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PubMed1975

[On the phenolic acids of vegetables. IV. Hydroxycinnamic acids and hydroxybenzoic acids of vegetables and potatoes (author's transl)].

Lettuce, endive and chicory exclusively, cornsalad and sweet fennel almost exclusively contain caffeic acid derivatives beside traces of ferulic acid. Parsley exclusively and spinach almost exclusively show p-coumaric acid derivatives. Compared to root, fruit and seed vegetables the contents of phenolic acids in green leaves are considerably high. Rhubarb is the only vegetable, which contains gallic acid (chief phenolic acid) beside hydroxycinnamic, protocatechuic and vanillic acid derivatives. Furthermore hydroxybenzoic acid derivatives (salicylic, gentisic and vanillic acid) occur in cornsalad, sweet fennel, parsley and spinach in small concentrations; cornsalad shows p-hydroxybenzoic acid (ca. 20 mg/kg). Onions (Allium cepa) contain almost only protocatechuic acid beside small amounts of p-hydroxybenzoic and vanillic acid. In the outer dry coloured skins protocatechuic acid reaches concentrations up to 2% of plant material; the internal pulpy tissues show lower concentrations (ca. 20 mg/kg). On the contrary to the bulbs the green leaves of onions like chive and leek contain almost exclusively compounds of ferulic and p-coumaric acid. Garlic even shows a different phenolic acid pattern of skins and internal tissues. The caffeic acid derivatives of potatoes are mainly localized to a 1--2 mm thick outer layer. The different localization of phenolic acids in the different parts of vegetable plants is discussed.

Caffeic Acids↗
PubMedDate not supplied

[Galascorbine structure, studied by nuclear magnetic resonance].

The chemical structure of a galascorbine molecule was studied by the nuclear magnetic resonance NMR technique. On the basis of the obtained NMR spectra a conclusion was drawn than galascorbine is ester ascorbic acid and tannin hydroxycarbon acids. This finding was confirmed by the results of independent studies in the products of interaction between ascorbic and gallic acids.

Ascorbic Acid↗
PubMedDate not supplied

[Preparatory metabolism of p-hydroxybenzoic acid in Candida tropicalis].

A technique of experimental adaptation was used to obtain mutants of Candida tropicalis which were able to utilize p-hydroxybenzoic acid as the sole source of carbon and energy. The preparatory metabolism of p-hydroxybenzoic acid involves the following stages: PHBA leads to quinol leads to hydroxyquinol leads to maleylacetic acid leads to beta-ketoadipic acid. The enzyme system which catalyzes oxidative decarboxylation of PHBA mediates also oxidative decarboxylation of protocatechuic, beta-resorcylic and gallic acids, i.e. compounds having a hydroxyl group in para position with respect to the carboxyl of hydroxyl derivatives of benzoic acid. Benzoic, salicyclic and gentisic acids are not substrates of this enzyme system. A technique is proposed for rapid indentification of beta-ketoadipic acid by thin-layer chromatography. The authors believe that methods used to study preparatory metabolism, on the basis of the Stanier theory of "simultaneous adaptation", are not quite reliable and may lead to erroneous conclusions.

Candida↗
PubMed1975

[On phenolic acids of vegetables. I. Hydroxycinnamic acids and hydroxybenzoic acids of brassica-species and leaves of other cruciferae (author's transl)].

The contents of phenolic acids in vegetables of the species Brassica almost totally consist of hydroxycinnamic acid compounds. In contrary to other species of vegetables sinapic acid is dominant. Leaves of radish (Rhaphanus sativus var. sativus and var. niger) mainly contain compounds of caffeic and p-coumaric acid; leaves of horse radish show only traces of hydroxycinnamic acids. In the group of hydroxybenzoic acid derivatives traces of salicylic and gentistic acid could be determined in almost all species and frequently vanillic acid. Protocatechnic acid was only identified in red cabbage, especially in the head, syringic acid in gardencress and p-hydroxybenzoic acid in horse radish leaves. No other hydroxybenzoic acids or hydroxycoumarins could be detected.

Caffeic Acids↗
PubMed1975

Differential isolatoion of Pythium species from soil by means of selective media,temperature, and pH.

Pythium aphanidermatum, with an optimum temperature for growth at 35C, grew welland was readily isolated from soil on pimaricin-vancomycin medium (MPVM) when incubated for 24h at 38-40C. The pH of the medium affected recovery; maximum numbers developed above pH 6.0. Other Pythium spp. were recovered on MPVM at 20-25C, but were excluded by incubation at 38-40C. These Pythium spp. included P. ultimun, P. paroecandrum, P. irregular, P. mamillatum, and an unidentified Pythium sp. These species grew well and were readily siolated from soil on gallic acid medium (GAM) when incubated for 24-8h at 20 C.P. aphanidermatum and P. myriotylum grew from mycelium on GAM, but their oospores did not germinate nor could they be isolated from soilon this medium. P. myriotylum grew well on MPVM, but was only rarely isolated, evenfrom soils with known high potential for disease caused by P. myriotylum. Propagules of Pythium were enumerated by a plate-dilution frequency method or by a smearplateethod is valuable for studies on the ecology, survival, and inoculum potential in soils with mixed populations of P. aphanidermatum and other Pythium spp.

