Effect of green tea powder (Camellia sinensis L. cv. Benifuuki) particle size on O-methylated EGCG absorption in rats; The Kakegawa Study

Abstract

Tea polyphenols, e.g., (-)-epigallocatechin-3-O-(3-O-methyl gallate (EGCG3"Me), (-)-epigallocatechin-3-O-gallate (EGCG), (-)-epigallocatechin (EGC), (-)-epicatechin-3-O-gallate (ECG), and (-)-epicatechin (EC), are believed to be responsible for the beneficial effects of tea. 'Benifuuki', a tea (Camellia sinensis L.) cultivar grown in Japan, is rich in the anti-allergic molecule epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3"Me). Pulverized Benifuuki green tea powder (BGP) is more widely distributed than leaf tea in Japan. Japanese people mix their pulverized tea with water directly, whereas it is common to drink leaf tea after extraction. However, few studies of the effects of BGP particle size on polyphenol bioavailability have been performed. This study was conducted to investigate the absorption of catechins in rats after the intragastric administration of Benifuuki green tea. Therefore, we assessed the plasma concentrations of catechins following the ingestion of BGP with different mean particle sizes (2.86, 18.6, and 76.1 μm) or Benifuuki green tea infusion (BGI) as a control in rats. The bioavailabilities of EGCG3"Me, EGCG, ECG, EGC, and EC were analyzed after the oral administration of a single dose of Benifuuki green tea (125 mg/rat) to rats. The plasma concentrations of tea catechins were determined by HPLC analysis combined with of electrochemical detection (ECD) using a coulometric array. The AUC (area under the drug concentration versus time curve; min μg/mL) of ester-type catechins (EGCG3"Me, EGCG, and ECG) for the BGP 2.86 μm were significantly higher than those in the infusion and 18.6 and 76.1 μm BGP groups, but the AUC of free-type catechins (EGC and EC) showed no differences between these groups. Regarding the peak plasma level of EGCG3"Me adjusted for intake, BGP 2.86 μm and BGI showed higher values than the BGP 18.6 and 76.1 μm groups, and the peak plasma levels of the other catechins displayed the same tendency. The present study demonstrates that the bioavailability of ester-type catechins (EGCG and ECG) can be improved by reducing the particle size of green tea, but the plasma level of EGCG3"Me in the BGI group was similar to that in the BGP 2.86 μm group. This result suggests that drinking Benifuuki green tea with a particle size of around 2 μm would deliver the anti-allergic EGCG3"Me and the anti-oxidant EGCG efficiently.

Comparison of (−)-Epigallocatechin-3-<i>O</i>-gallate (EGCG) and <i>O</i>-Methyl EGCG Bioavailability in Rats

“…Maeda-Yamamoto suggested that EGCG3″Me showed higher absorption than EGCG after oral administration of Benifuuki tea extract in rats and humans. 15,18) In previous studies, overestimation of the AUC po of EGCG3″Me and other catechins after administration of tea extract could have occurred, because of metabolism from EGCG to O-methyl EGCGs, in rats. 19) In addition, the elimination of EGCG from plasma was reported to be affected by other tea extract catechins.…”

“…15) Briefly, 50 µL of each plasma sample was mixed with 20 µL of 1% ascorbic acid/0.005% EDTA/0.2 M phosphate buffer (pH 6.5), 5 µL of β-D-glucuronidase (15.6 Units), 5 µL of sulfatase (1.25 Units), and 20 µL of water, and subsequently incubated at 37°C for 45 min.…”

Green Tea Extract Containing a Highly Absorbent Catechin Prevents Diet-Induced Lipid Metabolism Disorder

“…Pharmacokinetic analyses confirmed that EGCG3”Me has a significantly higher absorption rate from the intestine and a lower rate of disappearance from the blood than EGCG23. Therefore, although the amount of EGCG3”Me in Benifuuki tea is about one-quarter that of EGCG, the blood concentrations of these two catechins after ingestion of Benifuuki tea are almost identical23. This is considered to be the main reason why Benifuuki has greater anti-allergic activity than Yabukita.…”

“…In vivo and clinical studies have shown that Benifuuki has strong anti-allergic effects2122. Pharmacokinetic analyses confirmed that EGCG3”Me has a significantly higher absorption rate from the intestine and a lower rate of disappearance from the blood than EGCG23. Therefore, although the amount of EGCG3”Me in Benifuuki tea is about one-quarter that of EGCG, the blood concentrations of these two catechins after ingestion of Benifuuki tea are almost identical23.…”

Target molecules of food phytochemicals: Food science bound for the next dimension

“…Importantly, the gallate ester group in catechins may be the structural determinant of 67LR binding (3). Meanwhile 67LR was also shown to serve as a receptor for methylated derivatives of EGCg (73,74), which were found present in a unique tea cultivar and have potent anti-allergy activities(75)(76)(77)(78). On the other hand, other binding proteins have also been identified as significant molecules that…”