Pharmacokinetics of (-)-epigallocatechin-3-gallate in conscious and freely moving rats and its brain regional distribution

A liquid chromatography technique coupled with tandem mass spectrometry (LC-MS/MS) electrospray ionization was used to measure (-)-epigallocatechin-3-gallate (EGCG) in rat plasma. This method was applied to investigate the pharmacokinetics of EGCG in a conscious and freely moving rat by an automated blood sampling device. Multiple reaction monitoring (MRM) was used to monitor the transition of the deprotonated molecule m/z of 457 [M - H]- to the product ion 169 for EGCG and the m/z of 187 to 164 for the internal standard. The limit of quantification (LOQ) of EGCG in rat plasma was determined to be 5 ng/mL, and the linear range was 5-5000 ng/mL. The protein binding of EGCG in rat plasma was 92.4 +/- 2.5%. The brain distribution result indicated that EGCG may potentially penetrate through the blood-brain barrier at a lower rate. The disposition of EGCG in the rat blood was fitted well by the two-compartmental model after intravenous administration (10 mg/kg, iv). The elimination half-life of EGCG was 62 +/- 11 and 48 +/- 13 min for intravenous (10 mg/kg) and oral (100 mg/kg) administration, respectively. The pharmacokinetic data indicate that the oral bioavailability of EGCG in a conscious and freely moving rat was about 4.95%.     

Bioavailability and tissue distribution of sesamol in rat

Sesamol, generally regarded as the main antioxidative component in sesame oil, can be generated from sesamolin by roasting sesame seed or bleaching sesame oil. This paper reports the bioavailability of sesamol in Sprague-Dawley (SD) rats. Biological fluid was sampled following a dose of sesamol of 50 mg/kg by gastric gavage (p.o.) or by intravenous injection. The pharmacokinetic data of sesamol were calculated by noncompartmental model. The tissue distribution of sesamol (p.o., 100 mg/kg) in SD rats was also investigated. The concentration changes of sesamol were determined in various tissues and plasma within a 24 h period after oral administration of sesamol. The results showed that the oral bioavailability of sesamol was 35.5 +/- 8.5%. Sesamol was found to be able to penetrate the blood-brain barrier and go through hepatobiliary excretion. Sesamol conjugated metabolites were widely distributed in SD rat tissues, with the highest concentrations in the liver and kidneys and the lowest in the brain. It is postulated that sesamol is incorporated into the liver first and then transported to the other tissues (lung, kidneys, and brain). The major metabolites of sesamol distributed in the lung and kidney were glucuronide and sulfate.     

Mass spectrometric identification and high-performance liquid chromatographic determination of a flavonoid glycoside naringin in human urine

The aim of this study was to evaluate the absorption of a citrus flavonoid, naringin, as its glycosylated form. Six healthy volunteers (three males and three females) were studied. After a single oral administeration of 500 mg of naringin, intact naringin was isolated from 2-4 h urine. Isolated naringin was identified by the LC/electrospray ionization mass spectrometry (ESI-MS), MS/MS, and MS/MS/MS techniques. The cumulative urinary excretion of naringin and its metabolites (naringenin and naringenin glucuronides) was determined by HPLC for 0-24 h. Approximately 0.02% of the administered dose was recovered in urine as unchanged naringin, whereas urinary recoveries of naringenin and naringenin glucuronides were approximately 0.4 and 3.6% of the administered dose, respectively. It was concluded that trace amounts of orally administered naringin can be absorbed as the glycoside. However, it is not clear whether the glycoside is cleaved before or after absorption to generate naringenin.     

Sulfated ferulic acid is the main in vivo metabolite found after short-term ingestion of free ferulic acid in rats

The bioavailability of ferulic acid (FA; 3-methoxy-4-hydroxycinnamic acid) and its metabolites was investigated in rat plasma and urine after an oral short-term ingestion of 5.15 mg/kg of FA. Free FA, glucuronoconjugates, and sulfoconjugates were quickly detected in plasma with a peak of concentration found 30 min after ingestion. Sulfoconjugates were the main derivates ( approximately 50%). In urine, the cumulative excretion of total metabolites reached a plateau 1.5 h after ingestion, and approximately 40% were excreted by this way. Free FA recovered in urine represented only 4.9 +/-1.5% of the native FA consumed by rats. Glucuronoconjugates and sulfoconjugates represented 0.5 +/- 0.3 and 32.7 +/- 7.3%, respectively. These results suggested that a part of FA incorporated in the diet was quickly absorbed and largely metabolized in sulfoconjugates before excretion in urine.     

