Four New Chromone Derivatives from Colletotrichum gloeosporioides

Four previously unreported chromones, 5‐hydroxy‐2‐(hydroxymethyl)‐8‐methoxy‐4H‐chromen‐4‐one ( 1 ), (5R,7S)‐5,7‐dihydroxy‐2‐propyl‐5,6,7,8‐tetrahydro‐4H‐chromen‐4‐one ( 2 ), (5R,7S)‐5,7‐dihydroxy‐2‐methyl‐5,6,7,8‐tetrahydro‐4H‐chromen‐4‐one ( 3 ), and (5R,7S)‐5,7‐dihydroxy‐2‐[(E)‐prop‐1‐en‐1‐yl]‐5,6,7,8‐tetrahydro‐4H‐chromen‐4‐one ( 4 ), as well as one known analogue 5‐hydroxy‐2‐methyl‐4H‐chromen‐4‐one ( 5 ) were isolated from the fermentation broth of the endophytic fungus Colletotrichum gloeosporioides derived from the mangrove Ceriops tagal. Their structures were elucidated based on extensive spectroscopic analyses. The absolute configurations of 2 – 4 were determined by comparison the experimental and calculated electronic circular dichroism (ECD) spectra. Compound 2 showed cytotoxic activity against A549 cell line with the IC₅₀ value of 0.094 mm .     

In vivo antigenotoxic potential and possible mechanism of action of selected 4-hydroxy-2H-chromen-2-one derivatives

The in vivo sex‐linked recessive lethal test was carried out in Drosophila melanogaster to investigate whether or not five substituted 4‐hydroxy‐2H‐chromen‐2‐ones can modulate the genotoxicity of the well‐established mutagenic agent ethyl methanesulfonate (EMS). For this purpose, 3 days old Canton S males were treated with the potent mutagen EMS alone in concentration of 0.75 ppm, as well as in combination with one of the five 4‐hydroxycoumarins, namely diethyl 2‐(1‐(4‐hydroxy‐2‐oxo‐2H‐chromen‐3‐yl)ethylidene)malonate ( 2b ), 3‐(1‐(4‐hydroxy‐2‐oxo‐2H‐chromen‐3‐yl)ethylidene)pentane‐2,4‐dione ( 6b ), 4‐(4‐(4‐hydroxy‐2‐oxo‐2H‐chromen‐3‐yl)thiazol‐2‐ylamino) benzenesulfonic acid ( 4c ), 4‐hydroxy‐3‐(2‐(2‐nitropheny lamino)thiazol‐4‐yl)‐2H‐chromen‐2‐one ( 9c ), and (E)‐4‐hydroxy‐3‐(1‐(m‐tolylimino)ethyl)‐2H‐chromen‐2‐one ( 5d ), in concentration of 70 ppm. The frequency of germinative mutations increased significantly after the treatment with EMS and decreased after treatments with coumarins. The maximum reduction was observed after treatments with 2b , 6b , 4c , and 5d . By the formation of hydrogen bonds or electrostatic interactions with O⁶ of DNA guanine, tested coumarins prevent EMS‐induced alkylation. The results indicate a protective role of five 4‐hydroxycoumarins under the action of a strong mutagen. © 2012 Wiley Periodicals, Inc. J Biochem Mol Toxicol 26:322–330, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/jbt.21426     

Colomitides A and B: Novel Ketals with an Unusual 2,7‐Dioxabicyclo[3.2.1]octane Ring System from the Aquatic Fungus YMF 1.01029

Two novel diastereoisomeric bicyclic ketals, colomitides A and B ( 1 and 2 , resp.), together with the known (4RS)‐3,4‐dihydro‐4,8‐dihydroxynaphthalen‐1(2H)‐one ( 3 ) and preussomerin E ( 4 ), were isolated from liquid cultures of an unidentified freshwater fungus YMF 1.01029. Colomitides possess an unusual 2,7‐dioxabicyclo[3.2.1]octane skeleton. The chemical structures and relative configurations of compounds 1 and 2 were elucidated by spectroscopic means, including 2D‐NMR (HMBC, HMQC, TOCSY, ROESY, and ¹H,¹H‐COSY). Compounds 1, 2 , and 4 showed noticeable antifungal and antibacterial activities.     

