Studies on Biological Activity of Cyclic Imide Compounds

The structure-activity relationships of 3-phenyloxazolidine-2, 4-diones, 3-phenyl-4-imino-oxazolidine-2-ones and n-phenylcarbamates were investigated on Sclerotinia sclerotiorum by the agar medium dilution method. In addition, antimicrobial spectra of several compounds against other 15 pathogenic microbes were investigated by the same method. In each series, 3, 5-dihalo-substituents on benzene ring are essential to high antifungal activity against Sclerotinia sclerotiorum and in the case of n-phenylcarbamates, it is necessary that the α-position of alcohol moiety is substituted by such a group as cyano group, ethoxy-carbonyl group or carbamoyl group. α-Cyanoisopropyl N-(3, 5-dichlorophenyl) carbamate, 3-(3′, 5′-dichlorophenyl)-5, 5-dimethyl-4-iminooxazolidine-2-one and 3-(3′, 5′-dichlorophenyl)-5, 5-dimethyloxazolidine-2,4-dione were the most effective and completely inhibited the mycelial growth of Sclerotinia sclerotiorum at 3.2 γm (about l.0 ppm). In general, 3-(3′, 5′-dichlorophenyl) oxazolidine-2, 4-diones and related compounds are highly active against Sclerotinia sclerotiorum and Botrytis cinerea, and fairly active against Cochliobolus miyabeanus, Pellicularia filamentosa, Pellicularia sasakii and Alternaria kikuchiana.     

Evaluation of natural antioxidants of Leuzea carthamoides as a result of a screening study of 88 plant extracts from the European Asteraceae and Cichoriaceae

In recently, there has been a great interest in natural antioxidants as bioactive components of food, nutraceuticals or potential drugs against several diseases. In our study, 88 extracts from various parts of plants from European Asteraceae and Cichoriaceae were assayed for radical scavenging activity by means of DPPH (1,1-diphenyl-2-picryl hydrazyl radical) test using the SIA (Sequential injection analysis) method developed for this purpose in our laboratory. DPPH radical scavenging activity of all tested plant extracts was evaluated according to the IC₅₀ parameter. 29 extracts exhibited IC₅₀ value lower than 0.1 mg/mL. The leaves of Leuzea carthamoides (IC₅₀ = 0.046 mg/mL) were chosen as the most promising sample for a subsequent phytochemical study, which resulted in isolation of seven natural compounds, namely, 4′,5,7-trihydroxy-6-methoxyflavone (hispidulin) (1), 5, 7, 3′, 4′- tetrahydroxyflavanone (eriodictyol) (2), 3′,4′,5,7-pentahydroxy-6-methoxyflavonol (patuletin) (3), eriodictyol-7-β-glucopyranoside (4), 6-hydroxykaempferol-7-O-(6″-O-acetyl-β-D-glucopyranoside) (5), 4-hydroxybenzoic acid (6) and 3,4-dihydroxybenzoic acid (protocatechuic acid) (7). Antioxidant activity of the isolated compounds was evaluated by DPPH test and ferric reducing antioxidant power (FRAP) test and compared with trolox and quercetin. Both tests evaluated the flavonoid (5) as the most active antioxidant. This result was confirmed by comparison with known data concerning the structure/activity relationships of flavonoids.     

Organometallic-based antibacterial and antifungal compounds: transition metal complexes of 1,1′-diacetylferrocene-derived thiocarbohydrazone,carbohydrazone, thiosemicarbazone and semicarbazone

Organometallic-based, 1,1′-diacetylferrocene-derived antibacterial and antifungal thiocarbohydrazone, carbohydrazone, thiosemicarbazone and semicarbazone have been prepared by condensing equimolar amount of 1,1′-diacetylferrocene with thiocarbohydrazide, carbohydrazide thiosemicarbazide and semicarbazide, respectively. These were used as ligands for the preparation of their cobalt (II), copper (II), nickel (II) and zinc (II) metal complexes. All the synthesized ligands and their complexes were characterized by IR, NMR, elemental analyses, molar conductances, magnetic moments and electronic spectral data. These synthesized compounds were screened for their antibacterial activity against Escherichia coli, Bacillus subtillis, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi, and for antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata using the agar-well diffusion method. All the compounds showed good antibacterial and antifungal activity which increased on coordination with the metal ions thus, introducing a novel class of organometallic-based antibacterial and antifungal agents.     

