Tetraoxygenated xanthones and biflavanoids from the twigs of Garcinia merguensis

One new tetraoxygenated xanthone, merguensinone (1), along with one known xanthone, 1,5,6-trihydroxy-2-prenyl-6′,6′-dimethyl-2H-pyrano(2′,3′:3,4)xanthone (2) and five known biflavanoids, (?)-GB-1a (3), (?)-GB-2a (4), (+)-morelloflavone (5), (+)-volkensiflavone (6), and amentoflavone (7) were isolated from the methanol extract from the twigs of Garcinia merguensis. Their antibacterial activity against the standard Staphylococcus aureus ATCC 25923 and methicillin-resistant S. aureus and antioxidation activity with DPPH assay were examined.     

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.     

New pyranonaphthazarin and 2-naphthoic acid derivatives from the mangrove endophytic fungus Leptosphaerulina sp. SKS032

Two new compounds, named leptospyranonaphthazarin A (1) and leptosnaphthoic acid A (2), together with four known compounds (3–6) were isolated from an endophytic fungus Leptosphaerulina sp. SKS032. Their structures were assigned using spectroscopic methods, computational methods, and single-crystal X-ray diffraction analysis. In the antibiotic assay, compounds 1, 2, and 6 exhibited antibacterial activities against Staphylococcus aureus with minimal inhibitory concentration (MIC) values of 25.0, 50.0, and 50.0 μg/mL, respectively.     

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.     

Synthesis of novel 2-amino-4-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-6-aryl-4H-pyran-3-carbonitrile derivatives as antimicrobial and antioxidant agents

As a part of systematic investigation of synthesis and biological activities of indole analogues linked to various heterocyclic systems, we have synthesized new compounds viz., 2-amino-4-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-6-aryl-4H-pyran-3-carbonitriles (2a–i), 4,5-diamino-6-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-8-aryl-2-oxo-2,6-dihydrodipyrano [2,3-b:3,2-e]pyridine-3-carbonitriles (3a–i), 4-amino-5-(5′-substituted 2′-phenyl-1H-indol-3-yl)-7-aryl-1H-pyrano[2,3-d]pyrimidin-2(5H)-ones (4a–i), 4-amino-5-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-7-aryl-1H-pyrano[2,3-d]pyrimidin-2(5H)-thiones (5a–i), 4-(5′-subtituted 2′-phenyl-1H-indol-3′-yl)-6-aryl-1,4-dihydropyrano[2,3-c]pyrazol-3-amines (6a–i) and 5-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-7-aryl-3H-pyrano[2,3-d]pyrimidin-4(5H)-ones (7a–i). Antibacterial activity results revealed that, compound 6a showed promising activity versus Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae. Compound 6d exhibited good activity against S. aureus, K. pneumoniae and Pseudomonas aeruginosa. Antifungal activity results indicated that, compound 4d exhibited maximum zone of inhibition against Aspergillus oryzae and Aspergillus flavus. In case of antioxidant activity, compound 4a showed promising radical scavenging activity, ferric ions (Fe³⁺) reducing antioxidant power (FRAP) and metal chelating activity.     

3-Anhydro-6-hydroxy-ophiobolin A,a new sesterterpene inhibiting the growth of methicillin-resistant Staphylococcus aureus and inducing the cell death by apoptosis on K562, from the phytopathogenic fungus Bipolaris oryzae

A new ophiobolin derivative, 3-anhydro-6-hydroxy-ophiobolin A (1), as well as two known ophiobolin derivatives 3-anhydro-ophiobolin A (2) and 3-anhydro-6-epi-ophiobolin A (3) were isolated from the PDB culture of a phytopathogenic fungus Bipolaris oryzae. The structure of 1 was elucidated through 2D NMR and other spectroscopic techniques. Compound 1 exhibited strong antimicrobial activity against Bacille Calmette–Guerin, Bacillus subtilis, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus with MIC value of 12.5 μg/mL, and potent antiproliferative activity against cell lines HepG2 and K562 with IC₅₀ of 6.49 μM and 4.06 μM, respectively. Further studies on the cytotoxicity of compound 1 against K562 cells demonstrated that it induced apoptosis, observed by flow cytometric method. Preliminary structure–activity relationships of these ophiobolins and the mechanism of apoptosis induced by 1 were analyzed.     

