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.     

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.     

Enantiotopically Selective Oxidation of 1,5-Diols with Gluconobacters Preparation of (S)-Mevalonolactone

(±)-(2Z,4E)-α-Ionylideneacetic acid (2) was enantioselectively oxidized to (?)-(l′S)-(2Z,4E)-4′-hydroxy-α-ionylideneacetic acid (3), (+)-(1′R)-(2Z,4E)-4′-oxo-α-ionylideneacetic acid (4) and (+)-abscisic acid (ABA) (1) by Cercospora cruenta IFO 6164, which can produce (+)-ABA and (+)-4′-oxo-α-acid 4. This metabolism was confirmed by the incorporation of radioactivity from (±)-(2-¹⁴C)-(2Z,4E)-α-acid 2 into three metabolites. (?)-4′-Hydroxy-α-acid 3 was a diastereoisomeric mixture consisting of major 1′,4′-trance-4′-hydroxy-α-acid 3a and minor 1′,4′-cis-4′-hydroxy-α-acid 3b. These structures, 3a and 3b, were confirmed by ¹³C-NMR and ¹H-NMR analysis. Also, the enantioselectivity of the microbial oxidation was reexamined by using optically pure α-acid (+)-2 and (?)-2, as the substrates.     

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.     

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.     

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.     

Neolignans from stem bark of ocotea veraguensis

The stem bark of Ocotea veraguensis has yielded nine neolignans of which five appear to be novel. The new neolignans, which were identified on the basis of spectral characteristics, are^* (7S,8R,1′S,2′S,3′R,4′S)-Δ^8′-2′,4′-dihydroxy-3,3′5′-trimethoxy-4,5-methylenedioxy-1′,2′,3′,4′-tetrahydro-7.3′,8.1′-neolignan, (7S,8R,1′S,3′S,4′S)-Δ^8′-4,4'-dihydroxy-3,3′,5′-trimethoxy-1′,2′,3′,4′-tetrahydro-2′-oxo-7.3′,8.1′-neolignan, (7S,8S,1′R)-Δ^8′-3′,5′-dimethoxy-3,4-methylenedioxy-1′,4′-dihydro-4′-oxo-7.0.2′,8.1′-neolignan, (7S,8S,1′R )-Δ^8′-1′-methoxy-3,4-methylenedioxy-1′,6′-dihydro-6′-oxo-7.0.4′,8.3′-neolignan and (7S,8S)-Δ^8′-2′,6′-dimethoxy-3,4-methylenedioxy-7.0.3′,8.4′,1′.0.7′-neolignan.     

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.     

Relationship between Stereoisomerism and Biological Activity of Pyrethroids

(+)-trans-Homochrysanthemic acid, when boiled in dilute sulfuric acid, gives (+)-trans-ε-hydroxy-dihydrohomochrysanthemic acid, m.p. 176–7°, together with (+)-δ, δ-dimethyl-γ-isobutenyl-δ-valerolactone. The formation of optically active lactone from (+)-trans-homochrysanthemic acid provides another cogent evidence for the structure of the lactone previously deduced on the racemic compound.

The Arndt-Eistert reaction of the homo-acids give further higher homologues such as (±)-,(+)-trans-β-(3-isobutenyl-2, 2-dimethylcyclopropane-1)-propionic acids and (±)-cis-3-isobutenyl-2, 2 dimethylcyclobutane-1-acetic acid. Both trans-acids, in boiling dilute sulfuric acid, give the same (±)-γ-(1′, 1′, 4′-trimethyl-pent-2′-enyl)-butyrolactone together with the corresponding hydroxy-acids, optically inactive and active, respectively.

Complete resolution of (±)-trans-homochrysanthemic acid and (±)-trans-β-(3-isobutenyl-2, 2-dimethycyclopropane-1)-propionic acid was achieved by means of optically active α-phenylethylamine.     

Prenylated flavonoids from seeds of Calopogonium mucunoides

The seeds of Calopogonium mucunoides furnished 7-O-γ,γ-dimethylallyl-8-methoxy-3′,4′-dioxymethylene-isoflavone, 7-O-γ,γ-dimethylallyl-3′-hydroxy-4′-methoxyisoflavone, 7-O-γ,γ-dimethylallyl-3′,4′-dimethoxyisoflavone and 2S-di[6′',6′'-dimethylpyrano (2′',3′':7,8;2′',3′':4′,3′)]-flavanone whose structures were established by spectroscopic means involving the use of 400 MHz ¹H NMR with double irradiation and INDOR techniques.     

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.     

