Antidiabetic effect of kolaviron, a biflavonoid complex isolated from Garcinia kola seeds, in Wistar rats

BACKGROUND

Hypoglycaemic effect of kolaviron (KV), (biflavonoid from Garcinia kola) in streptozotocin (STZ)-diabetic rats has been established.

OBJECTIVES

To evaluate the possible protective effects of KV on cardiac, renal and hepatic tissues of STZ-diabetic rats.

METHODS

This study consists of four groups of 6 rats each. Groups one and two contained non-diabetic and untreated-diabetic rats, respectively. Groups three and four were made up of KV- and glibenclamide (GB) - treated diabetic rats, respectively.

RESULTS

STZ-intoxication caused a significant (p<0.05) increase in the relative weight of liver in diabetic rats. STZ-diabetic rats had significant increase (p<0.05) in the levels of fasting blood glucose (FBG), á-amylase and HbA1c. A marked and significant (p<0.05) increase in the levels of cardiac, renal and liver marker indices such as serum creatine kinase, lactate dehydrogenase, creatinine, urea and alanine aminotransferase were observed in untreated diabetic rats. Also, untreated diabetic rats had significantly (p<0.05) elevated urinary glucose and protein and, lowered creatinine clearance. In KV- and GB- treated groups, the levels of FBG, á-amylase and HbA1c were significantly (p<0.05) reduced, while treatment with KV significantly (p<0.05) attenuated the cardiac, renal and liver marker indices.

CONCLUSION

KV offered significant antidiabetic and tissues protective effects in the rats.

Antidyslipidemic and antioxidant activity of the constituents isolated from the leaves of Calophyllum inophyllum

In continuation of our drug discovery program on Indian medicinal plants, we isolated bioactive compounds (1-5) from the leaves of Calophyllum inophyllum and evaluated their antidyslipidemic activity in triton induced hyperlipidemia model. The calophyllic acid (1A) and isocalophyllic acid (1B) mixture, canophyllic acid (4) and amentoflavone (5) showed dose dependent lipid lowering activity in in vivo experiments. The compounds 1A+1B mixture and 3 also showed good in vitro antioxidant activity.

Simultaneous extraction and separation of flavonols and flavones from Chamaecyparis obtusa by multi-phase extraction using an ionic liquid-modified microsphere polymer

INTRODUCTION

Flavonols and flavones, especially quercitrin, myricetin and amentoflavone, are the main anti-bacterial and anti-cancer compounds in Chamaecyparis obtuse. Multi-phase extraction is a new method that can extract and separate target compounds simultaneously.

OBJECTIVE

An amino ionic liquid immobilised microsphere polymer was used as a multi-phase extraction sorbent to extract and separate quercitrin, myricetin and amentoflavone from Chamaecyparis obtusa.

METHODOLOGY

The sorbent and Chamaecyparis obtusa powder were packed into a single cartridge. Using a fixed volume of methanol with five repetitions, the target compounds were extracted from the powder to the sorbent. The sorbent was then washed with n-hexane to remove any interfering species and the target compounds were eluted sequentially using water, methanol and methanol containing 1% acetic acid (vol.).

RESULTS

Under the optimised conditions, 0.45 mg/g of quercitrin, 0.18 mg/g of myricetin and 0.12 mg/g of amentoflavone from 2.0 g of powder were obtained by multi-phase extraction using 0.3 g of sorbent.

CONCLUSION

The method described has a low deviation error, requires a small amount of solvent and is highly selective and reproducible.

[Study on the chemical constituents of Lonicera similes]

OBJECTIVE

To study the chemical constituents of flower buds of Lonicera similes.

METHODS

The chemical constituents were isolated and purified with macroporous resin, silica gel column chromatography, gel chromatography, ect. The structures were elucidated according to the references combined with the application of spectrum techniques such as 1H-NMR, 13C-NMR ect.

RESULTS

Nine compounds were isolated and their structures were identified as 5-hydroxyl-7,4'-dimethoxyflavone (I), rutin (II), quercetin (III), amentoflavone (IV), aesculetin (V), beta-sitosterol (VI), 5-hydroxyl-7,3', 4'-trimethoxyflavone (VIII), oleanolic acid (VIII), beta-daucosterin (IX).