Sesquiterpene Lactones from Centaurea zuccariniana and Their Antimicrobial Activity

Twenty‐nine compounds were isolated from the aerial parts of the Greek plant C. zuccariniana DC. The structures of the isolated compounds were established by means of NMR‐ (¹H,¹H‐COSY, ¹H,¹³C‐HSQC, HMBC, NOESY, and ROESY) and mass‐spectral analyses. These compounds comprise 13 sesquiterpene lactones, 14 flavonoids, two lignans, and one simple lactone. Among the isolated sesquiterpene lactones, three are new, namely one heliangolide, (1E,4Z)‐15‐hydroxy‐8α‐O‐(4′‐acetoxy‐3′‐hydroxy‐2′‐methylidenebutanoyl)‐6βH,7αH‐germacra‐1,4,11(13)‐trien‐6,12‐olide; and two eudesmanolides, 8α‐(4′,5′‐diacetoxyangeloyl)sonchucarpolide and one unusual eudesmanolide with an oxygenated bridge linking C(1) and C(4), named zuccarinin. The main sesquiterpene lactones were malacitenolide, cnicin, and 4′‐O‐acetylcnicin. These results are in agreement with those obtained from the previously studied Greek Centaurea sp. belonging to the section Acrolophus (Cass .) DC.; this finding could be of chemotaxonomic significance for the genus Centaurea. The in vitro antimicrobial activities of the isolated new sesquiterpene lactones were against eight bacteria and eight fungal species. A 96‐well microbioassay procedure for fast and easy evaluation of antibacterial and antifungal activities was applied to compare these compounds with commercial antibiotic and fungicide standards, and with previously isolated analogous sesquiterpene lactones tested by the same bioassay. All of the compounds tested showed moderate antibacterial, but significant antifungal activities; the present results corroborate with previous data, indicating that these types of compounds exhibit low or moderate antibacterial, but potent antifungal activities. The unusual eudesmanolide zuccarinin proved to be the most potent among the present tested sesquiterpene lactones, as well as among all previously tested eudesmanolides isolated from Greek Centaurea sp.     

A Novel Monoterpene?Stilbene Adduct with a 4,4‐Dimethyl‐2,3‐diphenylchromane Skeleton from Artocarpus xanthocarpus

Artoxanthochromane ( 1 ), a Diels? Alder‐type conjugation product of 4‐isopropenylresorcinol and oxyresveratrol, was isolated from the heartwood of Artocarpus xanthocarpus and characterized. The structure of 1 was elucidated as 2‐(2,4‐dihydroxyphenyl)‐3‐(3,5‐dihydroxyphenyl)‐7‐hydroxy‐4,4‐dimethylchromane by 1D‐ and 2D‐NMR spectroscopy, and other spectral evidences. A plausible metabolic mechanism was proposed to illustrate the biosynthetic pathway of artoxanthochromane. This compound exhibited mild mushroom tyrosinase inhibitory, and weak free radical‐scavenging activities on ABTS^+. and superoxide anion (O ) free radicals.     

Two New Antioxidant Phenylpropanoids from Lindelofia stylosa

Two new phenylpropanoids were isolated from Lindelofia stylosa (Kar . and Kir .) and characterized as 4‐hydroxy‐N‐{4‐[(E)‐3‐(4‐hydroxy‐3‐methoxyphenyl)prop‐2‐enamido]butyl}benzamide ( 1 ) and 2‐[3‐hydroxy‐4‐(4‐hydroxyphenoxy)phenyl]‐1‐(methoxycarbonyl)ethyl (E)‐3‐(3,4‐dihydroxyphenyl)prop‐2‐enoate ( 2 ). Four known compounds, i.e. two phenylpropanoids, p‐coumaric acid (=(E)‐3‐(4‐hydroxyphenyl)prop‐2‐enoic acid; 3 ) and ferulic acid (=(E)‐3‐(4‐hydroxy‐3‐methoxyphenyl)prop‐2‐enoic acid; 4 ), and two naphthalene glycosides, 8‐O‐β‐D ‐glucopyranosyltorachrysone ( 5 ) and 8‐O‐β‐D ‐glucopyranosyl‐6‐demethoxytorachrysone ( 6 ), were also isolated for the first time from the plant. Compounds 1 – 6 were subjected to various antioxidant assays, including DPPH radical‐ and superoxide anion‐scavenging, and Fe²⁺‐chelation assays. Compound 2 was found to be most active in all assays with potency nearly similar to that of propyl gallate. Besides 2 , compounds 1 and 5 were also found to be active in DPPH radical‐scavenging standard assay.     