Enhanced absorption of anthocyanins after oral administration of phytic acid in rats and humans

Many studies on the bioavailability of polyphenols have been reported. However, the relative urinary excretions of AC are also low, ranging from 0.004% to 0.1%. By contrast, other polyphenols show higher urinary excretion levels. Here, we studied the enhancing effects of phytic acid (IP6) on absorption of blackcurrant anthocyanins (BCAs) in rats and humans. In rats after oral administration of BCAs (as 241 mg of AC/kg body weight) in IP6 (0%, 0.25%, 0.5%, 1%, 2.5%) solution, the ACs recovery in urine was increased dependent on IP6 dose. These results suggest that the IP6 enhances gastrointestinal absorption of ACs. At the further analysis of IP6 enhancement effect in rat, whereas BCAs were normally passed through the stomach and duodenum within 2 h, in IP6 group, after 2-6 h post-administration, stomach and jejunum content's weights were specifically heavy, and large amounts of ACs were also detected in stomach, duodenum, and jejunum. These results suggested that the mixture of BCAs and IP6 reduced the gastrointestinal motility. Prolongation of ACs residue in gastrointestinal tract then caused the enhancing effects of IP6 on absorption of AC. In the human study, each subject was orally administrated a BCA beverage containing BCA concentrate (AC 4 mg/kg body weight), 1% of IP6, and 1% of sodium citrate as a pH stabilizer. Both the plasma level and the urinary excretion of AC were increased as compared to BCA administration without IP6. AC intake with IP6 may increase the bioavailability of AC to the comparative level as other polyphenols. Yet, phytic acid, being a strong chelator of important minerals, contributes to mineral deficiencies. An interference with iron uptake has been reported. Safety tests are therefore necessary before high dose IP6 can be used in foods.     

Identification of urinary and intestinal bacterial metabolites of ellagitannin geraniin in rats

Hydrolyzable tannins, including ellagitannins, occur in foods such as berries and nuts. Various biological activities, including antioxidant, antiviral, and antitumor activities, have been noted and reported for ellagitannins, but the absorption and metabolism of purified ellagitannins are poorly understood. We describe herein the characterization of urinary and intestinal microbial metabolites in rats after the ingestion of ellagitannins. Urine samples were collected after oral administration of ellagitannins such as geraniin ( 1), corilagin ( 2), and their related polyphenols. The suspension of rat intestinal microflora was anaerobically incubated with ellagitannins. Each sample was separated by column chromatography and/or preparative HPLC to give seven metabolites, M1- M7. The structures of these metabolites were determined on the basis of spectroscopic data and chemical evidence. These compounds, except for M1, were characterized as ellagitannin metabolites for the first time. Furthermore, among four major metabolites ( M1- M4) in urine, M2 showed an antioxidant activity comparable to intact geraniin and related polyphenols.     

Metabolism of grape seed polyphenol in the rat

The metabolism of grape seed polyphenol (GSP) has been investigated in rats by high-performance liquid chromatography analysis of the serum and urinary concentrations of the GSP metabolites (+)-catechin (CT), (-)-epicatechin (EC), 3'-O-methyl-(+)-catechin, and 3'-O-methyl-(-)-epicatechin. The serum concentration of these four metabolites reached a maximum 3 h after the oral administration of GSP. The urinary excretion of these GSP metabolites accounted for 0.254% (w/w) of the administered dose of GSP (1.0 g/kg), and the majority of these metabolites were excreted within 25 h of oral administration. The serum concentration and urinary excretion of these metabolites were also compared after the oral administration of different GSP monomers (gallic acid, CT, and EC), normal GSP, and the high molecular weight components of GSP (GSPH). No metabolites were detected in the serum of rats given GSPH. The urinary percentage excretion of the GSP metabolites derived from the respective monomers (CT or EC) did not vary with the administration of different substances (CT or EC, GSP, or GSPH). Taken together, these results suggest that only the monomers of GSP are absorbed and metabolized.     

