Inhibition effects of the classical pathway complement of isolated compounds from Quercus glauca

Species of the Quercus species is an evergreen broadleaf tree found not only in Korea but also in China, Taiwan, and Japan. Quercus species is the most commonly occurring plant among the 50 native species of the family Fagaceae in Korea, China, and Taiwan. Quercus species have been used for diarrhea, dysentery, dermatitis, and hemorrhagia in Korean folk medicine. The present study evaluated the anticomplement effect of constituents from Quercus species (Fagaceae) in classical pathway complement system. We have evaluated leaves of five species of the Quercus genus with regard to its anticomplement activity and have identified its active principles following activity-guided isolation. Bioactivity-guided fractionation of the 80% methanol extracts of the stem barks of Quercus glauca Thunberg has led to the isolation of galloyl derivatives, displaying high anticomplement activity. Four galloyl derivatives isolated from the leaves of Q. glauca, namely 6′- O-galloyl salidroside (1), methyl gallate (2), 1,2,3,6-tetragalloylglucose (3), and 1,2,6-trigalloylglucose (4). 1, 2, 3 and 4 showed inhibitory activity against complement system with 50% inhibitory concentrations (IC50) values of 224 μM, 362.4 μM, 32.3 μM, and 138.3 μM. Among the compounds tested, 3 showed the most potent anticomplement activity (IC50, 32.3 μM). This is the first report of the isolation and anticomplement activity from Q. glauca.

Decrease in the capacity for RuBP carboxylation and regeneration with the progression of cold-induced photoinhibition during winter in evergreen broadleaf tree species in a temperate forest

We measured the photosynthetic capacity (RuBP carboxylation and electron transport capacity at 25°C) and the maximum photochemical efficiency (Fv/Fm) from autumn to spring in saplings of two evergreen broadleaf tree species and examined the negative effects of photoinhibition on the photosynthetic capacity. Saplings were grown in pots under three simulated natural light environments typical of temperate forests: an open site, deciduous understorey and evergreen understorey. During winter, the photosynthetic capacity and Fv/Fm synchronously decreased in leaves in the sun, but not those in the shade. We found large differences in Fv/Fm and photosynthetic capacity, along with a positive correlation between Fv/Fm and the photosynthetic capacity among leaves in different light environments. In photoinhibited leaves that were transferred to the shade in mid-winter, photosynthetic capacity increased synchronously with the increment of Fv/Fm. The decrease in photosynthetic capacity in photoinhibited leaves and the synchronous recovery of photosynthetic capacity with photoinhibition supported the hypothesis that photoinhibition depressed the photosynthetic capacity during winter. We showed that difference in the degree of photoinhibition was responsible for the different winter photosynthetic capacity among leaves exposed to different light environments.