Procyanidin Units Research Articles

Antiviral Activity of Crude Hydroethanolic Extract from Schinus terebinthifolia against Herpes simplex Virus Type 1.

Herpes simplex virus infections persist throughout the lifetime of the host and affect more than 80 % of the humans worldwide. The intensive use of available therapeutic drugs has led to undesirable effects, such as drug-resistant strains, prompting the search for new antiherpetic agents. Although diverse bioactivities have been identified in Schinus terebinthifolia, its antiviral activity has not attracted much attention. The present study evaluated the antiherpetic effects of a crude hydroethanolic extract from the stem bark of S. terebinthifolia against Herpes simplex virus type 1 in vitro and in vivo as well as its genotoxicity in bone marrow in mammals and established the chemical composition of the crude hydroethanolic extract based on liquid chromatography-diode array detector-mass spectrometry and MS/MS. The crude hydroethanolic extract inhibited all of the tested Herpes simplex virus type 1 strains in vitro and was effective in the attachment and penetration stages, and showed virucidal activity, which was confirmed by transmission electron microscopy. The micronucleus test showed that the crude hydroethanolic extract had no genotoxic effect at the concentrations tested. The crude hydroethanolic extract afforded protection against lesions that were caused by Herpes simplex virus type 1 in vivo. Liquid chromatography-diode array detector-mass spectrometry and MS/MS identified 25 substances, which are condensed tannins mainly produced by a B-type linkage and prodelphinidin and procyanidin units.

Anti-inflammatory effects of the butanolic fraction of Byrsonima verbascifolia leaves: Mechanisms involving inhibition of tumor necrosis factor alpha, prostaglandin E2 production and migration of polymorphonuclear leucocyte in vivo experimentation

The leaves of Byrsonima verbascifolia (Malpighiaceae) are traditionally used to treat various diseases including inflammatory conditions. The main goal of this study was to evaluate the in vivo anti-inflammatory activity of the polar constituents from the butanolic fraction of B. verbascifolia leaves (BvBF), as well as to investigate the mechanisms involved in the anti-inflammatory activity. The polar constituents were identified by liquid chromatography coupled to diode array detector and mass spectrometry (LC-DAD–MS) and matrix-assisted laser desorption/ionization – time-of-flight mass spectrometry (MALDI-TOF MS) to obtain a complete chemical profile of the fraction. Forty-five compounds were detected in the BvBF by LC-DAD–MS/MS, including condensed tannins, phenolic acids, flavonoids (flavones and flavonols) and other compounds. In addition, several condensed tannins were identified by MALDI-MS/MS, which are composed predominantly by procyanidin units (PCY) and up to six flavan-3-ol units. The BvBF exhibited significant antioxidant and anti-inflammatory activities. The BvBF inhibited paw edema and polymorphonuclear (PMN) leukocyte migration to the footpad and pleural cavity induced by carrageenan. Furthermore, a minor dose (12.50mg/kg) of BvBF effectively decreased tumor necrosis factor alpha (TNF-α) and prostaglandin E2 (PGE2) levels in the footpad. These findings suggest that the mechanism of the anti-inflammatory action in the BvBF is linked to the inhibition of the production of inflammatory mediators such as TNF-α and PGE2 and the PMN cell migration.

Changes in the structural composition and reactivity of Acer rubrum leaf litter tannins exposed to warming and altered precipitation: climatic stress‐induced tannins are more reactive

