,N-trimethyltaurine. Sugars present were mainly floridoside, isofloridoside and mannoglyceric acid. Details of the structural elucidation of new compounds are also given.     

A new subspecies and two new combinations of Nothofagus Blume (Nothofagaceae) from Chile

One new subspecies ofNothofagusBlume,Nothofagus obliquasubsp.andina, is described from Chile, and two new combinations have been madeNothofagus obliquasubsp.valdivianaandNothofagus macrocarpacomb. nov.     

Antimalarial and antitubercular C-glycosylated benz[α]anthraquinones from the marine-derived Streptomyces sp. BCC45596

Three naturally new C-glycosylated benz[α]anthraquinone derivatives, urdamycinone E (1), urdamycinone G (2), dehydroxyaquayamycin (3) have been isolated from the marine Streptomycetes sp. BCC45596. Urdamycin E (4), the possible biosynthetic precursor of 1–3, has also been identified after a re-cultivation of the strain. These compounds (1–4) exhibited potent anti-Plasmodium palcifarum K1 strain with IC₅₀ values in a range of 0.0534–2.93 μg/mL and anti-Mycobacterium tuberculosis with minimum inhibition concentrations (MICs) in a range of 3.13–12.50 μg/mL. Cytotoxicity against KB, MCF-7, NCI-H187, and Vero cells was also evaluated.     

Synthèse et réactivite du méthyl-2-O-benzoyl-3-bromo-3,6-didésoxy-α-l-altropyranoside et du méthyl-2-O-benzoyl-3-bromo-3,6-didésoxy-4-O-méthyl-α-l-altropyranoside

Methyl 2-O-benzoyl-3-bromo-3,6-dideoxy-α-l-altropyranoside (4) and methyl 2-O-benzoy]-3-bromo-3,6-dideoxy-4-O-methyl-α-l-altropyranoside (5) have been prepared from methyl-α-l-rhamnopyranoside, respectively, in 2 and 3 steps. Reduction of 4 with lithium aluminium hydride followed by acid hydrolysis afforded the 3,6-dideoxy-l-arabino-bexose (l-ascarylose). The anhydro sugars 8 and 9 have been used as intermediates in the stereoselective synthesis of 6-deoxy-3-O-methyl-l-altropyranose (l-vallarose) and of 3-amino-3-degxy-l-altro sugars. Under azidolysis conditions, and according to the temperature, 5 gave unsaturated sugars such as 20 and the derived 26, or azido compounds such as 21 and 24, and the derived sugar methyl 2-amino-2,3,6-trideoxy-α-l-threo-hexopyranosid-4-ulose (25).     

DFT/B3LYP calculations,in vitro cytotoxicity and antioxidant activities of steroidal pyrimidines and their interaction with HSA using molecular docking and multispectroscopic techniques

As a part of our continuing program on the synthesis of steroidal heterocycles, it has been prepared a series of novel steroidal pyrimidine derivatives 4–6 via TMSCl, steroidal ketones (1c–3c), urea and benzaldehyde. The systems presented here, are novel scaffolds and have not been described before at 6th position of steroidal-6-one (1c–3c). Structural assignment of newly synthesized compounds was performed by DFT/B3LYP calculations as well as spectral and analytical data. The interactions of compounds (4–6) with HSA were studied by fluorescence spectroscopy, DLS, CD and molecular docking, under imitated physiological conditions. The antitumor activity has been tested in vitro against three cancer cell lines MDA-MB231 (breast carcinoma), HeLa (human cervical carcinoma), HepG2 (hepatic carcinoma) and one non-cancer normal cell lines, PBMCs (peripheral blood mononuclear cell) by MTT assay. In addition, in vitro antioxidant activity and apoptosis assay of the synthesized compounds (4–6) have also been investigated.     