Two New Steroids from an Endophytic Fungus Phomopsis sp.

Two new steroids, (14β,22E)‐9,14‐dihydroxyergosta‐4,7,22‐triene‐3,6‐dione ( 1 ) and (5α,6β,15β,22E)‐6‐ethoxy‐5,15‐dihydroxyergosta‐7,22‐dien‐3‐one ( 2 ), together with three known steroids, calvasterols A and B ( 3 and 4 , resp.), and ganodermaside D ( 5 ), were isolated from the culture broth of an endophytic fungus Phomopsis sp. isolated from Aconitum carmichaeli. The structures of these compounds were elucidated on the basis of spectroscopic analysis, and their inhibitory activities against six pathogenic fungi were evaluated. Most of the compounds showed moderate or weak antifungal activities in a broth‐microdilution assay.     

Bioactive metabolites from the sponge Suberea sp

Two new brominated compounds, subereaphenol K ( 2 ) and 2‐(3,5‐dibromo‐1‐ethoxy‐4‐oxocyclohexa‐2,5‐dien‐1‐yl)acetamide ( 3 ), together with subereaphenol B (methyl 2‐(2,4‐dibromo‐3,6‐dihydroxyphenyl)acetate; 1 ) with a revised structure, and five dibromotyrosine‐derived metabolites, 4 – 8 , were isolated from the sponge Suberea sp. and characterized by 1D‐ and 2D‐NMR spectroscopic and HR‐MS spectrometric data. Compounds 1, 2, 6 , and 8 exhibited various weak or moderate bioactivities, including antimicrobial and cytotoxic activities. Furthermore, compounds 1 and 2 inhibited human recombinant phosphodiesterase 4 (PDE4) with IC₅₀ values of 2 μM , whereas compounds 6 and 8 were less active.     

Chemical Composition and Antimicrobial Activity of Ageratina deltoidea

The chemical study of Ageratina deltoidea afforded grandiflorenic acid ( 1 ), ent‐kaurenoic acid ( 2 ), and eight benzylbenzoates ( 3  –  10 ), two of them, 3,5‐dimethoxybenzyl 2,3,6‐trimethoxybenzoate ( 5 ) and 4‐(β‐d ‐glucopyranosyloxy)‐3‐hydroxybenzyl 2,6‐dimethoxybenzoate ( 9 ), described for the first time. In addition, the new sesquiterpene lactone deltoidin C ( 13 ), together with the known 11 and 12 , the phenolic compounds: ayanin, 2,6‐dimethoxybenzoic acid, methyl 3,4‐dihydroxycinnamate, chlorogenic acid, and 3,5‐dicaffeoylquinic acid were also isolated. The structures of these compounds were determined by spectroscopic methods and chemical reactions. The antibacterial and antifungal activities of compounds 1  –  12 were evaluated on Staphylococcus aureus, Escherichia coli, and Candida albicans. Deltoidin A ( 11 ) was the most active antibacterial agent (MIC 16.0 μg ml^?1) against E. coli, and the ent‐kaurenoid derivatives ( 1  –  2 ) showed activity (MIC 31.0 μg ml^?1) against S. aureus.     

Two New Butenolides Produced by an Actinomycete Streptomyces sp.

