Presencia de actividad mutagénica en frijoles (Phaseolus vulgaris L) sin nitrosar / Mutagenic activity of beans (Phaseolus vulgaris) without nitrosation

Extractos acuosos de trece muestras de frijoles (Phaseolus vulgaris L) adquiridos en el mercado local fueron analizados por el método de Ames utilizando la cepa Salmonella typhimurium LT2 TA102. Cinco de las muestras mostraron actividad mutagénica (tasa de reversión mayor a 1,5). A diferencia de estudios anteriores, no se observó efecto sinérgico entre la sal y la nitrosación, individual o conjuntamente, sobre la actividad mutagénica detectada

Inhibitory effects of licochalcone A isolated from Glycyrrhiza inflata root on inflammatory ear edema and tumour promotion in mice.

Licochalcone A, 3-a,a-dimethylallyl-4,4'-dihydroxy-6-methoxychalcone, from the root of Glycyrrhiza inflata Beta (Leguminosae) (Xin-jiang liquorice) showed anti-inflammatory action towards mouse ear edema induced by arachidonic acid (AA) and 12-O-tetradecanoylphorbol 13-acetate (TPA) by topical application. Anti-tumour promoting action of licochalcone A was also observed in vivo for mouse skin papilloma initiated by dimethylbenz[a]anthracene (DMBA) and promoted by TPA. It inhibited in vitro 32Pi-incorporation to phospholipids in HeLa cells promoted by TPA. A competitive interaction of licochalcone A with the TPA-receptors in the cell membrane has been suggested.

Protein secondary structure of the isolated photosystem II reaction center and conformational changes studied by Fourier transform infrared spectroscopy.

The secondary structure of the photosystem II (PSII) reaction center isolated from pea chloroplasts has been characterized by Fourier transform infrared (FTIR) spectroscopy. Spectra were recorded in aqueous buffers containing H2O or D2O; the detergent present for most measurements was dodecyl maltoside. The broad amide I and amide II bands were analyzed by using second-derivative and deconvolution procedures. Absorption bands were assigned to the presence of alpha-helices, beta-sheets, turns, or random structure. Quantitative analysis revealed that this complex contained a high proportion of alpha-helices (67%) and some antiparallel beta-sheets (9%) and turns (11%). An irreversible decrease in the intensity of the band associated with the alpha-helices occurs upon exposure of the isolated PSII reaction center to bright illumination. This loss of alpha-helical content gave rise to an increase in other secondary structures, particularly beta-sheets. After similar pretreatment with light, sodium dodecyl sulfate polyacrylamide gel electrophoresis reveals lower mobility and solubility of constituent D1 and D2 polypeptides of the PSII reaction center. Some degradation of these polypeptides also occurs. In contrast, there is no change in the mobility of the two subunits of cytochrome b559. In the absence of illumination, the PSII reaction center exchanged into dodecyl maltoside shows good thermal stability as compared with samples in Triton X-100. Only at a temperature of about 60 degrees C do spectral changes take place that are indicative of denaturation.

Inhibitors of human and bovine trypsin and chymotrypsin in fenugreek (Trigonella foenum-graecum L.) seeds. Demonstration and purification.

Fenugreek contained proteinase inhibitors inhibiting 5-9 mg human trypsin, 5-7 mg bovine trypsin, 2-6 mg human chymotrypsin, and 1-3 mg bovine chymotrypsin per g seed material. About 30 inhibitors were electrophoretically detected, and 23 of them, inhibiting all the four enzymes, were characterized by means of their isoelectric points: a group of acid inhibitors (TFI-A1 to A10, pI 4.48-5.12), a group of neutral inhibitors (TFI-N1 to -N6, pI 5.91-6.71), and a group of basic inhibitors (TFI-B1 to -B7, pI 7.76-9.77). To eliminate the galactomannans which complicate further purification, coarsely ground seeds were separated by density into two fractions, seed coats + endosperm and cotyledons + embryos (C + E). Isolation of the fenugreek inhibitors by extraction of fraction C + E, followed by ammonium sulfate fractionation and affinity chromatography on anhydrotrypsin-Sepharose, resulted in an about 700-fold enrichment.

Determination of oxyfluorfen herbicide and oxyfluorfen amine residues in garbanzo beans by liquid chromatography.

