USDA-ARS, USA.
J Agric Food Chem. 2010 Apr 14;58(7):3940-9. doi: 10.1021/jf9028392.
Dietary flavonoids can be converted into phenolic acids by colonic microflora. Phenolic acids can then be absorbed into the circulation and may contribute to the health-promoting effects of the parent compounds. Phenolic acids can be further metabolized in other tissues via methylation and conjugation with glucuronide or sulfate. The objectives of this study were to identify and quantify the urinary excretion of 19 phenolic acids and their conjugates in rats fed three levels of a concentrated cranberry powder (3.3, 6.6, and 33 mg/kg of diet). The basic diet used was AIN93G diet containing very low amounts of any polyphenolic compounds. Of the phenolic acids studied, the amounts excreted varied by 4 orders of magnitude, with hippuric acid being excreted in the highest quantities. Amounts of 4-hydroxyphenylacetic acid (4HPAA), 3-hydroxyphenylacetic acid (3HPAA), 3-hydroxyphenylpropionic acid (3HPPA), and 4-hydroxycinnamic acid (4HCA) excreted were in the range of 18-33 microg/mg creatinine in animals fed the highest level of cranberry powder, whereas phenylacetic acid (PAA), gallic acid (GA), 3,4-dihydroxyphenylacetic acid (34HPAA), 3,4-dihydroxybenzoic acid (34HBA), 3,4-dihydroxycinnamic acid (34HCA), and 4-hydroxy-3-methoxycinnamic acid (FA) were excreted in the urine in concentrations of 0.1-2 microg/mg creatinine. As the amount of cranberry in the diet was increased, the amount of 4HPAA excreted decreased but the percentage of conjugated 4HPAA excreted increased (from 57 to 91%). For other phenolic acids analyzed, the percentage excreted in the conjugated form was approximately constant across levels of cranberry in the diet and ranged from 65 to 100% for the individual phenolic acids. Studies of bioactivity and health effects need to consider more than just the compound(s) in the food, because they can be metabolized to other lower molecular weight compounds, which in turn may also be methylated or conjugated in some form that may affect the perceived health effects.
膳食类黄酮可被结肠微生物群转化为酚酸。酚酸随后被吸收到循环中，并可能有助于母体化合物的促进健康的作用。酚酸可通过甲基化和与葡萄糖醛酸或硫酸盐结合而在其他组织中进一步代谢。本研究的目的是鉴定和定量测定给予三种浓缩蔓越莓粉（饮食 3.3、6.6 和 33mg/kg）的大鼠的尿排泄中 19 种酚酸及其共轭物。所使用的基础饮食为 AIN93G 饮食，其中含有极低量的任何多酚化合物。在所研究的酚酸中，排泄量相差 4 个数量级，以马尿酸排泄量最高。在给予最高水平蔓越莓粉的动物中，4-羟基苯乙酸（4-HPAA）、3-羟基苯乙酸（3-HPAA）、3-羟基苯丙酸（3-HPPA）和 4-羟基肉桂酸（4-HCA）的排泄量在 18-33μg/mg 肌酐范围内，而苯乙酸（PAA）、没食子酸（GA）、3,4-二羟基苯乙酸（34-HPAA）、3,4-二羟基苯甲酸（34-HBA）、3,4-二羟基肉桂酸（34-HCA）和 4-羟基-3-甲氧基肉桂酸（FA）在尿中的排泄浓度为 0.1-2μg/mg 肌酐。随着饮食中蔓越莓含量的增加，4-HPAA 的排泄量减少，但排泄的共轭 4-HPAA 的百分比增加（从 57%增加到 91%）。对于分析的其他酚酸，在饮食中蔓越莓的各个水平，以共轭形式排泄的百分比大致保持不变，范围为 65-100%，对于各个酚酸。对生物活性和健康影响的研究需要考虑的不仅仅是食物中的化合物，因为它们可以被代谢为其他低分子量化合物，而这些化合物反过来也可能以某种形式被甲基化或结合，这可能会影响到被感知的健康影响。