CONCLUSION

Among the nine isolated compounds, compounds I, II, III, IV, V, are flavonoids. Compounds I , IV, V, VII, VIII, IX are isolated from this plant for the first time.

Antiplasmodial and antibacterial activity of compounds isolated from Ormocarpum trichocarpum

Using activity-guided fractionation based on in vitro antibacterial assays, five biflavonoids, among them two new ones, were isolated from the aerial parts of Ormocarpum trichocarpum. The isolated compounds showed MIC values in the range of 4.0 to 136.7 µM against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Klebsiella pneumonia and IC50 values in the range of 4.30 to 94.32 µM against the chloroquine-sensitive D10 Plasmodium falciparum strain.

[Chemical constituents from Pleione bulbocodioides]

OBJECTIVE

To study the chemical constituents of Pleione bulbocodioides.

METHODS

The compounds were isolated by repeated column chromatography with silica gel, Sephadex LH-20 and ODS-HPLC. The structures were elucidated by analysis of spectroscopic data (1H-NMR, 13C-NMR).

RESULTS

Nine compounds were isolated from the EtOAc extract in the rhizoma of Pleione bulbocodioides. Their structures were identified as amentoflavone(I), kayaflavone(II), gymconopin D(III), methyl(4-OH) phenylacetate (IV), p-hydroxy benzaldehyde(V), p-hydroxybenzcic acid (VI), 4-oxopentanoic acid (VII), p-dihydroxy benzene (VIII), gastrodine (IX).

CONCLUSION

Compounds I - IX are isolated from this plant for the first time.

Platelet-activating factor (PAF) antagonistic activity of a new biflavonoid from Garcinia nervosa var. pubescens King

The methanol extract of the leaves of Garcinia nervosa var. pubescens King, which showed strong inhibitory effects on platelet-activating factor (PAF) receptor binding, was subjected to bioassay-guided isolation to obtain a new biflavonoid, II-3,I-5, II-5,II-7,I-4',II-4'-hexahydroxy-(I-3,II-8)-flavonylflavanonol together with two known flavonoids, 6-methyl-4'-methoxyflavone and acacetin. The structures of the compounds were elucidated by spectroscopic methods. The compounds were evaluated for their ability to inhibit PAF receptor binding to rabbit platelets using ³H-PAF as a ligand. The biflavonoid and acacetin showed strong inhibition with IC₅₀ values of 28.0 and 20.4 µM, respectively. The results suggest that these compounds could be responsible for the strong PAF antagonistic activity of the plant.

Bioactivity guided isolation of analgesic and anti-inflammatory constituents of Cnestis ferruginea Vahl ex DC (Connaraceae) root

ETHNOPHARMACOLOGICAL RELEVANCE

Cnestis ferruginea (CF) Vahl ex DC (Connaraceae) is a shrub widely used in Traditional African Medicine (TAM) for the treatment of various painful and inflammatory conditions.

AIM OF THE STUDY

To isolate the active pharmacological constituents responsible for the anti-inflammatory and antinociceptive properties of the methanolic root extract of C. ferruginea.

MATERIALS AND METHODS

The crude methanolic root extract of CF was sequentially fractionated into four sub extracts (chloroform, ethylacetate, n-butanol and the remaining aqueous fraction). The aqueous-butanol fractions, having showed significant inhibition of inflammation and pain, were subjected to fractionation through successive column chromatography on silica gel 60-120 mesh, eluted with a gradient of CHCl(3)-MeOH. Sixty five fractions were collected; fractions with similar TLC profiles were grouped into seven major fractions (1-7). Fraction 4 being the most active in bioassay was rechromatographed to obtain CF-2. Analgesic activity was evaluated using the acetic acid-induced writhing and hot plate tests in mice while carrageenan induced paw oedema test was used to investigate the anti-inflammatory actions of the fractions obtained.

