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PubMed2005

Proanthocyanidin biosynthesis--still more questions than answers?

Proanthocyanidins, also known as condensed tannins, are oligomers or polymers of flavan-3-ol units. In spite of important breakthroughs in our understanding of the biosynthesis of the major building blocks of proanthocyanidins, (+)-catechin and (-)-epicatechin, important questions still remain to be answered as to the exact nature of the molecular species that undergo polymerization, and the mechanisms of assembly. We review the structures of proanthocyanidins reported over the past 12 years in the context of biosynthesis, and summarize the outstanding questions concerning synthesis of proanthocyanidins from the chemical, biochemical and molecular genetic perspectives.

Molecular Structure↗
PubMed2005

Anti-thrombotic effect of proanthocyanidin, a purified ingredient of grape seed.

INTRODUCTION: Moderate and regular consumption of wine reduces the risk of acute coronary thrombotic events. The mechanism of the anti-thrombotic effect of wine is not clear. Extract or purified ingredients of grapes have not yet been studied for anti-thrombotic effect. MATERIALS AND METHODS: Anti-thrombotic effect of proanthocyanidin, a highly purified ingredient of grape seed, was assessed by a shear-induced thrombosis test in vitro and by a laser-induced thrombosis test in the mouse carotid artery, in vivo. RESULTS AND CONCLUSIONS: Intravenously (20 mg/kg body weight, BW) or orally (2 x 200 mg/kg BW) administered proanthocyanidin significantly inhibited the laser-irradiation induced thrombus formation in the carotid artery (both P=0.01). Subsequent to oral administration of proanthocyanidin, in vitro platelet reactivity to shear stress has been inhibited. The latter suggests that the in vivo anti-thrombotic effect of proanthocyanidin may be due to a direct inhibitory effect on platelets.

Animals↗
PubMed2002

Safety evaluation of proanthocyanidin-rich extract from grape seeds.

Proanthocyanidins, extracted from grape seeds, are widely used mainly as nutritional supplements. However, there has not been a systematic report to investigate toxicological studies on proanthocyanidins, especially in oral administration. In our studies, proanthocyanidin-rich extract from grape seeds was subjected to a series of toxicological tests to document its safety for use in various foods. The grape seed extract (GSE) was examined for acute and subchronic oral toxicity using Fischer 344 rats and for mutagenic potential by the reverse mutation test using Salmonella typhimurium, the chromosomal aberration test using CHL cells, and the micronucleus test using ddY mice. No evidence of acute oral toxicity at dosages of 2 and 4 g/kg, and no evidence of mutagenicity in the above tests was found. Administration of GSE as a dietary admixture at levels of 0.02, 0.2 and 2% (w/w) to the rats for 90 days did not induce noticeable signs of toxicity. The no-observed-adverse-effect level (NOAEL) of GSE in the subchronic toxicity study was 2% in the diet (equal to 1410 mg/kg body weight/day in males and 1501 mg/kg body weight/day in females). The results of our studies indicate a lack of toxicity and support the use of proanthocyanidin-rich extract from grape seeds for various foods.

Animals↗
PubMed2000

Chemopreventive effects of grape seed proanthocyanidin extract on Chang liver cells.

In an attempt to ameliorate the chemotherapy associated normal cell toxicity, in this study a known antioxidant, grape seed proanthocyanidin extract (GSPE) using Chang liver cells has been used. Chang liver cells were treated in vitro with idarubicin (Ida) (30 nM) and 4-hydroxyperoxycyclophosphamide (4-HC) (1 microg/ml) with or without proanthocyanidin (25 microg/ml). The cells were grown in vitro and the growth rate of the cells were determined using MTT assay. The results showed that the GSPE decreased growth inhibitory effects of Ida and 4-HC on Chang liver cells in vitro. Since these chemotherapeutic agents are known to induce apoptosis in the target cells, these cells were also analyzed for presence of apoptotic cells using flow cytometry. The GSPE decreased the number of apoptotic cell population induced by either chemotherapy. In an attempt to determine the mechanisms of ameliorating effects of proanthocyanidin, the expression of apoptosis/cell cycle/growth related genes, Bcl-2, p53 and c-myc was determined in the treated and control cells using Western blotting or reverse transcriptase-polymerase chain reaction (RT-PCR) techniques. There was an increased expression of Bcl-2 in the cells treated with GSPE. However, there was a significant decrease in the expression of other cell cycle related genes such as p53 and c-myc in these cells following treatment with GSPE. Thus, these results indicate that proanthocyanidin can be a potential candidate to ameliorate the toxic effects associated with chemotherapeutic agents used in treatment of cancer.

