Berberine (BBR) has indicated significant antimicrobial activity against a variety of organisms including bacteria, viruses, and fungi. The mechanism by which BBR initiates apoptosis remains poorly understood. In the present study, we demonstrated that BBR exhibited significant cytotoxicity in human hepatoma HepG2 cells. Herein, we investigated cytotoxicity mechanism of BBR in HepG2 cells. The results showed that the induction of apoptosis in HepG2 cells by BBR was characterized by DNA fragmentation, an increased percentage of annexin V, and the activation of caspase-3. The expressions of Bcl-2 protein and pro-caspase-3 were reduced by BBR in HepG2 cells. However, Bax protein was increased in the cells. BBR-induced apoptosis was preceded by increased generation of reactive oxygen species (ROS). NAC treatment, a scavenger of ROS, reversed BBR-induced apoptosis effects via inhibition of Bax activation and Bcl-2 inactivation. BBR-induced, dose-dependent induction of apoptosis was accompanied by sustained phosphorylation of MAP Kinases (JNK and p38 MAPK), ASK1, Akt, and p53. Furthermore, SB203580, p38 inhibitor, reduced the apoptotic effect of BBR, and blocks the generation of ROS and NO as well as activation of Bax. We found that the treatment of HepG2 cells with BBR triggers generation of ROS through Akt phosphorylation, resulting in dissociation of the ASK1-mediated activation of JNK and p38 pathways.

Cucurbitacins 1 and 2 were isolated from the root of Trichosanthes kirilowii by tyrosinase inhibitory activity-guided fractionation. Spectroscopic analysis revealed that compounds 1 and 2 were cucurbitacin D and 23,24-dihydro-cucurbitacin D, respectively. Compounds 1 and 2 effectively inhibited the activity of tyrosinase (IC(50) = 0.18 microM and 6.7 microM, respectively), and the synthesis of melanin (IC(50) = 0.16 microM and 7.5 microM, respectively) in B16/F10 melanoma cells.

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Miconazole (MIC), a regional antifungal agent, has been used worldwide in the treatment of superficial mycosis. However, the effect of MIC on skin pigmentation is not known. In this study, we investigated the inhibitory effect of MIC on melanogenesis in B16 melanoma cells. Tyrosinase activity and melanin content were dose dependently decreased by MIC as compared with untreated cells. The level of tyrosinase protein expression was reduced with treatment MIC. A decrease in cell proliferation was observed in B16 cells treated with MIC 30 m mM, indicating that the MIC-induced depigmenting effect was caused by inhibition of melanin synthesis and not by destruction of B16 cells. Furthermore, MIC markedly suppressed a a-melanocyte stimulating hormone or forskolin-induced tyrosinase activity in B16 cells. Therefore the depigmenting effect of MIC might be due to the inhibition of tyrosinase activity and tyrosinase expression, which eventually slows melanin biosynthesis. These results indicate that MIC may be a useful inhibitor of melanogenesis in B16 cells and suggest that it may have beneficial effects in the treatment of hyperpigmentation disorders such as ephelis and melasma.

Skin diseases are a hyperpigmentation, hypopigmentation and melanoma, etc. Among them, recent studies have focused on the hyperpigmentation, which is especially abnormally increased colorations or spots. Hyperpigmentation such as chloasma, coloration or freckles increased abnormally the amount of melanin in the epidermis. [1][2][3][4][5] Some of the principle causes of hyperpigmentation are exposured to ultraviolet light, genetic reasons, metabolism, inflammation, infection, the endocrine system and reminded scars. [6][7][8] Melanin is synthesized in melanosomes of the melanocyte. The formed melanin granules are moved from the melanocytes cytoplasmic extensions to keratinocytes. 9,10) The melanocytes produce melanin by a process that involves the transformation of tyrosine into 3,4-dihydroxyphenylalanine (DOPA) by the enzyme tyrosinase and the subsequent transformation of DOPA into melanin. 5,11,12) Tyrosinase is the key enzyme in the pathway of melanogenesis. Tyrosinase plays a regulatory role in the production of melanin.13-15) Accordingly, the regulation of tyrosinase may not only control melanin production but also develop new therapy for pigmentation. Pharmaceutical agents which control melanin production or melanin metabolism are used as whitening agents. A number of whitening compounds have been screened for their effectiveness in reducing melanogenesis. 16)Radix Trichosanthis (RT) is the dry roots of Trichosanthis kirilowii MAXIM. (Cucurbitaceae) collected in the spring and fall. It is used in traditional Chinese medicine as an antiphlogistic, antifebrile, and cough remedy. It was also found to be effective as an abortifacient.17) It was found that the active principle of RT is a basic protein named trichosanthin.18) Recently, we have demonstrated that the water extracts of RT dose-dependently inhibit melanin synthesis and also abrogate cAMP-induced melanogenesis in B16 cells, but develops cytotoxicity.19) Thus, it would be important to abrogate the deleterious effects of RT using agents with a more physiological action.Radix Ginseng (RG) is the dry root of Panax ginseng C.A. MEY. (Araliaceae), a worldwide well-known traditional Chinese medicine with the popular name "ginseng". The wildgrowing or cultivated ginseng root is collected in the fall and used as a tonic.20) The major constituents of ginseng are the saponins, which include 30 kinds of ginsenoside. 21,22) Recently, it has been shown that panaxadiol fraction and its ginsenosides could induce the antioxidant enzymes, such as superoxide dismutase and catalase, which are important for maintaining cell viability.23) Also RG possess adaptogen-like effect to foreign deleterious infringement. 24) In view of the above reports, it can be considered that RG inhibits the cytotoxicity caused by RT.Therefore, the present study was conducted to investigate the effects of RG and RT on the melanogenesis in B16 melanoma cells. MATERIALS AND METHODS Sample and Preparation of ExtractRT and RG were standardized articles of the Korean pharmacopoeia (KP). The extracts...