Phenylpropanoid derivatives from Clausena harmandiana fruits

A new phenylpropanoid derivative, harmandianone (1), along with four known compounds: verimol B (2), (E)-3-(2-hydroxy-4-methoxy-phenyl)propanoate (3), (E)-methyl p-coumarate (4), and (E)-5-methoxy-2-(prop-1-enyl)phenol (5) was isolated from the acetone extract of Clausena harmandiana fruits. All structures were characterized by spectroscopic methods (UV, IR, NMR and ESI-TOF-MS). Compounds 1 and 3–5 demonstrated weak antibacterial activity against Escherichia coli TISTR 780, methicillin-resistant Staphylococcus aureus SK1, Salmonella typhimurium TISTR 292 and S. aureus TISTR1466, with MIC values between 64 and 128 μg/mL.     

Cunninghamella blakesleeana-mediated biotransformation of a contraceptive drug,desogestrel, and anti-MDR-Staphylococcus aureus activity of its metabolites

Staphylococcus aureus is one of the most infectious agents among staphylococcal bacteria. Currently many strains of S. aureus have developed resistance against available antibiotics. Therefore, the treatment of infections caused by them is a major challenge. During current study, desogestrel (1), a contraceptive drug, was found to be a potent growth inhibitor of drug resistant strains of S. aureus. Therefore, in search of new and effective agents against multi-drug resistant S. aureus strains, whole-cell bio-catalytic conversion of desogestrel (1) by Cunninghamella blakesleeana ATCC 8688A at pH 7.0 and 25 °C was carried out, yielding three new metabolites, 13-ethyl-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-6β,15β,17β-triol (2), 13-ethyl-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-3β,6β,17β-triol (3), and 13-ethyl-11-methylene-18,19-dinor-17α-pregn-20-yn-3α,5α,6β,17β-tetraol (4), along with a known metabolite, 13-ethyl-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-6β,17β-dihydroxy-3-one (5). Among them, compounds 1–2 showed a potent activity against S. aureus EMRSA-17, S. aureus NCTC 13277 (MRSA-252), and S. aureus NCTC 13143, and clinically isolated Pakistani strain of S. aureus in an in vitro Microplate Alamar Blue Assay (MABA). Vancomycin was used as the standard drug in this assay. In addition, compound 1 also showed a significant activity against vancomycin-resistant S. aureus (VRSA) ATCC 700699. Compounds 1–5 were also evaluated against 3T3 normal cell line (mouse fibroblast) where they all were identified as non-cytotoxic. The present study thus provides new leads for the development of anti-bacterial drugs against MDR S. aureus.     

Bioactive polyhydroxylated steroids from the Hainan soft coral Sinularia depressa Tixier-Durivault

Two new steroids, (2β,3β,4α,5α,8β)-4-methylergost-24(28)-ene-2,3,8-triol (1) and (3β,7α)-24-methyl-7-hydroperoxycholest-5,24(28)-diene-3-ol (2), together with 13 known analogues (3–15) were isolated from the soft coral Sinularia depressa Tixier-Durivault. The structures of the new compounds were elucidated by detailed spectroscopic analysis and comparison with reported data. In the bioassay in vitro, compounds 3a, 4, and 14 exhibited potent PTP1B inhibitory activity, being similar as that of positive control oleanolic acid. Compound 14 also displayed a notable neuroprotective activity against both amyloid-β_25–35- and serum deprivation-induced injuries in SH-SY5Y cells while compound 11 showed a considerable antibacterial activity against Staphylococcus aureus. Preliminary structure–activity relationships of these steroids were discussed.     

Antimicrobial lignans derived from the roots of Streblus asper

Four new lignans, (7′R,8′S)-4,4'-Dimethoxy-strebluslignanol (1), 3'-Hydroxy-isostrebluslignaldehyde (2), 3,3'-Methylene-bis(4-hydroxybenzaldehyde) (3), and 4-Methoxy-isomagnaldehyde (4), and six known lignans (5–10), were isolated from the roots of Streblus asper. The structures of these molecules were elucidated through various spectroscopic methods of analysis, including 1D and 2D NMR. The stereochemistry at the chiral centres was determined using the CD spectrum and from coupling constant and optical rotation data. Compounds 1–6 showed good antimicrobial activity against Saccharomyces cerevisiae (ATCC 9763), Bacillus subtilis (ATCC 6633), Pseudomonas aeruginosa (ATCC 9027), Escherichia coli (ATCC 11775), and Staphylococcus aureus (ATCC 25923), with MIC values ranging from 0.0150 to 0.0940 μM.     