Anthocyanins↗
PubMed2002

Identification and in vitro biological activities of hop proanthocyanidins: inhibition of nNOS activity and scavenging of reactive nitrogen species.

Oligomeric proanthocyanidins constitute a group of water-soluble polyphenolic tannins that are present in the female inflorescences (up to 5% dry wt) of the hop plant (Humulus lupulus). Humans are exposed to hop proanthocyanidins through consumption of beer. Proanthocyanidins from hops were characterized for their chemical structure and their in vitro biological activities. Chemically, they consist mainly of oligomeric catechins ranging from dimers to octamers, with minor amounts of catechin oligomers containing one or two gallocatechin units. The chemical structures of four procyanidin dimers (B1, B2, B3, and B4) and one trimer, epicatechin-(4beta-->8)-catechin-(4alpha-->8)-catechin (TR), were elucidated using mass spectrometry, NMR spectroscopy, and chemical degradation. When tested as a mixture, the hop oligomeric proanthocyanidins (PC) were found to be potent inhibitors of neuronal nitric oxide synthase (nNOS) activity. Among the oligomers tested, procyanidin B2 was most inhibitory against nNOS activity. Procyanidin B3, catechin, and epicatechin were noninhibitory against nNOS activity. PC and the individual oligomers were all strong inhibitors of 3-morpholinosydnonimine (SIN-1)-induced oxidation of LDL, with procyanidin B3 showing the highest antioxidant activity at 0.1 microg/mL. The catechin trimer (TR) exhibited antioxidant activity more than 1 order of magnitude greater than that of alpha-tocopherol or ascorbic acid on a molar basis.

Anthocyanins↗
PubMed2003

Anthocyanin and proanthocyanidin content in selected white and red wines. Oxygen radical absorbance capacity comparison with nontraditional wines obtained from highbush blueberry.

Antioxidant capacity, as measured by oxygen radical absorbance capacity (ORAC(PE)), total phenolic, total and individual anthocyanins, and proanthocyanidin fraction contents were evaluated in red and white wines from grapes. A comparison in terms of antioxidant capacity is made with nontraditional wines made from highbush blueberry. Blueberries are among fruits that are best recognized for their potential health benefits. In red wines, total oligomeric proanthocyanidin content, including catechins, was substantially higher (177.18 +/- 96.06 mg/L) than that in white wines (8.75 +/- 4.53 mg/L). A relative high correlation in red wines was found between ORAC(PE) values and malvidin compounds (r = 0.75, P < 0.10), and proanthocyanidins (r = 0.87, P < 0.05). In white wines, a significant correlation was found between the trimeric proanthocyanidin fraction and peroxyl radical scavenging values (r = 0.86, P < 0.10). A moderate drink (1 drink per day, about 140 mL) of red wine, or white wine, or wine made from highbush blueberry corresponds to an intake of 2.04 +/- 0.81 mmol of TE, 0.47 +/- 0.15 mmol of TE, and 2.42 +/- 0.88 mmol of TE of ORAC(PE)/day, respectively.

Anthocyanins↗
PubMed2003

Screening of foods containing proanthocyanidins and their structural characterization using LC-MS/MS and thiolytic degradation.

A normal-phase HPLC-MS/MS method was applied to screen for proanthocyanidins in 88 different kinds of foods. Thirty-nine foods were found to contain proanthocyanidins. These foods include 19 kinds of fruits, eight cereals/beans, seven nuts, two beverages, two spices, and one vegetable. Twenty-five kinds of foods were found to contain both oligomeric (DP </= 10) and polymeric proanthocyanidins (DP > 10), and the other 14 foods contained only oligomers. Procyanidins with B-type linkages were detected as the only components in 21 foods and also as principal components in the others. Propelargonidins were identified in pinto bean, raspberry, strawberry, and almond, etc. Plum, avocado, peanut, curry, and cinnamon were identified as potential sources of A-type proanthocyanidins in addition to cranberry. Thiolytic degradation and MS/MS analyses indicated that the A-type linkages are present as a terminal unit in plum or between the extension units in curry, cinnamon, and avocado, whereas A-type linkages exist at both positions in cranberry and peanut.