RESULT

Amentoflavone (CF-2) was isolated from the aqueous/n-butanol fraction. CF-2 (12.5, 25 and 100 mg/kg; p.o) produced significant (P<0.05) dose dependent inhibition of pain response elicited by acetic acid and increased nociceptive reaction latency in hot plate test. In addition it produced significant (P<0.05) dose-dependent inhibition of oedema in the carrageenan-induced inflammation.

CONCLUSION

This study showed that amentoflavone is responsible for the analgesic and anti-inflammatory activity of Cnestis ferruginea.

Design and optimization of a semicontinuous hot-cold extraction of polyphenols from grape pomace

Grape pomace contains appreciable amounts of polyphenolic compounds such as anthocyanins and procyanidins which can be recovered for use as food supplements. The extraction of these polyphenols from the pomace is usually accomplished at slightly elevated temperatures, frequently employing hydroethanolic solvents. Due to governmental regulations and the cost involved in using ethanol as a solvent, as well as the loss in polyphenolics due to thermal degradation, improved extraction techniques are required. In this study, a semicontinuous extraction apparatus employing only water was developed to maximize the recovery of anthocyanins and procyanidins from red grape pomace (Vitis vinifera). Water is preheated prior to its entry to the extraction cell containing the grape pomace sample, where it is allowed to then flow continuously through the unheated extraction vessel prior to its collection at ambient conditions. Extraction variables that impacted the polyphenolic recovery included pomace moisture content (crude or dried), sample mass, water flow rate, and extraction temperature. A response surface method was used to analyze the results from the extraction, and the optimal conditions were found to be 140 °C and 9 mL/min water flow rate. These conditions can produce an extract containing 130 mg/100 g DW of anthocyanins and 2077 mg/100 g DW of procyanidins. Higher yields of polyphenolics were observed using crude (wet) rather than dried pomace, hence avoiding the need to dry the pomace prior to extraction. The described semicontinuous extraction method using only water as the extraction solvent under subcritical conditions allowed the efficient extraction of polyphenols from red grape pomace without the attendant loss of polyphenolic content due to having to heat the extraction vessel prior to commencement of extraction.

Bioguided fractionation and isolation of natural inhibitors of advanced glycation end-products (AGEs) from Calophyllum flavoramulum

Advanced glycation end-products (AGEs) are associated with many pathogenic disorders such as Alzheimer's disease, pathogenesis of diabetes, atherosclerosis or endothelial dysfunction leading to cardiovascular events. Clusiaceae and Calophyllaceae families are rich in compounds like polyphenols which are able to inhibit their formation and are therefore of great interest. Calophyllum flavoramulum Hend. & Wyatt-Sm., a native Malaysian plant, was selected after an anti-AGEs screening conducted on DCM and MeOH extracts from plants belonging to these aforementioned families. In a first study, bioguided fractionation of the MeOH leaf extract of C. flavoramulum afforded amentoflavone, 3-methoxy-2-hydroxyxanthone, 3,4-dihydroxy-tetrahydrofuran-3-carboxylic acid, quercitrin, 3,4-dihydroxybenzoic acid, canophyllol and apetalactone. Amentoflavone and 3-methoxy-2-hydroxyxanthone were found to be very potent (IC(50)=0.05 and 0.06 mM respectively), while anti-AGEs activities of quercitrin and 3,4-dihydroxybenzoic acid appeared as moderately strong (IC(50)=0.5 mM). In a second study, a systematic phytochemical study of the cyclohexane, DCM and EtOAc extracts obtained from the same plant was conducted to isolate the following products: flavoramulone, 6-deoxyjacareubin, rheediachromenoxanthone, 2,3-dihydroamentoflavone and benzoic acid. 3,4-Dihydroxy-tetrahydrofuran-3-carboxylic acid and flavoramulone were isolated for the first time and their structures were identified by means of IR, MS and NMR spectrometries.

