Related Phenolic Compounds Research Articles

Promotive effect of capillarol and related compounds on root growth

The promotion of root growth by capillarol [methyl 3‐(3‐methylbut‐2‐enoyl)‐4‐hydroxycinnamate] and related phenolic compounds were studied in relation to structure‐activity relationships. Concentrations above 5 × 10−5M capillarol stimulated the root growth of rice (Oryza sativa L. cv. Tanginbozu and cv. Nihonbare) seedlings to about 180% of the control value at 5 × 10−4M. Capillarol had no promotive and hardly any inhibitory effect on the growth of the second leaf sheath. Capillarol promoted the root growth also in seedlings of lettuce (Lactuca sativa L. cv. Grand Rapids) to ca 150% of the control value at 5 × 10−4M. The free acid form of capillarol (capillaric acid) was about as effective as capillarol. Para‐hydroxy‐ but not m‐methoxy‐ substituted cinnamic acid, phenylpyruvic acid, phenylacetic acid and amino‐hydrocinnamic acid could stimulate root growth, but p‐hydroxybenzoic acid was inactive. It is concluded that the important structural requirements for high root growth‐promoting activity of phenolic compounds are the hydroxyl group substitution at the C‐4 position of the benzene ring, and the propanoic or propenoic acid side chain at the C‐1 position. A possible mode of the action of capillarol on root growth‐promoting activity is also discussed.

Inhibition of Ethylene Biosynthesis by Salicylic Acid

Salicylic acid inhibited ethylene formation from ACC in self-buffered (pH 3.8) pear (Pyrus communis) cell suspension cultures with a K(1) (app) of about 10 micromolar after 1 to 3 hours incubation. Inhibition appeared noncompetitive. Among 22 related phenolic compounds tested, only acetylsalicylic acid showed similar levels of inhibition. Inhibition by salicylic acid was inversely dependent on the pH of the culture medium and did not require a continuous external supply of salicylate. When compared to known inhibitors of the ethylene forming enzyme, cobalt, n-propyl gallate, and dinitrophenol, inhibition by salicylic acid most closely resembled that by dinitrophenol but salicylic acid did not produce the same degree of respiratory stimulation. Results are discussed in terms of other known effects of salicylic acid on plants, pH-dependency, and the possible influence of salicylic acid on electron transport.

Anthelmintics for ruminants

There is now a wide range of potent broad-spectrum anthelmintics for cattle and small ruminants, including the benzimidazoles, the avermectins, tetrahydropyrimidines and imidothiazoles which are highly efficacious against parasite gastroenteritis and bronchitis. Fascioliasis can be controlled with the salicy-lanilide and related phenolic compounds, the benzimidazoles, albendazole and triclabendazole the latter being the first flukicide with excellent activity against all stages of liver fluke infestation. The major developments for anthelmintic therapy have been and will be in the use of intraruminal boluses with either sustained release or pulse release of anthelmintic and other methods for group medication. The implications of such strategies for helminth resistance and individual immunity require further evaluation.

The chemical constituents and economic plants of the Euphorbiaceae

A chemical review of the different classes of compounds which have been isolated from the Euphorbiaceae (other than the diterpenoids) is given. This includes triterpenoids and related compounds (sterols, alcohols and hydrocarbons), phenolic compounds (flavonoids, lignans, coumarins, tannins, phenanthrenes, quinones, phenolic acids, etc.), alkaloids, cyanogenic glucosides and glucosinolates. A summary of the industrial and medicinal uses of members of the Euphorbiaceae is provided.

Protective mechanisms and acclimation to solar ultraviolet‐B radiation in Oenothera stricta

Abstract Mechanisms of plant protection and acclimation to potentially damaging solar ultraviolet‐B (UV‐B, 280–320 nm) radiation incident on the Earth's surface were examined in Oenothera stricta. Attenuation of this radiation in the upper leaf epidermis reduces the penetration of UV‐B radiation to the mesophyll where damage to physiologically sensitive targets can occur. The epidermis is a highly selective radiation filter that can attenuate up to 95% of the incident UV‐B radiation and yet transmit between 70% and 80% of the visible radiation. Exposure to UV‐B radiation significantly reduced the degree of epidermal UV‐B transmittance by as much as 33%. No significant reduction in epidermal transmittance of visible radiation was observed as a result of UV‐B exposure. The plasticity in epidermal UV‐B transmittance results from production of flavonoid and related phenolic compounds in the tissue. Absorbance of UV‐B radiation in llavonoid extract solutions from epidermal and mesophyll tissues significantly increased by as much as 100% and 35%, respectively, after exposure to UV‐B radiation. Photosynthetic rates of leaves exposed to UV‐B radiation were not significantly reduced at dose rates representative of the radiation flux found in the habitat of this species, but significant photosynthetic depression was observed at dose rates that exceed the field UV‐B flux. The phenotypic plasticity in epidermal UV‐B transmittance resulting in decreased penetration of damaging UV‐B radiation to the mesophyll may reduce the rate of damage to a level where repair mechanisms can keep pace with reduced injury.

