Research On The Interaction Between Lfavonoids And Trypsin

Flavonoids is a kind of plant secondary metabolism products, and they are widespread infruits,vegetables,flowers. Flavonoids are researched and developed on medicine and food-fields for their biological functions,such as oxidation, antibacterial,anti-cancer,antitumor.Because there are many active Phenolic hydroxyls in the structures of flavonoids, they mayreacted with the Digestive enzymes after ingested into the human body. In this paper, wechosed flavonoids with different representative structures （dihydromyricetin, diosmetin,naringenin, apigenin, quercetin, luteolin, rutin, kaempferol） and studied the interactionbetween trypsin and flavonoids, discussed the mechanism of the intheraction preliminarily.Quercetin treatment led to the inhibition of trypsin’s catalytic activity. When theenzymatic activity was2.67×10⁷U, added quercetin was0.8μmol, treated for10mins under37℃, the inhibition rate reached32.5%; reaction time had litter relation with the inhibition,and the type of the inhibition effect is reversible competitive inhibition. Dihydromyricetintreatment led to the inhibition of catalytic activity. When the enzymatic activity was2.67×10⁷U, added dihydromyricetin was0.8μmol, treated for10mins under37℃, the inhibition ratereached34.8%. The order of the inhibition ratio is quercetin> luteolin> rutin> kaempferol>apigenin.This paper checked the change of the tryptic fluorescent characteristic after interactedwith the eight flavonoids. The results were these: the eight flavonoids all led the quenching ofintrinsic fluorescence of trypsin in physiological condition, and the fluorescence intensity oftrpsin at the maximum emission peak decreased regularly with the increase of the additiveamount of flavonoids. The quenching mechanism is a static quenching procedure for all therate constants of electron transfer fluorescence quenching were bigger than2.0×10¹⁰L mol^-1S^-1. The order of the fluorescence-quenching is quercetin>luteolin>rutin>kaempferol>apigenin>diosmetin. Flavonoids’ planer structure is beneficial to thefluorescence-quenching. After interaction, the heat stability and the pH stability had somedegree of improvement.This paper checked the change of the flavonoids’ antioxidant effects after interacted withtrypsin. The results were these: Trypsin had obvious inhibitions on the free radicalsscavenging activity （ABTS⁺·, DPPH·, OH·） of the measured eight flavonoids. When the added enzyme was1.03mg（enzymatic activity was2.67×10⁷U）, added quercetin was0.8μmol, after interacting at37℃for10mins, the clearance rate of quercitin for the three freeradicals could decreased39.1%,41.0%,42.1%. The order of the decrease of the clearance rateis quercetin> luteolin>kaempferol>rutin>apigenin. Considering the structures of the fiveflavonoids, we could infer preliminarily that the active sites between flavonoids and trypsinwere the active hydroxyls on the B ring and C ring. These sites were also the active sites forflavonoids to scavenge free radicals. There must be some relations between the interaction.