Bioactive cytosporone derivatives isolated from the mangrove-derived fungus Dothiorella sp. ML002

Three new cytosporone derivatives dothiorelones K–M (1, 2 and 7), together with six known ones (3–6, 8 and 9) were isolated from the mangrove-derived fungus Dothiorella sp. ML002. Their structures were determined by comprehensive 1D, 2D NMR spectroscopic and HR-ESI-MS spectroscopic data. Compounds 1, 2 and 5 displayed inhibitory activities against α-glucosidase with the IC₅₀ values of 22.0, 77.9 and 5.4 μg/mL, respectively. Additionally, compounds 1, 2, and 5 also exhibited antibacterial activities against Staphylococcus aureus (ATCC 6538) with the same MIC values of 50 μg/mL, respectively. The results indicated that cytosporone derivatives will be useful to as diabetes control agents.     

New antibacterial sesquiterpene aminoquinones from a Vietnamese marine sponge of Spongia sp.

Two new sesquiterpene aminoquinones, langcoquinones A (1) and B (2), together with seven known meroterpenoids (3⿿9), were isolated from the marine sponge Spongia sp. collected in Vietnam. Their structures were determined on the basis of spectroscopic analyses and comparisons with published data. The antibacterial activities of the isolated compounds (1⿿9) were investigated against four bacterial strains. Among these, the new sesquiterpene aminoquinones (1 and 2) and the known related compounds (3, 5, 6, 8, and 9) exhibited significant antibacterial activities against Staphylococcus aureus and Bacillus subtilis, with MICs ranging from 6.25 to 12.5 μM.     

Bibenzyl and phenolic glycosides from Pterospermum heterophyllum

A new bibenzyl, heterophyllic acid (1), and three new phenolic glycosides, heterophylloside A–C (2–4), along with two known phenolic glycosides oldhamioside (5) and 6′-O-vanilloylisotachioside (6) were isolated from Pterospermum heterophyllum. The structures of these compounds were elucidated on the basis of 1D, 2D NMR, MS spectroscopic analysis, and chemical methods. Their cytotoxic activities against KB and MCF-7 cancer cell lines were evaluated. Compound 2 showed significant cytotoxic activities.     

A new diterpene from the fungal mycelia of Hericium erinaceus

One new diterpene (1) and new compound (2), along with four known compounds (3–6) were isolated from the fungal mycelia of Hericium erinaceus by the tracking method of antibacterial activity. The structures of compounds (1–6) were elucidated on the basis of spectral data. Compound (3) showed strong antibacterial activity against Helicobacter pylori (ATCC43504) and compounds (1), (2) and (4) showed moderate antibacterial activity. Compound (1) exhibited good cytotoxicity against three human cancer cell lines (K562, LANCAP, HEP2).     

Six new dammarane-type triterpene saponins from the processed leaves of Panax notoginseng

Six new dammarane-type triterpenoid saponins, notoginsenosides SFt₅–SFt₁₀ (1–6) were isolated from the processed leaves of Panax notoginseng (Burk.) F.H.Chen (Araliaceae), together with eight known notoginsenosides (7–14), fourteen known ginsenosides (15−28), two known vinaginsenosides (29−30), and one known gypenoside (31). Their structures were established by detailed spectroscopic analysis (NMR, UV, IR, HRESI-MS) and acidic hydrolysis. Four compounds notoginsenoside SFt₁ (7), ginsenosides Rg₅ (17), C-Mc (23) and 20(R)–Rg₃ (25) have significant protective effects against L-glutamate-induced SH–SY5Y nerve injury (10 μM).     

Alkaloid and coumarins from the green fruits of Aegle marmelos

Five (1–5) and 15 known compounds (6–20) were isolated from the acetone extract of the green fruits of Aegle marmelos. The structure of compounds 1–5, marmesiline (1), 6-(4-acetoxy-3-methyl-2-butenyl)-7-hydroxycoumarin (2), 6-(2-hydroxy-3-hydroxymethyl-3-butenyl)-7-hydroxycoumarin (3), marmelonine (4) and 8-hydroxysmyrindiol (5), were determined on the basis of spectroscopic analyses. Antifungal and antibacterial activities of selected compounds were also evaluated.     