Inhibition of Clostridium botulinum by Antioxidants and Related Phenolic Compounds in Comminuted Pork

ABSTRACTAntioxidants, esters of p‐hydroxybenzoic acid and gallic acid, and related phenolic compounds were evaluated for their activity against growth and toxin production of C. botulinum types A and B in comminuted pork. With an inoculum level of 8,000 spores/g of meat most of the chemicals at a concentration of 1,000 ppm delayed first swell formation for less than 3 days beyond the control. For most compounds, the time to first swell formation beyond that of the control increased as the spore level per g of meat decreased. 8‐Hydroxyquinoline at a concentration of 200 ppm or in combination with sodium nitrite (40 ppm) inhibited the growth and toxin production of C. botulinum in comminuted pork for 60 days at 27°C. 8‐Hydroxyquinoline was more active in inhibition of growth and toxin production of C. botulinum in comminuted pork than in prereduced Thiotone‐yeast extract‐glucose broth.

Toxicity of phenolic compounds in relation to the size of a freshwater fish, Notopterus notopterus (pallas)

Fish, Notopterus notopterus, in four sizes (4.5 ± 1.0, 9.0 ± 1.0, 14.5 ± 1.2, and 22.6 ± 1.8 cm in length) were exposed to phenol (P), 2,4-dinitrophenol (DNP), and pentachlorophenol (PCP) separately, and also to their three combinations (PCP + DNP) P (highly antagonistic), (DNP + P) PCP (additive), and (P + DNP) PCP (highly synergistic) to evaluate the effect of fish size on the toxicity of these chemicals separately and in combination. The results reveal that with increased fish size (from 4.5 + 1.0 to 14.5 + 12 cm in length) toxicity of phenolic compounds decreased. On the contrary, the larger size fish (22.6 ± 1.8 cm in length) was comparatively more susceptible. This indicates that change in fish size does influence the toxicity of phenolic compounds.

Selective inhibition of a cyclic nucleotide independent protein kinase (G type casein kinase) by quercetin and related polyphenols

The effect of quercetin and a number of structurally related phenolic compounds upon the activity of three different purified protein kinases was examined. Whereas the catalytic subunit of a cyclic AMP-dependent protein kinase and an A type (using only ATP) cyclic nucleotide-independent casein kinase (CKA) were not affected, a G type (using GTP as well as ATP) casein kinase (CKG) was selectively inhibited by several bioflavonoid structures. Kinetic studies showed that quercetin behaved as a competitive inhibitor toward the nucleotidic substrate and exhibited a high affinity for the ATP ( K i = 0.75 μM) and GTP ( K i = 0.22 μM) site of the enzyme. Considering the CKG inhibitory potency of a series of flavonoid, cinnamic acid and coumarin derivatives, it is suggested that the biological activity lays upon a common structural feature involving a phenolic ring bearing a side chain with conjugated double bonds and an oxygenated function, as found in the coumaroyl residue. These observations suggest that quercetin and related compounds may lead to a shift in intracellular protein phosphorylations by selectively inhibiting a particular type of protein kinase activity (CKG). It remains to be established whether this process may contribute to the mechanism of action of flavonoids upon cellular metabolism, particularly in the case of malignant cells.

Crystal and molecular structure of isogarcinol

The controversy with regard to the structures of the closely related polyisoprenylated phenolic compounds, garcinol, isogarcinol, camboginol, cambogin, xanthochymol and isoxanthochymol is cleared by X-ray crystallographic analysis of the naturally occurring isogarcinol. The unusual UV spectral characteristics of the chromophore of isogarcinol are discussed.

Induction of Reversible Tolerance of Algal Cells to Various Herbicides. I. Inhibition of Photosynthesis by Phenol Herbicides and Dibromothymoquinone, Its Reversal and Development of Insensitivity to Different Herbicides

Abstract Inhibition of photosynthetic O2 evolution of algal cells by phenol herbicides (e. g. ioxynil, di-iodonitrophenol, dinitrothymol) and dibromothymoquinone is reversed during treatment within one or two hours. Addition of the same or related inhibitory phenolic compounds as well as of dibromothymoquinone in higher concentrations to these pretreated algae causes no inhibitory effect. The cells become temporarily resistant to these inhibitors. Algal cells pretreated with phenol herbicides are still sensitive to diuron and representatives of some other groups of herbicides. After treatment with dibromothymoquinone, however, the sensitivity of cells to diuron is lowered.