Culture Media↗
PubMed1975

Autoxidation in milk rich in linoleic acid. I. An objective method of measuring autoxidation and evaluating antioxidants.

Autoxidation was studied in milk obtained from cows fed on formaldehyde-treated casein-safflower oil supplement. The fat of this milk contained high levels of linoleic acid. A rapid disappearance of dissolved oxygen (DO), measured by using a oxygen electrode, from milk samples stored at 0 degrees C in tubes without head-space, coincided with the development of oxidized flavours detected organoleptically. A correlation coefficient of 0.9 with 69 degrees of freedom (P smaller than 0.001) was obtained between the amount of DO disappearing and the taste panel scores for oxidized flavours. Butylated hydroxyanisole, sesamol, nordihydroguaiaretic acid, ethoxyquin, or butylated hydroxyanisole with propylgallate or tocopherols, when added in emulsified form to the milk at the rate of 10-15 mg/l milk checked the development of oxidized flavours and the rapid disappearance of DO. Other antioxidants tested were either ineffective or imparted off-flavours to milk. Samples of mare's milk neither developed oxidized flavours nor showed rapid disappearance of DO over a test period of 8 d. The oxygen electrode provides a convenient and sensitive method for studying autoxidation and evaluating antioxidants in milk.

Animals↗
PubMed1992

HIV-1 reverse transcriptase inhibitor from Phyllanthus niruri.

An aqueous extract of Phyllanthus niruri (Euphorbiaceae) inhibited human immunodeficiency virus type-1 reverse transcriptase (HIV-1-RT). The inhibitor against HIV-1-RT in this plant was purified by combination of three column chromatographies, Sephadex LH-20, cellulose, and reverse-phase high-performance liquid chromatography. The inhibitor was then identified by nuclear magnetic resonance (NMR) spectra as repandusinic acid A monosodium salt (RA) which was originally isolated from Mallotus repandus. The 50% inhibitory doses (ID50) of RA on HIV-1-RT and DNA polymerase alpha (from HeLa cells) were 0.05 microM and 0.6 microM, respectively, representing approximately a 10-fold more sensitivity of HIV-1-RT compared with DNA polymerase alpha. RA was shown to be a competitive inhibitor with respect to the template-primer while it was a noncompetitive inhibitor with respect to the substrate. RA as low as 10.1 microM inhibited HIV-1-induced cytopathogenicity in MT-4 cells. In addition, 4.5 microM of RA inhibited HIV-1-induced giant cell formation of SUP-T1 approximately 50%. RA (2.5 microM) inhibited up to 90% of HIV-1 specific p24 antigen production in a Clone H9 cell system.

Antigens, Viral↗
PubMed1979

Oxidative and demethylating activity of multiple forms of laccase from Pholiota mutabilis.

1. The inducible and constitutive forms of laccase from the fungus Pholiota mutabilis show both the oxidative and demethylating activity, which proves the bifunctional character of the enzyme. 2. The oxidative/demethylating activity ratio of the forms induced either with ferulic or syringic acid is different from that shown by the constitutive form. 3. Splitting of one methoxyl group from the methoxyphenol substrate is associated with the release of one molecule of methanol.

Agaricales↗
PubMed1978

[High-performance liquid chromatography in the determination of organic acids in wine].

We shall distinguish the case of non aromatic organic acids from that one of phenolic acids. In the first one, we have applied to wines a method used for fruit-juices by Palmer and List, 1973. After contact of the wine with a strong acid resin, its is injected on anion exchange resin Aminex A 25 precolumn (formiate form) which retains all the organic acids. The precolumn is washed with water to eliminate neutral components, then connected with the chromatographic column which contains the same resin. The different acids are eluted with a solution of natrium formiate at 70 degrees C. They are detected by differential refractometry (galacturonic, lactic, malic, succinic, tartric acids) and by ultraviolet at 254 nm (shikimic acid). Beside these compounds which are identified by their retention volumes, others not yet attributed peaks are detected. The limits of detection are 2 mg/l for shikimic acid, 30 mg/l for tartric acid and 15 mg/l for the others. Analysis time is about one hour. In the case of phenolic acids, we extract them from wine by diethyl ether after saturation with NaCl or by demixtion. The determination of phenolic acids is done on the ether extract or on the organic layer of the demixtion. Chromatography is obtained on octadecylsilanised column (RP 18) with solvent gradient (from 10% methanol in KH2PO4O,1 M pH 2,1 to 60% methanol in the same buffer) and detection in ultraviolet at 254 nm. The knowledge of recovery of acids by diethyl ether or by demixtion permits to obtain their concentrations in wine. The different so determinated phenolic acids are: gallic, 4 hydroxybenzoic, cafeic, vanillic, syringic and para coumaric acids. We have applied these methods to 32 wines for phenolic acids and 80 wines for non aromatic acids. Some results are presented in the case of 24 wines issued from Gamay and 8 wines from Pinot and it appears that tartric and shikimic acids have more important average concentrations in the former than in the latter.