Three new biflavonoids from Chinese dragon's blood, Dracaena cochinchinensis

Three new biflavonoids, named (2RyS)-3'-methoxy-8-methylsocotrin-4'-ol (1), (2SyR)-3'-methoxy-8-methylsocotrin-4'-ol (2), and (2RyR)-8-methylsocotrin-4'-ol (3), were isolated from Chinese Dragon's blood [Dracaena cochinchinensis (Lour.) S. C. Chen], together with two known ones. The structures of these new biflavonoids were elucidated by a combination of HR-ESI-MS, 1H NMR, 13C NMR, HMQC, and HMBC spectra. The absolute configurations of compounds 1-4 were determined by quantum chemical calculation of the circular dichroism spectrum and comparison with the experimental CD spectrum.

Procyanidin xylosides from the bark of Betula pendula

A procyanidin dimer xyloside, catechin-(4α→8)-7-O-β-xylopyranosyl-catechin, was isolated from the inner bark of Betula pendula and its structure was determined using 1D and 2D NMR, CD and high-resolution ESIMS. Interestingly, the 7-O-β-xylopyranose unit was found to be present in the lower terminal unit of the dimer. In addition to this procyanidin dimer xyloside, an entire series of oligomeric and polymeric procyanidin xylosides was detected. Their structures were investigated by hydrophilic interaction HPLC-HRESIMS. Procyanidin glycosides are still rarely found in nature.

Black tea polyphenols inhibit tumor proteasome activity

Tea is a widely consumed beverage and its constituent polyphenols have been associated with potential health benefits. Although black tea polyphenols have been reported to possess potent anticancer activities, the effect of its polyphenols, theaflavins on the tumor's cellular proteasome function, an important biological target in cancer prevention, has not been carefully studied. Here black tea extract (T5550) enriched in theaflavins inhibited the chymotrypsin-like (CT) activity of the proteasome and proliferation of human multiple myeloma cells in a dose-dependent manner. Also an isolated theaflavin (TF-1) can bind to, and inhibit the purified 20S proteasome, accompanied by suppression of tumor cell proliferation, suggesting that the tumor proteasome is an important target whose inhibition is at least partially responsible for the anticancer effects of black tea.

Isolation and structure elucidation of highly antioxidative 3,8″-linked biflavanones and flavanone-C-glycosides from Garcinia buchananii bark

The aim of this study was to identify antioxidants from Garcinia buchananii bark extract using hydrogen peroxide scavenging and oxygen radical absorbance capacity (ORAC) assays. LC-MS/MS analysis, 1D- and 2D-NMR, and circular dichroism (CD) spectroscopy led to the unequivocal identification of the major antioxidative molecules as a series of three 3,8″-linked biflavanones and two flavanone-C-glycosides. Besides the previously reported (2R,3R,2″R,3″R)-naringenin-C-3/C-8″ dihydroquercetin linked biflavanone (GB-2; 4) and (2R,3S,2″R,3″R)-manniflavanone (3), whose stereochemistry has been revised, the antioxidants identified for the first time in Garcinia buchananii were (2R,3R)-taxifolin-6-C-β-D-glucopyranoside (1), (2R,3R)-aromadendrin-6-C-β-D-glucopyranoside (2), and the new compound (2R,3S,2″S)-buchananiflavanone (5). The H₂O₂ scavenging and the ORAC assays demonstrated that these natural products have an extraordinarily high antioxidative power, especially (2R,3S,2″R,3″R)-manniflavanone (3) and GB-2 (4), with EC₅₀ values of 2.8 and 2.2 μM, respectively, and 13.73 and 12.10 μmol TE/ μmol. These findings demonstrate that G. buchananii bark extract is a rich natural source of antioxidants.

2-Arylbenzofuran, flavonoid, and tyrosinase inhibitory constituents of Morus yunnanensis

Two novel 2-arylbenzofuran dimers, morusyunnansins A and B (1 and 2), two new biflavonoids, morusyunnansins C and D (3 and 4), two new flavans, morusyunnansins E and F (5 and 6), and four known flavans (7-10) were isolated from the leaves of Morus yunnanensis. Compounds 5-8 showed potent inhibitory effects on mushroom tyrosinase with IC(50) values ranging from 0.12 ± 0.02 to 1.43 ± 0.43 μM.