Comparison of the Inhibition of Photosynthetic Reactions in Chloroplasts by Dibromothymoquinone, Bromonitrothymol and Ioxynil

Abstract The inhibition of photosynthetic electron flow in broken chloroplasts by dibromothymoquinone and dibromothymohydroquinone (DBMIBH2) is reversed by dithiothreitol (DTT) as well as by serum albumin. The reversal of DBMIBH2 inhibition by DTT shows a time lag, that of DBMIB only, when chloroplasts and DBMIB had been preilluminated. This is to show that chloroplasts reduce DBMIB and that probably DBMIBH2 is the actual inhibitor species. Bromonitrothymol, ioxynil and related inhibitory phenolic compounds have a different relation­ ship of inhibitory potency to chemical structure than DCMU and the analogous triazinone herbicide metribuzin but nevertheless inhibit photosynthetic electron flow at the same functional site. This is supported by the finding that labelled metribuzin is displaced from the thylakoid membrane by bromonitrothymol and ioxynil indicating identical binding sites. On the other hand inhibition by the phenolic inhibitors bromonitrothymol and ioxynil but not that of DCMU and metribuzin has a time lag of about 4 min.

On the inhibition of microsomal drug metabolism by olychlorinated biphenyls (PCB) and related phenolic compounds

The in vitro metabolism of p-nitroanisole, aminopyrine, and aniline by rat liver microsomal monoxygenases were studied in the presence of different polychlorinated biphenyl (PCB) mixtures and some related hydroxybiphenyls. The tested PCB mixtures contained preferably dichloro- (di-CB), tetrachloro- (tetra-CB), or hexachlorobiphenyls (hexa-CB). All PCB were competitive inhibitors of only aminopyrine demethylation by normal microsomes ( K i 22–39 μM). In microsomes of PCB-pretreated rats the aminopyrine demethylation was inhibited noncompetitively by di-CB and hexa-CB whereas tetra-CB remained a competitive inhibitor ( K i 12 μM). Moreover, after PCB pretreatment all PCB were competitive inhibitors of p-nitroanisole demethylation. 2-OH-biphenyl and 4-OH-biphenyl caused competitive inhibition of aminopyrine demethylation and aniline hydroxylation but failed to inhibit p-nitroanisole metabolism by normal microsomes. Chlorinated 4-hydroxybiphenyls inhibited competitively the metabolism of both type I and type II substrates. However, after PCB pretreatment all phenolic compounds caused uncompetitive inhibition of aniline hydroxylation.

Polymerization of 1-naphthol and related phenolic compounds by an extracellular fungal enzyme

An extracellular phenol oxidase was isolated from the culture filtrate of the fungus Rhizoctonia praticola by gel filtration on Sephadex G-200. The enzyme catalyzed the polymerization of 1-naphthol to dimeric, trimeric, tetrameric, and pentameric compounds as determined by mass spectrometry. One product with a molecular weight of 286 was identified as 4,4′-bi-1-naphthol. Other compounds that were dimerized or polymerized by the enzyme were phenol, o-methoxyphenol (guaiacol), p-methylphenol ( p-cresol), 2,6-dimethoxyphenol, and 1,3- and 1,5-dihydroxynaphthalene. The product from 2,6-dimethoxyphenol was isolated and identified as 3,5,3′,5′-tetramethoxydiphenoquinone.

Spore Germination of Diplodia gossypina in the Presence of Carbohydrates and Phenolic Compounds in Relation to Boll Rot of Cotton

Spore Germination of Diplodia gossypina in the Presence of Carbohydrates and Phenolic Compounds in Relation to Boll Rot of Cotton

Phenolic compounds in relation to phytoalexin biosynthesis in hypocotyls of Phaseolus vulgaris

The major phenolic compounds in Phaseolus vulgaris hypocotyls are flavonol glycosides, leucoanthocyanins and hydroxycinnamic acid derivatives. These appear to account for all the reactivity of extracts towards Folin's reagent, when allowance has been made for interfering compounds. Treatment of the hypocotyls with drops of mercuric chloride solution or a culture filtrate of Penicillium expansum causes the production of the phytoalexin phaseollin but only small changes in the levels of endogenous phenols. Coumestrol, a compound related to phaseollin, is produced at the same time. It is suggested that phytoalexin formation in P. vulgaris may represent a specific stimulation of isoflavonoid metabolism which is separate from any general increase in phenol metabolism associated with cell necrosis.

