Pulvinic Acid Research Articles

A new synthesis of pulvinic acids.

Reaction of zinc enolates e.g. (6) derived from arylacetates with 2-aryl-3-methoxymaleic anhydrides e.g. (3) gives intermediates viz (8) which can be dehydrated to Z -and E -isomers of permethylated pulvinic acids; treatment of the latter with trimethylsilyl iodide provides the corresponding pulvinic acids e.g. gomphidic acid (1).

New syntheses of pulvinic acids via reformatsky-type reactions with aryl-methoxymaleic anhydrides

The reaction of zinc enolates, viz(13), derived from arylacetates with 2-aryl-3-methoxymaleic anhydrides gives β-hydroxy ester intermediates viz(17) which can be dehydrated to Z- and E- isomers of permethylated pulvinic acids. Thus, the intermediate (17) derived from (15) and (16) produces the Z- and E-isomers (23) and (24) respectively, of permethylated gomphidic acid. In a similar manner, the geometrical isomers of permethylated isogomphidic acid [(27) and (28)] and methyl leprapinate [(29) and (30)] are synthesised from appropriate arylacetate and aryl methoxymaleic anhydride precursors.Treatment of permethylated pulvinic acids with trimethylsilyl iodide provides a facile method of producing the corresponding pulvinic acids. By this method gomphidic acid (2), isogomphidic acid (31) and atromentic acid (32b) have been prepared. Both (2) and (32b) were identical with the natural metabolites isolated from Gomphidius glutinosus and Xerocomus chrysenteron respectively.

The relationships ofPisolithus (Sclerodermataceae) to other fleshy fungi with particular reference to the occurrence and taxonomic significance of hydroxylated pulvinic acids

In the light of the discovery of hydroxylated pulvinic acids in the gasteromycetePisolithus arhizus, a possible relationship with the boletoid fungi and their relatives is explored. Biogenetic inter-relationships are indicated, including the host range ofApiocrea chrysosperma, and the distribution of phenylpyruvate-derived pigments offered in schematic form.

A naphthalenoid pulvinic acid derivative from the fungus Pisolithus tinctorius

Fruitbodies of the ectomycorrhizal fungus Pisolithus tinctorius contain a high concentration of a naphthalenoid pulvinic acid derivative, which was identified by chemical and spectroscopic methods.

Dioxolanones as synthetic intermediates. Part 3. Biomimetic synthesis of pulvinic acids

The reaction of the phosphorane (16) with methyl arylglyoxylates gives 5-(α-methoxycarbonyl-arylidene)-2,2-pentamethylene-1,3-dipxolan-4-ones [5′(α-methoxycarbpnylarylidene)cyclohexane-spiro-2′-(1′,3′-dioxolan)-4′-ones] which have been treated with the lithium enolates of t-butyl phenylacetic esters to provide a biomimetic synthesis of pulvinic acids. By this method pulvinic acid (2), vulpinic acid (1), and the unsymmetrically substituted compounds, leprapinic acid (3), and xerocomic acid (4) have been prepared; the last named was obtained via an intermediate (28) in which the phenolic groups were protected as benzyl ethers.

An inducible lactone hydrolase yielding 2,5-diphenyl-3-hydroxy-4-oxo-2-hexendioic acid from pulvinic acid

Abstract The metabolism of vulpinic acid by an unclassified soil micro-organism was studied. A new compound, 2,5-diphenyl-3-hydroxy-4-oxo-2-hexendioic acid (DHOHA) was isolated from the reaction mixture of a cell-free preparation and pulvinic acid. The existence of a hydrolase which catalyses the conversion of vulpinic acid to pulvinic acid was detected in cell-free preparation, and an inducible lactone hydrolase capable of converting pulvinic acid to DHOHA was purified 130-fold and characterized. This enzyme had a MW of ca 34 000, a K m for pulvinic acid at pH optimum (pH 7.0) less than 10 − 6 M, p I = 5.0, and was inhibited by p -chloromercuriphenylsulfonate and diethylpyrocarbonate. The enzyme was highly specific for pulvinic acid. The initial degradative steps proposed for this organism are vulpinic acid → pulvinic acid → DHOHA.

Vulpinic and Pinastric Acids as Lichen Antiherbivore Compounds: Contrary Evidence