Two new butenolides, (4S)‐4,10‐dihydroxydodec‐2‐en‐1,4‐olide ( 1 ) and (4S)‐4,8,10‐trihydroxy‐10‐methyldodec‐2‐en‐1,4‐olide ( 2 ), together with three known compounds, MKN‐003B ( 3 ), MKN‐003C ( 4 ), and cyclo(Ala‐Leu) ( 5 ), were isolated from the culture broth of a bacterium of the genus Streptomyces derived from soil environment. The structures of these compounds were elucidated on the basis of spectroscopic analysis. The inhibitory activities of the butenolides against eight pathogenic fungi were evaluated. All of the butenolides showed moderate‐or‐weak antifungal activities in a broth microdilution assay.     

Antifungal Monoterpene Derivatives from the Plant Endophytic Fungus Pestalotiopsis foedan

A new monoterpene lactone, (1R,4R,5R,8S)‐8‐hydroxy‐4,8‐dimethyl‐2‐oxabicyclo[3.3.1]nonan‐3‐one ( 1 ), along with one related known compound, (2R)‐2‐[(1R)‐4‐methylcyclohex‐3‐en‐1‐yl]propanoic acid ( 2 ), were isolated from the liquid culture of the plant endophytic fungus Pestalotiopsis foedan obtained from the branch of Bruguiera sexangula. The structure and absolute configuration of 1 were determined on the basis of extensive analysis of NMR spectra combined with computational methods via calculation of the optical rotation (OR) and ¹³C‐NMR. Both compounds exhibited strong antifungal activities against Botrytis cinerea and Phytophthora nicotianae with MIC values of 3.1 and 6.3 μg/ml, respectively, which are comparable to those of the known antifungal drug ketoconazole. Compound 2 also showed modest antifungal activity against Candida albicans with a MIC value of 50 μg/ml.     

Merosesquiterpenoids and Ten‐Membered Macrolides from a Soft Coral‐Derived Lophiostoma sp. Fungus

One new merosesquiterpenoid, craterellin D ( 1 ), along with one known analog, craterellin A ( 2 ), and five known ten‐membered macrolides, 3 – 7 , were isolated from a soft coral‐derived Lophiostoma sp. fungus. The absolute configuration of 1 was established based on biogenetic consideration with the co‐isolated analog 2 , whose configuration was determined by modified Mosher's method and single‐crystal X‐ray diffraction analysis using CuK_α radiation. The absolute configuration of 3 was determined by X‐ray diffraction analysis using CuK_α radiation. Compounds 2 and 3 showed antibacterial activities against Bacillus cereus with a MIC value of 3.12 μM .     

Enantiomeric Polyketides from the Starfish‐Derived Symbiotic Fungus Penicillium sp. GGF16‐1‐2

One new racemic mixture, penicilliode A ( 1 ) and four pairs of enantiomeric polyketides, penicilliode B and C ( 2 and 3 ) and coniochaetone B and C ( 4 and 5 ), were obtained from the starfish‐derived symbiotic fungus Penicillium sp. GGF16‐1‐2. Interestingly, the strain GGF16‐1‐2 can produce enantiomers. The absolute configuration of 1 was determined by X‐ray diffraction (XRD) analysis, and the absolute configurations of 2 – 4 were determined by the optical rotation (OR) values and electronic circular dichroism (ECD) calculations. Compounds 1 – 5 were firstly isolated from the marine‐derived fungus Penicillium as racemates, and 2 – 5 were separated by HPLC with a chiral stationary phase. All the compounds were evaluated for their antibacterial, cytotoxic and inhibitory activities against PDE4D2.     

New Metabolites from Endolichenic Fungus Pleosporales sp.

Eight new metabolites were obtained from the culture of an endolichenic fungus, Pleosporales sp. Their structures were determined as three terphenyl derivatives, cucurbitarins A–C ( 1 – 3 , resp.), two structurally related compounds, cucurbitarins D and E ( 4 and 5 , resp.), two benzocoumarins, 3,10‐dihydroxy‐4,8‐dimethoxy‐6‐methylbenzocoumarin ( 6 ) and 3,8,10‐trihydroxy‐4‐methoxy‐6‐methylbenzocoumarin ( 7 ), as well as one cyclohexenone, (5R)‐5‐hydroxy‐2,3‐dimethylcyclohex‐2‐en‐1‐one ( 8 ), based on the spectroscopic data.     