Transition state analysis. I. Correlation between solvent stretching frequencies and C vs. O product ratios in alkylation of ambient anions. A new explanation for the observed product ratios

A new explanation is presented for the O to C product ratios observed in alkylation reactions of ethyl acetoacetate and related enolic and phenolic compounds, based on a Hammond postulate analysis of the nature of the transition states involved. The explanation not only covers the effects of solvent and the nature of the metal cation, but also encompasses the previously unexplained effect of the alkyl halide structure. From the latter effect, ground state interaction between solvent and alkyl halide is predicted. Evidence consistent with this interaction is found in linear free energy relationships between the ΔΔG‡ (C vs. O) values for various alkyl halides and the stretching frequency of the solvent (S=O of DMSO; P=O of HMPA) when measured as alkyl halide solutions.

Leucoanthocyanins and related phenolic compounds of carob pods (Ceratonia siliqua)

AbstractThe phenolic compounds present in green carob pods were separated into five components. These were characterised on the bases of solubility, mobility on paper, nature of products of hydrolysis by Penicillium tannase, nature of products yielded on heating with dilute and concentrated hydrochloric acid solution, and nature of products yielded on alkali fusion. The major leucoanthocyanins in green carob pods were highly polymerised leucodelphinidins. A large amount of, and many kinds of, hydrolysable tannins were found. Two crystalline galloyl glucose compounds were isolated.The phenolic compounds present in ripe carob pods were fractionated into four preparations. Hydrolysable tannins present in green pods, were either not found or present only in low concentrations. On the other hand, gallic acid was found in large amounts in ripe pods. The main leucoanthocyanin in ripe pods also was leucodelphinidin. The gallic acid found in ripe pods could be derived from the hydrolysable tannins in green pods by enzymic hydrolysis.

Flavonoid and certain related phenolic compounds in parts of the tobacco flower

Identification and distribution studies have been made of flavonoid and related phenolic compounds present in four kinds of floral appendages of tobacco. Stamens contained rutin, scopolin, esculetin, chlorogenic acid, glucose derivatives of p-coumaric and ferulic acids, and an unknown glucoside of kaempferol. The last three were found only in stamens. Corollas (petals) contained scopolin, esculetin, chlorogenic acid, rutin, nictoflorin, isoquercitrin, astragalin, rutin-7-glucoside, and nictoflorin-7-glucoside. The last five compounds named were found only in the petals. The last three have not been reported previously to be present in tobacco tissue. The calyxes or sepals contained esculetin, chlorogenic acid, scopolin, rutin, a quercetin-3-diglucoside, quercetin-3,3′-dimethyl ether, and quercetin-3-methyl ether. The last three were present only in the calyxes. The pistils contained esculetin and chlorogenic acid, but none of the above flavonol glycosides or methyl ether derivatives.

Mechanisms of thermal degradation of phenolic condensation polymers. III. Cleavage of phenolic segments during the thermal degradation of uncured epoxy resins

The phenolic cleavage of the uncured epoxy resins is further substantiated by the semiquantitative study with the aid of the mass spectrometer analysis. In general, the phenolic cleavage (at 475°C.) of the epoxylated novolac resin, D.E.N. 438 resin, was found to be similar to that of the unepoxylated novolac resin. For both cases, cresols and phenol were the major products as a result of the homolytic cleavage and the subsequent hydrogen abstraction. At the same time, a small amount of xanthene or the substituted xanthenes appeared in the mixture presumably due to the dehydration of related phenolic compounds. A small amount of C6H5OC3H3 or C6H4OC3H4 could indicate that there could be some cyclization of the glycidyl ether side chain of the epoxylated novolac resin. For the epoxylated bisphenol-A resin, D.E.R. 331 resin, the phenolic cleavage at high temperature appeared to follow two major and one minor scheme. The first type of cleavage is undoubtedly homolytic to yield isopropylphenol, C2H5 phenols, cresols, and phenol. The second type cleavage was not found in the above two resins and is heterolytic in nature. This cleavage resulted in the formation of isopropenyl-phenol. Due to the presence of C6H5OC3H3 or C6H4OC3H4, it is postulated that the cyclization of the glycidyl ether side chain may also, take place.

Flavonoids and related phenolic compounds produced in the first internode of Sorghum vulgare Pers. in darkness and in light.

Knowledge of C15 intermediates in the biosynthesis of anthocyanins is scanty or controversial. Recently, chalcones (7) and leucoanthocyanins (2) have been postulated as intermediates from evidence based on kinetic studies and isotope experiments. Downs and Siegelman (3) have studied the photocontrol of anthocyanin synthesis in seedlings of Sorghum vulgare. The anthocyanin has been identified as an acylated cyanidin-3-glucoside, and possible C9 precursors of this pigment have been studied with isotope techniques (1). Since the first internode (mesocotyl) of Sorghum can be easily grown in the dark and forms large amounts of the red anthocyanin only in the light, this material was examined in hopes that intermediates in anthocyanin biosynthesis might be accumulated under appropriate conditions. It was necessary first to know what phenolic compounds were present in conmpletely dark-grown internodes and what changes took place upon illumination.