Antioxidative and melanogenesis-inhibitory activities of caffeoylquinic acids and other compounds from moxa.

The MeOH extract of moxa, the processed leaves of Artemisia princeps PAMP. (Asteraceae), exhibited potent 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity and melanogenesis-inhibitory activity in α-melanocyte-stimulating hormone (α-MSH)-stimulated B16 melanoma cells. Eight caffeoylquinic acids, 1 and 6-12, five flavonoids, 13-17, two benzoic acid derivatives, 18 and 19, three coumarin derivatives, 20-22, four steroids, 23-26, and six triterpenoids, 27-32, were isolated from the MeOH extract. Upon evaluation of compounds 1, 6-23, and four semisynthetic caffeoylquinic acid esters, 2-5, for their DPPH radical-scavenging activity, 15 compounds, 1-13, 17, and 19, showed potent activities (IC(50) 3.1-16.8 μM). The 15 compounds exhibited, moreover, potent inhibitory activities (51.1-92.5% inhibition) against peroxidation of linoleic acid emulsion at 10 μg/ml concentration. In addition, when 27 compounds, 1-8, 10, 12, 13, 15-18, 20-25, and 27-32, were evaluated for their inhibitory activity against melanogenesis in α-MSH-stimulated B16 melanoma cells, five caffeoylquinic acids, i.e., chlorogenic acid (1), ethyl chlorogenate (3), propyl chlorogenate (4), isopropyl chlorogenate (5), and butyl chlorogenate (6), along with homoorientin (17) and vanillic acid (18), exhibited inhibitory activities with 33-62% reduction of melanin content at 100 μM concentration with no or almost no toxicity to the cells (89-114% of cell viability at 100 μM). Western blot analysis showed that compound 6 reduced the protein levels of microphtalmia-associated transcription factor (MITF), tyrosinase, tyrosine-related protein 1 (TRP-1), and TRP-2 mostly in a concentration-dependent manner, suggesting that this compound inhibits melanogenesis on α-MSH-stimulated B16 melanoma cells by, at least in part, inhibiting the expression of MITF, followed by decreasing the expression of tyrosinase, TRP-1, and TRP-2. Furthermore, four compounds, 13, 15, 16, and 30, exhibited cytotoxicities against HL60 human leukemia cell line (IC(50) 7.0-11.1 μM), and nine compounds, 14-16, 23, 26-28, 31, and 32, showed inhibitory effects (IC(50) 272-382 mol ratio/32 pmol 12-O-tetradecanoylphohrbol-13-acetate (TPA)) against Epstein-Barr virus early antigen (EBV-EA) activation induced by TPA in Raji cells.

Akihisa T ，Kawashima K ，Orido M ，Akazawa H ，Matsumoto M ，Yamamoto A ，Ogihara E ，Fukatsu M ，Tokuda H ，Fuji J ... -  《-》

Biological activities of phenolic compounds and triterpenoids from the galls of Terminalia chebula.

Nine phenolic compounds, including two phenolic carboxylic acids, 1 and 2, seven hydrolyzable tannins, 3-9, eight triterpenoids, including four oleanane-type triterpene acids, 10-13, and four of their glucosides, 14-17, isolated from a MeOH extract of the gall of Terminalia chebula Retz. (myrobalan tree; Combretaceae), were evaluated for their inhibitory activities against melanogenesis in B16 melanoma cells induced by α-melanocyte-stimulating hormone (α-MSH), against the Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol 13-acetate (TPA) in Raji cells, and against TPA-induced inflammation in mice. Their 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activities and cytotoxic activities against four human cancer cell lines were also evaluated. Compounds 6-9 and 12 exhibited potent inhibitory activities against melanogenesis (39.3-66.3% melanin content) with low toxicity to the cells (74.5-105.9% cell viability) at a concentration of 10 μM. Western-blot analysis revealed that isoterchebulin (8) reduced the protein levels of MITF (=microphtalmia-associated transcription factor), tyrosinase, and TRP-1 (=tyrosine-related protein 1), mostly in a concentration-dependent manner. Eight triterpenoids, 10-17, showed potent inhibitory effects on EBV-EA induction with the IC50 values in the range of 269-363 mol ratio/32 pmol TPA, while these compounds exhibited no DPPH scavenging activities (IC50 >100 μM). On the other hand, the nine phenolic compounds, 1-9, exhibited potent radical-scavenging activities (IC50 1.4-10.9 μM) with weak inhibitory effects on EBV-EA induction (IC50 460-518 mol ratio/32 pmol TPA). The tannin 6 and seven triterpenoids, 10-16, have been shown to inhibit TPA-induced inflammation (1 μg/ear) in mice with the ID50 values in the range of 0.06-0.33 μmol/ear. Arjungenin (10) exhibited inhibitory effect on skin-tumor promotion in an in vivo two-stage mouse-skin carcinogenesis test based on 7,12-dimethylbenz[a]anthracene (DMBA) as initiator and with TPA as promoter. Compounds 1, 2, 4, 5, 7-9, 12, and 13, against HL60 cell line, compounds 1 and 4, against AZ521 cell line, and compounds 1, 11, and 12, against SK-BR-3 cell line, showed moderate cytotoxic activities (IC50 13.9-73.2 μM).