Synthetic amides toxic to the leaf-cutting ant Atta sexdens rubropilosa L. and its symbiotic fungus

• 1 Nine synthetic amides similar to natural N‐piperidine‐3‐(4,5‐methylenedioxyphenyl)‐2‐(E)‐propenamide and N‐pyrrolidine‐3‐(4,5‐methylenedyoxiphenyl)‐2‐(E)‐propenamide were synthesized and identified by their spectroscopic data.
• 2 The toxicity of these synthetic amides to the Atta sexdens rubropilosa workers and the antifungal activity against Leucoagaricus gongylophorus, the symbiotic fungus of the leaf‐cutting ants, were determined.
• 3 Workers ants that were fed daily on an artificial diet to which these compounds were added had a higher mortality rate than the controls for N‐pyrrolidine‐3‐(3′,4′‐methylenedioxyphenyl)‐2‐(E)‐propenamide and N‐benzyl‐3‐(3′,4′‐methylenedioxyphenyl)‐2‐(E)‐propenamide at a concentration of 100 µg/mL.
• 4 The completely inhibition (100%) of the fungal growth was observed with N‐piperidine‐3‐(3′,4′‐methylenedioxyphenyl)‐2‐(E)‐propenamide and N,N‐diethyl‐3‐(3′,4′‐methylenedioxyphenyl)‐2‐(E)‐propenamide at concentrations of 50 and 100 µg/mL and N‐pirrolidine‐3‐(3′,4′‐methylenedioxyphenyl)‐2‐(E)‐propenamide at a concentration of 100 µg/mL.
• 5 The possibility of controlling these insects in the future using synthetic piperamides that can simultaneously target both organisms is discussed.

     

Two antibacterial biphenyls from rhynchosia suaveolens

Two new biphenyls characterized as 4-(3-methyl-but-2-enyl)-5-methoxy-[1,1′-biphenyl]-3-ol 1 and 2-carboxy-4-(3-methyl-but-2-enyl)-5-methoxy- [1,1′-biphenyl]-3-ol 5 have been isolated from Rhynchosia suaveolens. Both compounds displayed antibacterial activity.     

Caldensinic acid,a prenylated benzoic acid from Piper caldense

The CH₂Cl₂ and MeOH extracts from leaves of Piper caldense were subjected to chromatographic separation procedures to afford the new prenylated benzoic acid, caldensinic acid (3-[(2′E,6′E,10′E)-11′-carboxy-3′,7′,15′-trimethylhexadeca-2′,6′,10′,14′-tetraenyl]-4,5-dihydroxybenzoic acid) whose structure was determined by spectral analysis, mainly NMR (¹H, ¹³C, HSQC, HMBC) and ESI-MS. The natural compound and derivatives displayed antifungal activity against the phytopathogenic fungi Cladosporium cladosporioides and C. sphaerospermum by direct bioautography.     

Induced accumulation of tyramine,serotonin, and related amines in response to Bipolaris sorokiniana infection in barley

The inducible metabolites were analyzed in barley leaves inoculated with Bipolaris sorokiniana, the causal agent of spot blotch of barley. HPLC analysis revealed that B. sorokiniana-infected leaves accumulated 4 hydrophilic compounds. They were purified by ODS column chromatography and preparative HPLC. Spectroscopic analyses revealed that they were tyramine (1), 3-(2-aminoethyl)-3-hydroxyindolin-2-one (2), serotonin (3), and 5,5′-dihydroxy-2,4′-bitryptamine (4). Among these, 2 and 4 have not been reported as natural products. They showed antifungal activity in an assay of inhibition of B. sorokiniana conidia germination, suggesting that they play a role in the chemical defense of barley as phytoalexins. The accumulation of 1–4 was examined also in the leaves of rice and foxtail millet. Rice leaves accumulated 2, 3, and 4, whereas foxtail millet leaves accumulated 3 and 4 in response to pathogen attack, suggesting the generality of accumulation of 3 and 4 in the Poaceae species.     