Antimicrobial and Cytotoxic Activity of Extracts of Ferula heuffelii Griseb. ex Heuff. and Its Metabolites

The antimicrobial and cytotoxic activities of isolates (CHCl₃ and MeOH extracts and selected metabolites) obtained from the underground parts of the Balkan endemic plant Ferula heuffelii Griseb . ex Heuff . were assessed. The CHCl₃ and MeOH extracts exhibited moderate antimicrobial activity, being more pronounced against Gram‐positive than Gram‐negative bacteria, especially against Staphylococcus aureus (MIC=12.5 μg/ml for both extracts) and Micrococcus luteus (MIC=50 and 12.5 μg/ml, resp.). Among the tested metabolites, (6E)‐1‐(2,4‐dihydroxyphenyl)‐3,7,11‐trimethyl‐3‐vinyldodeca‐6,10‐dien‐1‐one ( 2 ) and (2S*,3R*)‐2‐[(3E)‐4,8‐dimethylnona‐3,7‐dien‐1‐yl]‐2,3‐dihydro‐7‐hydroxy‐2,3‐dimethylfuro[3,2‐c]coumarin ( 4 ) demonstrated the best antimicrobial activity. Compounds 2 and 4 both strongly inhibited the growth of M. luteus (MIC=11.2 and 5.2 μM , resp.) and Staphylococcus epidermidis (MIC=22.5 and 10.5 μM , resp.) and compound 2 additionally also the growth of Bacillus subtilis (MIC=11.2 μM ). The cytotoxic activity of the isolates was tested against three human cancer cell lines, viz., cervical adenocarcinoma (HeLa), chronic myelogenous leukemia (K562), and breast cancer (MCF‐7) cells. The CHCl₃ extract exhibited strong cytotoxic activity against all cell lines (IC₅₀<11.0 μg/ml). All compounds strongly inhibited the growth of the K562 and HeLa cell lines. Compound 4 exhibited also a strong activity against the MCF‐7 cell line, comparable to that of cisplatin (IC₅₀=22.32±1.32 vs. 18.67±0.75μM ).     

Enzymatic Hydrolysis of Esters Containing a Tetrazole Ring

The lipase‐catalyzed enantioselective hydrolysis of acetates containing tetrazole moiety was studied. Among all tested lipases, Novozyme SP 435 allowed to obtain optically active 4‐(5‐aryl‐2H‐tetrazol‐2yl)butan‐2‐ol and 1‐(5‐aryl‐2H‐tetrazol‐2yl)‐propan‐2‐ol and their acetates with the highest optical purities (ee = 95%‐99%) and excellent enantioselectivity (E>100). Some of the synthesized tetrazole derivatives were screened for their antifungal activity. Racemic mixtures of 4‐[5‐(4‐chlorophenyl)‐2H‐tetrazol‐2‐yl)butan‐2‐ol as well as pure enantiomers of this compound showed promising antifungal activity against F. sambucinum, F. oxysporum, C. coccodes, and A. niger. Chirality 26: 811–816, 2014. © 2014 Wiley Periodicals, Inc.     

Antifungal metabolites from the roots of Diospyros virginiana by overpressure layer chromatography

A preparative overpressure layer chromatography (OPLC) method was successfully used for the separation of two new natural compounds, 4‐hydroxy‐5,6‐dimethoxynaphthalene‐2‐carbaldehyde ( 1 ) and 12,13‐didehydro‐20,29‐dihydrobetulin ( 2 ) together with nine known compounds, including 7‐methyljuglone ( 3 ), diospyrin ( 4 ), isodiospyrin ( 5 ), shinanolone ( 6 ), lupeol ( 7 ), betulin ( 8 ), betulinic acid ( 9 ), betulinaldehyde ( 10 ), and ursolic acid ( 11 ) from the acetone extract of the roots of Diospyros virginiana. Their identification was accomplished by 1D‐ and 2D‐NMR spectroscopy and HR‐ESI‐MS methods. All the isolated compounds were evaluated for their antifungal activities against Colletotrichum fragariae, C. gloeosporioides, C. acutatum, Botrytis cinerea, Fusarium oxysporum, Phomopsis obscurans, and P. viticola using in vitro micro‐dilution broth assay. The results indicated that compounds 3 and 5 showed high antifungal activity against P. obscurans at 30 μM with 97.0 and 81.4% growth inhibition, and moderate activity against P. viticola (54.3 and 36.6%). It appears that an optimized OPLC system offers a rapid and efficient method of exploiting bioactive natural products.     

