Ionylideneacetic Acids and Abscisic Acid Biosynthesis by Cercospora rosicola

Several compounds having the basic α-ionylideneacetic acid structure were tested in Cercospora rosicola resuspensions. At 100 μm, all the compounds inhibited abscisic acid (ABA) biosynthesis. Time studies with unlabelled and deuterated (2Z,4E)- and (2E,4E)-α-ionylideneacetic acids showed rapid conversions into both (2Z,4E)- and (2E,4E)-4′-keto-α-ionylideneacetic acids as major products. Incorporation of the label into ABA was specific for the 2Z,4E-isomer. Minor products, identified by GC-MS, were (2Z,4E)- and (2E,4E)-4′-hydroxy-α-ionylideneacetic acids and (2Z,4E)-1′-hydroxy-α-ionylideneacetic acid. The conversion to (2Z,4E)-l′-hydroxy-α-ionylideneacetic acid has not been previously reported and was specific for the 2Z,4E-isomer. A time study for the conversion of methyl esters of [²H₃]-(2Z,4E)- and [²H₃]-(2E,4E)-4′-keto-α-ionylideneacetates showed a slow introduction of the l′-hydroxyl group and specificity for 2Z,4E-isomer. Conversion of the ethyl esters of (2Z,4E)- and (2E,4E)-l′-hydroxy-α-ionylideneacetates into the ethyl esters of both ABA and (2E,4E)-ABA demonstrated that ABA can be formed by oxidation of the 4′-position after the insertion of the 1′-hydroxy group. The ethyl 1′-hydroxy acids were also isomerized to the corresponding ethyl (2Z,4E)- and ethyl (2E,4E)-3′-hydroxy-β-ionylideneacetates. Ethyl (2Z,4E)-1′-hydroxy acid also gave small amounts of ethyl l′,4′-trans-diol of ABA. These results suggest that ABA may be formed through a (2Z,4E)-1′-hydroxy-α-ionylidene-type intermediate in addition to the previously proposed route through (2Z,4E)-4′-keto-α-ionylideneacetic acid.     

Isolation of 2-Isopropyl-4,4-dimethyl-5-vinylidene-2-cyclopenten-1-one and 2-Isopropyl-3-isopentyl-maleic Anhydride from the Pyrolytic Products of 2-Isopropylmalic acid

(R)-[2-¹⁴C]-Mevalonic acid (MVA) lactone was incorporated into (-)-4′-hydroxy-y-ionylideneacetic acid (4?-hydroxy-y-acid), which was first isolated from the culture broth of Cercospora cruenta. 4?-Hydroxy-γ-acid was then metabolized to (+)-(2Z,4E)-4′-oxo-α-ionylideneacetic acid and (+)-(2Z,4E)-′14′-dihydroxy-γ-ionylideneacetic acid. The latter was converted to (+)-abscisic acid (ABA) with a high incorporation ratio by the fungus.     

Metabolism of (2Z,4E)-γ-Ionylideneethanol and (2Z,4E)-γ-Ionylideneacetic Acid in Cercospora cruenta

[2–¹⁴C]-(2Z,4E)-γ-Ionylideneethanol and [2–¹⁴C]-(2Z,4E)-γ-ionylideneacetic acid were converted by Cercospora cruenta to [2–¹⁴C]-(2Z,4E)-1′,4′-dihydroxy-γ-ionylideneacetic acid and [2-¹⁴C]-(2Z,4E)-4′-hydroxy-γ-ionylideneacetic acid, which are intermediates of ABA biosynthesis in C. cruenta.     

Conversion of (2Z,4E)-5-(1′,2′-epoxy-2′,6′,6′-trimethylcyclohexyl)-3-methyl-2,4-pentadienoic acid to xanthoxin acid by Cercospora cruenta, a fungus producing (+)-abscisic acid

(±)-(2Z,4E)-5-(1′,2′-epoxy-2′,6′,6′-trimethylcyclohexyl)-3-methyl-2,4-pentadienoic acid was metabolized by Cercospora cruenta, which has the ability to produce (+)-abscisic acid (ABA), to give (±)-(2Z,4E)-xanthoxin acid, (±)-(2Z,4E)-5′-hydroxy-1′,2′-epoxy-1′,2′-dihydro-β-ionylideneacetic acid, (±)-1′,2′-epoxy-1′,2′-dihydro-β-ionone and trace amounts of ABA.     

