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Green tea polyphenols are reported to possess substantial antiinflammatory and chemopreventive properties. However, the molecular mechanism of chemopreventive activity of green tea polyphenols is not fully understood. An abnormally elevated level of cyclooxygenase-2 (COX-2) is implicated in the pathogenesis of carcinogenesis. In the present study, we found that pretreatment of the green tea extract enriched with catechin and epigallocatechin gallate (EGCG) by gavage inhibited COX-2 expression induced by the tumor promoter 12-0-tetradecanoylphorbol-13-acetate (TPA) in mouse skin. Similarly, EGCG downregulated COX-2 in TPA-stimulated human mammary epithelial cells (MCF-10A) in culture. To further elucidate the underlying mechanism of COX-2 inhibition by green tea extract and EGCG, we examined their effects on the activation of extracellular signal-regulated protein kinase (ERK) and p38 mitogen-activated protein kinase (MAPK), which are upstream enzymes known to regulate COX-2 expression in many cell types. Pretreatment with EGCG as well as green tea extract caused a decrease in the activation of ERK. In addition, EGCG inhibited the catalytic activity of ERK and p38 MAPK, suggesting that these signal-transducing enzymes could be potential targets for previously reported antitumor promoting activity of EGCG. KEY WORDS: * chemoprevention * epigallocatechin gallate(EGCG) * cyclooxygenase-2(COX-2) * mitogenactivated protein kinase (MAPK) * human mammary epithelial cell (MCF- 10A) * mouse skin carcinogenesis

Extracts and fractions from the aerial parts of herbal materials of Saussurea involucrata Kar et Kir ex Maxim (Compositae) were investigated for their whitening activity against mouse-derived immortalized melanocyte cell line. The extract of wild herbs (FS2) possessed a better inhibition (28.2% growth) against melanin cells than that (46.7%) of cultivated herbs (FS1). The whole extracts and middle-polar partitioning fraction show the inhibitory effects, whereas the water-soluble parts show a poor activity in the same assay. [ABSTRACT FROM AUTHOR]

Because of its excellent optical properties and good stability, all-inorganic halide perovskite CsPbX 3 (X = I, Br, Cl) has been attracting interest for use in light-emitting diodes (LEDs). One challenge is improving the efficacy of the spatial confinement of excitons for higher luminescence efficiency. Here, we present a simple yet very effective strategy to form fine-grain-structured CsPbBr 3 polycrystalline films prepared by thermal co-evaporation. The strategy involves controlling growth kinetics by adjusting the deposition rate, which, along with growth temperature, determines the nucleation rate and therefore the eventual grain structure. A correlation between deposition rate and average grain size was noted except for a very large deposition rate when there were large hillocks, which we attributed to the peculiar growth behavior of PbBr 2 films. The growth conditions that produced a nanoscale grain structure and textured orientations without large hillocks also resulted in the highest luminescence efficiency as we anticipated. With the optimized CsPbBr 3 light emitters, we demonstrate a green-light-emitting (at 524 nm) LED with a maximum current efficiency of 1.07 cd/A and an extremely narrow electroluminescence spectrum of 18 nm, a result that highlights the potential of vacuum-processed CsPbBr 3 films for high-efficiency LEDs.