The lichen-eating slug Pallifera varia consistently ate discs cut from the thallus of Cetraria pinastri, which produces vulpinic and pinastric acids, and rejected those from the morphologically similar C. oakesiana, which produces fatty acids including caperatic acid. In a second experiment, acetone extracts of the pre- ferred C. pinastri did not deter feeding activity by the slugs but those of the avoided C. oakesiana did. Concentrations of vulpinic and pinastric acids in the thalli of C. pinastri appear to be too low to deter P. varia grazing. Caperatic acid and the other fatty acids ofC. oakesiana appear to be more effective antiherbivore compounds than the vulpinic and pinastric acids of C. pinastri. For nearly 100 years investigators have been suggesting that certain lichen compounds protect slow-growing thalli from predation, although the suggestion has sometimes been hotly debated (reviews: Smith 1921; Gerson & Seaward 1977; Rundel 1978). Two com- pounds most frequently mentioned as defense compounds are the pulvinic acid derivatives vulpinic and pinastric acids. Smith commented (1921) that, although lichen substances appeared from evidence available at that time to be general irritants when consumed, lichens were never poisonous except in two instances: Letharia vulpina, which produces vulpinic acid, and Cetraria pinastri, which produces both vulpinic and pinastric acids. In more recent laboratory studies, vulpinic acid has been shown to elicit significant reductions in the feeding activity of several invertebrate grazers (Slansky 1979; Stephenson & Rundel 1979). Slansky's results, obtained using larvae of the polyphagous insect pest Spodoptera ornithogalli (Guenee), suggested that vulpinic acid functioned as a deterrent rather than a poison; when larvae were forced to consume food treated with vulpinic acid or starve, larval growth was not significantly different from that of control larvae. Even if vulpinic acid is not the potent toxin it was once believed to be, however, it appeared from Slansky's and other studies that vulpinic acid is at least a repellant or an inhibitor compound capable of discouraging generalist herbivore feeding. This paper reports results of feeding-preference studies done using the lichen herbivore Pallifera varia Hubricht, a slug species from western Virginia known to consume lichens (Lawrey 1980). These results suggest that vulpinic acid and the related pulvinic acid de- rivative pinastric acid are not as universally inhibitory to lichen herbivores as they are frequently assumed to be.

One Pot One Step Photoconversion of Pulvinic Acid Dilactone to p-Methoxyvulpinic Acid

Abstract The utility of singlet oxygen-methanol as a reagent for nuclear methoxylation of complex organic natural products is illustrated by a one pot one step photoconversion of pulvinic acid dilactone to p-methoxyvulpinic acid. The study is important from biogenetic considerations.

The Species of Chrysothrix

AbstractThe lichen genus Chrysothrix Mont, is shown to comprise four species: C. candelaris (L.) Laundon comb, nov., C. chlorina (Ach.) Laundon comb, nov., C. chrysophthalma (P. James) P. James & Laundon comb, nov., and C. pavonii (Fr.) Laundon comb. nov. (C. noli-tangere (Mont.) Mont.). The genera Pulveraria Ach. and Temnospora Massal. are placed in the synonymy of Chrysothrix nom. cons., and all bright yellow, leprose, sterile lichens with pulvinic acid derivatives, formerly included in Lepraria and Crocynia, are referred to the genus. Chrysothrix oceanica Rasanen is excluded; it probably belongs to Caloplaca. A key to and detailed accounts of the recognized species are included. There are three chemotypes of Chrysothrix candelaris, one of which is probably of hybrid origin.

Novel photochemical conversion of pulvinic acid to leprapinic acid

Pulvinic acid, an important Lichen acid from the lower variety of lichens has been converted to leprapinic acid in good yields. The conversion has a significance in the biogenesis of lichen acids.

Separation and identification of lichen acids of the pulvinic acid series

AbstractLichen acids, pulvinic acid, vulpinic acid, pinastric acid, leprapinic acid, lsoplnastric acid and pulvinic acid dilactone, which occur in certain yellow varieties of lichens and are difficult to separate, have been successfully separated and identified by TLC on chlorobenzene‐impregnated silica gel plates.

Synthetic approaches towards 4-ylidenebutenolides and 4-ylidenetetronic acids. Regioselective nucleophilic additions to unsymmetrically substituted maleic anhydrides

The application of unsymmetrically substituted maleic anhydrides in the synthesis of but-2-enolides, 4-hydroxybut-2-enolides, 4-ylidenebut-2-enolides, and 4-ylidenetetronic acid derivatives is examined. Reduction of 2-methylmaleic anhydride with metal hydride agents leads to a mixture of but-2-enolides (8a) and (8b), and 4-hydroxybut-2-enolides (7a) and (7b) corresponding to ca. 88% regioselective hydride ion attack at the more hindered (C-1) carbonyl function in the anhydride. Similar reductions of methoxy-substituted anhydrides (13) and (16) were completely regioselective and led to tetronic acid and 4-hydroxytetronic acid products resulting from hydride ion attack at only C-1 in the anhydrides.Condensation of the phosphorane (22a) with 2-methylmaleic anhydride produced largely the E-ylidenebutenolide (23), accompanied by smaller amounts of the Z-butenolides (24) and (25) : similar condensations with the anhydrides (16a) and (16b) were totally regioselective and produced Z,E-mixtures of ylidenetetronic acids corresponding to attack at C-1 in the anhydrides. The addition of ethylmagnesium bromide to 2-methylmaleic anhydride, followed by dehydration of the intermediate carbinol, led to a 3 : 2 mixture of the ylidenebut-2-enolides (39) and (40), whereas the corresponding reaction with the 2-methoxy-anhydride (16b) was more selective producing only (41).These studies have provided a basis for the development of syntheses of the ‘pulvinone,’‘pulvinic acid,’ and ‘multicolic acid’ groups of natural pigments.