Antifungal Activity of Volatile Compounds Produced by an Edible Mushroom Hypsizygus marmoreus against Phytopathogenic Fungi

Volatile compounds with antifungal activity produced by edible mushrooms have potential as biological control agents to combat fungal diseases and reduce fungicide use in agriculture. Here we investigated the antifungal activity of volatile compounds produced by the edible mushroom Hypsizygus marmoreus (TUFC 11906) against eight phytopathogenic fungi. The results showed that volatile compounds from the mycelia and culture filtrates (CFs) of H. marmoreus had antifungal activity against some phytopathogenic fungi. Among them, the mycelial growth and conidial germination of Alternaria brassicicola were significantly inhibited by 60 and 100%, respectively. Moreover, the volatile compounds from CFs inhibited the lesion formation of A. brassicicola on detached cabbage leaves by 94%. The volatile compounds had higher antifungal activity against A. brassicicola than other fungi. With the removal of the volatile compounds from conidia of A. brassicicola, the conidia began to germinate, which indicates fungistatic activity of the compounds. The volatile compounds were isolated from the CFs of H. marmoreus, and the major volatile compound with antifungal activity was estimated to be 2‐methylpropanoic acid 2,2‐dimethyl‐1‐(2‐hydroxy‐1‐methylethyl)propyl ester. As the volatile compound produced by H. marmoreus is a product of an edible mushroom and has fungistatic activity against some phytopathogenic fungi, especially A. brassicicola, it may be possible to use the compounds as a novel safe agent for protecting crops in the field and during storage.     

1‐Phenyl‐3‐pentanone,a Volatile Compound from the Edible Mushroom Mycoleptodonoides aitchisonii Active Against Some Phytopathogenic Fungi

Volatiles produced by mycelia of mushrooms with aromatic odour were investigated for their antifungal activity against plant‐pathogenic fungi. The results of the screening of 23 species of basidiomycetes revealed that volatile substances from mycelia of Mycoleptodonoides aitchisonii (TUFC10099), an edible mushroom, strongly inhibited the mycelial growth, spore germination and lesion formation on host leaves of some plant‐pathogenic fungi including Alternaria alternata, A. brassicicola, A. brassicae, Colletotrichum orbiculare and Corynespora cassiicola. The volatile compounds were isolated from the culture filtrate of M. aitchisonii, and 1‐phenyl‐3‐pentanone was identified as a major antifungal volatile. The compound had significantly inhibitory activity against plant‐pathogenic fungi at 35 ppm. This is the first report that the volatile compound produced by mycelia of M. aitchisonii has antifungal activity against plant‐pathogenic fungi.     

Zoosporicidal metabolites from an endophytic fungus Cryptosporiopsis sp. of Zanthoxylum leprieurii

Two polyketides, cryptosporiopsin A (1) and hydroxypropan-2′,3′-diol orsellinate (3), and a natural cyclic pentapeptide (4), together with two known compounds were isolated from the culture of Cryptosporiopsis sp., an endophytic fungus from leaves and branches of Zanthoxylum leprieurii (Rutaceae). The structures of these metabolites were elucidated on the basis of their spectroscopic and spectrometric data. Cryptosporiopsin A and the other metabolites exhibited motility inhibitory and lytic activities against zoospores of the grapevine downy mildew pathogen Plasmopara viticola at 10–25 μg/mL. In addition, the isolated compounds displayed potent inhibitory activity against mycelial growth of two other peronosporomycete phytopathogens, Pythium ultimum, Aphanomyces cochlioides and a basidiomycetous fungus Rhizoctonia solani. Weak cytotoxic activity on brine shrimp larvae was observed.     

4′-Aza-3′,5′-dihomothymidine and Derivatives

Abstract

A series of 3′-branched 4′-azanucleoside analogues have been prepared. These compounds comprise three asymmetric atoms, two carbons and one nitrogen. They constitute nucleoside analogues imparted with a “flickering configuration”, the nitrogen inversion replacing a D-L epimerization of their natural congeners. The 1′,3′-cis and 1′,3′-trans isomers have been separated and their configuration established by ¹H NMR and the X-ray diffraction structure of one crystalline example. The configurations of the frozen invertomers were assessed by low temperature ¹H NMR experiments assisted by molecular mechanics simulations. None of these compounds exhibited any significant in vitro antiviral activity.     

Antifungal activity of some plant extracts on some pathogenic fungi

The inhibitory activity of five plant extracts viz. Artemisia absinthium L., Rumex obtusifolius L., Taraxacum officinale Weber ex Wiggers, Plantago lanceolata L. and Malva sylvestris L. were evaluated against the mycelial growth of three fungi Alternaria alternata (Fr.) Keissler, Penicillium expansum Link ex Thom. and Mucor piriformis Fisher that cause rot diseases in fruits and vegetables resulting in low yield and quality of fruits and vegetables. Results revealed that all the concentrations of plant extracts brought about significant inhibition in the mycelial growth of these pathogenic fungi. However, the highest concentration caused maximum inhibition in the mycelial growth followed by lower concentrations of plant extracts. The extract of A. absinthium leaves at highest concentration (S) proved highly effective in inhibiting the mycelial growth of all these pathogenic fungi followed by other plant extracts. These plants thus may have potential as the new natural fungicide for management of fungal rot diseases.     

