[Test for urokinase-type plasminogen activator inhibitor of edible plants in vitro]

To study the effect of anti-progression activity of edible plants using urokinase as the biomarker.

Based on the assay of urokinase activity with peptide of Glu-Gly-Arg as the reaction substrate, extract of 25 fruits and 37 vegetables and water extract of tea were reacted against urokinase activity after Spectrozyme UK [carbobenzyl-1-gamma-Glu(alpha-t-BuO)-Gly-Arg-rho-nitroanilide. 2C2H5OH] was added and the residual urokinase activity was measured by the microplate photometer.

About half of the fruit and vegetable samples showed urokinase inhibitory activity (UIA) at 20% or more and among them lemon, kiwi-fruit, peas, spinach and pumpkin showed effects over 80%, while garlic, radish, Japanese butterbur, garland chrysanthemum, celery, plum, pineapple and grape ranged between 50% and 79%. Average UIA of 51 kinds of tea was 83.2% and among them 28 kinds showed UIA over 90% and other 20 kinds of tea ranged from 70% to 89%. Green tea showed inhibitory effects on urokinase activity more powerful than black tea and Oolong tea. On the other hand, vegetable showed various UIA with different ways of processing. Comparing the effects of various solvents, garlic extracted with methanol, spinach with ethyl acetate, and pumpkin and radish with water showed highest UIA.

Popular fruits, vegetables and tea in daily life could inhibit urokinase activity and may be helpful in the prevention of malignant tumor formation.