Characterization of (2S,2'R,3'R)-2-(2',3'-[3H]-Dicarboxycyclopropyl)glycine Binding in Rat Brain

Abstract: [(2S,2′R,3′R)-2-(2′,3′-[³H]Dicarboxycyclopropyl)glycine ([³H]DCG IV) binding was characterized in vitro in rat brain cortex homogenates and rat brain sections. In cortex homogenates, the binding was saturable and the saturation isotherm indicated the presence of a single binding site with a K_D value of 180 ± 33 nM and a B_max of 780 ± 70 fmol/mg of protein. The nonspecific binding, measured using 100 µM LY354740, was <30%. NMDA, AMPA, kainate, l (?)-threo-3-hydroxyaspartic acid, and (S)-3,5-dihydroxyphenylglycine were all inactive in [³H]DCG IV binding up to 1 mM. However, several compounds inhibited [³H]DCG IV binding in a concentration-dependent manner with the following rank order of potency: LY341495 = LY354740 > DCG IV = (2S,1′S,2′S)-2-(2-carboxycyclopropyl)glycine > (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid > (2S,1′S,2′S)-2-methyl-2-(2-carboxycyclopropyl)glycine > l -glutamate = ibotenate > quisqualate > (RS)-α-methyl-4-phosphonophenylglycine = l (+)-2-amino-3-phosphonopropionic acid > (S)-α-methyl-4-carboxyphenylglycine > (2S)-α-ethylglutamic acid > l (+)-2-amino-4-phosphonobutyric acid. N-Acetyl-l -aspartyl-l -glutamic acid inhibited the binding in a biphasic manner with an IC₅₀ of 0.2 µM for the high-affinity component. The binding was also affected by GTPγS, reducing agents, and CdCl₂. In parasagittal sections of rat brain, a high density of specific binding was observed in the accessory olfactory bulb, cortical regions (layers 1, 3, and 4 > 2, 5, and 6), caudate putamen, molecular layers of the hippocampus and dentate gyrus, subiculum, presubiculum, retrosplenial cortex, anteroventral thalamic nuclei, and cerebellar granular layer, reflecting its preferential (perhaps not exclusive) affinity for pre- and postsynaptic metabotropic glutamate mGlu2 receptors. Thus, the pharmacology, tissue distribution, and sensitivity to GTPγS show that [³H]DCG IV binding is probably to group II metabotropic glutamate receptors in rat brain.     

Two new dihydrobenzofuran-type neolignans from Breynia fruticosa

(7S,8R,7′S)-9,7′,9′-Trihydroxy-3,4-methylenedioxy-3′-methoxy [7-O-4′,8-5′] neolignan (1) and (7S,8R,7′S)-9,9′-dihydroxy-3,4-methylenedioxy-3′,7′-dimethoxy [7-O-4′,8-5′] neolignan (2), two new natural dihydrobenzofuran-type neolignans, along with 9,9′-dihydroxy-3,4-methylenedioxy-3′-methoxy [7-O-4′,8-5′] neolignan (3) and (-)-machicendiol (4), were isolated from the whole plants of Breynia fruticosa. The structures of 1 and 2, including the absolute configurations, were determined by spectroscopic methods and circular dichroism (CD) techniques. The absolute configuration of 4 was confirmed by calculations of the OR spectrum, together with OR and ECD spectra of its p-bromobenzoate ester (4a).     

Synthesis and Absolute Configuration of Pyriculol

A total synthesis of optically active pyriculol is described. The Wittig reaction between an aldehyde 19 and a triphenylphosphonium ylide 12 gave an intermediate 20. Successive treatment of 20 with p-toluenesulfonic acid, active manganese dioxide, and potassium carbonate gave (3′R,4′S)-pyriculol (23), which was identical with natural pyriculol (1) in all respects. From this synthesis, the absolute stereochemistry of pyriculol (1) was determined to be 2-[(3′R,4′S)-3′,4′-dihydroxy- (1′E,5′E)-1′,5′-heptadienyl]-6-hydroxybenzaldehyde     

Biosynthesis of pisatin: Experiments with enantiomeric precursors

Feeding experiments in cupric chloride-treated Pisum sativum pods and seedlings have demonstrated the preferential incorporation of (+)-(6aS,11aS)-[³H]maackiain over (?)-(6aR, 11aR)-[¹⁴C]maackiain into (+)-(6aR, 11aR)-pisatin, establishing that the 6a-hydroxylation of pterocarpans proceeds with retention of configuration. (+)- (6aR,11aR)-6a-hydroxymaackiain was similarly incorporated much better than (?)-(6aS,11aS)-6a- hydroxymaackiain. Where (?)-isomers were incorporated, optical activity measurements on the pisatin produced indicated significant synthesis of (?)-pisatin as well as the normal (+)-pisatin. 7,2′-Dihydroxy-4′,5′- methylenedioxyisoflav-3-ene and both enantiomers of 7,2′-dihydroxy-4′,5′-methylenedioxyisoflavan were poor precursors of pisatin.     