Beverages↗
PubMed2005

Antioxidant activity of A-type proanthocyanidins from Geranium niveum (Geraniaceae).

Geranium niveum S. Watson (Geraniaceae) is a medicinal herb widely used by the Tarahumara Indians of Mexico. This species is rich in proanthocyanidins and other phenolics. Previous in vitro assays have demonstrated that proanthocyanidins exhibited antiinflammatory, antiviral, antibacterial, enzyme-inhibiting, antioxidant, and radical-scavenging properties. In view of its medicinal use and chemical composition, the aim of the present study was to determine the in vitro antioxidant activity of the extracts and two proanthocyanidins (geranins A and D) from the roots of G. niveum by using seven different assay systems, namely, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide anion (O2*-), hydrogen peroxide (H2O2), hydroxyl radical (OH*), hypochlorous acid (HOCl), and singlet oxygen ((1)O2). Two known antioxidants, resveratrol and ascorbic acid, were used as positive controls. The results showed that geranins A and D and the extracts were able to scavenge ABTS, DPPH, O2*-, OH*, and HOCl. The scavenging ability of geranins A and D was similar to that of resveratrol and ascorbic acid in the following assays: ABTS, O2*-, and HOCl. The scavenging capacity of ascorbic acid for DPPH was higher than that of both geranins and resveratrol. On the other hand, the OH* scavenging action of both geranins and resveratrol was similar. The methanol-CHCl3 (1:1) extract had a higher ability to scavenge ABTS, DPPH, and O2*- radicals than the chloroform extract. In turn, the latter was more potent than the methanol-CHCl3 (1:1) extract as OH* or HOCl scavenger agent. Neither geranins A and D nor the extracts were able to scavenge H2O2 and (1)O2. In conclusion, G. niveum roots have proanthocyanidins with powerful radical scavenging in vitro activity. This property may partially explain the wide use of this plant in the Tarahumara indigenous system of medicine for the treatment of gastrointestinal illnesses (other than spasms), pain, and fevers associated with oxidative stress.

Anthocyanins↗
PubMed2002

In vitro inhibition of [3H]-angiotensin II binding on the human AT1 receptor by proanthocyanidins from Guazuma ulmifolia bark.

A bioassay-guided fractionation of the 70% acetone extract of the bark of Guazuma ulmifolia Lam. on the inhibition of angiotensin II binding to the AT 1 receptor led to the isolation and identification of bioactive oligomeric and polymeric proanthocyanidins consisting mainly of (-)-epicatechin units. The displacement of [3H]-angiotensin II binding was dose-dependent and correlated with the degree of polymerization of the different fractions containing proanthocyanidins. A strong displacement was seen for the residual fraction suggesting that the most active substances corresponding to the highly polymerized proanthocyanidins. Angiotensin II AT 1 receptor binding might be considered as a potentially interesting biological activity of proanthocyanidins contributing to the very broad spectrum of biological activities of the condensed tannins.

Angiotensin II↗
PubMed1998

Proanthocyanidins from grape seeds promote proliferation of mouse hair follicle cells in vitro and convert hair cycle in vivo.

For the purpose of discovering natural products which possess hair growing activity, we examined about 1000 kinds of plant extracts concerning growth-promoting activity with respect to hair follicle cells. After an extensive search, we discovered that proanthocyanidins extracted from grape seeds promote proliferation of hair follicle cells isolated from mice by about 230% relative to controls (100%); and that proanthocyanidins possess remarkable hair-cycle-converting activity from the telogen phase to the anagen phase in C3H mice in vivo test systems. The profile of the active fraction of the proanthocyanidins was elucidated by thiolytic degradation and tannase hydrolysis. We found that the constitutive monomers were epicatechin and catechin; and that the degree of polymerization was 3.5. We demonstrated the possibility of using the proanthocyanidins extracted from grape seeds as agents inducing hair growth.

