Determination of steroid hormones in bovine milk by LC-MS/MS and their levels in Swiss Holstein cow milk.

Synthetic and natural steroid hormones have attracted some attention in recent years as endocrine active substances (EAS) that interact or interfere with the endocrine system. Endogenous hormones occur naturally in food of animal origin, among which bovine milk represents an important source. This study was conducted to determine the occurrence of steroid hormones (oestrogens, androgens, progestogens and glucocorticoids) in cow's milk samples from three farms in Switzerland. An isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of 12 hormones in milk. Some hormonal levels from individual cows showed large variations. The average levels of the hormones analysed (17α-estradiol = 31 ng kg(-)(1), 17ß-estradiol = 6 ng kg(-)(1), estrone = 159 ng kg(-)(1), 4-androstenedione = 684 ng kg(-)(1), progesterone = 15486 ng kg(-)(1), 17-hydroxyprogesterone = 214 ng kg(-)(1), cortisone = 112 ng kg(-)(1), and cortisol = 235 ng kg(-)(1)) were comparable with literature data. Estriol, testosterone and androstenediols were not detected at their respective limit of quantification. No significant differences of hormonal content among milk from cows at different lactation/calving numbers were evidenced, except for progesterone and 4-androstenedione. Due to confounding parameters linked to the physiological stage of the animal, like pregnancy and gestational stage (pregnancy trimester), the causal correlation between the variation of the levels for these two hormones and the lactation/calving number could not be unambiguously demonstrated.

Biotransformation of caffeoyl quinic acids from green coffee extracts by Lactobacillus johnsonii NCC 533.

The potential of Lactobacillus johnsonii NCC 533 to metabolize chlorogenic acids from green coffee extract was investigated. Two enzymes, an esterase and a hydroxycinnamate decarboxylase (HCD), were involved in this biotransformation. The complete hydrolysis of 5-caffeoylquinic acid (5-CQA) into caffeic acid (CA) by L. johnsonii esterase occurred during the first 16 h of reaction time. No dihydrocaffeic acid was identified in the reaction mixture. The decarboxylation of CA into 4-vinylcatechol (4-VC) started only when the maximum concentration of CA was reached (10 µmol/ml). CA was completely transformed into 4-VC after 48 h of incubation. No 4-vinylphenol or other derivatives could be identified in the reaction media. In this study we demonstrate the capability of L. johnsonii to transform chlorogenic acids from green coffee extract into 4-VC in two steps one pot reaction. Thus, the enzymatic potential of certain lactobacilli might be explored to generate flavor compounds from plant polyphenols.

First synthesis, characterization, and evidence for the presence of hydroxycinnamic acid sulfate and glucuronide conjugates in human biological fluids as a result of coffee consumption.

A systematic investigation of the human metabolism of hydroxycinnamic acid conjugates was carried out. A set of 24 potential human metabolites of coffee polyphenols has been chemically prepared, and used as analytical standards for unequivocal identifications. These included glucuronide conjugates and sulfate esters of caffeic, ferulic, isoferulic, m-coumaric and p-coumaric acids as well as their dihydro derivatives. A particular focus has been made on caffeic and 3,4-dihydroxyphenylpropionic acid derivatives, especially the sulfate conjugates, for which regioselective preparation was particularly challenging, and have so far never been identified as human metabolites. Ten out of the 24 synthesized conjugates have been identified in human plasma and/or urine after coffee consumption. A number of these conjugates were synthesized, characterized and detected as hydroxycinnamic acid metabolites for the first time. This was the case of dihydroisoferulic acid 3'-O-glucuronide, caffeic acid 3'-sulfate, as well as the sulfate and glucuronide derivatives of 3,4-dihydroxyphenylpropionic acid.