Pharmacokinetic study of nobiletin and tangeretin in rat serum by high-performance liquid chromatography-electrospray ionization-mass spectrometry

Nobiletin (NOB) and tangeretin (TAN), two of the main polymethoxylated flavones (PMFs) in citrus, influence a number of key biological pathways in mammalian cells. Although the impacts of NOB and TAN on glucose homeostasis and cholesterol regulation have been investigated in human clinical trials, much information is still lacking about the metabolism and oral bioavailability of these compounds in animals. In this study, NOB and TAN were administered to rats by gavage and intraperitoneal (ip) injection, and the blood serum concentrations of these compounds and their main metabolites were monitored by high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS). In addition to the administered compounds, two metabolites of TAN and eight metabolites of NOB were detected and measured over 24 h. With identical oral doses, nearly 10-fold higher absorption of NOB occurred compared to TAN. For both compounds, maximum levels of glucuronidated metabolites occurred in the blood serum at later time points (～5-8 h) compared to the earlier T(max) values for NOB and TAN. In most cases the glucuronides occurred at substantially higher concentrations than the aglycone metabolites. Low levels of NOB and TAN and their metabolites were detectable in rat blood serum even at 24 h after treatment.     

Toxico-kinetics, recovery, and metabolism of napropamide in goats following a single high-dose oral administration

Toxicokinetic behavior, recovery and metabolism of napropamide (a pre-emergent herbicide) and its effect on Cytochrome P(450) of liver microsomal pellet were studied following a single high-dose oral administration of 2.5 g kg(-1) and continuous (7 days) oral administration of 500 mg kg(-1) in black Bengal goat. Napropamide was detected in blood at 15 min and the maximum quantity was recovered at 3 h after administration. The absorption rate constant (Ka) value was low indicating poor absorption from the gastrointestinal tract. High elimination half-life (t(1/2) beta) and low body clearance (Cl(B)) values coupled with higher transfer of compound from tissue to central compartment (K(21)) suggest that napropamide persisted in the blood for a long time, i.e., after 72 h of oral administration. The recovery percentage of napropamide, including metabolites, from goats varied from 75.94 to 80.08 and excretion of the parent compound through feces varied from 18.86 to 21.59%, indicating that a major portion of the orally administered napropamide was absorbed from the gastrointestinal tract of goat. Napropamide significantly increased the Cytochrome P(450) content of liver microsomal pellet. The recovery of metabolites from feces, urine, and tissues ranged from 4.2--6.2, 40.81--49.42, and 2.7--11.6%, respectively, during a 4--7 day period. The material balance of napropamide (including metabolites) following a single high-dose oral administration at 2.5 g kg(-1) during 4--7 days after dosing was found to be in the range of 75--80%.     

Bound ferulic acid from bran is more bioavailable than the free compound in rat

Ferulic acid (FA) is reported as a good antioxidant absorbed by human or rat but only few data deal with the influence of the food matrix on its bioavailability and with its potential protection against cardiovascular diseases and cancer. Wheat bran is used as a source of ferulic acid, the compound being mainly bound to arabinoxylans of the plant cell walls. Pharmacokinetic profiles of FA and its metabolites are established in rats. Free and conjugated FA quickly appear in plasma, reach a plateau 1 h after intake and remain approximately constant at 1 microM up to 24 h. 2.3% of FA are eliminated in urine. Compared with results obtained after intake of free FA, the presence of FA-arabinoxylans bonds in the food matrix increases the occurrence time of FA in the organism and decreases the level of urinary excretion in 24 h. Nevertheless, sulfated FA is still the main plasmatic form. The antioxidant activity of plasmas of rats fed with a standard diet (containing no FA), pure ferulic acid (5.15 mg FA/kg bw) or bran (4.04 mg FA/kg bw) are measured in an ex vivo test using AAPH as free radical inducer. Plasmas of rats fed with bran show a better antioxidant activity than the control group and the pure FA supplemented group, increasing the resistance of erythrocytes to hemolysis by factors of 2 and 1.5, respectively. These results show the good bioavailability of FA from bran and its potential efficiency to protect organism against pathology involving radical steps of development.     

Absorption and urinary excretion of (-)-epicatechin after administration of different levels of cocoa powder or (-)-epicatechin in rats.

(-)-Epicatechin is a major polyphenol component of cocoa powder. The absorption and urinary excretion of (-)-epicatechin following administration of different levels of either cocoa powder (150, 750, and 1500 mg/kg) or (-)-epicatechin (1, 5, and 10 mg/kg) were evaluated in rats. Both the sum of plasma (-)-epicatechin metabolites at 1 h postadministration and peak plasma concentrations increased in a dose-dependent fashion. The sum of (-)-epicatechin metabolites in urine, excreted within 18 h postadministration, also increased with dose. Moreover, the sum of (-)-epicatechin metabolites excreted in urine reached the same level in both (-)-epicatechin and cocoa powder administration groups for equivalent amounts of (-)-epicatechin. These results suggest that, in the dose range examined in this study, bioavailability of (-)-epicatechin following administration of either (-)-epicatechin or cocoa powder shows dose dependence and that the various compounds present in cocoa powder have little effect on the bioavailability of (-)-epicatechin in cocoa powder.     