Synthesis and Biological Activity of Methyl 3-Demethyl-Abscisate and Its Related Analogs

To elucidate the role of the methyl substituent on the side chain of abscisic acid (ABA), we synthesized (2Z,4E)-3-demethyl-α-ionylideneacetic acid (4) and its related analogs, methyl (2Z)-3-demethyl-β-ionylideneacetate 1′,2′-epoxide (9) and methyl (2Z) and (2E)-3-demethyl-abscisate (12) and (13). The biological assay of these compounds suggested that the 3-methyl group on the side chain of ABA was indispensable to biological activity.     

Potential Pathogenicity of Candida maltosa IAM 12248

The stereochemistry of (+)-(2Z,4E)-trans-1′,4′-dihydroxy-γ-ionylideneacetic acid, a major metabolite from Cercospora cruenta, a fungus found to produce (+)-abscisic acid, was reexamined as to its ¹H?¹H-Cosy and Noesy 2D-NMR spectra, and it was proved to have a chair conformation with an axial pentadienoate moiety. Further, the metabolism of (+)-[14C]-1′,4′-dihydroxy-γ-ionylideneacetic acid in tomato plants suggested the possibility of it being a biosynthetic intermediate of ABA in plants.     

Residue of Kitazin P Metabolite in Rice Plants and Soil

Debutenoyl-aspertetronin A was synthesized from γ-valerolactone-γ-carboxylic acid (4) via 2, 5-dihydro-3-hydroxy-2-methyl-5-oxo-2-furanpropanoic acid. Starting from (?)-(S)-4, (+)-(S)-5-hexyl-4-hydroxy-5-methyl-2(5H)furanone (19) was synthesized, and by comparison of its optical rotation with that of an authentic sample it was proved that aspertetronin A had (R) configuration, and gregatin A had (S) configuration at their respective chiral carbon.     

Synthesis and plant growth inhibitory activities of (+)- and (−)-(2Z,4E)-5-(1′,2′-epoxy-2′,6′,6′-trimethylcyclohexyl)-3-methyl-2,4-pentadienoic acid

Chiral (+)- and (?)-enantiomers of (2Z,4E)-5-(1′,2′-epoxy-2′,6′,6′-trimethylcyclohexyl)-3-methyl-2,4-pentadienoic acid have been synthesized from the chiral epoxy alcohols (+)- and (?)-1′,2′-dihydro-1′,2′-epoxy-β-ionone, which were prepared by Katsuki-Sharpless' asymmetric epoxidation of β-cyclogeraniol. The (+)-enantiomer showed strong inhibitory activity in a rice seedling and lettuce germination assay, whereas the (?)-enantiomer was 10³-times less active.     

Three Antinematodal Diterpenes from Euphorbia kansui

Three compounds, 20-O-acetyl-[3-O-(2′E,4′Z)-decadienoyl]-ingenol (1), 20-O-acetyl-[5-O-(2′E,4′Z)-decadienoyl]-ingenol (2) and 3-O-(2′E,4′Z)-decadienoylingenol (3), were isolated from Euphorbia kansui under the bioassay-guided method. Each compound showed the same antinematodal activity against the nematode, Bursaphelenchus xylophilus, at a minimum effective dose (MED) of 5 μg/cotton ball.     

Synthesis and Antimicrobial Activity of Chiral cis-Cycloheximide Isomers

Such (+)- and (?)-cis-cycloheximide isomers as isocyclohcximide (1a, 1b), α-epiisocycloheximide (2a, 2b) and neocycloheximide (3a, 3b) were synthesized by aldol condensation of (?)-(2R, 4R)- and (+)-(2S, 4S)-cis-2,4-dimethyl-1-cyclohexanone (5a, 5b). obtained by microbial resolution, with 4-(2-oxoethyl)-2,6-piperidinedione (7). The absolute configuration of the (?)-cis-ketone 5a was confirmed by chemical correlation with natural (2S, 4S, 6S, αR)-cycloheximide (4). The newly synthesized isomer, (?)-α-epiisocycloheximide (2b), showed strong antimicrobial activity against S. cerevisiae andP. oryzae close to that of natural cycloheximide (4).     

