Design, synthesis and inhibitory activities of 8-(substituted styrol-formamido)phenyl-xanthine derivatives on monoamine oxidase B

The design and synthesis of two series of 8-(substituted styrol-formamido)phenyl-xanthine derivatives are described. Their in vitro monoamine oxidase B (MAO-B) inhibition were tested and the effect of substituents on the N-7, phenyl and the substituted positions are discussed. It was observed that compound 9b displayed significant MAO-B inhibition activity and selectivity, fluorine substitution plays a key role in the selectivity of MAO-B inhibition, and the styrol-formamido group at position-3' may enhance the activity and selectivity of 8-phenyl-xanthine analogues. These results suggest that such compounds may be utilized for the development of new candidate MAO-B inhibitors for treatment of Parkinson's disease.     

Piperine from the fruits of Piper longum with inhibitory effect on monoamine oxidase and antidepressant-like activity

A bioassay-guided isolation of the ethanol extract from the fruits of Piper longum yielded a known piperidine alkaloid, piperine, as a monoamine oxidase (MAO) inhibitor. Piperine showed an inhibitory effect against MAO-A (IC50 value: 20.9 microM) and MAO-B (IC50 value: 7.0 microM). Kinetic analyses by a Lineweaver-Burk plot clearly indicated that piperine competitively inhibited MAO-A and MAO-B with Ki values of 19.0+/-0.9 microM and 3.19+/-0.5 microM, respectively. The inhibition by piperine was found to be reversible by dialysis of the incubation mixture. In addition, the immobility times in the tail suspension test were significantly reduced by piperine, similar to that of the reference antidepressant fluoxetine, without accompanying changes in ambulation when assessed in an open-field. These results suggest that piperine possesses potent antidepressant-like properties that are mediated in part through the inhibition of MAO activity, and therefore represent a promising pharmacotherapeutic candidate as an antidepressant agent.     

Six new constituents from an Ascomycete,Chaetomium quadrangulatum,found in a screening study focused on monoamine oxidase inhibitory activity

A screening study focusing on monoamine oxidase inhibitory activity on the EtOAc extract of an Ascomycete Chaetomium quadrangulatum, which previously gave five unique chromones possessing this activity (chaetoquadrins A-E (1-5)), this time afforded six new constituents termed chaetoquadrins F-K (6-11) in addition to 1-5. The structures of 6-11 have been deduced on the basis of spectral and chemical data, and 7 and 8 have shown appreciable monoamine oxidase inhibitory activity.     

Scopuquinolone B,a new monoterpenoid dihydroquinolin-2(1H)-one isolated from the coral-derived Scopulariopsis sp. fungus

Further chemical investigation of the secondary metabolites of the fungus Scopulariopsis sp. led to the discovery of a new alkaloid, scopuquinolone B (1). The structure of compound 1 was elucidated by extensive NMR spectroscopic data, CD spectrum and analysis of its Dess-Martin oxidation derivative. Compound 1 was evaluated for antilarval settlement activity of barnacle Balanus amphitrite and showed promising antifouling activity with an EC₅₀ value of 0.103 μM and a high therapeutic ratio of 222.     

Effects of carbon source on expression of alcohol oxidase activity and on morphologic pattern of YR-1 strain, a filamentous fungus isolated from petroleum-contaminated soils