Procyanidins from wild grape (Vitis amurensis) seeds regulate ARE-mediated enzyme expression via Nrf2 coupled with p38 and PI3K/Akt pathway in HepG2 cells

Procyanidins, polymers of flavan-3-ol units, have been reported to exhibit many beneficial health effects such as antioxidant and anti-carcinogenic effects. In this study, we investigated the cancer chemopreventive properties of procyanidins from wild grape (Vitis amurensis) seeds in particular their roles in inducing phase II detoxifying/antioxidant enzymes as well as in modulating the upstream kinases. Ethanolic extract of V. amurensis seeds was fractionated with a series of organic solvents and finally separated into six fractions, F1–F6. Chemical properties of the procyanidins were analyzed by vanillin assay, BuOH-HCl test, and depolymerization with phloroglucinol followed by LC/MS analysis. The F5 had the highest procyanidin content among all the fractions and strongly induced the reporter activity of antioxidant response element as well as the protein expression of nuclear factor E2-related factor (Nrf2) in HepG2 human hepatocarcinoma cells. The procyanidin-rich F5 also strongly induced the expression of the phase II detoxifying and antioxidant enzymes such as NAD(P)H:quinone oxidoreductase1 and hemeoxygenase1. Phosphorylations of the upstream kinases such as MAPKs and PI3K/Akt were significantly increased by treatment with procyanidin fraction. In addition, the procyanidin-mediated Nrf2 expression was partly attenuated by PI3K inhibitor LY294002, and almost completely by p38 inhibitor SB202190, but neither by JNK inhibitor SP600125 nor by MEK1/2 inhibitor U0126. Taken together, the procyanidins from wild grape seeds could be used as a potential natural chemopreventive agent through Nrf2/ARE-mediated phase II detoxifying/antioxidant enzymes induction via p38 and PI3K/Akt pathway.

A new biflavonoid with antiviral activity from the roots of Wikstroemia indica

A new biflavonoid, 4'-methoxydaphnodorin E, was isolated from the antiviral fraction of Wikstroemia indica against respiratory syncytial virus (RSV). Its structure was determined on the basis of extensive spectroscopic data including HR-ESI-MS and 2D NMR. The biflavonoid was tested for its in vitro anti-RSV activity with cytopathic effect (CPE) reduction assay, and displayed potent effect with 50% inhibitory concentration (IC₅₀) value of 2.8 μM and selective index (SI) value of 5.4.

Glucuronidation and methylation of procyanidin dimers b2 and 3,3″-di-o-galloyl-b2 and corresponding monomers epicatechin and 3-o-galloyl-epicatechin in mouse liver

PURPOSE

The 3,3″-di-O-galloyl ester of procyanidin B2 (B2G2) is a component of grape seed extract that inhibits growth of human prostate carcinoma cell lines. In preparation for studies in mice, its hepatic metabolism was examined in vitro and compared to B2 and the corresponding monomers, epicatechin (EC) and 3-O-galloyl-epicatechin (ECG).

METHODS

Compounds were incubated with liver microsomes or cytosol containing cofactors for glucuronidation, sulfation or methylation, and products analyzed by liquid chromatography-mass spectrometry (LC-MS). B2G2 was administered orally to mice and plasma analyzed by LC-MS for unmodified procyanidin and metabolites.

RESULTS

Glucuronides and methyl ethers of B2 and B2G2 were formed in small amounts. In contrast, EC and ECG were largely or completely converted to glucuronides, sulfates and methyl ethers under the same incubation conditions. B2G2 given orally to mice was partially absorbed intact; no significant metabolites were detected in plasma.

CONCLUSIONS

Glucuronidation and methylation of procyanidins B2 and B2G2 occurred but were minor processes in vitro. B2G2 was partially absorbed intact in mice after oral dosing and did not undergo significant metabolism. Unlike the flavanol monomers EC and ECG, therefore, B2G2 bioavailability should not be limited by metabolism. These results paved the way for ongoing pharmacokinetic and efficacy studies.