Farnesyl and α-Ionylideneethyl Tertiary and Quaternary Amines: Their Influence on Abscisic Acid Biosynthesis by Cercospora rosicola

Farnesyl and α-ionylideneethyl compounds with tertiary and quaternary amine functional groups were synthesized and their effects on abscisic acid (ABA) biosynthesis of Cercospora rosicola observed. The trimethylammonium compounds were lethal at 10 μm and inhibitory at 10 μm, but lesser amounts of α-ionylideneethyltrimethylammonium iodide enhanced ABA biosynthesis. N,N-Dimethylfarnesylamine had little effect on ABA biosynthesis. N,N-Dimethyl (2Z,4E)- and (2E,4E)-α-ionylideneethylamines inhibited ABA biosynthesis at 100 μm but had no or little effect at lower concentrations. Farnesol and farnesylpyrophosphate (FPP) enhanced ABA biosynthesis. FPP appears to be both a precursor and an inducer and farnesol is an inducer of ABA biosynthesis. N,N-Dimethyl (2Z,4E)- and (2E,4E)-α-ionylideneethylamines were converted to N,N-dimethyl (2Z,4E)- and (2E,4E)-4′-keto-α-ionylideneethylamines, respectively. These conversions are analogous to those reported for α-ionone and α-ionylideneacetic acids and show that basic as well as acidic and neutral compounds with α-ionone type rings can undergo oxidation at the 4′-position. α-Ionylideneacetic acids inhibited growth of C. rosicola and the dimethylamines enhanced growth. Complete feedback inhibition was obtained with 400 μm of ABA.     

(10E,12Z,15Z)-9-Hydroxy-10,12,15-octadecatrienoic Acid Methyl Ester as an Anti-inflammatory Compound from Ehretia dicksonii

The methanol extract of Ehretia dicksonii provided (10E,12Z,15Z)-9-hydroxy-10,12,15-octadecatrienoic acid methyl ester (1) which was isolated as an anti-inflammatory compound. Compound 1 suppressed 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-induced inflammation on mouse ears at a dose of 500 μg (the inhibitory effect (IE) was 43%). Linolenic acid methyl ester did not inhibit this inflammation at the same dose. However, the related compounds of 1, (9Z,11E)-13-hydroxy-9,11-octadecadienoic acid (5) and (9Z,11E)- 13-oxo-9,11-octadecadienoic acid (6), showed potent activity (IE_{500 μg} of 63% and 79%, respectively). Compounds 1, 4 ((9Z,12Z,14E)-16-hydroxy-9,12,14-octadecatrienoic acid), 5 and 6 also showed inhibitory activity toward soybean lipoxygenase at a concentration of 10 μg/ml.     

Constituents of Limonia acidissima inhibit LPS-induced nitric oxide production in BV-2 microglia

The ethyl acetate (EtOAc) soluble fraction of the 85% ethanol (EtOH) extract of the dried bark of Limonia acidissima potently inhibited nitric oxide (NO) production in lipopolysaccharide (LPS) activated BV-2 cells, a microglial cell line. Bioassay-guided column chromatography separation afforded a new stereoisomer of neolignan, (7’E)-(7R,8S)-4-hydroxy-3,5’-dimethoxy-4’,7-epoxy-8,3’-neolig-7’-en-9,9’-diyil diacetate (1), together with two known lignans, (+)-yangambin (2) and (+)-syringaresinol (3), three known triterpenoids, hederatriol (4), basic acid methyl ester (5), and 3β-hydroxyolean-12-en-11-one (6), and four known fatty acid derivatives, cascarillic acid (7), (+)-α-dimorphecolic acid (8), 8(R)-hydroxylinoleic acid (9), and (6Z,9Z,12Z)-pentadecatrienoic acid (10). The structure of the new compound 1 was elucidated by detailed analysis of spectroscopic data and circular dichroism (CD) spectroscopy. Compounds 1, 3-6, and 8-10 isolated from L. acidissima significantly reduced NO production in LPS-stimulated BV-2 microglia cells.     

