In Vitro Anti-inflammatory Activity of White Tea Oligopeptide Fractions

Objective Anti-inflammatory activity of oligopeptide fractions in white tea was evaluated by the lipopolysaccharide-induced RAW264.7 cell method.

Method The oligopeptides extract of Shoumei and Baimudan White Teas were separated and purified in fractions by differential molecular weight, hydrophilicity, and electric charge using Sephadex G-15 chromatography, C18 solid-phase extraction, and strong anion and cation chromatography. Lipopolysaccharide-induced RAW264.7 cells were used in an in vitro test to determine the anti-inflammatory activity of the fractions based on their inhibition rates against NO, TNF-α, and IL-1β. Oligopeptide fractions showing significant anti-inflammatory potentials were sequenced and chemically analyzed by UPLC-Q-Orbitrap-MS.

Result The oligopeptide fractions of low molecular weight were higher in the anti-inflammatory activity than those of medium or high molecular weight. The hydrophobic fractions were higher in the activity than the hydrophilic ones. And the negatively charged fractions were higher in the activity than the positively charged fractions. Of all the selected fractions, the low molecular weight, hydrophobic G15-3(MD) with basic amino acids at the N- and C-termini showed the strongest anti-inflammatory effect that was not significantly different from what exerted by dexamethasone (P>0.05). It contained 5 bands in the sequence and displayed significant inhibition rates on NO, TNF-α, and IL-1β at (34.21±2.53)%, (52.36±6.24)%, and (76.43±1.41)%, respectively.

Conclusion Molecular weight of the oligopeptide fractions isolated from the two varieties of white tea seemed to be the most critical factor, followed by electric charge and hydrophilicity/polarity, that correlated with the in vitro anti-inflammatory effect on the RAW264.7 cells. And the low molecular weight, hydrophobic G15-3(MD) was found to be strongly anti-inflammatory like the commonly used drug, dexamethasone, for inflammation. It was postulated that the KRW and FGGN peptides in G15-3(MD) might contribute significantly to the outstanding activity.