Pharmacokinetics of cycloalliin, an organosulfur compound found in garlic and onion, in rats

Cycloalliin, an organosulfur compound found in garlic and onion, has been reported to exert several biological activities and also to remain stable during storage and processing. In this study, we investigated the pharmacokinetics of cycloalliin in rats after intravenous or oral administration. Cycloalliin and its metabolite, (3R,5S)-5-methyl-1,4-thiazane-3-carboxylic acid, in plasma, urine, feces, and organs was determined by a validated liquid chromatography-mass spectrometry method. When administered intravenously at 50 mg/kg, cycloalliin was rapidly eliminated from blood and excreted into urine, and its total recovery in urine was 97.8% +/- 1.3% in 48 h. After oral administration, cycloalliin appeared rapidly in plasma, with a tmax of 0.47 +/- 0.03 h at 25 mg/kg and 0.67 +/- 0.14 h at 50 mg/kg. Orally administered cycloalliin was distributed in heart, lung, liver, spleen, and especially kidney. The Cmax and AUC0-inf values of cycloalliin at 50 mg/kg were approximately 5 times those at 25 mg/kg. When administered orally at 50 mg/kg, cycloalliin was excreted into urine (17.6% +/- 4.2%) but not feces. However, the total fecal excretion of (3R,5S)-5-methyl-1,4-thiazane-3-carboxylic acid was 67.3% +/- 5.9% (value corrected for cycloalliin equivalents). In addition, no (3R,5S)-5-methyl-1,4-thiazane-3-carboxylic acid was detected in plasma (<0.1 microg/mL), and negligible amounts (1.0% +/- 0.3%) were excreted into urine. In in vitro experiments, cycloalliin was reduced to (3R,5S)-5-methyl-1,4-thiazane-3-carboxylic acid during anaerobic incubation with cecal contents of rats. These data indicated that the low bioavailability (3.73% and 9.65% at 25 and 50 mg/kg, respectively) of cycloalliin was due mainly to reduction to (3R,5S)-5-methyl-1,4-thiazane-3-carboxylic acid by the intestinal flora and also poor absorption in the upper gastrointestinal tract. These findings are helpful for understanding the biological effects of cycloalliin.     

Urinary and plasma levels of resveratrol and quercetin in humans, mice, and rats after ingestion of pure compounds and grape juice

The present study investigates the bioavailability of resveratrol and quercetin in humans, mice, and rats after oral ingestion of grape juice preparations or pure aglycones. Oral administration of resveratrol and quercetin to humans yielded detectable levels of resveratrol, quercetin, and their derivatives in the plasma and urine. Urinary levels of resveratrol, quercetin, and their metabolites were observed in human subjects receiving 600 and 1200 mL of grape juice, whereas quercetin metabolites were identified in urine samples even after receiving 200 mL of grape juice. The cumulative amounts of resveratrol and quercetin excreted in the urine of mice receiving concentrated grape juice for 4 days were 2.3 and 0.7% of the ingested doses, respectively. After i.g. administration of resveratrol to rats (2 mg/kg), up to 1.2 microM resveratrol was observed in the plasma. The study demonstrates that the glycoside forms of resveratrol and quercetin in grape juice are absorbed to a lesser extent than the aglycones.     

Metabolism of 7-fluoro-6-(3,4,5,6-tetrahydrophthalimido)-4- (2-propynyl)-2H-1,4-benzoxazin-3(4H)-one (S-53482, flumioxazin) in the rat: II. Identification of reduced metabolites

On single oral administration of (14)C-S-53482 [7-fluoro-6-(3,4,5, 6-tetrahydrophthalimido)-4-(2-propynyl)-2H-1,4-benzoxazin-3( 4H)-one, Flumioxazin] labeled at the 1- and 2-positions of tetrahydrophthaloyl group to rats at 1 (low dose) or 100 (high dose) mg/kg, the radiocarbon was almost completely eliminated within 7 days after administration in both groups with generally very low residual (14)C tissue levels. The predominant excretion route was via the feces. The major fecal and urinary metabolites involved reduction or sulfonic acid addition reactions at the 1,2-double bond of the 3,4,5,6-tetrahydrophthalimide moiety and hydroxylation of the cyclohexene or cyclohexane ring. One urinary and four fecal metabolites were identified using chromatographic techniques and spectroanalyses (NMR and MS). Three of five identified metabolites were unique forms, reduced at the 1,2-double bond of the 3,4,5, 6-tetrahydrophthalimide moiety. On the basis of the metabolites identified in this study, the metabolic pathways of S-53482 in rats are proposed. To specify tissues forming reduced metabolites, an in vitro study was conducted. Reduction was found to take place in red blood cells.     