Two new anti-plasmodial flavonoid glycosides from Duranta repens

The CHCl₃-soluble fraction of the whole plant of Duranta repens showed anti-plasmodial activity against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum, with IC₅₀ values of 8.5?±?0.9 and 10.2?±?1.5?μg/mL, respectively. From this fraction, two new flavonoid glycosides, 7-O-α-d-glucopyranosyl-3,4′-dihydroxy-3′-(4-hydroxy-3-methylbutyl)-5,6-dimethoxyflavone (1) and 7-O-α-d-glucopyranosyl(6′′′-p-hydroxcinnamoyl)-3,4′-dihydroxy-3′-(4-hydroxy-3-methylbutyl)-5,6-dimethoxyflavone (2), along with five known flavonoids, 3,7,4′-trihydroxy-3′-(4-hydroxy-3-methylbutyl)-5,6-dimethoxyflavone (3), 3,7-dihydroxy-3′-(4-hydroxy-3-methylbutyl)-5,6,4′-trimethoxyflavone (4), 5,7-dihydroxy-3′-(2-hydroxy-3-methyl-3-butenyl)-3,6,4′-trimethoxyflavone (5), 3,7-dihydroxy-3′-(2-hydroxy-3-methyl-3-buten-yl)-5,6,4′-trimethoxyflavone (6), and 7-O-α-d-glucopyranosyl-3,5-dihydroxy-3′-(4′′-acetoxy-3′′-methylbutyl)-6,4′-dimethoxyflavone (7), have been isolated as anti-plasmodial principles. Their structures were deduced by spectroscopic analysis including 1D and 2D NMR techniques. The compounds (1–7) showed potent anti-plasmodial activities against D6 and W2 strains of Plasmodium falciparum, with IC₅₀ values in the range of 5.2–13.5?μM and 5.9–13.1?μM, respectively.     

Highly selective biotransformation of (+)-(1S)- and (−)-(1R)-camphorquinone by Aspergillus wentii

Abstract

To clarify the structures of biotransformation products and metabolic pathways, the biotransformation of monoterpenoids, (+)- and (?)-camphorquinone (1a and b), has been investigated using Aspergillus wentii as a biocatalyst. Compound 1a was converted to (?)-(2S)-exo-hydroxycamphor (2a), (?)-(2S)-endo-hydroxycamphor (3a), (?)-(3S)-exo-hydroxycamphor (4a), (?)-(3S)-endo-hydroxycamphor (5a), and (+)-camphoric acid (6a). Compound 1b was converted to (+)-(2R)-exo-hydroxycamphor (2b), (+)-(2R)-endo-hydroxycamphor (3b), (+)-(3R)-exo-hydroxycamphor (4b), (+)-(3R)-endo-hydroxycamphor (5b), and (?)-camphoric acid (6b). Compound 1a mainly produced 2a (65.0%) with stereoselectivity, whereas 1b afforded 3b (84.3%) with high stereoselectivity. These structures were confirmed by gas chromatography–mass spectrometry, infrared, ¹H nuclear magnetic resonance (NMR), and ¹³C NMR spectral data. The products illustrate the marked ability of A. wentii for enzymatic oxidation and ketone reduction.     

Ionones and βIonylideneacetic Acids: Their Influence on Abscisic Acid Biosynthesis by Cercospora rosicola

Several ionones and β-ionylideneacetic acids inhibited absicisic acid (ABA) biosynthesis in Cercospora rosicola at 100 μm. At lower concentrations, α-ionone, 1′,2′-dihydroxy-l′,2′-dihydro-β-ionone and 4′-keto-α-ionone enhanced ABA biosynthesis. Conversions of ionones by C. rosicola were identified by GC-MS as: α-ionone to 4′-keto-α-ionone, 4′-keto-α-ionol and dehydrovomifoliol; and 1′-hydroxy-α-ionone to dehydrovomifoliol. The oxidations of α-ionone and its analogs parallel those of the α-ionylideneacetic acids. The β-ionylideneacetic acids were generally oxidized to more polar forms. Metabolites identified by GC-MS were 3′-hydroxy-, 3′-keto- and 1′,2′-epoxy-1′,2′-dihydro-β-ionylideneacetic acids. The fungus rapidly metabolized most exogenous materials to more polar forms.     