Ring-opening reactions of sucrose epoxides: Synthesis of 4′-derivatives of sucrose

The 2,1′-O-isopropylidene derivative (1) of 3-O-acetyl-4,6-O-isopropylidene-α-d-glucopyranosyl 6-O-acetyl-3,4-anhydro-β-d-lyxo-hexulofuranoside and 2,3,4-tri-O-acetyl-6-O-trityl-α-d-glucopyranosyl 3,4-anhydro-1,6-di-O-trityl-β-d-lyxo-hexulofuranoside have been synthesised and 1 has been converted into 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl 1,6-di-O-acetyl-3,4-anhydro-β-d-lyxo-hexulofuranoside (2). The S_N2 reactions of 2 with azide and chloride nucleophiles gave the corresponding 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl 1,3,6-tri-O-acetyl-4-azido-4-deoxy-β-d-fructofuranoside (6) and 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl 1,3,6-tri-O-acetyl-4-chloro-4-deoxy-β-d-fructofuranoside (8), respectively. The azide 6 was catalytically hydrogenated and the resulting amine was isolated as 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl 4-acetamido-1,3,6-tri-O-acetyl-4-deoxy-β-d-fructofuranoside. Treatment of 5 with hydrogen bromide in glacial acetic acid followed by conventional acetylation gave 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl 1,3,6-tri-O-acetyl-4-bromo-4-deoxy-β-d-fructofuranoside. Similar S_N2 reactions with 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl 1,6-di-O-acetyl-3,4-anhydro-β-d-ribo-hexulofuranoside (12) resulted in a number of 4′-derivatives of α-d-glucopyranosyl β-d-sorbofuranoside. The regiospecific nucleophilic substitution at position 4′ in 2 and 12 has been explained on the basis of steric and polar factors.     

Flavonoids,stilbenoids, and phenolic derivatives from the stems of Gnetum macrostachyum (Gnetaceae)

Gnetum species have been traditionally consumed as food and used as folk medicine to treat various pathological conditions. Ten compounds including three simple phenolic compounds (1–3), five stilbenoids (4, 5, 8–10), and two C-glycosyl flavanones (6 and 7), were isolated from the stems of Gnetum macrostachyum Hook. f. The structures of these compounds were elucidated by the analysis of spectroscopy data and their comparison with the reported values. This is the first report of the isolation of compounds 1–4 and 6–9 from G. macrostachyum. Compounds 1–3, 6, and 7 have not been previously reported from the genus Gnetum. The C-glycosyl flavanones in G. macrostachyum can be used as chemotaxonomic markers.     

Neolignans from the seeds of Prunus tomentosa (Rosaceae) and their chemotaxonomic interest

The role of neolignans in the chemotaxonomy of the genus Prunus has long been neglected. In this study, two new dihydrobenzofuran neolignans tomentosanans A (12) and B (14), together with 15 known neolignans, were isolated from the seeds of Prunus tomentosa. This is the first report on the occurrence of compounds 1–12, 14, 15 and 17 in the genus Prunus. The biosynthetic pathways of these neolignans are also summarized. Together, these neolignans represent a phytochemical fingerprint for P. tomentosa, which may be used for identification of Prunus species.     

Degraded diterpenoids from the stem bark of Neoboutonia mannii

Neoboutomannin (1), a degraded diterpenoid dimer, and manniorthoquinone (2), another degraded diterpenoid, have been isolated from the stem bark of Neoboutonia mannii Benth (Euphorbiaceae), together with the known 3-acetylaleuritolic acid (3), 3,6-dihydroxy-9-methoxy-1,7-dimethylphenanthrene (4) and sitosterol 3-O-β-d-glucopyranoside (5). Their structures were elucidated on the basis of spectral studies and comparison with published data. Compounds 1, 3, 4 and 5 were evaluated for their antibacterial and antifungal activities. 1, 3 and 4 were active against Enterococcus faecalis, Staphylococcus aureus, Proteus mirabilis and three Candida species, Candida albicans ATCC 9002, Candida tropicalis and Candida parapsilosis. Compound 5 was inactive against all the bacterial and fungal species used.     