Metabolic pathway of cyanidin 3-O-beta-D-glucopyranoside in rats

For better understanding of the physiological function of anthocyanins, the absorption and metabolism of cyanidin 3-O-beta-D-glucopyranoside (Cy3G), which is one of the major anthocyanins in colored food materials, were precisely investigated. Combining two modalities newly developed, that is, highly sensitive semi-micro-HPLC and vein cannulation, Cy3G and its four major metabolites (M1-M4) were detected in the blood plasma of rats after oral administration of Cy3G (100 mg/kg of body mass). The plasma concentration of Cy3G reached its maximum at 15 min after the ingestion. Metabolite 2 (M2) and metabolite 3 (M3) showed their maximum plasma levels at 15 and 30 min, respectively, whereas metabolite 1 (M1) and metabolite 4 (M4) showed their maximum levels at 60 and 120 min, respectively. The maximum plasma concentrations of the four metabolites were in the following order: M3 (21 nM) > M4 (20 nM) > M1 (8.5 nM) > M2 (5 nM). When Cy3G was directly injected into the neck vein, only M2 and M3 were detected in the plasma, indicating that both M1 and M4 were produced during absorption from the gastrointestinal tract. Tandem MS analysis of the metabolites showed that M2 and M3 were monomethylated Cy3G, while M1 and M4 were glucuronides of Cy and methylated Cy, respectively. M3 was assigned as peonidin 3-O-beta-D-glucopyranoside (Pn3G) from the comparison of the retention time of authentic Pn3G.     

Full-Scale Remediation of a Jet Fuel-Contaminated Soil: Assessment of Biodegradation, Volatilization, and Bioavailability

Here, we addressed biodegradation vs. volatilization processes, and also bioavailability limitations during biopile remediation of soil initially contaminated by more than 5,000 mg/kg of hydrocarbons. In order to select bioremediation strategies, we first conducted a biotreatability study, which included geochemical, textural, and microbiological characterization of the soil matrix. Next, we implemented five bioremediation approaches onsite in real-scale biopiles. In order to monitor hydrocarbon depletion and to distinguish between biological and non-biological processes, we analyzed chemical biomarkers by means of gas chromatography?Cmass spectrometry. In addition, a comprehensive study of soil grain size and its implications on bioavailability were studied. Furthermore, the evolution of microbial populations was also examined. Two of the strategies implemented in the biopiles (the combination of a slow-release fertilizer and a surfactant, and the use of an oleophilic fertilizer respectively) reduced the soil hydrocarbon content to under 500 mg/kg in 5 months. Additional results from this study indicate that volatilization was the predominant degradation process for light hydrocarbons (below 12 carbon atoms), whereas heavier compounds were mainly biodegraded. However, even in the most favorable situation, a residual concentration of hydrocarbons linked to the finer fraction of the soil was found.     

Organochlorine pesticide residues in strawberries from integrated pest management and organic farming

A rapid, specific, and sensitive method based on the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) method and a cleanup using dispersive solid-phase extraction with MgSO(4), PSA, and C18 sorbents has been developed for the routine analysis of 14 pesticides in strawberries. The analyses were performed by three different analytical methodologies: gas chromatography (GC) with electron capture detection (ECD), mass spectrometry (MS), and tandem mass spectrometry (MS/MS). The recoveries for all the pesticides studied were from 46 to 128%, with relative standard deviation of <15% in the concentration range of 0.005-0.250 mg/kg. The limit of detection (LOD) for all compounds met maximum residue limits (MRL) accepted in Portugal for organochlorine pesticides (OCP). A survey study of strawberries produced in Portugal in the years 2009-2010 obtained from organic farming (OF) and integrated pest management (IPM) was developed. Lindane and β-endosulfan were detected above the MRL in OF and IPM. Other OCP (aldrin, o,p'-DDT and their metabolites, and methoxychlor) were found below the MRL. The OCP residues detected decreased from 2009 to 2010. The QuEChERS method was successfully applied to the analysis of strawberry samples.     