• Climate change could increase the frequency with which plants experience abiotic stresses, leading to changes in their metabolic pathways. These stresses may induce the production of compounds that are structurally and biologically different from constitutive compounds. • We studied how warming and altered precipitation affected the composition, structure, and biological reactivity of leaf litter tannins in Acer rubrum at the Boston-Area Climate Experiment, in Massachusetts, USA. • Warmer and drier climatic conditions led to higher concentrations of protective compounds, including flavonoids and cutin. The abundance and structure of leaf tannins also responded consistently to climatic treatments. Drought and warming in combination doubled the concentration of total tannins, which reached 30% of leaf-litter DW. This treatment also produced condensed tannins with lower polymerization and a greater proportion of procyanidin units, which in turn reduced sequestration of tannins by litter fiber. Furthermore, because of the structural flexibility of these tannins, litter from this treatment exhibited five times more enzyme (β-glucosidase) complexation capacity on a per-weight basis. Warmer and wetter conditions decreased the amount of foliar condensed tannins. • Our finding that warming and drought result in the production of highly reactive tannins is novel, and highly relevant to climate change research as these tannins, by immobilizing microbial enzymes, could slow litter decomposition and thus carbon and nutrient cycling in a warmer, drier world.

Extraction of condensed tannins from grape pomace for use as wood adhesives

The extraction of condensed tannins from grape pomace was examined using a mixture water–sodium hydroxide at 120°C. The extracts were characterized by solution 13C NMR and have showed characteristic consistent with that of condensed tannins with dominant procyanidin units. The tannin fractions reactivity toward formaldehyde was studied by gel time analysis and thermomechanical analysis in bending. It has been demonstrated that the extracts obtained by using 10% of NaOH (w/w) displayed promising properties for adhesive applications.

Variation of Proanthocyanidins in Lotus Species

The proanthocyanidin (PA) chemistry of 12 Lotus species of previously unknown PA content was examined in comparison with agricultural cultivars of L. pedunculatus, L. corniculatus, and L. tenuis and a "creeping" selection of L. corniculatus. Herbage harvested in winter 2000 and again in spring had extractable PA concentrations, estimations of which varied between 0.2 and 10.9% of dry matter. The four novel Lotus spp. with the highest concentrations were selected for further evaluation together with the agricultural accessions. PA concentrations in herbage were estimated for individual plants harvested in spring 2001 and bulk samples harvested in summer 2002-2003. PA oligomer and polymer fractions were separated by Sephadex LH-20 chromatography from aqueous acetone PA extracts of herbage. The chemical characteristics of the fractions were examined by acid catalyzed degradation with benzyl mercaptan, (13)C nuclear magnetic resonance spectroscopy, electrospray ionization (ESI), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). A wide variation was found in the chemical composition, mean degree of polymerization (mDP), and polydispersity of PAs from Lotus spp. Fractions from L. americanus, L. corniculatus "creeping selection," and L. pedunculatus consisted predominantly of prodelphinidin (PD) units, whereas PA from L. angustissimus and L. corniculatus consisted predominantly of procyanidin (PC) units. An approximately equal composition in terms of PC and PD units was found in L. parviflorus and L. suaveolens. In L. angustissimus, epicatechin is dominant in both extender and terminal units. In all Lotus PA fractions, the 2,3-cis isomers (epicatechin or epigallocatechin) predominated. Only trace amounts of PA were extracted from L. tenuis. The mDP of the PA fractions ranged from 8 to 97, with high mDP found only for L. pedunculatus and L. americanus. In the ESI-MS and MALDI-TOF-MS of the L. angustissimus PA fraction, ions for homo-PC oligomers were dominant, whereas ions for hetero-oligomers predominated in the other Lotus spp. Ions indicative of A-type linkages were observed in the MS of L. americanus. The results are discussed in terms of possible relationships between the concentration and composition of the PAs of Lotus spp. and ecological factors.

MALDI-TOF mass spectrometry and PSD fragmentation as means for the analysis of condensed tannins in plant leaves and needles

