Determination of cyclopiazonic acid in peanuts and corn by thin layer chromatography

A thin layer chromatographic system including densitometry has been developed for determining cyclopiazonic acid in peanuts and corn. Samples are extracted with methanol-chloroform (20 + 80); the extract is stripped of most interferences by partitioning with aqueous sodium bicarbonate followed by acidification and repartitioning with chloroform. After thin layer chromatography and derivatization with dimethylaminobenzaldehyde-HCl spray, the toxin is quantitated by reflection densitometry at 540 nm. The recovery of cyclopiazonic acid averages 90% for peanuts and 85% for corn. The absolute detection limit is 25 ng per spot which translates to a detection limit of 125 micrograms/kg for a 50 g sample.     

Contribution to the quantification of humic acids by thin layer chromatography

Increasing amounts from 2.5 to 45 μg of one synthetic and seven natural humic acids were chromatographed on silica gel thin layers using ammonia 25% and propanol in the ratio 70:30 v/v as mobile phase. The fragments of humic acids produced under the influence of the alkaline mobile phase were separated in three band-shaped chromatographic fractions, whose lengths were transverse to the direction of the mobile phase. Since the fragments were not formed in constant ratios from different quantities of the same humic acid, the length of a fraction could only reflect its content of humic substance, whereas the sum of lengths of the three fractions (F) reflected quantities of the humic acid (x) at starting points. Similar F-x curves were obtained from humic acids extracted from similar origins, even when the locations of the samples, particle weights of the humic acids or the pH values at which they were extracted were different. The mathematical relation between F and x for quantities of humic acids up to 15–20 μg possessed high correlation coefficients and may be thus applied for the estimation of unknown concentrations of humic acids extracted from similar origins.     

Identification of mammalian feces by thin layer chromatography of coprostanol: collaborative study

Mammalian feces contain coprostanol (5 beta-cholestan-3 beta-ol). In this study, 7 collaborators each tested 45 unknown specimens by a thin layer chromatographic method that uses coprostanol as an indicator of feces. The materials tested were 5 replicates each of 3 test portion sizes (0.5, 1.0, and 5.0 mg) of cockroach excreta (negative), and cow and rat feces (both positive). Of 315 specimens tested, 261 (82.9%) were correctly identified; there were 5 false positives, 26 false negatives, and from 1 collaborator, 23 inconclusive results.     

Determination of bergapten in fragrance preparations by thin layer chromatography and spectrophotofluorometry.

A method has been developed for the determination of bergapten (5-methoxypsoralen), a known phototoxin, in perfumes,colognes, and toilet waters. The bergapten and other lactonic compounds were first isolated from the sample by a series of extractions. The extract containing the bergapten was diluted to a known volume and a aliquot was spotted on a thin layer chromatographic (TLC) plate coated with silica gel G. After 2-dimensional development with hexane - carbon tetrachloride - tert - butylamine (180+12+9) and hexane-toluene-ethyl acetate-acetic acid (100+10+15+0.5), the TLC plate was dried and the emitted fluorescence of bergapten was measured, using a spectrophotofluorometer equipped with a TLC accessory and coupled to an automatic digital integrator. The amount of bergapten was determined by comparing its peak area to those of bergapten standards. The average recovery for levels of 0.001, 0.005, and 0.01% bergapten was 88%.     

3-(4'-hydroxyl-3',5'-dimethoxyphenyl)propionic acid, an active principle of kimchi, inhibits development of atherosclerosis in rabbits