Animals↗
PubMed2002

Grape seed proanthocyanidins improved cardiac recovery during reperfusion after ischemia in isolated rat hearts.

BACKGROUND: Increasing evidence shows that red wine consumption has cardioprotective effects. These effects have been attributed to the polyphenolic compounds in grapes. OBJECTIVE: We studied the effects of red grape seed proanthocyanidins on the recovery of postischemic function in isolated rat hearts. DESIGN: Two groups of rats were fed different doses of proanthocyanidin-rich extract for 3 wk and another group was untreated and served as controls. The animals were then anesthetized and the hearts were isolated and subjected to 30 min of ischemia followed by 2 h of reperfusion. Coronary effluents were collected during the third minute of reperfusion for measurement of oxygen free radicals by using electron spin resonance spectroscopy. RESULTS: In rats treated with 50 and 100 mg grape seed proanthocyanidins/kg, the incidence of reperfusion-induced ventricular fibrillation was reduced from its control value of 92% to 42% and 25%, respectively (P < 0.05 for both). The incidence of ventricular tachycardia showed the same pattern. In rats treated with 100 mg proanthocyanidins/kg, the recovery of coronary flow, aortic flow, and developed pressure after 60 min of reperfusion was improved by 32% +/- 8%, 98% +/- 8%, and 37% +/- 3%, respectively (P < 0.05 for all) compared with untreated control rats. Electron spin resonance studies indicated that proanthocyanidins significantly inhibited the formation of oxygen free radicals. In rats treated with 100 mg proanthocyanidins/kg, free radical intensity was reduced by 75% +/- 7% (P < 0.05) compared with the control rats. CONCLUSION: Grape seed proanthocyanidins have cardioprotective effects against reperfusion-induced injury via their ability to reduce or remove, directly or indirectly, free radicals in myocardium that is reperfused after ischemia.

Animals↗
PubMed2005

Proanthocyanidins--a final frontier in flavonoid research?

Proanthocyanidins are oligomeric and polymeric end products of the flavonoid biosynthetic pathway. They are present in the fruits, bark, leaves and seeds of many plants, where they provide protection against predation. At the same time they give flavor and astringency to beverages such as wine, fruit juices and teas, and are increasingly recognized as having beneficial effects on human health. The presence of proanthocyanidins is also a major quality factor for forage crops. The past 2 years have seen important breakthroughs in our understanding of the biosynthesis of the building blocks of proanthocyanidins, the flavan-3-ols (+)-catechin and (-)-epicatechin. However, virtually nothing is known about the ways in which these units are assembled into the corresponding oligomers in vivo. Molecular genetic approaches are leading to an understanding of the regulatory genes that control proanthocyanidin biosynthesis, and this information, together with increased knowledge of the enzymes specific for the pathway, will facilitate the genetic engineering of plants for introduction of value-added nutraceutical and forage quality traits.

Antineoplastic Agents, Phytogenic↗
PubMed2005

Amelioration of doxorubicin-induced myocardial oxidative stress and immunosuppression by grape seed proanthocyanidins in tumour-bearing mice.

We have investigated the protective effects of grape seed proanthocyanidins on doxorubicin-induced toxicity in tumour-bearing mice. The intraperitoneal administration of doxorubicin (2 mg kg(-1) every other day, cumulative dosage for 18 mg kg(-1)) significantly inhibited the growth of sarcoma 180, and induced myocardial oxidative stress with decreased superoxide dismutase and glutathione peroxidase activity while increasing malondialdehyde formation in the heart or serum. Doxorubicin-induced myocardial oxidative stress also reduced lactate dehydrogenase and creatine kinase activity in the heart and elevated their levels in the serum. Doxorubicin also affected immune functions of tumour-bearing mice with significantly decreased interleukin-2 (IL-2) and interferon-gamma (INF-gamma) production, and slightly decreased natural killer (NK) cell cytotoxicity, lymphocyte proliferation and CD4+/CD8+ ratio. It markedly increased the percentages of cytotoxic T cells (CD3+CD8+), helper T cells (CD3+CD4+), IL-2R+CD4+, and IL-2R+ cells as compared with untreated tumour-bearing mice. The intragastric administration of proanthocyanidin (200 mg kg(-1) daily) significantly inhibited tumour growth, and increased NK cell cytotoxicity, lymphocyte proliferation, CD4+/CD8+ ratio, IL-2 and INF-gamma production. Moreover, proanthocyanidin strongly enhanced the anti-tumour effect of doxorubicin and the above immune responses, and completely eliminated myocardial oxidative stress induced by doxorubicin. In conclusion, intragastric administration of proanthocyanidin could enhance the anti-tumour activity of doxorubicin and ameliorate doxorubicin-induced myocardial oxidative stress and immunosuppression in tumour-bearing mice.