Acetates↗
PubMed1978

Resolution of the initial phase controversy in the thiamine-polyphenol reaction.

The kinetics of interactions between thiamine and seven polyphenols were followed by two types of thiochrome assays. The assays on the reaction mixture showed the extremely rapid initial phase whereas those on the eluate of the mixture previously treated by the Decalso column did not. The former assay methods also produced higher estimates of thiamine modification than the latter over the period of 3 hours of reaction. Arguments are given to show the probable non-existence of the observed extremely rapid initial phase. Reinterpretation of some past results are also presented.

Caffeic Acids↗
PubMed1978

The activation by Ca2+ of platelet phospholipase A2. Effects of dibutyryl cyclic adenosine monophosphate and 8-(N,N-diethylamino)-octyl-3,4,5-trimethoxybenzoate.

Thrombin-induced release of arachidonic acid from human platelet phosphatidylcholine is found to be more than 90% impaired by incubation of platelets with 1 mM dibutyryl cyclic adenosine monophosphate (Bt2 cyclic AMP) or with 0.6 mM 8-(N,N-diethylamino)-octyl-3,4,5-trimethoxybenzoate (TMB-8), an intracellular calcium antagonist. Incorporation of arachidonic acid into platelet phospholipids is not enhanced by Bt2 cyclic AMP. The addition of external Ca2+ to thrombin-treated platelets incubated with Bt2 cyclic AMP or TMB-8 does not counteract the observed inhibition. However, when divalent cation ionophore A23187 is employed as an activating agent, much less inhibition is produced by Bt2 cyclic AMP or TMB-8. The inhibition which does result can be overcome by added Ca2+. Inhibition of arachidonic acid liberation by Bt2 cyclic AMP, but not by TMB-8, can be overcome by high concentrations of A23187. When Mg2+ is substituted for Ca2+, ionophore-induced release of arachidonic acid from phosphatidylcholine of inhibitor-free controls is depressed and inhibition by Bt2 cyclic AMP is slightly enhanced. The phospholipase A2 activity of platelet lysates is increased by the presence of added Ca2+, however, the addition of either A23187 or Bt2 cyclic AMP is without effect on this activity. We suggest that Bt2 cyclic AMP may promote a compartmentalization of Ca2+, thereby inhibiting phospholipase A activity. The compartmentalization may be overcome by ionophore. By contrast, TMB-8 may immobilize platelet Ca2+ stores in situ or restrict access of Ca2+ to phospholipase A in a manner not susceptible to reversal by high concentrations of ionophore.

Arachidonic Acids↗
PubMed1978

The use of short-term tests to measure the preventive action of reducing agents on formation and activation of carcinogenic nitroso compounds.

The effect of reducing agents on the nitrosation of methylguanidine (MG) and on the in vitro activation of dimethylnitrosamine (DMN) was examined by measuring DNA-repair synthesis (unscheduled incorporation of [3h]TdR), shifts in alkaline sucrose gradients, frequency of chromosome aberrations, and clone-forming capacity of cultured human fibroblasts. The reducing agents examined were sodium ascorbate, cysteine, cysteamine, and propyl gallate. Since the short-term bioassays used can be quantitated, it has become relatively easy to detect the inhibitory action of reducing compounds on the nitrosation reaction of MG and metabolic activation (with S-9 preparation) of the precarcinogen DMN, to measure their effective dose range, and to establish the most effective ratios between inhibitory agent and reactant. The results indicate that DNA-repair synthesis is a suitable short-term test for studying the numerous combinations and premutations between several carcinogenic or non-carcinogenic agents, and for estimating the capacity of inhibitory agents to affect formation and activation of chemical carcinogens.

Adolescent↗
PubMed1992

Calcium activation of hyperpolarization response to acetylcholine in coronary endothelial cells.

Hyperpolarization response to acetylcholine (ACh) in endothelial cells was studied by intracellular recording of an intact endothelium preparation of guinea pig coronary artery. The hyperpolarization requires the presence of extracellular Ca2+ and the response was progressively blocked by MnCl2 or by removal of extracellular Ca2+. The intracellular Ca2+ antagonist, 3,4,5-trimethoxybenzoic acid 8-(diethylamino)octyl ester hydrochloride (TMB-8, 10 microM), was also effective in abolishing the hyperpolarization. Cyclopiazonic acid, an inhibitor of the sarcoplasmic reticulum Ca2+ pump, potentiated the hyperpolarization to ACh but inhibited caffeine-induced hyperpolarization. These findings suggest that ACh-induced hyperpolarization is mediated by an increase in cytosolic Ca2+ due to influx of extracellular Ca2+ and release of Ca2+ from an internal IP3-sensitive store. The rise in cytosolic Ca2+ level was modulated by a caffeine-sensitive pool that is inhibited by cyclopiazonic acid.

Acetylcholine↗