Hypoglycemic effect of Coffea arabica leaf extracts and major bioactive constituents.

The present study focused on investigating the antioxidant, antiglycation activity, digestive enzymes inhibition, bioaccessibility and hypoglycemic effect of C. arabica leaves extracts. The extracts deactivated the O2•-, ROO•, H2O2, HOCl reactive oxygen species. Coffee leaves showed strong inhibition of α-glucosidase (IC50 = 40.30 µg mL-1) greater than the isolated metabolites and acarbose. There was also inhibition of pancreatic lipase (IC50 = 56.43 µg mL-1) in addition to a hypoglycemic effect in zebrafish similar to acarbose and metformin. With the exception of rutin, all biocompounds were detected at all stages of in vitro digestion. Finally, these results suggest that C. arabica leaf extracts possess antidiabetic and anti-obesity properties that can be attributed to the main metabolites and the synergistic action between them.Communicated by Ramaswamy H. Sarma.

Dietary ethanol extract of mango increases antioxidant activity of pork.

Ethanol extract of mango seeds (EEMS) are composed of several polyphenolic compounds with considerable in vitro antioxidant activity that can be used in pig feed and may contribute positively to meat quality characteristics. The aim of this study was to evaluate the effect of EEMS as a source of antioxidants in growing-finishing pig diets on meat quality, lipid stability, sulfhydryl groups non-proteinaceous (SG-NP), total phenolic compounds, total antioxidant potential and total antioxidant activity of meat after 1 and 7 days of refrigeration storage. Thirty-two (60-day-old) barrows, weighing 20.20 ±â€¯1.34 kg, were used in a randomized block design consisting of eight animals with four treatment regimens. Treatments consisted of: Control = no dietary antioxidant; butylated hydroxytoluene (BHT) = diet with 200 ppm BHT; EEMS200 = diet with 200 ppm EEMS; EEMS400 = diet with 400 ppm EEMS. At 145 days of age and average weight of 95.47 ±â€¯6.19 kg, the animals were slaughtered and loin samples were collected and frozen before for qualitative analysis and evaluation of the effect of subsequent storage for 1 or 7 days at 8 °C on lipid stability, SG-NP, phenolic compounds, total antioxidant capacity and total antioxidant activity Meat from animals fed EEMS400 diet showed lower cooking loss (P < 0.0001) and higher non-protein sulfhydryl groups, phenolic compounds and total antioxidant activity at both 1 and 7 days of storage (P < 0.0001) compared to the other treatments. Greater antioxidant capacity was observed at 1 day storage in the meat of animals that consumed EEMS regardless of concentration when compared to the control group (P < 0.01). The dietary inclusion of EEMS to pig diets is more effective at 400 ppm in improving meat quality after cooking and antioxidant parameters of pork.

Secondary plant substances in various extracts of the leaves, fruits, stem and bark of Caraipa densifolia Mart.

Thirty secondary plant substances were detected in various extracts of the leaves, fruits, stem and bark of Caraipadensifolia Mart. Phenolic compounds were preliminarily identified and quantitated by HPLC-ESI-MS and the structures of the compounds, purified by semi-preparative HPLC, were further characterized by nano-ESI-MS-MS. The presence of gallic acid, 3,4-dihydroxybenzoic acid, neochlorogenic acid, chlorogenic acid, methyl gallate, p-coumaric acid quinate, epicatechin, procaynidin dimer B(2), procyanidin trimer C(1), syringic acid, 1,2,3,6-tetragallate glucoside, 1,3,4,6-tetragallate glucoside, corilagin, ellagic acid, methyl ellagic acid rhamnoside, quercetin-3-O-rhamnoside, two apigenin-C-glycosides (vitexin and isovitexin) and two luteolin-C-glycosides (orientin and isoorientin) are reported in this species for the first time. In addition, the previously reported following terpenoids, lupeol, lupenone, betulinic acid, betulin, friedelin and a previously non-characterized terpenoid in this species, friedelinol were identified and quantitated by GC-MS. A previously identified sterol was beta-sitosterol along with stigmasterol in this species for the first time. The vitamins alpha-tocopherol and gamma-tocopherol were also identified in extracts of the leaves of Caraipa species for the first time. The data shows that the botanical parts of C. densifolia Mart. has a much richer spectrum of secondary plant substances than previously reported.