Antibacterial activity of two biflavonoids from Garcinia livingstonei leaves against Mycobacterium smegmatis

Amentoflavone and 4' monomethoxy amentoflavone were previously isolated from Garcinia livingstonei leaves. These compounds had good activities (MIC 6 and 8 μg/ml) against some nosocomial bacteria. In this study, the activity of these purified compounds were tested against fast-growing non-pathogenic Mycobacterium smegmatis. Amentoflavone was the most active compound, with an MIC of 0.60 ± 0.70 mg/ml. The MIC of 4' monomethoxy amentoflavone and the positive control isoniazid against Mycobacterium smegmatis were similar 1.40 ± 1.56 and 1.30 ± 1.70 mg/ml respectively. Although, Mycobacterium smegmatis is a non-pathogenic fast growing mycobacterium the activities of these compounds may also be useful in combating infections by pathogenic Mycobacterium spp.

Structural characterization and identification of biflavones in Selaginella tamariscina by liquid chromatography-diode-array detection/electrospray ionization tandem mass spectrometry

Biflavonoids, a special class of flavonoids, are widely distributed in gymnosperm plants and have various biological activities. They are also major bioactive ingredients in Selaginella tamariscina. In this work, we report the use of high-performance liquid chromatography with a diode-array detector (HPLC-DAD) and electrospray ionization multi-stage tandem mass spectrometry (ESI-MS(n)) to study the fragmentation behavior of three main types of biflavonoids using seven biflavonoid reference compounds and analyze the biflavonoids in Selaginella tamariscina. The most useful fragmentations in terms of structural identification are those involving the C-ring cleavage of biflavonoids. For amentoflavone-type biflavonoids (containing flavonoid parts I and II), fragmentation on the flavonoid part II at positions 1/3 and 0/4 are the primary pathways, whereas the chances are greater for C-ring cleavage fragmentation occurring on flavonoid part I at positions 1/3 and 1/4 for robustaflavone-type biflavonoids. However, the predominant diagnostic ions of the specific C-O-C-connected hinokiflavone-type biflavonoids are a series of ions resulting from the rupture of the connective C-O bond. Based on the fragmentation patterns of these reference compounds, 17 biflavonoids were identified in an extract of Selaginella tamariscina, three of which have not been previously reported as constituents of this plant. This study provides a powerful approach for the online structural elucidation and identification of different types of biflavonoids and positional isomers from Selaginella tamariscina and other biflavonoids distributed in related plants and prescriptions.

A novel biflavonyloxymethane from Pongamia pinnata and its radical quenching activity

The root bark of Pongamia pinnata Pierre (syn P. glabra Vent.) has afforded a new biflavonyloxymethane, pongabiflavone, along with a known furanoflavone, 3-methoxy-(7, 8, 2", 3") furanoflavone. The structure of this new compound was elucidated from extensive spectral studies, including 2D-NMR spectroscopic experiments. The antioxidant, radical quenching activity- superoxide and nitric oxide quenching activities of both pongabiflavone and previously isolated karanjabiflavone have been evaluated which can be a key to cure Psoriasis.

Biflavonoids from Caper (Capparis spinosa L.) fruits and their effects in inhibiting NF-kappa B activation

Caper (Capparis spinosa L.) fruits have been widely used as food and folk medicine in the Mediterranean basin and in central and west Asia. In this study, two biflavonoids, isoginkgetin, and ginkgetin, together with three other flavonoids, were isolated from caper fruits. Their chemical structures were elucidated by spectroscopic analyses and comparison with literature. To our knowledge, isoginkgetin, ginkgetin and sakuranetin were identified in caper for the first time. Notably, it is also the first time that biflavonoids have ever been found in the Capparidaceae. Concentrations of the two biflavonoids were measured in caper fruits collected from four major growing areas in northwest China. The anti-inflammatory effects of the flavonoids from caper fruits were evaluated by secreted placental alkaline phosphatase (SEAP) reporter assay, which was designed to measure nuclear factor-kappa B (NF-κB) activation. Isoginkgetin and ginkgetin showed inhibitory effects in initial screen at 20 μM, while the effect of ginkgetin was much greater than that of isoginkgetin. In a dose-response experiment, the IC(50) value of ginkgetin was estimated at 7.5 μM, suggesting it could be a strong NF-κB inhibitor and worthy of study in vivo.