Manosroi A ，Jantrawut P ，Ogihara E ，Yamamoto A ，Fukatsu M ，Yasukawa K ，Tokuda H ，Suzuki N ，Manosroi J ，Akihisa T ... -  《-》

Melanogenesis inhibitory activity of sesquiterpenes from Canarium ovatum resin in mouse B16 melanoma cells.

Four known sesquiterpene alcohols, i.e., 1-4, ten triterpene alcohols, i.e., 5-14, and four triterpene acids, i.e., 15-18, were isolated from the MeOH extract of Canarium ovatum resin (elemi resin). Upon evaluation of the previously described compounds 1-18 on the melanogenesis in B16 melanoma cells induced with α-melanocyte-stimulating hormone (α-MSH), three sesquiterpene alcohols, i.e., cryptomeridiol (1), 4-epicryptomeridiol (2), and cadin-1(14)-ene-7α,11-diol (4), exhibited inhibitory effects with 27.4-34.1 and 39.0-56.9% reduction of melanin content at 50 and 100 μM, respectively, with no or very low toxicity to the cells (80.9-103.9% of cell viability at 100 μM). Western-blot analysis revealed that compounds 1 and 2 reduced the protein levels of MITF (=microphtalmia-associated transcription factor), tyrosinase, and TRP-2 (=tyrosine-related protein 2), mostly in a concentration-dependent manner, suggesting that these compounds exhibit melanogenesis inhibitory activity on α-MSH-stimulated B16 melanoma cells by, at least in part, inhibiting the expression of MITF, followed by decreasing the expression of tyrosinase and TRP-2. Three sesquiterpene alcohols, i.e., 1, 2, and 4, are, therefore, considered to be valuable as potential skin-whitening agents.

Kikuchi T ，Watanabe K ，Tochigi Y ，Yamamoto A ，Fukatsu M ，Ezaki Y ，Tanaka R ，Akihisa T ... -  《-》

Melanogenesis-inhibitory activity of aromatic glycosides from the stem bark of Acer buergerianum.

A new benzyl glucoside, 3-O-demethylnikoenoside (1), along with eleven known compounds, including seven aromatic glycosides, 2-8, three lignans, 9-11, and one cyclitol, 12, were isolated from the BuOH-soluble fraction of a MeOH extract of Acer buergerianum stem bark. The structures of the new compound were elucidated on the basis of extensive spectroscopic analyses and comparison with literature. Upon evaluation of compounds 1-12 on melanogenesis in B16 melanoma cells induced with α-melanocyte-stimulating hormone (α-MSH), three compounds, i.e., hovetrichoside B (8), pinoresinol 4-O-β-D-glucopyranoside (9), and pinoresinol 4-O-β-D-apiofuranosyl-(1→2)-β-D-glucopyranoside (10), have been found to exhibit inhibitory effects with 41-49% melanin content compared to the control at 100 μM and low cytotoxicity to the cells (81-92% cell viability at 100 μM). Western blot analysis showed that compound 8 reduced the protein levels of MITF (=microphtalmia-associated transcription factor) and tyrosinase, in a concentration-dependent manner, suggesting that 8 inhibits melanogenesis in α-MSH-stimulated B16 melanoma cells by, at least in part, inhibiting the expression of MITF, followed by decreasing the expression of tyrosinase. On the other hand, upon Western blotting, compound 9 was found to reduce the protein levels of tyrosinase and TRP-2, while it increased MITF and TRP-1 (=tyrosine-related protein 1), in a concentration-dependent manner, indicating that 9 inhibits melanogenesis in α-MSH-stimulated B16 melanoma cells by, at least in part, inhibiting the expression of tyrosinase and TRP-2.

Akihisa T ，Orido M ，Akazawa H ，Takahashi A ，Yamamoto A ，Ogihara E ，Fukatsu M ... -  《-》

Glycosidic inhibitors of melanogenesis from leaves of Momordica charantia.

Eight glycosidic compounds, 1-8, including two new compounds, (4ξ)-α-terpineol 8-O-[α-L-arabinopyranosyl-(1→6)-β-D-glucopyranoside] (5) and myrtenol 10-O-[β-D-apiofuranosyl-(1→6)-β-D-glucopyranoside] (7), were isolated from the BuOH-soluble fraction of a MeOH extract of Momordica charantia leaves. The structures of the new compounds were elucidated on the basis of extensive spectroscopic analyses and comparison with literature. Upon evaluation of compounds 1-8 on the melanogenesis in B16 melanoma cells induced with α-melanocyte-stimulating hormone (α-MSH), these compounds were found to exhibit inhibitory activities with 7.1-27.0% and 23.6-46.4% reduction of melanin content at 30 μM and 100 μM, respectively, with no or almost no toxicity to the cells (80.0-103.5% of cell viability at 100 μM). Western blot analysis showed that compound 7 reduced the protein levels of MITF, tyrosinase, TRP-1, and TRP-2 mostly in a concentration-dependent manner, suggesting that this compound inhibits melanogenesis on the α-MSH-stimulated B16 melanoma cells by, at least in part, inhibiting the expression of MITF, followed by decreasing the expression of tyrosinase, TRP-1, and TRP-2.

Kikuchi T ，Zhang J ，Huang Y ，Watanabe K ，Ishii K ，Yamamoto A ，Fukatsu M ，Tanaka R ，Akihisa T ... -  《-》