Characterization of a rare triterpenoid and minor phenolic compounds in the root bark of Anisophyllea dichostyla R. Br.

Anisophyllea dichostyla R. Br. (Anisophylleaceae), is a small shrub which grows widely in regions of the Democratic Republic of Congo (DRC) where its root barks are used in folk medicine for the treatment of many debilitating diseases. In a previous work [Khallouki, F., Haubner, R., Hull, W.E., Erben, G., Spiegelhalder, B., Bartsch, H., Owen, R.W., 2007. Isolation, purification and identification of ellagic acid derivatives, catechins and procyanidins from the root barks of Anisophyllea dichostyla R. Br. Food and Chemical Toxicology 45, 472-485] on this species, an appreciable number (16) of phenolic antioxidants (3.32 g/kg) such as ellagitannins (27%) and polyhydroxyflavan-3-ols (catechins and procyanidins; 73%) were isolated and identified. Two fractions, as well as containing minor phenolic compounds also showed evidence of a secondary plant substance similar to a triterpenoid. Following purification of the triterpenoid by semi-preparative HPLC, and recrystallization, the structure was elucidated as bryonolic acid as evinced by comprehensive spectroscopic analyses including (1)H and (13)C NMR, DEPT, COSY, ROESY, HMQC, HMBC, HPLC-ESI-MS and GC-MS experiments. Bryonolic acid, which is extremely rare in nature, is therefore reported in the family Anisophylleaceae for the first time. Furthermore, the following minor phenolic compounds namely tyrosol, 2-(3-methoxy, 4-hydroxyphenyl)-ethanol, vanillin, syringaldehyde, vanillic acid, syringic acid, gallic acid and ferulic acid were also identified by GC-MS in this species for the first time.

Polyphenol composition and antioxidant potential of Hibiscus esculentus L. fruit cultivated in Nigeria.

Consumption of certain fruits and vegetables is now widely associated with chemoprevention of degenerative diseases like cancer and cardiovacsular disorders because of their antioxidant components. Polyphenols, a heterogeneous group of compounds, are one of these constituents. Hibiscus esculentus L. (Family Malvaceae), commonly referred to as okro, okra, or lady's finger, is an important component of diet in Nigeria and other countries in sub-Saharan Africa. In this article, we describe the polyphenol composition and antioxidant potential of H. esculentus of Nigerian origin. Quercetin glucoside (quercetrin) and an unidentified flavonoid were detected. In vitro antioxidant assay of methanol extract of the fruits showed potent antioxidant/radical scavenging activities with 50% inhibitory concentration values of 25 and 43 microL when analyzed by the xanthine oxidase and 2-deoxyguanosine methods, respectively. These data suggest that H. esculentus, popular especially during the rainy season in Nigeria and many tropical West, Central, and Eastern African countries, is a good contributor to the antioxidant status and disease chemoprevention of people in these countries.

Evaluation of the polyphenol composition and antioxidant activity of African variety of Dacryodes edulis (G.Don) H.J Lam fruit.

Polyphenols are abundant micronutrients in our diet that have been credited with chemoprevention of diseases associated with oxidative stress. In this study, we investigated the whole ripened fruit of Dacryodes edulis (G.Don) H.J Lam, a multipurpose tree growing in West and Central Africa and other countries bordering the Gulf of Guinea, for polyphenol content as well as its antioxidant/radical scavenging capacity. Analysis of the methanol extract of the fruit by high-performance liquid chromatography coupled to an ultraviolet dual-array detector and mass-selective detector revealed the presence of catechol (9.27 mg/kg), gallate (10.40 mg/kg), methylgallate (0.88 mg/kg), ellagic acid (3.10 mg/kg), quercetin (0.21 mg/kg), and quercetin rhamnoside (0.76 mg/kg). The extract showed very high antioxidant potential (50% inhibitory concentration [IC(50)] = 14 microL), but a rather weak radical scavenging activity (IC(50) = 357 microL), when tested in vitro with the xanthine oxidase and 2-deoxyguanosine assay model systems, respectively. These results suggest that consumption of D. edulis could contribute to prevention of diseases that are related to oxidative stress.