Structure–activity relationship study of phenylpyrazole derivatives as a novel class of anti-HIV agents

The structure–activity relationship of phenylpyrazole derivative 1 was investigated for the development of novel anti-HIV agents. Initial efforts revealed that the diazenyl group can be replaced by an aminomethylene group. In addition, we synthesized various derivatives by the reductive amination of benzaldehydes with 5-aminopyrazoles and carried out parallel structural optimization on the benzyl group and the pyrazole ring. This optimization led to a six-fold more potent derivative 32j than the lead compound 1, and this derivative has a 3′,4′-dichloro-(1,1′-biphenyl)-3-yl group.     

Decomposition of Lipid Hydroperoxide by Choline and Ethanolamine

The leaves of thyme (Thymus vulgaris L.) were found to contain new compounds, 4′-hydroxy-5,5′-diisopropyl-2,2′-dimethyIbiphenyl-3,4-dione (1), 5,5′-diisopropyl-2,2′-dimethylbiphenyl-3,4,3′,4^/-tetraone (2), and 4,4′-dihydroxy-5,5′-disopropyl-2,2′-dimethylbiphenyl-3,6-dione (3a). These structures were determined by chemical and spectroscopic methods. The deodorant activity of compound 1 against methyl mercaptan was more effective than that of rosmanol, carnosol and sodium copper chlorophylline.     

Effect of extracts from in vitro-grown shoots of <Emphasis Type="Italic">Quillaja saponaria</Emphasis> Mol. on <Emphasis Type="Italic">Botrytis cinerea</Emphasis> Pers.

The ethanolic and aqueous extracts from in vitro shoots of Quillaja saponaria Mol. (Quillay) were studied for their antifungal activity against the phytopathogenic fungus Botrytis cinerea Pers. These extracts reduced conidial germination and mycelial growth of B. cinerea, ethanolic extracts being more active than aqueous extracts. In addition, the damage areas produced by this fungus on tomato leaves and strawberry fruits pre-treated with quillay extracts were diminished. The fungitoxic effect of in vitro-grown quillay extract was similar to those obtained with commercial fungicides of both natural (BC-1000) and synthetic (iprodione–dicarboximide) origin. On the other hand, the antifungal action of quillay extracts obtained from adult trees naturally grown was only slightly superior to the fungitoxic activity of the extract from in vitro plants. HPLC analysis of the extract showed that it contained saponins and some phenolic compounds such as chlorogenic, caffeic, vanillic, and salicylic acids, and scopoletin, which have been identified as antifungal agents on phytopathogenic fungi. The results obtained in this work, suggests that extracts of in vitro-grown quillay have an important protective effect against B. cinerea and support the use of an in vitro culture system as a biotechnological alternative to obtain environmental safe antifungal quillay extracts to control B. cinerea, contributing to the preservation of this indigenous Chilean species.     

Synthesis of Pogostone-Inspired Dehydroacetic Acid Derivatives and Their Antifungal Activity against Sclerotinia sclerotiorum (Lib.) de Bary

In an effort to exploit the natural antifungal pogostone, its simplified scaffold dehydroacetic acid (DHA) was used as a lead compound to semi-synthesize 56 DHA derivatives ( I1 – 48 , II , III , and IV1 – 6 ). Among them, compound IV4 exhibited the most potent antifungal activity with 11.0 μM EC₅₀ against mycelial growth of Sclerotinia sclerotiorum (Lib.) de Bary whose sclerotia production was also completely suppressed at this concentration. Furthermore, IV4 could completely inhibit infection cushion formation of S. sclerotiorum on rape leaves and achieved a preventive efficacy of 90.2 % at 500 μM, which was on the same level as that of commercial boscalid at 30 μM (88.7 %). The results of physiological and ultrastructural studies indicated that IV4 might disrupt the cell membrane permeability or induce the imbalance of mitochondrial membrane potential homeostasis to exert the antifungal mode of action. Besides, the robust and predicative three-dimensional quantitative structure-activity relationship (3D-QSAR) models were developed and discussed herein.     

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.     