Soluble alcohol oxidase (AO) activity was detected in the supernatant fraction of a high-speed centrifugation procedure after ballistic cellular homogenization to break the mycelium from a filamentous fungus strain named YR-1, isolated from petroleum-contaminated soils. AO activity from aerobically grown mycelium was detected in growth media containing different carbon sources, including alcohols and hydrocarbons but not in glucose. In previous work, zymogram analysis conducted with crude extracts from aerobic mycelium of YR-1 strain indicated the existence of two AO enzymes originally named AO-1 and AO-2. In the present study, we were able to separate the AO-1 band into two bands depending on culture conditions, carbon source, and polyacrylamide gel electrophoresis (PAGE) separation conditions; the enzyme activity pattern in zymograms from cell-free extracts exhibited three different bands after native PAGE. New nomenclature was used for upper bands AO-1 and AO-2 and lower band AO-3, respectively. The expression of AO activity was studied in the absence of glucose in the culture media and in the presence of hydrocarbons or petroleum as sole carbon source, suggesting that AO expression could be subjected to two regulatory possibilities: carbon catabolite regulation by glucose and induction by hydrocarbons. The possibility of catabolic inhibition of AO by glucose in the active enzyme was also tested, and the results confirm that this kind of regulatory mechanism is not present in AO activity.     

Retention of some monoamine oxidase inhibitory drugs on a β-cyclodextrin polymer-coated silica column

The retention of seventeen monoamine oxidase inhibitory drugs (mono- and disubstituted derivatives of propargylamine) was determined on a β- cyclodextrin polymer (β-CDP)-coated silica column using methanol-0.05 M K₂HPO₄ (6:4, v/v) as the eluent. The inclusion complex formation between the drugs and a water-soluble β-cyclodextrin polymer was studied by charge-transfer chromatography carried out on reversed- phase TLC layers. The capacity factors were correlated with the various physico-chemical parameters and with the inclusion complex-forming capacity of the monoamine oxidase inhibitory drugs. Calculations indicated that the inclusion complex-forming capacity of the drugs does not influence their retention on a β-CDP column, that is, the water-soluble and water-insoluble β-CDPs show different retention characteristics. The specific hydrophilic adsorption surface of the solutes significantly influences the retention in HPLC. The results suggest that the selectivity of the β-CDP-coated silica support may be different from that of the traditional alkyl-bonded reversed-phase columns.     

Design,synthesis and MAO inhibitory activity of 2-(arylmethylidene)-2,3-dihydro-1-benzofuran-3-one derivatives

A series of 2-(arylmethylidene)-2,3-dihydro-1-benzofuran-3-one derivatives(aurones, 1–20) were synthesized and screened for their inhibitory activity against h MAO. Seventeen compounds(1–5, 7–17,19) were found to be selective towards h MAO-B, while two were non-selective(6 and 20) and one(18)selective towards h MAO-A. Compound 17(Ki = 0.10 0.01 mmol/L) was found to be equally potent and selective towards h MAO-B, when compared with the standard drug Selegiline(Ki = 0.12 0.01 mmol/L).Nature and position of substitution in aryl ring at 2nd position of benzofuranone influences h MAO-B inhibitory potency, while their structural bulkiness influences selectivity between h MAO-A and h MAO-B.Molecular docking simulation was also carried out to understand the interaction of inhibitor with the enzyme at molecular level, and we found the docking results were in good agreement with the experimental values. Comparison of the activity profile of the aurones with their corresponding flavones reported earlier by our group revealed that there exists no difference in potency as well as selectivity.     

Lactose hydrolysis and formation of galactooligosaccharides by a novel immobilized β-galactosidase from the thermophilic fungus Talaromyces thermophilus

β-Galactosidase from the fungus Talaromyces thermophilus CBS 236.58 was immobilized by covalent attachment onto the insoluble carrier Eupergit C with a high binding efficiency of 95%. Immobilization increased both activity and stability at higher pH values and temperature when compared with the free enzyme. Especially the effect of immobilization on thermostability is notable. This is expressed by the half-lifetime of the activity at 50°C, which was determined to be 8 and 27 h for the free and immobilized enzymes, respectively. Although immobilization did not significantly change kinetic parameters for the substrate lactose, a considerable decrease in the maximum reaction velocity V _max was observed for the artificial substrate o-nitrophenyl-β-d-galactopyranoside (oNPG). The hydrolysis of both oNPG and lactose is competitively inhibited by the end products glucose and galactose. However, this inhibition is only very moderate as judged from kinetic analysis with glucose exerting a more pronounced inhibitory effect. It was evident from bioconversion experiments with 20% lactose as substrate, that the immobilized enzyme showed a strong transgalactosylation reaction, resulting in the formation of galactooligosaccharides (GalOS). The maximum yield of GalOS of 34% was obtained when the degree of lactose conversion was roughly 80%. Hence, this immobilized enzyme can be useful both for the cleavage of lactose at elevated temperatures, and the formation of GalOS, prebiotic sugars that have a number of interesting properties for food applications.     