Isolation, purification and identification of ellagic acid derivatives, catechins, and procyanidins from the root bark of Anisophyllea dichostyla R. Br.

The root bark of Anisophyllea dichostyla R. Br. is traditionally used in the Democratic Republic Congo for the treatment of several conditions such as anorexia, fatigue and intestinal infections. We have identified and quantitated several polyphenol antioxidants in the methanol extract of the root bark (120g). The polyphenol content (3.32g/kg) was predominantly ellagitannins (25%) and polyhydroxyflavan-3-ols (catechins and procyanidins, 75%) with 3'-O-methyl-3,4-methylenedioxo ellagic acid 4'-O-beta-d-glucopyranoside and (-)-epicatechin as the major species in each class. These two compounds and the following species were identified unequivocally by NMR spectroscopy: (+)-catechin, (-)-epicatechin 3-O-gallate, 3-O-methyl ellagic acid, 3,3'-di-O-methyl ellagic acid, 3'-O-methyl-3,4-methylenedioxo ellagic acid, 3'-O-methyl-3,4-methylenedioxo ellagic acid 4'-O-beta-d-glucopyranoside, and 3'-O-methyl ellagic acid 4-O-beta-d-xylopyranoside. The following additional compounds were purified by semi-preparative HPLC and tentatively identified on the basis of UV spectra, HPLC-ESI-MS and nano-ESI-MS-MS: (+)-catechin-3-O-beta-d-glucopyranoside, epicatechin-(4beta-->8)-catechin (procyanidin B(1)), epicatechin-(4beta-->8)-epicatechin (procyanidin B(2)), an (epi)catechin trimer, 3-O-methyl ellagic acid 4-O-beta-d-glucopyranoside, (-)-epicatechin 3-O-vanillate, 3,4-methylenedioxo ellagic acid 4'-O- beta-d-glucopyranoside, and 3,3'-di-O-methyl ellagic acid 4-O-beta-d-xylopyranoside. Fractionation of the raw extract by column chromatography on silicic acid yielded 10 fractions. In the hypoxanthine/xanthine oxidase antioxidant assay system, CC-9 which contained a range of polyphenols dominated by (-)-epicatechin-O-gallate proved to be the most potent antioxidant fraction (IC(50)=52 micro g/mL) in terms of ROS scavenging. In terms of XO inhibition CC-8, dominated by (epi)catechin trimer and which also contained appreciable amounts of 3'-O-methyl ellagic acid 4'-O-beta-d-xylopyranoside, as well as the catechins (+)-catechin-3-O-beta-d-glucopyranoside, epicatechin-(4beta-->8)-catechin (procyanidin B(1)), and (-)-epicatechin 3-O-gallate, proved to be the most potent (IC(50)=36 micro g/mL).

Contribution of linseed intake to urine and serum enterolignan levels in German females: a randomised controlled intervention trial.

Linseeds are a rich source of lignans, secondary plant substances which are suggested to possess chemopreventive effects inter alia with regard to breast cancer. In a randomised controlled trial 40 German women were informed about "5-a-day" and encouraged to increase their dietary intake of fruit and vegetables. Moreover 19 participants were randomly assigned to an intervention group supplemented with ground linseeds (20 g/d) over a 2-month period. Before and after intervention, urine and blood samples were collected after an overnight fast. Analysis was by intention-to-treat and the outcome parameters of interest were enterolignan concentrations. After linseed supplementation, enterolignan concentrations (mean) measured as their glucuronides by a newly developed high performance liquid chromatography electrospray mass spectrometry (HPLC-ESI-MS) in serum (122 nmol/l) as well as in urine (72 micromol/l) showed a significant increase (P<0.01) compared to pre-intervention values (47 nmol/l and 29 micromol/l). In the control group enterolignan levels were raised slightly but did not reach significance. Serum and urinary enterolignans of the whole collective showed a good pairwise correlation.