Evaluation of single and joint effect of metabolites isolated from marine sponges,Fasciospongia cavernosa and Axinella donnani on antimicrobial properties

The biochemical mechanisms that marine sponges have developed as a chemical defense to protect themselves against micro and subsequent macrobiofouling process might comprise a potential alternative for the preventing attack of biofilm forming bacteria. The present study investigated the antimicrobial activity of a series of major secondary metabolites isolated from the sponges Fasciospongia cavernosa and Axinella donnani against fouling bacteria. Secomanoalide (1), dehydromanoalide (2) and cavernosine (3) have been isolated from F. cavernosa. Their structures were determined by MS, ¹H NMR spectra analyses and by comparison with those reported in the literature. The most promising activity was exhibited by the metabolites from A. donnani, that is, cerebroside (5) against three strains Aeromonas hydrophila subsp. salmonicida A449 and Erythrobacter litoralis. Our investigation revealed that combined metabolites 1, 2 and 3 retained strong activity but individual metabolite had moderate activity indicating that activity probably results from synergistic interactions between multiple compounds. The antibacterial screening of compounds 3, 5 and synergistic effect of 1–3 against fouling bacteria has been studied for the first time. Further, isolation of manoalide related compounds and their synergistic screening can be accelerated for the development of new biofilm inhibitors.     

The synthesis of d-ribofuranosyl derivatives of methyl propiolate and a study of the activating influence of the ester group in cylcoaddition reactions

2,3,5-Tri-O-benzyl-D-ribofuranosyl bromide (17) has been converted into methyl 3-(2,3,5-tri-O-benzyl-β-d-ribofuranosyl)propiolate (8) and its α anomer 10 in 21 and 42% yields, respectively, by reaction with the silver salt of methyl propiolate. Attemps to prepare 8 from (β-d-ribofuranosyl)ethyne (1) by standard methods were unsuccesful. The reactions of the esters 8 and 10 and the ethyne 1 with several 1,3-dipoles have been examined. With diazomethene, 8 and 10 gave the pyrazole esters 20 and 28, respectively, whereas the ethyne 1 reacted more slowly to give a mixture of 23 (37%) and 26(31%). The ester 10 was converted into the triazoles 32 (51%) and 36 (34%) by reaction with benzyl azide. Treatment of the ester 10 with phenylhydrazine gave the pyrazolone 38 in 71% yield. A number of the products of dipolar addition have been converted into new d-ribofuranosyl-pyrazoles and -triazoles by hydrogenolysis.     

Neuroactive diol and acyloin metabolites from cone snail-associated bacteria

The bacterium Gordonia sp. 647 W.R.1a.05 was cultivated from the venom duct of the cone snail, Conus circumcisus. The Gordonia sp. organic extract modulated the action potential of mouse dorsal root ganglion neurons. Assay-guided fractionation led to the identification of the new compound circumcin A (1) and 11 known analogs (2–12). Two of these compounds, kurasoin B (7) and soraphinol A (8), were active in a human norepinephrine transporter assay with K_i values of 2575 and 867 nM, respectively. No neuroactivity had previously been reported for compounds in this structural class. Gordonia species have been reproducibly isolated from four different cone snail species, indicating a consistent association between these organisms.     

Chemical constituents from the aerial parts of Ajania fruticulosa

The isolation and identification of sixteen compounds extracted from the aerial parts of A. fruticulosa have been reported in the present study, including eight flavonoids (1, 2, 3, 4, 5, 6, 7 and 8), three terpenoids (9, 10 and 11), two sterols (12 and 13), one lignan (14), one fatty acid (15) and one fatty acid ethyl ester (16), wherein six compounds (2, 3, 4, 5, 10 and 14) have been isolated from A. fruticulosa for the first time. Furthermore, among the identified compounds, three compounds (6, 7 and 11) have also been reported for the first time in the genus Ajanin and three compounds (8, 15 and 16) have not been isolated and reported from other plants of the family Asteraceae. In addition, the chemotaxonomic significance of these compounds was discussed.     

Antibacterial constituents from Leucosceptrum canum

Four new long-chain compounds, leucoperoxyterpene (1), leucoester (2), leucoic acid (3), and leucoenoic acid (4) has been isolated from aerial parts of the medicinal plant Leucosceptrum canum together with fifteen known compounds. Compound 1 was found to be a member of the rare class of peroxy open chain natural products. The structures of all compounds were assigned by means of modern spectroscopic techniques. All compounds were tested for their antibacterial activities against Bacillus subtilis, Escherichia coli, Micrococcus luteus, Pseudomonas agarici, Streptococcus minor, and Streptococcus ferus, in which, compounds 1, and 10–15 exhibited potent to moderate activities.