Formation of (-⊃-1′,2′-epi-2-cis-xanthoxin acid from a precursor of abscisic acid

Tomato shoots and avocado mesocarp supplied with (±)-[2-¹⁴C]-5-(1,2-epoxy-2,6,6-trimethylcyclohexyl)-3-methylpenta-cis-2-trans-4-dienoic acid metabolize it into (+)-abscisic acid and a more polar material that was isolated and identified as (?)-epi-1′(R),2′(R)-4′(S)-2-cis-xanthoxin acid. The (+)-1′(S),2′(S)-4′(S)-2-cis-xanthoxin acid recently synthesized from natural violaxanthin, has the 1′,2′-epoxy group on the opposite side of the ring to that of the 4′(S)-hydroxyl group and the compound is rapidly converted into (+)-abscisic acid. The 1′,2′-epoxy group of (?)-1′,2′-epi-2-cis-xanthoxin acid is on the same side of the ring as the 4′(S) hydroxyl group: the compound is not metabolized into abscisic acid. The configuration of the 1′,2′-epoxy group probably controls whether or not the 4′(S) hydroxyl group can be oxidized. (+)-2-cis-Xanthoxin acid is probably not a naturally occurring intermediate because a ‘cold trap’, added to avocado fruit forming [¹⁴C]-labelled abscisic acid from [2-¹⁴C]mevalonate, failed to retain [¹⁴C] label.     

New coumarins from Coleonema album

Six coumarins have been isolated from the aerial parts of Coleonema album and identified as ulopterol, 7-(3′, 3′-dimethylallyloxy)-coumarin, (R)-(+)-2′,3′-epoxy-suberosin, and the novel coumarins (R)-(+)-7-(2′, 3′-epoxy-3′-methylbutoxy)-coumarin, (R)-(+)-7-(2′,3′-dihydroxy-3′-dihydroxy-3′-methylbutoxy)-coumarin and (R)-(+)-7-methoxy-8-(2′,3′-epoxy-3′-methylbutoxy)-coumarin.     

A Preparation of Cow's Late Colostrum Fraction Containing αs1-Casein Promoted the Proliferation of Cultured Rat Intestinal IEC-6 Epithelial Cells

The asymmetric epoxidation of (±)-methyl (2Z,4E)-1′,4′-dihydroxy-α-ionylideneacetates is described for the preparation of chiral abscisic acid. A conventional Shapless kinetic resolution of (±)-1′,4′-cis-dihydroxyacetate with diethyl l-tartarate and then two simple steps of conversion gave (S)-abscisic acid, which was also obtained by the combination of (±)-1′,4′-trans-dihydroxyacetate with diethyl d-tartarte. Finally, (S)-abscisic acid was obtained in a 25% overall yield from the racemic mixture.     

Metabolism of Chiral Ionylideneacetic Acids on the Abscisic Acid Biosynthetic Pathway in Cercospora

A Chiralcel OJ column was used to determine the absolute configuration of naturally occurring α-ionylideneacetic acid from Cercospora rosicola and γ-ionylideneacetic acid from C. cruenta as (R) enantiomers in accordance with their biosynthetic product, (S)-ABA. Both enantiomers of [1, 2-¹³C₂]-α and γ-ionylideneacetic acids were prepared and fed to C. rosicola and C. cruenta. Six combinations of feeding experiments comparatively and unequivocally demonstrated stereoselectivity in the biosynthetic conversions, including stepwise hydroxylation at C-1′ and 4′. Enzymatic isomerization from the γ to α-intermediate was suggested not to be involved in ABA biosynthesis in C. rosicola.     

Neolignans from mezilaurus itauba

The wood bark of Mezilaurus itauba afforded in addition to seven known neolignans, three new compounds rel-(7R,8R,1′S,3′S)-Δ^5′,8′-5′-methoxy-3,4-methylenedioxy-1′,2′,3′,4′-tetrahydro-2′,4′-dioxo-7.3′,8.1′-neolignan, rel-(7S,8S,1′S, 2′S, 3′R, 4′S)-Δ^8′-2′,4′-dihydroxy-3,4-methylenedioxy-1′,2′,3′,4′,5′,6′-hexahydro-5′-oxo-7.3′,8.1′-neolignan and rel-(7S,8S)-Δ^8′-6′-hydroxy 5′-methoxy-3,4-methylenedioxy-7·O·2′,8.3′-neolignan. The latter compound has been detected previously in Aniba terminalis. The structures were elucidated by spectroscopic methods and comparison with related compounds.