Syntheses of permethylated derivatives of pinastric acid and gomphidic acid, pulvinic acid pigments of lichen and fungi

The application of 2-aryl O-methyltetronic acids (7) and (20) to the total synthesis of permethylated derivatives of pulvinic acid pigments found in Lepraria flava and Gomphidius glutinosus is described. Metallation of the tetronic acid (7), followed by treatment with methyl benzoylformate and dehydration of the intermediate carbinol led to O-methyl pinastric acid (9), identical with the O-methyl derivative of natural pinastric acid from L. flava. In a similar manner the tetronic acid (11) and methyl 4-methoxybenzoylformate gave O-methylisopinastric acid (12), and condensation between (20) and methyl 4-methoxybenzoylformate led to permethylated gomphidic acid (21). Comparison of 1H n.m.r. shift data for (21) with those reported for gomphidic acid from G. glutinosus established structure (2b) for the natural metabolite.

Pilzpigmente,XXXV[1]. 3-O-Methylvariegatsäure und verwandte Pulvinsäurederivate aus Kulturen von Hygrophoropsis aurantiaca (Boletales) / Pigments of Fungi, XXXV 3-0-Methylvariegatic Acid and Related Pulvinic Acid Derivatives from Cultures of Hygrophoropsis aurantiaca (Boletales)

From cultures of Hygrophoropsis aurantiaca in addition to variegatic acid (1), methyl variegate (2) and variegatorubin (5), three new derivatives of pulvinic acid have been isolated. They were identified as 3-O-methylvariegatic acid (3), its methyl ester 4 and 3-O-methylvariegatorubin (6) by means of spectroscopy and comparison with synthetic samples.

New Synthetic Nitrogen-Derivatives of Pulvinic Acid

Abstract Pulvinic acid lactams have been synthesized by reaction of the lichen compound vulpinic acid and 2-hydroxyethoxy-acetamide. The structure were established by consideration of infrared, mass and nuclear magnetic resonance spectra.

Biosynthesis of the xylerythrin-type pigments in Peniophora sanguinea

The hypothesis that biosynthesis of the xylerythrin-type pigments occurs via a pulvinic acid intermediate was confirmed by controlled biological experiments.

Incorporation of phenylpropanes into xylerythrin-type pigments in Peniophora sanguinea

Culture experiments with the fungus Peniophora sanguinea showed that the xylerythrin-type pigments of this organism are bio-synthesized via a pulvinic acid intermediate.

Synthesis of the pulvinic acid pigments of lichen and fungi

The total syntheses of permethylated derivatives of gomphidic acid (4a) and pinastric acid (5a), the pulvinic acid pigments found in Gomphidius glutinosus and Lepraria flava, respectively, are described.

Clitocybe Illudens: Its Cultivation, Chemistry, And Classification

SUMMARY Clitocybe illudens is a tetrapolar fungus. The conditions required for the completion of its life cycle in the laboratory have been determined. It is the only Clitocybe species from which the illudin group of sesquiterpenes has been isolated. Further, it produces compounds of the pulvinic acid group, a type of compound found in species of Xerocomus, Suillus, Paxillus, Gomphidius, Hydnum, and Hydnellum, but not in other Clitocybe species (except in Clitocybe subilludens with which it may be conspecific). Its chemical as well as it morphological distinctiveness support its exclusion from the genus Clitocybe. In the course of an investigation of single-basidiospore cultures of Clitocybe illudens (Schw.) Sacc. a number of biological and chemical properties of the fungus were examined: cultural characteristics, matingtype reactions, fruiting in the laboratory, and production of unusual metabolites. Single-basidiospore cultures (9-30 per sporophore) of C. illudens were isolated from each of 10 sporophores collected from 1965 to 1969, in seven localities in New York and New Jersey. The basidiospores were germinated at 25 C on 2% malt extract agar in Petri dishes. Germination after 10 da was close to 100%. A culture was obtained, with the aid of a dissecting microscope, by cutting out a block of agar containing a single, germinating basidiospore. Subsequently, it was found necessary to purify further the resulting cultures, either by isolating a single, germinating oidium of each, or a single hyphal tip. To determine the mating types of the cultures, these were combined in pairs within each strain, on the same medium at 25 C. Combinations made by placing inocula 3 cm apart on the medium in the center of a Petri dish did not readily form heterokaryons. Therefore, combinations were made on sterile, dry, paper discs (the type used to assay for penicillin). The disc was placed on the medium in the center of a Petri dish. Mycelial suspensions of each culture were prepared by lifting off the aerial mycelium of a culture with a sterile metal spatula, and crushing this on the inside of a test tube in 10 ml of sterile distilled water. One

Pilzpigmente, XIX / Pigments of Fungi, XIX

The NMR spectra of pulvinic acids show large differences in the chemical shifts of the 2,6 and 2′, 6′ aromatic protons. This allows an unambiguous differentiation between the two possible isomers of unsymmetrically substituted pulvinic acids. Xerocomic acid, isoxerocomic acid and gomphidic acid have been shown to possess structures 1 a, 1 b and 2 a respectively.