Oxyfluorfen and oxyfluorfen amine were determined by liquid chromatography (LC) with ultraviolet (UV) and photoconductivity detection (PCD). A simple extraction procedure acceptably recovered both analytes from garbanzo beans over a wide range of fortifications (0.05 to 20 ppm) (83 +/- 4 for oxyfluorfen; 85 +/- 4 for oxyfluorfen amine). Percent recoveries decreased slightly as the fortification level decreased. Both analytes could be determined simultaneously at a concentration greater than 0.2 ppm in garbanzo beans. Detection limits were 3 ng for oxyfluorfen and 100 ng for oxyfluorfen amine using LC/UV, and 12 ng for both oxyfluorfen and oxyfluorfen amine with LC/PCD. Different knitted reaction coils and photoreactors were evaluated. Photoproduct yields and identification were determined by ion chromatography. The LC/PCD method measures oxyfluorfen and oxyfluorfen amine separately and has a shorter analysis time, while the standard method using gas chromatography measures total residues and is more sensitive.

Periandradulcins A, B and C: phosphodiesterase inhibitors from Periandra dulcis Mart.

During the course of our screening of bioactive natural products, three new saponins named periandradulcins A (1), B (2) and C (3) were isolated as phosphodiesterase (PDE, EC 3.1.4.17) inhibitors from 80% MeOH extract of the roots of Periandra dulcis Mart. (Leguminosae) by a combination of column chromatography and reversed- and normal-phase high-performance liquid chromatography (HPLC). On the basis of 1H-, 13C- and two-dimensional nuclear magnetic resonance (NMR) spectral data and chemical evidence, their chemical structures were characterized as 3-O-beta-[alpha-L-rhamnopyranosyl(1----2)-beta-D-xylopyranosyl(1----2)-b eta-D- glucuronopyranosyl]-30-hydroxyl-25-formylolean-18-ene-22 beta-O-syringate, 3-O-beta-[alpha-L-rhamnopyranosyl(1----2)-beta-D- xylopyranosyl(1----2)-beta-D-glucuronopyranosyl]-22 beta-hydroxyl-25- formylolean-12-ene and 3-O-beta-[alpha-L-rhamnopyranosyl(1----2)-beta-D- glucopyranosyl(1----2)-beta-D-glucuronopyranosyl]-22 beta-hydroxyl-25-formylolean-18-ene, respectively. The concentrations of periandradulcins A, B and C required to give 50% inhibition (IC50 values) of PDE from bovine heart, were 0.033, 7.6 and 7.7 microM, respectively. Compound 1 was the most potent among the known PDE inhibitors; it inhibited PDE-I (IC50:0.0022 microM) twenty and forty times more effectively than PDE-II and -III, respectively.

Exposure to N-nitrosamines and other risk factors for gastric cancer in Costa Rican children.

The hypothesis that endogenous chemical nitrosation in the normal stomach in early life could play a crucial role in inducing chronic atrophic gastritis/intestinal metaplasia in later life was tested by applying the N-nitrosoproline (NPRO) test to 12-h urine samples from about 50 children (aged 8-14 years) living in high- and low-risk areas for stomach cancer. The median values of NPRO and the sum of four nitrosamino acids analysed were 0.28-0.84 micrograms/12 h and 0.75-1.75 micrograms/12 h, respectively. The NPRO level after proline intake was significantly higher in children from a high-risk area than in those from a low-risk area (p less than 0.04), and markedly reduced after ingestion of ascorbic acid and proline (p less than 0.05). Urinary nitrate level was lower than that of adults. NPRO levels on the day of proline intake, however, correlated well with nitrate levels (p less than 0.001), indicating that children in a high-risk area in Costa Rica have high endogenous nitrosation potential. Blood samples were also collected from about 300 children (aged 7-20 years) and analysed for antibodies against Campylobacter pylori, a suspected gastritis-causing bacteria. About 71% of children in both high- and low-risk areas for stomach cancer had antibodies. In addition, raw and cooked beans, which are consumed very frequently in Costa Rica, were collected from families in both areas and analysed for levels of nitrite/nitrate, total N-nitroso compounds and genotoxicity in the SOS chromotest.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on the preparative capability of the horizontal flow-through coil planet centrifuge and high-performance liquid chromatography in the separation of polar compounds from Oxytropis ochrocephala Bunge.

Horizontal flow-through coil planet centrifuge (CPC) and high-performance liquid chromatography (HPLC) techniques were used for separation of polar compounds from a crude ethanol extract of Oxytropis ochrocephala Bunge, a poisonous legume plant widely distributed in northwestern China. The performance of these two chromatographic methods was compared in terms of column efficiency, peak resolution, separation time, sample loading capacity, etc. The results indicated that two polar compounds in the crude extract were equally well separated by these two methods. HPLC gave comparable peak resolution in shorter separation time while its sample loading capacity was limited to the mg range. The CPC method required a long separation time, but yielded a higher purity of fractions with a much greater capacity.