The effects of 3-(4'-hydroxyl-3',5'-dimethoxyphenyl)propionic acid (HDMPPA) originating from Korean cabbage kimchi were investigated, showing an antioxidant effect on the prevention of atherosclerosis in hypercholesterolemic rabbits. Twenty-one 3-month-old rabbits were fed an atherogenic diet containing 0.5% (w/w) cholesterol and 10% (w/w) coconut oil, whereas another two groups were given an atherogenic diet with intravenous injection of either HDMPPA or simvastatin (0.33 mg/kg/day) for 4 weeks. HDMPPA inhibited the oxidative modification of low-density lipoprotein (IC 50 = 1.4 microg/mL) and increased 2,2'-diphenyl-1-picrylhydrazyl radical scavenging activity (IC 50 = 0.78 microg/mL) in a dose-dependent manner. In hypercholesterolemic rabbits, the thickness of intima of aorta of the HDMPPA group was significantly reduced (control versus HDMPPA, 42%; simvastatin, 38%) without a plasma cholesterol-lowering effect. Thiobarbituric acid reactive substance formation in the plasma of the HDMPPA group was significantly decreased compared to that of the control group. Furthermore, the generation of vascular reactive oxygen species in HDMPPA group was suppressed as the cyclooxygenase-2 protein level decreased. These findings suggest that HDMPPA prevents the development of aortic atherosclerosis in high-cholesterol-fed rabbits. The antiatherosclerotic effect of HDMPPA may be due to an antioxidative effect at a low dose without cholesterol-lowering effects.     

Quantitative determination of tris-(2,3-dibromopropyl) phosphate by densitometry of thin layer chromatograms

The flame retardant tris-(2,3-dibromopropyl) phosphate (Tris) was chromatographed on silica gel thin layer plates, using ethyl acetate-hexane (30+70) as the developing solvent. Tris was visualized by spraying the chromatogram with 1% aqueous silver nitrate followed by exposure to ultraviolet light for 40 min. Tris appeared as dark gray spots on a white background; the spots were quantitated by densitometry at 660 nm. The lower level of sensitivity was 50 ng; calibration plots were linear from 50 to 800 ng. The procedure was developed to determine the levels of unmetabolized Tris remaining after exposure to sewage sludge suspensions. Recovery of Tris from 3 sewage sludge samples fortified at the 1.0 ppm level averaged 97%.     

Photodegradation of 1-(2-chlorobenzoyl)-3-(4-chlorophenyl) urea in different media and toxicity of its reaction products

The photodegradation of 1-(2-chlorobenzoyl)-3-(4-chlorophenyl) urea in simulated air, methanol, dioxane, hexane, and water, with a xenon lamp as light source, was studied. The rate constants and half-lives of this compound in various media under nitrogen or oxygen were determined. The photoreaction products were analyzed with HPLC-UV, GC-MS, and direct probe MS and found to have some differences in different cases. With (32)P postlabeling DNA adduct formation experiments, one of the main products, 2-chorobenzamide, was found to be able to form a DNA adduct.     

Comparison of microbial communities in percolating water from plow layer and subsoil layer estimated by phospholipid fatty acid (PLFA) analysis

Abstract

The amount and composition of phospholipid fatty acids (PLFAs) in the percolating water taken from different depths of soil (10 cm, PW10; 40 cm, PW40) and floodwater (FW) in a paddy field were compared during the period of rice cultivation. The amounts of PLFAs in PW10, PW40, and FW ranged from 22.6 to 46.2 μg L^?1, from 22.3 to 54.5 μg L^?1, and from 82.9 to 179.0 μg L^?1, respectively. The PLFA profiles in PW10, PW40, and FW were similar to each other and 16 : 1ω7c, 18 : 1ω7, and 16 : 0 PLFAs were dominant components, irrespective of the sampling site and sampling time. High proportions of straight mono-unsaturated PLFAs ranging from 42.0 to 76.5% suggested that Gram-negative bacteria were the major members in the microbial communities of the water samples studied. A potential indicator of the environmental stresses imposed upon the microbiota that was represented by the trans vs. cis ratio of 16 : 17 PLFA was constantly low (< 0.05), indicating that the microbial communities at these sites were hardly stressed.     

Simultaneous determination of kaempferol and quercetin in Heteropogon Contortus (L.) Beauv. by validated high-performance thin layer chromatography

Presently, the fingerprint analysis of kaempferol and quercetin has been developed simultaneously via High-Performance Thin Layer Chromatography (HPTLC) from leaves, stem, and inflorescence of Heteropogon contortus. The HPTLC method for kaempferol and quercetin was optimized with the elution of toluene: ethyl acetate: formic acid (7:3:0.5 v/v) as a mobile phase. The fingerprint analysis of kaempferol and quercetin was developed at R_f values of 0.39 and 0.24, respectively, and densitometric evaluation was done at 254 nm. The linear regression data for the calibration curve of both the compounds show a good linear relationship in the concentration range of 2–12 nanogram spot^?1. The suggested method has been validated in terms of limit of detection (LOD) and limit of quantification (LOQ), precision, specificity, sensitivity, and accuracy. Present results show that maximum amount of kaempferol and quercetin is found in leaf extracts (35.80 and 17.01 milligram/gram of dry weight, respectively) of H. contortus.     