Effects of hydroxylated polychlorinated biphenyls on mouse liver mitochondrial oxidative phosphorylation

The effects of three tetrachlorobiphenylols [2′,3′,4′,5′-tetrachloro-2-biphenylol (1); 2′,3′,4′,5′-tetrachloro-4-biphenylol (2); and 2′,3′,4′,5′-tetrachloro-3-biphenylol (3)]; three monochlorobiphenylols [5-chloro-2-biphenylol (5), 3-chloro-2-biphenylol (6); and 2-chloro-4-biphenylol (7)] and a tetrachlorobiphenyldiol [3,3′,5,5′-tetrachloro-4,4′-biphenyldiol (4) on respiration, adenosine triphosphatase (ATPase)] activity, and swelling in isolated mouse liver mitochondria have been investigated. Tetrachlorobiphenylols (1–3) and the tetrachlorobiphenyldiol (4) inhibited state-3 respiration in a concentration-dependent manner with succinate as substrate (flavin adenine dinucleotide [FAD]-linked) and the tetrachlorobiphenyldiol (4) caused a more pronounced inhibitory effect on state-3 respiration than the other congeners. The monochlorobiphenylols 5–7 were less active as inhibitors of state-3 mitochondrial respiration and significant effects were observed only at higher concentration (≥0.4 μM). However, in the presence of the nicotinamide adenine dinucleotide (NAD)-linked substrates (glutamate plus malate), hydroxylated PCBs (1–7) significantly inhibited mitochondrial state-3 respiration in a concentration-dependent manner. Compounds 5, 6, and 7 uncoupled mitochondrial oxidative phosphorylation only in the presence of FAD-linked substrate as evidenced by increased oxygen consumption during state-4 respiratory transition, stimulating ATPase activity, releasing oligomycin-inhibited respiration, and inducing mitochondrial swelling (5, 6, and 7). Tetrachlorobiphenylols 1, 2, and 3 had no effect on mitochondrial ATPase activity while the tetrachlorobiphenyldiol, 4, decreased the enzyme activity. The possible inhibitory site of electron transport by these compounds and their toxicologic significance is discussed.     

Purification and Characterization of Chlorophyllase from Alga (Phaeodactylum tricornutum) by Preparative Isoelectric Focusing

Chlorophyllase from a diatom alga (Phaeodactylum tricornutum) was obtained and the partially purified extract has been further purified using preparative isoelectric focusing on a Rotofor cell. Three fractions, FI, FII, and FIII, were separated from the Rotofor cell and salt and ampholytes were removed to give fractions FI′, FII′, and FIII′, respectively. Enzyme fractions FI′, FII′, and FIII′, respectively. Enzyme fractions FI′, FII′, and FIII′ showed specific activities of 15.2 × 10^?4, 226.7 ×10^?4 and 33.8 × 10^?4 µmol/mg protein/min, respectively. Most of the enzyme activity (84%) was in fraction FII′. The optimum pH for chlorophyllase activity was 8.0 for FI′ and 8.5 for both FII′ and FIII′. Apparent K_m values for enzyme fractions FI′, FII′, and FIII′ were 2.1nM, 2.3nM, and 2.0 nM, respectively. Enzyme fractions FII′ and FIII′ showed higher chlorophyllase activity towards the partially purified chlorophyll when it was compared to that with the crude chlorophyll as well as with both chlorophylls a and b. However, the enzyme fraction FI′ had higher activity towards the crude chlorophyll when it was compared to that with both chlorophylls a and b, but with a preference for chlorophyll a over chlorophyll b. The inhibitory effect of diisopropyl flurophosphate (DIFP) on chlorophyllase activity demonstrates a noncompetitive inhibitor kinetics with K_i values of 1.29mM, 2.14mM, and 0.71mM for FI′. FII′, and FIII′, respectively.     

Antiproliferative constituents from Aphananthe aspera leaves

Extensive screening for the antiproliferative activity of different compounds found in trees was performed by extracting the leaves of Aphananthe aspera (Thunb.) Planch and then using chromatographic separation to afford 2 new compounds, (2S,4R)-2-carboxy-4-(E)-p-caffeoyl-1-methyl-hydroxyproline (1) and 5-O-caffeoyl quinic acid-(7′R,8′S,7′′E)-3′,4′,3′′-dihydroxy-4′′,7′-epoxy-8′,5′′-neolign-7′-ene-9- carboxyl (2). In addition, 6 known compounds were discovered from the leaves of this plant. The structural determination of all compounds, including their absolute configurations, was established by UV, IR, HRESIMS, 1D and 2D NMR, and CD spectroscopy. The novel compound 1 showed strong antiproliferative activity against human breast adenocarcinoma cells MCF-7 and MDA-MB-231.