Neosappanone A, a xanthine oxidase (XO) inhibitory dimeric methanodibenzoxocinone with a new carbon skeleton from Caesalpinia sappan

A novel dimeric methanodibenzoxocinone, named neosappanone A (1), possessing a unique unprecedented novel carbon framework, has been isolated from the heartwood of Caesalpinia sappan L. of Vietnam, and its structure was elucidated on the basis of spectroscopic analysis. Neosappanone A (1) competitively inhibited xanthine oxidase in a concentration-dependent manner (IC₅₀, 29.7 μM; K_i, 16.3 μM).     

Structure and synthesis of nectrisine, a new immunomodulator isolated from a fungus.

The structure of a novel immunomodulator, nectrisine (1), has been elucidated on the basis of chemical and spectroscopic evidence. Its absolute stereochemistry was predicted on the basis of the dibenzoate chirality rule and finally confirmed by a synthesis from D-glucose.     

1-methyl-2-undecyl-4(1H)-quinolone as an irreversible and selective inhibitor of type B monoamine oxidase

The inhibitory compound of monoamine oxidase (MAO) activity was isolated from the CH(2)Cl(2) fraction of the fructus of Evodia rutaecarpa and identified as 1-methyl-2-undecyl-4(1H)-quinolone (1). Compound 1 showed a selective inhibition of type B MAO (MAO-B) activity with the IC(50) value of 15.3 microM using a substrate kynuramine, but did not inhibit type A MAO (MAO-A) activity. The kinetic analysis using Lineweaver-Burk plots indicated that compound 1 competitively inhibited MAO-B activity with the K(i) value of 9.91 microM. The inhibition of MAO-B by compound 1 was found to be irreversible by dialysis of the incubation mixture. These results suggest that compound 1 is a potent irreversible inhibitor of MAO-B, and may regulate catecholamine content in the neurons.     

Synthesis and plant growth inhibitory activity of both enantiomers of pyricuol, a phytotoxin isolated from rice blast disease fungus Magnaporthe grisea

Both enantiomers and racemate of pyricuol, a phytotoxin isolated from the rice blast disease fungus, Magnaporthe grisea, have been synthesized by using Stille coupling and [2,3]-Wittig rearrangement reactions as the key steps. Both enantiomers induced dark necrotic lesions on rice leaves almost equally, but did not affect the growth of rice second leaf sheath and the germination of lettuce. Only natural enantiomer promoted the root growth of rice and lettuce.     

Phenolic constituents of licorice. III. Structures of glicoricone and licofuranone, and inhibitory effects of licorice constituents on monoamine oxidase

Two new phenolic compounds, glicoricone (3) and licofuranone (4), were isolated from a species of licorice brought from the northwestern region of China, and their structures were assigned. Among the twelve licorice constituents examined for the inhibition of monoamine oxidase (MAO), six compounds, 3, 4, genistein (6), licopyranocoumarin (7), licocoumarone (14) and glycyrrhisoflavone (15), inhibited the enzyme with the IC50 (concentration required for 50% inhibition of the enzyme activity) values of 6.0 x 10(-5)-1.4 x 10(-4) M. Glycyrrhizin (1) also inhibited MAO with the IC50 value of 1.6 x 10(-4) M.     