Animals↗
PubMed2003

Liquid chromatographic/electrospray ionization mass spectrometric studies of proanthocyanidins in foods.

The proanthocyanidins in three foods (pinto beans, plums and cinnamon) were studied with electrospray ionization (ESI) mass spectrometry (MS) in the negative mode following separation by normal-phase high-performance liquid chromatography. The MS/MS analysis demonstrated that the major ions derived from heterocyclic ring fission and retro-Diels-Alder reaction of flavan-3-ol provided information about the hydroxylation pattern and type of interflavan bond. The connection sequence of the oligomers was identified through diagnostic ions derived from quinone methide (QM) cleavage of the interflavan bond. Novel heterogeneous B-type proanthocyanidins containing (epi)afzelechin as subunits were identified in pinto beans. Proanthocyanidins with interestingly different A-type linkages were identified in plums and cinnamon. In efforts aimed at extending the identification capacity of ESI-MS to polymers, we found that the polymeric procyanidins fragmented readily instead of forming multiply charged ions in the negative ESI mode. Fragmentation patterns were proposed based on our data obtained by ESI-MS/MS and ESI time-of-flight MS.

Chromatography, Liquid↗
PubMed2005

Characterisation of proanthocyanidin aglycones and glycosides from rose hips by high-performance liquid chromatography-mass spectrometry, and their rapid quantification together with vitamin C.

Fifteen individual proanthocyanidin aglycones and 19 glycosides, together with a complex mixture of chromatographically non-separated tetra- to octameric proanthocyanidin glycosides were detected--the non-separated glycosides being novel natural products--and characterised from dog rose hips using high-performance liquid chromatography-electrospray ionisation mass spectrometry (HPLC-ESI-MS). Along with these phenolics, a 50% aqueous ethanol extract of rose hips was found to contain high levels of Vitamin C. A simple and rapid HPLC method assisted by diode array detection for the estimation of the total concentration of proanthocyanidin aglycones and glycosides, as well as Vitamin C, in rose hip extracts was developed.

Ascorbic Acid↗
PubMed2004

Kola acuminata proanthocyanidins: a class of anti-trypanosomal compounds effective against Trypanosoma brucei.

Human African trypanosomiasis is undergoing an alarming rate of recrudescence in many parts of sub-Saharan Africa. Yet, there is no successful chemotherapy for the disease due to a limited number of useful drugs, side effects and drawbacks of the existing medication, as well as the development of drug resistance by the parasite. Here we describe a new lead anti-trypanosomal compound isolated from Kola acuminata (Makasu). We purified a proanthocyanidin by chromatographic procedures and confirmed its homogeneity and structure by Nuclear Magnetic Resonance and Matrix-Assisted Laser Desorption Ionisation Time-of-Flight mass spectrometry, respectively. In vitro, this compound potently induced growth arrest and lysis of bloodstream form trypanosomes in a dose- and time-dependent manner. In a mouse model, it exhibited a trypanostatic effect that extended the life of infected, treated animals up to 8 days post-infection against the 4 days for infected, untreated animals. The proanthocyanidin showed a low cytotoxicity against mammalian cells, whereas treated-BF showed massive enlargement of their flagellar pocket and lysosome-like structures caused by an intense formation of multivesicular bodies and vesicles within these organelles. The observed ultrastructural alterations caused rupture of plasma membranes and the release of cell contents, indicative of a necrotic process rather than a programmed cell death. Interestingly, the proanthocyanidin acted against BF but not procyclic form trypanosomes. This new anti-trypanosomal compound should be further studied to determine its efficacy and suitability as an anti-trypanosomal drug and may be used as a tool to define novel specific drug targets in BF trypanosomes.

