Promotion of ABCG2 gene expression by neolignans from Piper longum L.

We focused on Piper longum L., a herbal drug produced in Myanmar, which has a renoprotective effect. Thus, we attempted to isolate and identify compounds that enhance the expression of the ABCG2 gene from the aerial parts of the plant except for the fruit. Among the various P. longum extracts, we isolated and identified the components. Using Caco-2 cells, the hABCG2 mRNA expression-enhancing effects of the isolated compounds were compared with the positive reference compound (3-methylcholanthrene [3MC]) using real-time polymerase chain reaction. Six compounds were isolated and identified from the methanol extract of P. longum. Among the isolated compounds, licarin A and neopomatene had lower toxicity and higher hABCG2 mRNA expression-enhancing effects in Caco-2 cells. Suppression of hAhR expression by siRNA reduced the activity of licarin A and neopomatene, as well as the hAhR agonist 3MC, suggesting that these 2 compounds may act as hAhR agonists to promote hABCG2 expression.

Amino Acid Conjugates of ent-Beyerane-type Diterpenoids and Oleanane-type Triterpenoids: Synthesis and Evaluation of Cytotoxic Activities.

The aim of this study was to increase the cytotoxic activities of terpenoids via amino acid conjugation. Thus, 21 new ester derivatives (5-15, 19-27, and 29) were prepared by conjugation of the hydroxy groups in ent-beyerane-type diterpenoids (4) and oleanane-type triterpenoids (18), and their cytotoxic activity against three human cancer cell lines (leukemia, lung, and stomach) were evaluated. The prepared compounds showed cytotoxic effects; in particular, all amino acid conjugates of ent-beyerane-type diterpenoids (5-13) exhibited potent cytotoxic activity (IC50 1.0-3.7 µM for HL60, 1.7-8.2 µM for A549, and 2.5-11.7 µM for MKN45). In addition, no differences were observed in the cytotoxic activities of l- and d-type amino acid conjugates.

Rapid removal of detergent in glycolipids using ionic liquids.

Detergent removal in glycolipid after sample preparation, such as enzymatic reaction or isolation of detergent-resistant membrane microdomain, is indispensable for further structural characterization. We previously established the rapid and effective method of detergent removal in glycolipid samples from glass test tube using 1,2-dichloroethane (DCE) washing. However, the use of DCE has several drawbacks, such as environmental risks, harmful effects (potentially carcinogenic), and high vaporability and flammability. To solve the issue, we used ionic liquids to remove detergents from glycolipid samples, and found 1-butyl-3-methylimidazolium iodide was a suitable alternative for DCE.

Effect of Compounds from Moringa oleifera Lam. on in Vitro Non-Alcoholic Fatty Liver Disease (NAFLD) Model System.

Non-alcoholic fatty liver disease (NAFLD) is currently the most common chronic liver disease in the world, with a prevalence of 25 % in many countries. To date, no drug has been approved to treat NAFLD, therefore, the use of phytochemicals to prevent this disease is meaningful. In this study, we focused on the effects of Moringa oleifera Lam. on diabetes, attempted to isolate compounds that regulate NAFLD. Compounds 1 and 2 were isolated from the ethyl acetate fraction of M. oleifera. Spectral data revealed that they were 1-hydroxy-3-phenylpropan-2-yl benzoate (1) and benzyl benzylcarbamate (2), respectively. The three-dimensional structure of compound 1 was determined by single crystal X-ray structural analysis. Neither compound was toxic to HepG2 cells, and compound 1 was found to have a concentration-dependent inhibitory effect on intracellular lipid accumulation induced by stimulation of linoleic acid (LA). As a result of measuring the effects of compound 1 on the intracellular lipid production-related protein, it was found that compound 1 enhanced protein expression that promotes lipolysis. On the other hand, since the action of compound 1 was similar to that of PPARα agonists, it is deduced that compound 1 enhanced the activity of PPARα and further enhanced the expression of lipolytic proteins, which is related to the suppression of intracellular lipid accumulation. Furthermore, as the result of docking simulation, compound 1 had a higher binding affinity to the ligand binding site of PPARα than fenofibrate, which is a PPARα agonist, and thus compound 1 was considered to be promising as an agonist of PPARα.

Cardiac glycosides from the roots of Streblus asper Lour. and their apoptosis-inducing activities in A549 cells.

Phytochemical investigation of the roots of Streblus asper Lour. resulted in the isolation of six previously undescribed cardiac glycosides, designated 2'-de-O-methylstrebloside (1), cannogenol-3α-O-ß-D-gluopyranosyl-(1 â†’ 4)-6-deoxy -2,3-dimethoxyl-ß-D-fucopyranoside (2), periplogenin-3-O-α-L-rhamnopyranosyl -(1 â†’ 4)-6-deoxy-ß-D-allopyranoside (3), 5-de-O-hydroxylstrebloside (4), 5ßH-16ß-hydroxylkamaloside (5), and 17S, 21R-21-hydroxylstrebloside (6), and three known analogues (7-9). The structures were elucidated using NMR spectroscopic techniques, mass spectrometry, and comparison of the spectroscopic data with previously reported data. Compound 6 is a novel C-21 hydroxyl cardiac glycoside, its absolute configuration was established from the analysis of computational ECD calculations and NMR spectroscopic data. The effects of the cardiac glycosides on apoptosis and cytotoxicity were examined in human A549 lung cancer cells. All the compounds showed remarkable inhibitory activities, with IC50 values in the range of 0.01-6.08 µM. Furthermore, compound 3 was able to significantly inhibit A549 cell growth proliferation via the induction of apoptosis, due to the activation of caspases-3, -8 and -9 in A549 cells, as revealed by Western blot analysis.