Comparison of the amino acid sequences of the lectins from seeds of Dioclea lehmanni and Canavalia maritima.

The amino acid sequences of the major lectins from the seeds of Dioclea lehmanni and Canavalia maritima were determined by DABITC/PITC microsequence analysis of peptides derived from the proteins by enzymatic digestions with trypsin, chymotrypsin and the protease from S. aureus V8. These sequences were found to be very similar to those of the lectins from Dioclea grandiflora and Canavalia ensiformis (Con A). The D. lehmanni lectin was unusual amongst legume lectins in that it contained a single Cys.

Composition, structure, functionality, and chemical modification of legume starches: a review.

The major carbohydrate of the legume seed is starch, which represents up to 45% of the total seed weight. In recent years, substantial progress has been made in understanding the relationship between starch structure and functionality. However, these studies have been mainly on cereal and tuber starches. The present status of knowledge on the composition, structure, functionality, digestibility, and chemical modification of legume starches is reviewed. In addition present concepts of granule structure, gelatinization, retrogradation, and rheology are also reviewed. Future research needs in the area of legume starch chemistry are discussed.

Effect of sprouting on the nitrogenous constituents and mineral composition of pigeon pea (Cajanus cajan) seeds.

The study was aimed at evaluating the effect of sprouting on nitrogenous constituents and mineral composition of cream pigeon pea seeds. After 48 and 96 h of sprouting, there were increases in % moisture, crude protein, ash except during the 96 h; total nitrogen (TN), total non-protein nitrogen (TNPN); protein nitrogen (PN) and true protein nitrogen (TP). Sprouting caused increases in mineral levels except for phosphorus (P). Sprouting for 48 h offers greater advantage over 96 h.

The biochemical composition and nutritional potential of the tribal pulse, Mucuna gigantea (Willd) DC.

Seeds of the tribal pulse, Mucuna gigantea, were analysed for proximate composition, total (true) seed proteins, seed protein fractionation, amino acid composition, minerals and antinutritional factors. Crude proteins, crude lipids, ash and nitrogen free extractives constituted 30.62%, 9.03%, 5.99% and 42.79%, respectively. The calorific values of 100 g dry matter of seed material is 374.91 kCal. The essential amino acids, leucine + isoleucine, are present in relatively large quantities. The seeds are rich in minerals like K, Ca, Mg and Fe. Antinutritional substances like total free phenols and tannins, trypsin inhibitor activity and haemagglutinating activity also were investigated.

[Studies on the chemical constituents of Flemingia philippinensis].

Two new prenylated flavonoids, flemiphilippinin C (I) and flemiphilippinin D (II) have been isolated from the root of Flemingia philippinensis (Merr. et Rolfe) Li along with four known compounds. The structure of I and II were elucidated as 7-(.4'-hydroxy-3'-methoxyphenyl)-5-hydroxy-2, 2-dimethyl-10-prenyl-2H,6H-benzo-[1,2-b:5,4-b']dipyran-6-one and 5,7,2',4'-tetrahydroxy-6,8-diprenylisoflavanone, respectively, on the basis of chemical and spectroscopic data. The four known compounds were identified as 5,7,3',4'-tetrahydroxy-6,8-diprenylsilflavone (III), flemichin D (IV), beta-sitosterol (VI) and lupeol (VII), and a mixture of n C22-C30 aliphatic acid (V). Compounds III and IV showed significant cytotoxic activities against P388 cell cultures.

Lipoxygenase-mediated secretory effect of canatoxin the toxic protein from Canavalia ensiformis seeds.

Canatoxin was shown to induce serotonin release from rabbit platelets and rat brain synaptosomes, as well as to release insulin from isolated pancreatic islets. All these effects were dose-dependent and were inhibited by lipoxygenase inhibitors, such as nordihydroguaiaretic acid and esculetin, but not by indomethacin, a cyclooxygenase inhibitor. The data suggest that canatoxin-induced secretory effect results from the activation of the lipoxygenase pathway which would elicit exocytosis. Thus, canatoxin might be a useful tool for the study of biological events that involve lipoxygenase mediation.

Red kidney bean poisoning in the UK: an analysis of 50 suspected incidents between 1976 and 1989.

Between July 1976 and February 1989, 50 incidents of suspected red kidney bean poisoning were reported in the UK. Nine incidents in which nausea, vomiting and diarrhoea developed within 1-7 h of ingestion, were confirmed by the detection of haemagglutinin in the beans. The diagnosis was made on a further 23 incidents on the basis of symptoms, incubation time and the description of preparation of beans prior to consumption. The haemagglutinin (lectin), which occurs naturally in the red kidney bean, is inactivated by thorough cooking of well soaked beans. In many of the outbreaks reported the implicated beans were consumed raw or following an inadequate heat process.

