Isolation And Purification Of Condensed Tannins From The Leaf Of Manilkara Zapota Van Royen And Its Structure And Bioactivities

Manilkara zapota van Royen, the fruit of which is full of nutriments, is a kind of evergreen tree. Manilkara zapota has long been used as medicine, such as astringent. It was determined that the leaf of Manilkara zapota contained a mount of TP and ECT, they are measured to be333.4+7.10mg/g and184.4+23.64mg/g.50%ethanol and70%actone were used to extract condensed tannins from the leaf of manilkara zapota. And the structures, antityrosinase activities and antioxidant activities were further identified. The results are as follows:The structures of the condensed tannins isolated from the leaf of manilkara zapota have been investigated with13C nuclear magnetic resonance (13C NMR) and high performance liquid chromatography electrospray ionization mass spectrometry (HPLC-ESI-MS) coupled with thiolysis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analyses. The results showed that the condensed tannins isolated by50%ethanol and70%actone had little of different in the monomer units and degree of polymerization, and they all contained propelargonidin (PP) and procyanidin (PC). The polymer chain lengths of the condensed tannins were detected to be trimers to hexadecamer. B-type linkages were present in all these compounds.The inhibitory mechanism of condensed tannins from the manilkara zapota on monophenolase and o-diphenolase activity of tyrosinase has been studied. The results showed that the steady-state rate of monophenolase has been decreased and the lag time has been lengthened with the increase of concentration of condensed tannins. When the concentration of the condensed tannins extracted by70%actone came to be60μg/mL, the steady-state rate of monophenolase has been decreased39.1%, and the lag time has been extended from123.4s to395.4s. To the condensed tannins extracted by50%ethanol, when the concentration came to be60μg/mL, the steady-state rate of monophenolase has been decreased57.4%, and the lag time has been extended from95.4s to331.0s. The inhibition on o-diphenolase activity can be obviously observed. The results showed that the inhibitor’s concentration leading to50%activity lost (ICso) is estimated to be20.97μg/mL and13.35μg/mL to70%actone extracted condensed tannins and50%ethanol extracted condensed tannins, respectively.The anoxidant activities of the condensed tannins extracted by70%actone and50%ethanol from the leaf of manilkara zapota were further investigated by the DPPH, FRAP, and ABTS methods. The value of IC50to DPPH method were80.24±0.73μg/mL,73.23±0.70μg/mL; IC50of ABTS method were149.93±3.97μg/mL and84.90±2.84μg/mL; The results of FRAP method were2.60±0.13mmol AAE/g and3.24±0.41mmol AAE/g.