Degradation studies on benzoxazinoids. Soil degradation dynamics of (2R)-2-O-beta-D-glucopyranosyl-4-hydroxy-(2H)- 1,4-benzoxazin-3(4H)-one (DIBOA-Glc) and its degradation products, phytotoxic allelochemicals from Gramineae

Wheat (Triticum aestivum L.) has been found to possess allelopathic potential and studies have been conduced to apply wheat allelopathy for biological weed control. 2,4-Dihydroxy-(2H)-1,4-benzoxazin-3(4H)-one (DIBOA) is a common product found in wheat, corn, and rye exudates and it can be released to the environment by that way. In this report, the stability of DIBOA is studied in two soils from crop lands of wheat cv. Astron and cv. Ritmo. These varieties were selected by their concentrations of DIBOA and 2,4-dihydroxy-7-methoxy-(2H)-1,4-benzoxazin-3(4H)-one (DIMBOA) from aerial parts and by the bioactivities of their aqueous extracts in the growth of wheat coleoptile sections. The degradation rate of DIBOA in these soils was measured in laboratory tests during 90 h by high-pressure liquid chromatography methods. These analyses demonstrate that DIBOA was transformed primarily into 2-benzoxazolinone (BOA). This transformation was similar in both soil types with an average half-life of 43 h. The degradation studies for BOA show its biotransformation to 2-aminophenoxazin-3-one (APO) with a half-life of 2.5 days. Therefore, BOA is an intermediate product in the biotransformation from DIBOA to APO in these wheat crop soils and is consistent with previous findings. APO was not degraded after three months in soil, suggesting that its degradation rate in soil is very slow.     

Analysis of neurotoxin 3-N-oxalyl-L-2,3-diaminopropionic acid and its alpha-isomer in Lathyrus sativus by high-performance liquid chromatography with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) derivatization

A method was developed for the quantitative determination of the neurotoxic nonprotein amino acid, 3-N-oxalyl-L-2,3-diaminopropionic acid (beta-ODAP), and its nontoxic alpha-isomer, 2-N-oxalyl-L-2, 3-diaminopropionic acid (alpha-ODAP), in the plant samples of Lathyrus sativus after derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) by reversed-phase high-performance liquid chromatography (HPLC). Hippuric acid was used as an internal standard. A linear response was recorded in the concentration rang 0.32-32 nmol with r > 0.999. The RP HPLC detection limit for both isomers is 1.8 ng. According to different experimental needs, a ternary gradient system can be used to determine toxin and other nonprotein amino acids. The RP HPLC method and a colorimetric method were compared for measuring ODAP.     

Metabolism of 7-fluoro-6-(3,4,5,6-tetrahydrophthalimido)-4- (2-propynyl)-2H-1,4-benzoxazin-3(4H)-one (S-53482) in rat. 1. Identification of a sulfonic acid type conjugate

To examine the metabolic fate of 7-fluoro-6-(3,4,5, 6-tetrahydrophthalimido)-4-(2-propynyl)-2H-1,4-benzoxazin-3( 4H)-one (S-53482), rats were given a single oral dose of [phenyl-(14)C]-S-53482 at 1 (low) or 100 (high) mg/kg. The radiocarbon was almost completely eliminated within 7 days after administration in both groups. (14)C recoveries (expressed as percentages relative to the dosed (14)C) in feces and urine were 56-72 and 31-43%, respectively, for the low dose and 78-85 and 13-23%, respectively, for the high dose. S-53482 and seven metabolites were identified in urine and feces. Six of them were purified by several chromatographic techniques and identified by spectroanalyses (NMR and MS). Alcohol derivatives and an acetoanilide derivative were isolated from urine. Three sulfonic acid conjugates having a sulfonic acid group incorporated into the double bond of the 3,4,5,6-tetrahydrophthalimide moiety were isolated from feces. On the basis of the metabolites identified in this study, the metabolic pathways of S-53482 in rats are proposed.