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.

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.

Characterization of alkyl phenols in cashew (Anacardium occidentale) products and assay of their antioxidant capacity.

In this study the content of anacardic acids, cardanols and cardols in cashew apple, nut (raw and roasted) and cashew nut shell liquid (CNSL) were analysed. The higher amounts (353.6 g/kg) of the major alkyl phenols, anacardic acids were detected in CNSL followed by cashew fibre 6.1 g/kg) while the lowest (0.65 g/kg) amounts were detected in roasted cashew nut. Cashew apple and fibre contained anacardic acids exclusively, whereas CNSL also contained an abundance of cardanols and cardols. Cashew nut (raw and roasted) also contained low amounts of hydroxy alkyl phenols. Cashew nut shell liquid was used for a basic fractionation of the alkyl phenol classes and the individual anacardic acids, major cardanols and cardols were purified to homogeneity from these fractions by semi-preparative HPLC and definitively identified by nano-ESI-MS-MS, GC-MS and NMR analyses. The hexane extracts (10 mg/ml) of all cashew products tested plus CNSL, displayed significant antioxidant capacity. Cashew nut shell liquid was the more efficient (inhibition=100%) followed by the hexane extract of cashew fibre (94%) and apple (53%). The antioxidant capacity correlated significantly (P<0.05) with the concentration of alkyl phenols in the extracts. A mixture of anacardic acids (10.0 mg/ml) showed the higher antioxidant capacity (IC50=0.60 mM) compared to cardols and cardanols (IC50>4.0 mM). The data shows that of these substances, anacardic-1 was by far the more potent antioxidant (IC50=0.27 mM) compared to cardol-1 (IC50=1.71 mM) and cardanol-1 (IC50>4.0 mM). The antioxidant capacity of anacardic acid-1 is more related to inhibition of superoxide generation (IC50=0.04 mM) and xanthine oxidase (IC50=0.30 mM) than to scavenging of hydroxyl radicals. At present a substantial amount of cashew fibre is mostly used in formulations of animal or poultry feeds. The data presented in this study, indicates that this waste product along with CNSL, both of which contain high contents of anacardic acids, could be better utilized in functional food formulations and may represent a cheap source of cancer chemopreventive agents.

Nitrosatable amines and nitrosamide formation in natural stimulants: Cola acuminata, C. nitida and Garcinia cola.

Three varieties of kola nut, Cola acuminata, C. nitida and Garcinia cola, of Nigerian origin, were analysed for their content of primary and secondary amines, and assessed for their relative methylating potential due to nitrosamide formation. Primary and secondary amines were determined as benzene sulfonamides by gas chromatography/thermal energy analysis (GC/TEA). Dimethylamine, methylamine, ethylamine and isopentylamine were detected in all kola nut varieties, while pyrrolidine, piperidine and isobutylamine were detected in one or more varieties. Estimated average total daily intake of aliphatic amines by a typical kola nut chewer varied from 260 to 1040 micrograms/day for secondary amines and from 2430 to 9710 micrograms/day for primary amines. Methylating activity of the nitrosated kola nuts, expressed as N-nitroso-N-methylurea equivalents, was also determined by GC/TEA. Methylating activity was significantly higher in kola nuts (170-490 micrograms/kg) than has ever been reported for a fresh plant product. These data suggest that the possible role of kola nut chewing in human cancer aetiology should be explored in countries where kola nuts are widely consumed as stimulants.

Secondary amine precursors to nitrosamines in human saliva, gastric juice, blood, urine and faeces.

It has been suggested that the endogenous nitrosation of aliphatic, cyclic and heterocyclic secondary amines in the urinary bladder of patients with chronic urinary bacterial infections and in the human stomach may provide an important additional source of exposure to carcinogenic volatile N-nitrosamines. The most commonly occurring nitrosatable secondary amines found in human saliva, gastric juice, blood, urine and faeces are dimethylamine (DMA), pyrrolidine (PYR) and piperidine (PIP). All of 40 analysed samples of gastric juice contained 0.87 +/- 0.89 (SEM) microgram/ml DMA, 39 contained 1.35 +/- 2.53 microgram/ml PIP, 36 contained 0.18 +/- 0.15 microgram/ml PYR and 14 contained 0.05 +/- 0.11 microgram/ml diethylamine. Nitrate (14.0 +/- 15.7 microgram/ml) was present in all samples and 11 of 40 samples contained 0.43 +/- 1.38 microgram/ml nitrite. Only one gastric juice sample with pH less than 4.5 contained nitrite (0.1 microgram/ml). In paraplegics, patients with bladder augmentations and two control groups without bacterial infections of the urinary bladder, a mean daily excretion of 40.5-49.7 mg/day DMA, 19.4-23.8 mg/day PYR and 26.1-31.7 mg/day PIP was found. In both patient groups suffering from chronic bacterial infection of the urinary bladder, the corresponding volatile N-nitrosamines were formed by endogenous nitrosation and excreted in urine.

Mean daily intake of volatile N-nitrosamines from foods and beverages in West Germany in 1989-1990.

The levels of volatile N-nitrosamines were determined in 38 alcoholic drinks and 215 food samples prepared for human consumption using standard culinary practices. The analyses used gas chromatography-thermal energy analysis. Detectable levels were found in 80 (31.5%) of the individual samples. The average daily intake of volatile N-nitrosamines in West Germany in 1989-1990 was found to be: 0.28 microgram N-nitrosodimethylamine (NDMA)/day, 0.011 microgram N-nitrosopyrrolidine (NPYR)/day and 0.015 microgram N-nitrosopiperidine (NPIP)/day for men, and 0.17 microgram NDMA/day, 0.011 microgram NPYR/day and 0.015 microgram/NPIP/day for women. For men, 31% of the daily NDMA exposure results from the consumption of beer.

Mean daily intake of primary and secondary amines from foods and beverages in West Germany in 1989-1990.

264 samples of foods and beverages from the German market in 1989-1990 were analysed for primary and secondary amines. Amines were determined as benzenesulphonyl chloride derivatives by gas chromatography with chemiluminescense detection. The mean daily intake of primary amines was calculated to be 29 mg/day for women and 37 mg/day for men. For secondary amines, the mean daily intake was 6 mg/day for women and 8 mg/day for men.

Determination of primary and secondary amines in foodstuffs using gas chromatography and chemiluminescence detection with a modified thermal energy analyser.

A simple method is described for the determination of primary and secondary amines in foodstuffs by gas chromatography with a modified thermal energy analyser, operated in the nitrogen mode. Food samples were subjected to mineral oil vacuum distillation and the isolated amines were derivatized with benzenesulphonyl chloride to form the corresponding sulphonamides, which were fractionated to yield primary and secondary amine derivatives using a modified Hinsberg procedure. The detection limit for individual amines using a 10-g food sample was 10 micrograms/kg (ppb) and recoveries were in excess of 80%.