Purification and Properties of β-Galactosidases from Bacillus circulans

Six compounds, Z- and E-fadyenolide (3, 4), 1-ally1-2,3-(methylenedioxy)-4,5-dimethoxy-benzene (5), 4-methoxy-3,5-bis (3′-methyl-2′-butenyl)-benzoic acid (6), 2,6-dihydroxy-4-methoxy-dihydrochalcone (7), and 5-hydroxy-7-methoxyflavanone (8) were isolated from three species of Jamaican Piper, Piper fadyenii, C.D.C., Piper aduncum L. and Piper hispidum Sw. Three amides (9 ~ 11) of 3,5-dimethoxy-4-oxo-5-phenylpent-2-enoic acid using piperidine, pyrrolidine and morpholine, respectively, were synthesized from compounds 3 and 4, and tested for insecticidal activity against the tick Boophilus microplus (Canestrini) and the flour feetle, Tribolium confusum Duval. In our experiment, compounds 9 ~ 11 inhibited ovogenesis of B. microplus and were toxic to T. confusum. Compounds 3 ~ 8 were found to have no activity.     

The Synthesis of Carbocyclic 5′-Nor Thymidine and an Isomer as Oligonucleotide Monomers

Abstract

The chiral synthesis of (1S,3S,4S)-1-(3,4-dihydroxycyclopent-1-yl)-1H?thymine (carbocyclic 5′-nor thymidine, 4) has been achieved in 5 steps from (+)-(lR,4S)-4-hydroxy-2-cyclopenten-1-yl acetate (5) and N³?benzoylthymine. Compound 4 is viewed as a monomeric building block for poly-T-like oligomers.     

Preparation of Optically Pure cis-2,4-Dimethyl-l-cyclohexanones,the Key Intermediates in Cycloheximide Synthesis,Using Microbial Resolution

Asymmetric hydrolysis of acetate (10) of (±)-t-2,t-4-dimethyl-r-l-cyclohexanol with Bacillus subtilis var. niger gave (?)-(lS,2S,4S)-2,4-dimethyl-l-cyclohexanol (6a) and (+)-(1R,2R,4R)-acetate (10b) with high optical purities. Optically pure (?) and (+)-alcohols (6a and 6b) were prepared via corresponding 3,5-dinitrobenzoates. Oxidation of alcohols (6a and 6b) with chromic acid gave optically pure (?)-(2S,4S) and (+)-(2R,4R)-2,4-dimethyl-l-cyclohexanones (2a and 2b), respectively.     

Ferulic acid dehydrodimers from wheat bran: isolation,purification and antioxidant properties of 8-0-4-diferulic acid

Summary

Wheat bran contains several ester-linked dehydrodimers of ferulic acid, which were detected and quantified after sequential alkaline hydrolysis. The major dimers released were: trans-5-[(E)-2-carboxyvinyl]-2-(4-hydroxy-3-methoxy-phenyl)-7-methoxy-2,3-dihydrobenzofuran-3-carboxylic acid (5–8-BendiFA), (Z)-β-(4-[(E)-2-carboxyvinyl]-2-methoxy-phenoxy)-4-hydroxy-3-methoxycinnamic acid (8-O-4-diFA) and (E,E)-4,4′-dihydroxy-5,5′-dimethoxy-3,3′-bicinnamic acid (5–5-diFA). trans-7-hydroxy-1-(4-hydroxy-3methoxyphenyl)-6-methoxy-1,2-dihydro-naphthalene-2,3-dicarboxylic acid (8–8-diFA cyclic form) and 4,4′-dihydroxy-3,3′-dimethoxy-β,β'-bicinnamic acid (8–8-diFA non cyclic form) were not detected. One of the most abundant dimers, 8-O-4-diFA, was purified from de-starched wheat bran after alkaline hydrolysis and preparative HPLC. The resultant product was identical to the chemically synthesised 8-O-4-dimer by TLC and HPLC as confirmed by ¹H-NMR and mass spectrometry. The absorption maxima and absorption coefficients for the synthetic compound in ethanol were: λ_max: 323 nm, λ_min: 258 nm, ε_λmax (M^?1cm^?1): 24800 ± 2100 and ε₂₈₀ (M^?1cm^?1): 19700 ± 1100. The antioxidant properties of 8-O-4-diFA were assessed using: (a) inhibition of ascorbate/iron-induced peroxidation of phosphatidylcholine liposomes and; (b) scavenging of the radical cation of 2,2′-azinobis (3-ethyl-benzothiazoline-6-sulphonate) (ABTS) relative to the water-soluble vitamin E analogue, Trolox C. The 8-O-4-diFA was a better antioxidant than ferulic acid in both lipid and aqueous phases. This is the first report of the antioxidant activity of a natural diferulate obtained from a plant.