Animals↗
PubMed2006

Ingestion of IH636 grape seed proanthocyanidin extract to prevent selenite-induced oxidative stress in experimental cataract.

PURPOSE: To investigate whether dietary supplementation with IH636 grape seed proanthocyanidin extract (GSPE) prevents selenite-induced cataract. SETTING: Department of Ophthalmology, Gulhane Military Medical Academy, Ankara, Turkey. METHODS: Thirty Spraque-Dawley rat litters were put randomly into 3 groups. In group 1 (n = 10), sodium selenite (30 nmol/g body weight) was injected subcutaneously on postpartum day 10. In group 2 (n = 10), sodium selenite (30 nmol/g body weight) was injected on postpartum day 10 and oral GSPE (100 mg/kg body weight) was given for 1 week after sodium selenite injection. Only subcutaneous saline was injected in group 3 (control, n = 10). The development of cataract was assessed for 3 weeks, and its density was graded and photographed with a slitlamp. Removed rat lenses were analyzed for glutathione (GSH) and malondialdehyde (MDA). RESULTS: All of the rats in group 1 had cataract between stage 6 and stage 3. In group 2, only 5 of 10 eyes had cataract between stage 3 and stage 2 and no cataract occurred in the remaining 5 rats. The difference between mean cataract stages in group 1 and group 2 was significant (P<.05). The mean GSH level in group 1 was significantly lower than in group 2 and controls (P<.05). The mean MDA level in group 1 was significantly higher than in group 2 and controls (P<.05). CONCLUSIONS: IH636 grape seed proanthocyanidin extract effectively suppressed cataract formation in rats. Routine consumption of grape seed proanthocyanidin extract in the form of food or dietary supplement may offer a prophylactic measure against onset and progression of cataract.

Administration, Oral↗
PubMed2005

Proanthocyanidin exposure to B6C3F1 mice significantly attenuates dimethylnitrosamine-induced liver tumor induction and mortality by differentially modulating programmed and unprogrammed cell deaths.

Proanthocyanidins are of current interest as chemopreventive agents. The potential of the pre-, post- and co-exposure of proanthocyanidin-rich grape seed extract (GSPE) in preventing, reducing and/or delaying dimethylnitrosamine (N-nitrosodimethylamine, DMN)-induced liver tumorigenesis, carcinogenesis and mortality in male B6C3F1 mice was determined. Animals were divided into six groups: I-control, II-GSPE alone, III-DMN alone, IV-GSPE+DMN, V-DMN exposure (3 months) followed by GSPE diet (9 months) and VI-GSPE diet (3 months)+DMN (3 months)+control diet (6 months). DMN exposure (0-8 weeks: 5mg/kg; 8-12 weeks: 10mg/kg, i.p.) was limited to a total period of 3 months. GSPE was incorporated in laboratory chow (ADI: 100mg/kg b.w.). Animals were sacrificed at 3 month intervals, and serum chemistry, liver histopathology, integrity of hepatic genomic DNA, antioxidant status, and rates of apoptotic and necrotic cell deaths were determined. DMN-induced liver tumor formation (85%) and animal lethality (38%) were powerfully antagonized by co-administration of GSPE+DMN (tumor positive: 45%; death: 11%). More than 75% of the DMN-treated animals had numerous tumors (five or more), which were significantly reduced in the GSPE+DMN group (35%). GSPE also negatively influenced other protocols specifically designed to test initiation and progression phases. Thus, GSPE was instrumental in modulating metabolic cascades and regulated orchestration of cell death processes involved during the multistage tumorigenic process. These results unraveled that long-term exposure to proanthocyanidin-rich grape seed extract may serve as a potent barrier to all three stages of DMN-induced liver carcinogenesis and tumorigenesis by selectively altering oxidative stress, genomic integrity and cell death patterns in vivo.

Animals↗