MALDI-TOF mass spectrometry and 13C NMR spectroscopy were applied to unveil typical characteristics of condensed tannins of leaves and needles from willow ( Salix alba), spruce ( Picea abies) and beech ( Fagus sylvatica) of three tree species that are ubiquitous in German forests and landscapes. For further evaluation, lime ( Tilia cordata) was included. The 13C NMR spectroscopy confirmed the purity of the condensed tannin fractions and the efficiency of the procedure used for their extraction. While signals representative for procyanidin units are observable in all liquid-state 13C NMR spectra, resonance lines of prodelphinidin were only detected in those obtained from the condensed tannins of spruce needles and beech leaves. Typical signals in the chemical shift region between 70 and 90 ppm demonstrated the presence of stereoisomers (catechin/epicatechin; gallocatechin/ epigallocatechin). The MALDI-TOF mass spectra of the condensed tannins show signals of polymers of up to undecamers. Supporting the observations from the NMR spectroscopy, the mass spectra of the willow and lime leaf condensed tannins were identified as polymers with mainly procyanidin units, while the polymers of the spruce needle and beech leaves exhibit varying procyanidin/prodelphinidin ratios. Post source decay (PSD) fragmentation lead to a sequential loss of monomers and allowed a detailed characterization and sequencing of individual chains. In the case of the condensed tannins of lime this technique clearly excludes a pelargonidin terminal unit followed by a prodelphinidin unit, which would result in the same molecular masses as a polymer solely built up of procyanidin units.

Removal of cadmium and mercury ions from aqueous solution by sorption on treated Pinus pinaster bark: kinetics and isotherms

Formaldehyde pretreated Pinus pinaster bark was used to sorb Cd 2+ and Hg 2+ from aqueous solutions. The sorption kinetics showed hyperbolic dependence of the proportion of cation adsorbed on time, and the sorption isotherms were satisfactorily fitted by Freundlich equations, with k and n values showing Hg 2+ to be more efficiently sorbed than Cd 2+. Except for low cation concentrations, for which sorption was practically total at all initial pH⩾6, sorption increased in this range, in keeping with a mechanism based on ion exchange with the hydroxyl protons of ring B of the procyanidin units of the tannins in the bark.

The influence of various phenolic compounds on scavenging activity assessed by an enzymatic method

The effect of pure monomeric and dimeric procyanidins on superoxide anion radicals (O2°−) was studied with an enzymatic method and their IC50 was determined. A comparative study of the results suggested that the antiradical potential of these phenolic compounds closely depends on their stereochemical structure. Modification of the chiral carbon, C3 involved in the oxidation mechanism induces differences in the scavenging action of (+)-catechin (2R : 3S) or (−)-epicatechin (2R : 3R). The stereochemical conformation of the interflavan linkage (axial or pseudo) according to the chemical nature of dimeric procyanidin units also influences the radical oxidation mechanism. The nature of the interflavan linkage between the two units in dimeric procyanidins (C4–C8 or C4–C6 linkage) is an important factor responsible for effectiveness of the behaviour polyphenols towards O2°−. The extraction of oligomeric procyanidins in grape seeds enabled us to study the effect of polymerisation and galloylation on their scavenging activities. The results clearly showed that the molecular scavenging mechanism of these molecules is closely connected with their spatial conformation. © 1999 Society of Chemical Industry

Identification of procyanidins in cocoa (Theobroma cacao) and chocolate using high-performance liquid chromatography/mass spectrometry.

Monomeric and oligomeric procyanidins present in cocoa and chocolate were separated and identified using a modified normal-phase high-performance liquid chromatography (HPLC) method coupled with on-line mass spectrometry (MS) analysis using an atmospheric pressure ionization electrospray chamber. The chromatographic separation was achieved using a silica stationary phase in combination with a gradient ascending in polarity. This qualitative report confirms the presence of a complex series of procyanidins in raw cocoa and certain chocolates using HPLC/MS techniques. Although both cocoa and chocolate contained monomeric and oligomeric procyanidin units 2-10, only use of negative mode provided MS data for the higher oligomers (i.e., >pentamer). Application of this method for qualitative analysis of proanthocyanidins in other food products and confirmation of this method as a reliable quantitative tool for determining levels of procyanidins in cocoa, chocolate, and other food products are currently being investigated.