Method for analysis of tannic acid and its metabolites in biological samples: application to tannic acid metabolism in the rat

A new analytical method for measuring tannic acid (TA) using tannase was developed and applied to the investigation of TA metabolism in the rat following oral administration at a dose of 1.0 g/kg. The proposed method for TA determination was based on the enzymatic hydrolysis of TA to gallic acid (GA) and subsequent determination by HPLC. TA metabolites were determined by HPLC. 4-O-Methylgallic acid (4-OMGA), pyrogallol (PY), and resorcinol (RE) were detected in serum. TA was excreted into urine as GA (0.01%), 4-OMGA (0.10%), PY (0.24%), and RE (2.06%) and into feces as TA (62.74%), GA (0.19%), PY (0.02%), and RE (0.76%) within 54 h after oral administration. It was suggested that >60% of TA remained unchanged but that some was hydrolyzed to GA by tannase in the intestine and further metabolized to 4-OMGA, PY, and RE.     

Effect of variety, processing, and storage on the flavonoid glycoside content and composition of lettuce and endive

Eight varieties of lettuce (Lactuca sativum) and three varieties of endive (Cichorium endivia) were analyzed for flavonoid composition and content. Total flavonoid contents, expressed as units of aglycon for fresh material, were in the ranges of 0.3-229 microg/g for lettuce and 44-248 microg/g for endive. Five quercetin conjugates [quercetin 3-O-galactoside, quercetin 3-O-glucoside, quercetin 3-O-glucuronide, quercetin 3-O-(6-O-malonyl)glucoside, and quercetin 3-O-rhamnoside] and luteolin 7-O-glucuronide were measured in the green-leafed lettuce and an additional two cyanidin conjugates [cyanidin 3-O-glucoside and cyanidin 3-O-[(6-O-malonyl)glucoside]] in the red-leafed varieties. Three kaempferol conjugates [kaempferol 3-O-glucoside, kaempferol 3-O-glucuronide, and kaempferol 3-O-[6-O-malonyl)glucoside]] were measured in each of the endive varieties. The presence and identity of kaempferol 3-O-(6-O-malonyl)glucoside in endive was shown for the first time. Shredding of lettuce leaf followed by exposure to light produced significant losses of the flavonoid moiety in the green oak leaf (94%), red oak leaf (43%), iceberg (36%), green batavia (25%), lollo biondo (24%), and lollo rosso (6%) samples, whereas cos and green salad bowl samples did not show an overall loss. Shredding of endive also produced loss of the flavonoid moiety in escarole (32%), fine frisee (13%), and coarse frisee (8%). Significant demalonation was observed for both the quercetin and cyanidin glucosides in lettuce, whereas a similar degradation of the kaempferol analogue was found in endive tissue. Storage of whole heads of both lettuce and endive in the dark at 1 degrees C and 98% humidity for 7 days resulted in losses of total flavonol glycosides in the range of 7-46%. The identification of the amounts, position of substitution, and nature of the sugars is important for understanding the potential bioavailability and biological activities of flavonoids in salads.     

Characterization and quantification of proteins in lecithins

Several methods for extraction and quantification of proteins from lecithins were compared. Extraction with hexane-2-propanol-water followed by amino acid analysis is the most suitable method for isolation and quantification of proteins from lecithins. The detection limit of the method is 15 mg protein/kg lecithin, and the quantification limit is 50 mg protein/kg. The relative repeatability limits for samples containing 0-500 and 500-5000 mg protein/kg sample were 12.6 and 7.5%, respectively. The protein recovery ranged between 101 and 123%. The protein content has been determined in different kinds of lecithins. The results were as follows: standard soy lecithins (between 232 and 1338 mg/kg), deoiled soy lecithin (342 mg/kg), phosphatydylcholine-enriched soy lecithins (not detectable and 163 mg/kg), sunflower lecithins (892 and 414 mg/kg), and egg lecithin (50 mg/kg). The sodium dodecyl sulfate-polyacrylamide gel electrophoresis protein patterns of the standard soy and sunflower lecithins are very similar to those of soy flour. The protein profile of the egg lecithin shows several bands with a broad range of molecular masses. The molecular masses of the main proteins of soy lecithins and soy flour have been determined by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and ranged from 10.5 to 52.2 kDa. Most of the major proteins from soy and sunflower lecithins identified by MALDI-MS and electrospray tandem MS belong to the 11S globulin fraction, which is one of the main fractions of soy and sunflower seeds. In addition, the seed maturation protein P34 from the 7S globulin fraction of soy proteins has also been identified in soy lecithins. This protein has been reported as the most allergenic protein in soybean.