The total synthesis of (−)-connatusin A, a hirsutane-type sesquiterpene isolated from the fungus Lentinus connatus BCC8996

The title sesquiterpenoid natural product 1 has been prepared for the first time using the enantiomerically pure cis-1,2-dihydrocatechol 3 as starting material. Key steps associated with the synthesis include a Diels-Alder cycloaddition reaction of the acetonide 5 with cyclopentenone (4) and an oxa-di-π-methane rearrangement of bicylco[2.2.2]octenone 6 derived from the initial adduct. The product of this sequence, the cyclopropannulated triquinane 7, was elaborated, over a further eight steps including those involving Upjohn dihydroxylation and Swern oxidation protocols, to the target 1. A single-crystal X-ray analysis served to confirm the structure of this synthetically derived material.     

Transformation of arsenic(V) by the fungus Fusarium oxysporum melonis isolated from the alga Fucus gardneri

A fungus isolated from the macroalga Fucus gardneri was identified by using 28S rDNA sequence analysis, 99% similarity match, as Fusarium oxysporum meloni. The fungus was exposed to arsenic(V) (500 ppb) in artificial seawater to investigate the possibility that the fungus is the source of the metabolic activity that results in the presence of arsenosugars in the macroalga. High‐performance liquid chromatography coupled with inductively coupled plasma mass spectrometry was used to identify the arsenic species in the fungus, and in the growth medium. The fungus was able to accumulate arsenic(V) and an increase in arsenite and dimethylarsinate was also observed. Some reduction of arsenate led to a small increase of arsenite in the growth medium. The fungus does not seem to be involved with the accumulation of arsenosugars by the Fucus. Copyright © 2002 John Wiley & Sons, Ltd.     

New diterpene pyrone-type compounds, metarhizins A and B, isolated from entomopathogenic fungus, Metarhizium flavoviride and their inhibitory effects on cellular proliferation

To date, entomopathogenic fungi have not been extensively examined by natural product chemists. In this study, we isolated novel pyrone diterpene-type compounds, metarhizins A (1) and B (2), from methanol extracts of entomopathogenic fungus, Metarhizium flavoviride. They showed potent and selective antiproliferative activity against both insect and human cancer cell lines. These results indicate that metarhizins A (1) and B (2) can be used as novel lead compounds for anti-cancer agents and probes for cell cycle regulation. To further investigate the structural requirements for this inhibitory activity, we synthesized many metarhizin derivatives and evaluated their antiproliferative activities.     

Bioactive xanthoquinodins and epipolythiodioxopiperazines from Chaetomium globosum 7s-1, an endophytic fungus isolated from Rhapis cochinchinensis (Lour.) Mart

Abstract

A new xanthoquinodin B9 (1), together with two known xanthoquinodins, xanthoquinodin A1 (2) and xanthoquinodin A3 (3), three epipolythiodioxopiperazines, chetomin (4), chaetocochin C (5) and dethio-tetra(methylthio)chetomin (6), and four other compounds, chrysophanol (7), emodin (8), alatinone (9), and ergosterol (10) were isolated from the endophytic fungus Chaetomium globosum 7s-1, isolated from Rhapis cochinchinensis (Lour.) Mart. All isolated structures were established based on their spectroscopic data analyses. Compounds 1–6 showed antibacterial activity against Gram positive bacteria with MICs ranging from 0.02?pM to 10.81 µM. Compounds 1–6 also exhibited cytotoxicity against KB, MCF-7 and NCI-H187 cancer cell lines (IC₅₀ 0.04–18.40 µM). However, they were cytotoxic towards a normal cell line (Vero cell) with IC₅₀ values ranging from 0.04 to 3.86 µM.     

Synthesis to determine the absolute configuration of (−)-pyricuol, a phytotoxin isolated from rice blast disease fungus Magnaporthe grisea

The absolute configuration of (−)-pyricuol, a phytotoxin isolated from rice blast disease fungus Magnaporthe grisea, was determined to be R by synthetic studies.