The condensed tannins of Leptarrhena pyrolifolia

A proanthocyanidin (PA) polymer, a condensed tannin, was isolated, purified and characterized from the leaves of Leptarrhena pyrolifolia. The predominant extension units in the polymer were (−)-epicatechin and (+)-gallocatechin with traces of (−)-epigallocatechin. (+)-Catechin was the predominant terminal unit. The PA polymer contained both prodelphinidin and procyanidin units in the estimated ratio of ca 1. The cis: trans ratio and the number-average M r of the polymer were determined and are discussed.

Condensed tannins. Base-catalysed reactions of polymeric procyanidins with phloroglucinol: intramolecular rearrangements

Reactions of polymeric procyanidins with phloroglucinol at pH 12.0 and temperatures of 23 or 50 °C gave epicatechin-(4β)-phloroglucinol (7), by cleavage of the interflavanoid bond between procyanidin units with subsequent addition of phloroglucinol, and (+)-catechin from the terminal unit. The phloroglucinol adduct (7) rearranged to an enolic form of 8-(3,4-dihydroxyphenyl)-7-hydroxy-6(2,4,6-trihydroxyphenyl)bicyclo[3.3.1]nonane-2,4,9-trione (9). Rearrangement of a dimeric procyanidin phloroglucinol adduct resulted in the formation of 3′-{8-(3,4-dihydroxyphenyl)-7-hydroxy-2,4,9-trioxobicyclo[3.3.1 ]nonan-6-yl}-4-(3,4-dihydroxyphenyl)-2′,3,4′,5,6′,7-hexahydroxyflavan (10), also in an enolic form. (+)-Catechin, from the terminal unit, gave catechinic acid, an enolic form of 6-(3,4-dihydroxyphenyl)-7-hydroxybicyclo[3.3.1]nonane-2,4,9-trione (4).

Condensed tannins: base-catalysed reactions of polymeric procyanidins with toluene-α-thiol. Lability of the interflavanoid bond and pyran ring

Reaction of polymeric procyanidins (condensed tannins) with toluene-α-thiol at pH 12.0 and 23 °C gave predominantly one stereoisomer of 1,3-bisbenzylthio-1-(3,4-dihydroxyphenyl)-3-(2,4,6-trihydroxyphenyl) propan-2-ol (10) by stereoselective reaction at C-4 and C-2 of the quinone methide derived from the upper 2,3-cis procyanidin units. Smaller amounts of two isomers of 1-benzylthio-1-(3,4-dihydroxyphenyl)-3-(2,4,6-trihydroxyphenyl)propan-2-ol (4) were obtained by reaction at the C-2 of catechin obtained from the terminal units. At higher temperatures, (10) loses toluene-α-thiol preferentially from C-1 to give 1-benzylthio-1-(3,4-dihydroxyphenyl)-3-(2,4,6-trihydroxyphenyl)propan-2-one (11) by a tautomeric rearrangement of the quinone methide via an enol to the ketone. Loss of toluene-α-thiol from (4) gave 1-(3,4-dihydroxyphenyl)-3-(2,4,6-trihydroxyphenyl)propan-2-one (5) by a similar rearrangement. This compound further rearranges to 1-(3,4-dihydroxyphenyl)-4,6-dihydroxyindan-2-one (6).

Enantiomerism: A characteristic of the proanthocyanidin chemistry of the monocotyledonae

Abstract Proanthocyanidin polymers containing 2,3- cis -procyanidin units with a partly racemic mixture of 2 R (the normal configuration) and 2 S units are widespread in the Monocotyledonae, being present in several families in the Arecidae, Commelinidae and Lilliidae.

Proanthocyanidins of barley and sorghum; composition as a function of maturity of barley ears

Sorghum vulgare seeds contain a proanthocyanidin polymer consisting largely of 2,3- cis procyanidin units with M̄ n, 2500. Hordeum vulgare ears contain low levels of proanthocyanidin oligomers containing 2–4 units, and composed largely of 2,3- trans procyanidin and prodelphinidin units with catechin as the terminal unit. The concentration of the oligomers in barley ears was virtually constant throughout the 33 day growth and ripening period.