Tetrahydroamentoflavone (THA) from Semecarpus anacardium as a potent inhibitor of xanthine oxidase

ETHNOPHARMACOLOGICAL RELEVANCE

Seed of Semecarpus anacardium L. is widely used in Indian traditional medicine; Ayurveda and Sidha, for treatment of inflammatory disorders and gout.

AIM OF THE STUDY

The present study was aimed at isolation of a compound for its potential to inhibit xanthine oxidase (XO), over expression of which lead to inflammation and gout.

MATERIALS AND METHODS

Activity guided fractionation of S. anacardium seed was conducted using liquid-liquid partition and preparative HPLC. The fractions were evaluated for their XO inhibition and antioxidant activity. The ethyl acetate fraction with the highest XO activity yielded a biflavonoid compound tetrahydroamentoflavone (THA). Lineweaver-Burk (LB) plot for the XO inhibition of THA and allopurinol was constructed from the kinetic data.

RESULTS

IC₅₀ values of THA and allopurinol for XO inhibition were 92 and 100 nM respectively and their corresponding values for K(i) were 0.982 and 0.612 μM respectively.

CONCLUSION

THA was a potent XO inhibitor which could be considered as a drug candidate or chemopreventive agent, after establishing its pharmacological and clinical evaluation. The study results appear to support the claim of the traditional medicine with respect to the efficacy of S. anacardium seed against inflammation and gout.

Procyanidins are potent inhibitors of LOX-1: a new player in the French Paradox

Lectin-like oxidized LDL receptor-1 (LOX-1) is an endothelial receptor for oxidized LDL (oxLDL) and plays multiple roles in the development of cardiovascular diseases. We screened more than 400 foodstuff extracts for identifying materials that inhibit oxLDL binding to LOX-1. Results showed that 52 extracts inhibited LOX-1 by more than 70% in cell-free assays. Subsequent cell-based assays revealed that a variety of foodstuffs known to be rich in procyanidins such as grape seed extracts and apple polyphenols, potently inhibited oxLDL uptake in Chinese hamster ovary (CHO) cells expressing LOX-1. Indeed, purified procyanidins significantly inhibited oxLDL binding to LOX-1 while other ingredients of apple polyphenols did not. Moreover, chronic administration of oligomeric procyanidins suppressed lipid accumulation in vascular wall in hypertensive rats fed with high fat diet. These results suggest that procyanidins are LOX-1 inhibitors and LOX-1 inhibition might be a possible underlying mechanism of the well-known vascular protective effects of red wine, the French Paradox.

Procyanidin-rich fractions from Parkia biglobosa (Mimosaceae) leaves cause redox-sensitive endothelium-dependent relaxation involving NO and EDHF in porcine coronary artery

AIM OF THE STUDY

Parkia biglobosa leaves are traditionally used as an antihypertensive agent in Benin. The present study assessed the vasorelaxant activity of different Parkia biglobosa leaf extracts using isolated porcine coronary artery rings.

MATERIALS AND METHODS

A hydroalcoholic leaf extract was submitted to a multi-step liquid-liquid fractionation with solvents of increasing polarity and the polyphenolic content of the different fractions was analyzed. Vascular reactivity of the different extracts was assessed using porcine coronary artery rings, in the presence or absence of specific pharmacological inhibitors.

RESULTS

The hydroalcoholic, ethyl acetate and butanolic extracts contained mainly procyanidins and monomeric flavonoids. Parkia biglobosa leaf crude extract induced a redox-sensitive endothelium-dependent relaxation mediated by both nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF). The fractionation of the butanolic extract generated 6 fractions, two of which induced stronger vasorelaxation than the original extract and they had a higher phenolic content.

CONCLUSIONS

Parkia biglobosa leaf extract is able to induce endothelium-dependent NO- and EDHF-mediated relaxation in porcine coronary artery rings. The vasorelaxant activity is dependent on their phenolic content and appears to involve mainly procyanidins.