Isolation and structure elucidation of phenolic antioxidants from Tamarind (Tamarindus indica L.) seeds and pericarp.

Although it is already known that Tamarind (Tamarindus indica L.) seeds contain phenolic substances, the individual components of the seeds have not been fully identified and quantitated, and in the case of Tamarind pericarp not reported. Therefore, major polyphenolic compounds were extracted using organic solvents and the metabolites were isolated by semi-preparative high performance liquid chromatography. Their structures were elucidated by liquid chromatography-electrospray-ionisation-mass spectrometry (LC-ESI-MS), nano-electrospray-ionisation mass spectrometry (ESI-MS), and where possible by gas chromatography-mass spectrometry (GC-MS) and 1H and 13C NMR. Quantitative analysis of polyphenolic compounds in Tamarind seeds and pericarp was conducted by analytical high performance liquid chromatography (HPLC), calculated against standard curves of authentic compounds. The yields of total phenolic compounds after Soxhlet extraction with methanol were 6.54 and 2.82 g/kg (dry weight) in the seeds and pericarp respectively. The profile (%) of polyphenolics in Tamarind pericarp was dominated by proanthcyanidins (73.4) in various forms (+)-catechin (2.0), procyanidin B2 (8.2), (-)-epicatechin (9.4), procyanidin trimer (11.3), procyanidin tetramer (22.2), procyanidin pentamer (11.6), procyanidin hexamer (12.8) along with taxifolin (7.4), apigenin (2.0), eriodictyol (6.9), luteolin (5.0) and naringenin (1.4) of total phenols, respectively. The content of Tamarind seeds comprised only procyanidins, represented (%) mainly by oligomeric procyanidin tetramer (30.2), procyanidin hexamer (23.8), procyanidin trimer (18.1), procyanidin pentamer (17.6) with lower amounts of procyanidin B2 (5.5) and (-)-epicatechin (4.8). Extraction of Tamarind pericarp and seeds using acetone:methanol:acetic acid gave only procyanidin oligomers, but in much higher yield and variety. The antioxidant capacities of the Soxhlet methanolic extracts were determined, and indicates that Tamarind may be an important source of cancer chemopreventive natural products in tropical regions.

Olives and olive oil in cancer prevention.

Epidemiologic studies conducted in the latter part of the twentieth century demonstrate fairly conclusively that the people of the Mediterranean basin enjoy a healthy lifestyle with decreased incidence of degenerative diseases. The data show that populations within Europe that consume the so-called 'Mediterranean diet' have lower incidences of major illnesses such as cancer and cardiovascular disease. Studies have suggested that the health-conferring benefits of the Mediterranean diet are due mainly to a high consumption of fibre, fish, fruits and vegetables. More recent research has focused on other important factors such as olives and olive oil. Obviously fibre (especially wholegrain-derived products), fruits and vegetables supply an important source of dietary antioxidants. What is the contribution from olives and olive oil? Apparently the potential is extremely high but epidemiologic studies rarely investigate consumption of these very important products in-depth, perhaps due to a lack of exact information on the types and amounts of antioxidants present. Recent studies have shown that olives and olive oil contain antioxidants in abundance. Olives (especially those that have not been subjected to the Spanish brining process) contain up to 16 g/kg typified by acteosides, hydroxytyrosol, tyrosol and phenyl propionic acids. Olive oil, especially extra virgin, contains smaller amounts of hydroxytyrosol and tyrosol, but also contains secoiridoids and lignans in abundance. Both olives and olive oil contain substantial amounts of other compounds deemed to be anticancer agents (e.g. squalene and terpenoids) as well as the peroxidation-resistant lipid oleic acid. It seems probable that olive and olive oil consumption in southern Europe represents an important contribution to the beneficial effects on health of the Mediterranean diet.