The effect of the consumption of red kidney beans (Phaseolus vulgaris) on the growth of rats and the implications for human populations.

Raw Red Kidney beans (Phaseolus vulgaris) at a level as low as 1% of diet have been shown to cause death in rats in two weeks. Beans cooked at 100 degrees for 30 mins, and incorporated at a level as high as 20% of diet do not retard growth when tested against casein. However, when beans which have cooked at 70 degrees for 30 mins are incorporated growth retardation is almost as great as that which occurs when raw beans are fed. The small amount of lectin present in beans cooked at 70 degrees might be responsible for this effect.

Amino acid sequence and disulfide bridges of affinity purified Kunitz-type chymotrypsin inhibitor from winged bean seed (Psophocarpus tetragonolobus (L.) DC).

The primary sequence of the affinity purified chymotrypsin inhibitor, WBCI, isolated from the albumin fraction of Psophocarpus tetragonolobus (L.) DC cv. UPS-122 seed was determined. The inhibitor consisted of a single polypeptide chain of 183 amino acids (Mr 20285) and the four half-cystine residues in the molecule formed two intramolecular disulfide bridges equivalent to those in other Kunitz-type seed inhibitors. The sequence of this chymotrypsin inhibitor was identical to that of chymotrypsin inhibitor-3 from cultivar UPS-31 and it showed about 50% sequence similarity to the winged bean acidic (WBTI-2, pI 5.1) and basic (WBTI-1, pI 8.9) trypsin inhibitors. Sequence similarities to other Kunitz-type seed inhibitors are discussed.

Identification and characterization of a GroEL homologue in Rhodobacter sphaeroides.

A protein closely related to the Escherichia coli GroEL protein has been isolated from Rhodobacter sphaeroides. Native and SDS-polyacrylamide gel electrophoresis of this protein have shown that it is present in the cell as a multimeric complex of Mr 670,000 which is composed of a monomer of Mr 58,000. Antisera raised against the Mr 58,000 polypeptide have been shown to cross-react with GroEL and the alpha subunit of the pea plastid chaperonin. The N-terminal amino acid sequence of the Mr 58,000 polypeptide is identical to that of GroEL at 15 of 19 residues and is also closely related to the alpha subunit of the pea plastid chaperonin, though less so to the beta subunit.

Characterization of U6 small nuclear RNA cap-specific antibodies. Identification of gamma-monomethyl-GTP cap structure in 7SK and several other human small RNAs.

The cap structure in human U6 small nuclear (sn)RNA, gamma-monomethylguanosine triphosphate (meGTP), was conjugated to human serum albumin and used as antigen to raise polyclonal antibodies in rabbits. The resulting antibodies reacted specifically with meGTP but not with GTP, GDP, GMP, meGMP, meATP, meCTP, meUTP, or with methyl phosphate in enzyme-linked immunosorbent assay and/or in radioimmunoassays. Although less efficiently, meGDP was also recognized by these antibodies. Indirect immunofluorescence studies with anti-meGTP antibodies showed predominantly nuclear immunofluorescence. Anti-meGTP antibodies immunoprecipitated intact U6 snRNA from a mixture of HeLa cell RNAs. In addition to the U6 snRNA, anti-meGTP antibodies immunoprecipitated several additional small RNAs that varied in length from approximately 50 to 330 nucleotides. These RNAs contained the meGTP cap structure and are structurally distinct from U6 snRNA. One of these meGTP-containing RNAs was found to be previously characterized 7SK RNA; human 7SK RNA synthesized in vitro also contained the same cap structure. Results obtained in this study provide evidence for the presence of gamma-monomethyl-GTP cap structure in a wide spectrum of human cellular RNAs. These antibodies will be useful in studying the structure and function of this new family of small RNAs.

An improved high performance liquid chromatographic method for thiamin analysis in foods.

A high performance liquid chromatography (HPLC) procedure for the determination of thiamin in foods has been developed. Acid and enzymatic extracts of food samples were subjected to purification and chromatographic conditions which allowed the quantification of thiamin in foods with only a low content. Reverse-phase ion pair chromatography, using mixtures of sodium hexanesulfonate and sodium heptanesulfonate as counterions and detection at 254 nm, was employed. The lowest detection limit for thiamin was 0.5 ng/injection. Analyses of four samples of legumes and lyophilized meat and milk and the recovery for standard thiamin are given. Mean recovery values of extraction and purification procedure ranged over 97-98%.