Bioactivity of natural O‐prenylated phenylpropenes from Illicium anisatum leaves and their derivatives against spider mites and fungal pathogens

A variety of volatile phenylpropenes, C₆‐C₃ compounds are widely distributed in the plant kingdom, whereas prenylated phenylpropenes are limited to a few plant species. In this study, we analysed the volatile profiles from Illicium anisatum leaves and identified two O‐prenylated phenylpropenes, 4‐allyl‐2‐methoxy‐1‐[(3‐methylbut‐2‐en‐1‐yl)oxy]benzene [O‐dimethylallyleugenol ( 9 )] and 5‐allyl‐1,3‐dimethoxy‐2‐(3‐methylbut‐2‐en‐1‐yl)oxy]benzene [O‐dimethylallyl‐6‐methoxyeugenol ( 11 )] as major constituents. The structure–activity relationship of a series of eugenol derivatives showed that specific phenylpropenes, including eugenol ( 1 ), isoeugenol ( 2 ) and 6‐methoxyeugenol ( 6 ), with a phenolic hydroxy group had antifungal activity for a fungal pathogen, whereas guaiacol, a simple phenolic compound, and allylbenzene had no such activity. The eugenol derivatives that exhibited antifungal activity, in turn, had no significant toxicant property for mite oviposition. Interestingly, O‐dimethylallyleugenol ( 9 ) in which the phenolic oxygen was masked with a dimethylallyl group exhibited a specific, potent oviposition deterrent activity for mites. The sharp contrast in structural requirements of phenylpropenes suggested distinct mechanisms underlying the two biological activities and the importance of a phenolic hydroxy group and its dimethylallylation for the structure‐based design of new functional properties of phenylpropenes.     

The Chemical Constituents of Endophytic Fungus Trichoderma sp. MFF‐1

A fungal strain named MFF‐1 was isolated from the flower of Pyrethrum cinerariifolium. Based on the sequence at the internal transcribed spacer (ITS) region, this strain was identified as a Trichoderma sp. Two new compounds, including a mitorubrin derivative and its potential biogenetic precursor, together with a known compound, were isolated from the cultures of the endophytic fungus. Their structures were established by spectroscopic methods and determined to be (3S*,6R*,7R*)‐3,4,5,6,7,8‐hexahydro‐7‐hydroxy‐7‐methyl‐8‐oxo‐3‐[(E)‐prop‐1‐enyl]‐1H‐isochromen‐6‐yl 2,4‐dihydroxy‐6‐methylbenzoate ( 1 ), named deacetylisowortmin, (E)‐2‐(hydroxymethyl)‐3‐(2‐hydroxypent‐3‐enyl)phenol ( 2 ), and wortmannin ( 3 ). All compounds were assayed for antimicrobial activity. Compound 3 showed activity against Candida albicans and Bacillus cereus.     

Unexpected formation of 3-chloro-1-hydroxy-2,6-diarylpiperidin-4-ones: Synthesis,antibacterial and antifungal activities

New 3-chloro-1-hydroxy-2,6-diarylpiperidin-4-ones 18–22 were synthesized, characterized by melting point, elemental analysis, MS, FT-IR, one-dimensional NMR (¹H & ¹³C) spectroscopic data and evaluated for their in vitro antibacterial and antifungal activities. All the newly synthesized compounds exerted a wide range of antibacterial activities against the entire tested gram-positive and gram-negative bacterial strains except Escherichia coli. Compounds 21 and 22 exerted strong antifungal activities against Aspergillus flavus, mucor and Microsporum gypsuem. In addition, compound 20 was more potent against Rhizopus.