Minor phenolics from Angelica keiskei and their proliferative effects on Hep3B cells

A new coumarin, (?)-cis-(3′R,4′R)-4′-O-angeloylkhellactone-3′-O-β-d-glucopyranoside (1) and two new chalcones, 3′-[(2E)-5-carboxy-3-methyl-2-pentenyl]-4,2′,4′-trihydroxychalcone (4) and (±)-4,2′,4′-trihydroxy-3′-{2-hydroxy-2-[tetrahydro-2-methyl-5-(1-methylethenyl)-2-furanyl]ethyl}chalcone (5) were isolated from the aerial parts of Angelica keiskei (Umbelliferae), together with six known compounds: (R)-O-isobutyroyllomatin (2), 3′-O-methylvaginol (3), (?)-jejuchalcone F (6), isoliquiritigenin (7), davidigenin (8), and (±)-liquiritigenin (9). The structures of the new compounds were determined by interpretation of their spectroscopic data including 1D and 2D NMR data. All known compounds (2, 3, and 6–9) were isolated as constituents of A. keiskei for the first time. To identify novel hepatocyte proliferation inducer for liver regeneration, 1–9 were evaluated for their cell proliferative effects using a Hep3B human hepatoma cell line. All isolates exhibited cell proliferative effects compared to untreated control (DMSO). Cytoprotective effects against oxidative stress induced by glucose oxidase were also examined on Hep3B cells and mouse fibroblast NIH3T3 cells and all compounds showed significant dose-dependent protection against oxidative stress.     

Characterization of a xylose containing oligosaccharide,an inhibitor of multidrug resistance in Staphylococcus aureus,from Ipomoea pes-caprae

Pescaprein XVIII (1), a type of bacterial efflux pump inhibitor, was obtained from the CHCl₃-soluble resin glycosides of beach morning glory (Ipomoea pes-caprae). The glycosidation sequence for pescaproside C, the glycosidic acid core of the lipophilic macrolactone 1 containing d-xylose and l-rhamnose, was characterized by means of several NMR techniques and FAB mass spectrometry. Recycling HPLC also yielded eight non-cytotoxic bacterial resistance modifiers, the two pescapreins XIX (2) and XX (3) as well as the known murucoidin VI (4), pecapreins II (6) and III (7), and stoloniferins III (5), IX (8) and X (9), all of which contain simonic acid B as their oligosaccharide core. Compounds 1–9 were tested for in vitro antibacterial and resistance-modifying activity against strains of Staphylococcus aureus possessing multidrug resistance efflux mechanisms. All of the pescapreins potentiated the action of norfloxacin against the NorA over-expressing strain by 4-fold (8 μg/mL from 32 μg/mL) at a concentration of 25 μg/mL.     

Two cytotoxic triterpenes from cultures of a Kenyan Laetiporus sp. (Basidiomycota)

HPLC profiling of the mycelial culture of a poroid basidomycete collected in Mount Elgon, Kenya, which probably represents a new species of the genus Laetiporus, led to isolation of two previously undescribed lanostane type triterpenes.We propose the trivial names laetiporins A (1) and B (2). In addition, five known ones: dehydrosulphurenic acid (3), sulphurenic acid (4), eburicoic acid (5), 15α-hydroxytrametenolic acid (6) and trametenolic acid (7) were also isolated. The laetiporins (1–2) exhibited significant cytotoxic effects against various human cancer cells. The known compounds (3–5) and (7) also showed moderate cytotoxic activity, but none of the compounds showed any significant antimicrobial activity.     

N-Formyllapatin A,a new N-formylspiroquinazoline derivative from the marine-derived fungus Penicillium adametzioides AS-53

N-Formyllapatin A (1), a new spiroquinazoline derivative, and four known quinazoline metabolites, lapatins A (2) and B (3), prelapatin B (4), and glyantrypine (5), along with two known indolediketopiperazine derivatives, fumitremorgin B (6) and verruculogen (7), were characterized from Penicillium adametzioides AS-53, a fungus obtained from the fresh tissue of an unidentified marine sponge. The structure of compound 1 was established by detailed interpretation of NMR and MS data, and its absolute configuration was established by a single-crystal X-ray diffraction analysis. N-Formyllapatin A (1) represents the first N-formylspiroquinazoline secondary metabolite. Compounds 3 and 5–7 showed moderate inhibitory activity against aqua-pathogenic bacterial Vibrio harveyi.