Tokoronin Contained in Dioscorea tokoro Makino ex Miyabe Suppressed α-MSH-Induced Melanogenesis in B16 Cells via Suppression of Classical MAPK Pathway Activation.

In this study, melanogenesis inhibition in B16 cells by eight compounds, namely, tokorogenin, tokoronin, yononin, gracillin, proto-yonogenin, proto-tokoronin, proto-yononin, and proto-gracillin, isolated from Dioscorea tokoro Makino ex Miyabe were evaluated. The results of the cytotoxicity and α-MSH-induced melanogenesis inhibition effects of the eight compounds revealed that tokoronin was the most effective in terms of low-cytotoxicity and melanogenesis inhibition. Tokoronin downregulated α-MSH-induced melanogenesis via suppression of the expression of the three types of melanogenesis-related enzymes [tyrosinase, tyrosinase-related protein-1 (TRP-1), TRP-2] by the inhibition of phospho-microphthalmia-associated transcription factor (p-MITF) and cAMP response element binding protein (CREB) levels. p-MITF and CREB are regulated by various kinases [Akt, mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (MAPK), and c-jun N-terminal kinase (JNK)]. As the results of measurement of the combined effects of tokoronin with inhibitors or promoters of these kinases, no change in the biological activity of tokoronin by Akt inhibitor (wortmannin) or p38 MAPK inhibitor (SB202190) was observed, however, the effect of tokoronin was reduced by the MEK/ERK inhibitor (U0126) and promoted by the MEK/ERK activator (FGF2). Therefore, it was deduced that tokoronin first inactivated ERK; then, it suppressed p-MITF and CREB levels; and finally, α-MSH-induced melanogenesis was suppressed.

(-)-O-Methylcubebin from Vitex trifolia Enhanced Adipogenesis in 3T3-L1 Cells via the Inhibition of ERK1/2 and p38MAPK Phosphorylation.

In this study, for the purpose of elucidation for antidiabetic components, we isolated and identified compounds that could become lead compounds for the development of antidiabetic agents from the herbal medicine Vitex trifolia, which is used for liver protection in Myanmar. Three kinds of lignan, (-)-O-methylcubebin (MC), (-)-hinokinin, and (-)-cubebin, were isolated from the ethyl acetate extract of the leaves of V. trifolia, using various chromatography. Among the three isolated compounds, MC showed the strongest effects to increase intracellular lipid accumulation in 3T3-L1 cells. From the results of the elucidation of the MC's effects on the adipogenesis of 3T3-L1 cells, the downsizing of adipocytes and the promotion of the expression of adipogenesis-related proteins, as well as adiponectin, were observed. On the other hand, since the activity of MC was inhibited by antagonists of PPARγ and improved by inhibitors of the classical mitogen-activated protein kinase (MAPK) pathway and p38MAPK pathway, MC was considered to be an agonist of PPARγ, and furthermore promoted adipogenesis via the inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) and p38MAPK phosphorylation. Although MC showed similar effects to those of rosiglitazone (RO) used as a positive control, RO promoted the migration of GLUT4 from the cytoplasm to the cell membrane, whereas MC did not show such an effect. From the abovementioned results, it was considered that MC could be a lead compound for the development of antidiabetic drugs that does not show weight gain, which is a side effect of RO.

Synthesis of Lanostane-Type Triterpenoid N-Glycosides and Their Cytotoxicity against Human Cancer Cell Lines.

Seventeen lanostane-type triterpenoid derivatives (2 - 18), including 11N-glycosides (8 - 18), were synthesized from the natural triterpenoid, lanosterol (1), and were evaluated for their cytotoxicity against the human cancer cell lines, HL-60, A549, and MKN45, as well as the normal human lung cells, WI-38. Among them, N-ß-d-2-acetamido-2-deoxyglucoside (10) showed cytotoxicity against HL-60, A549, MKN45, and WI-38 cells (IC50 0.0078 - 2.8 µm). However, N-ß-d-galactoside (12) showed cytotoxicity against HL-60 and MKN45 cells (IC50 0.0021 - 4.0 µm), but not the normal WI-38 cells. Furthermore, Western blot analysis suggested that 12 induces apoptosis by activation of caspases-3, 8, and 9. These results will be useful for the synthesis of other tetracyclic triterpenoids or steroid N-glycosides to increase their cytotoxicity and apoptosis-inducing activities.

Cytotoxic and Apoptosis-inducing Activities of Taraxastane-type Triterpenoid Derivatives in Human Cancer Cell Lines.

Twenty-eight taraxastane-type triterpenoid derivatives 4 - 31 were prepared from the naturally occurring triterpenoids faradiol (1) and heliantriol C (3). The cytotoxic activities of these compounds and arnidiol (2) were evaluated in leukemia (HL60), lung (A549), duodenal (AZ521), and breast (SK-BR-3) cancer cell lines. 21-Oxoarnidiol (18) and faradiol 3,16-di-O-l-alaninate (31) exhibited potent cytotoxicity, with 50% inhibitory concentrations of 0.5 - 2.7 µm. In particular, flow cytometric analysis indicated that compound 31 induced typical apoptotic cell death in HL60 cells. These results suggested that taraxastane-type triterpenoid derivatives might provide useful antitumor agents with apoptosis-inducing activity.

Effects of Various 5,7-Dihydroxyflavone Analogs on Adipogenesis in 3T3-L1 Cells.

We studied the effects of twelve 5,7-dihydroxyflavone analogs on adipogenesis in 3T3-L1 cells. Among the compounds, luteolin, diosmetin, and chrysoeriol partly inhibited adipogenesis by blocking the accumulation of triacylglycerol in the cells. Conversely, tricetin facilitated triacylglycerol accumulation in the cells. The induction of lipogenesis or lipolysis may depend on the number and bonding position of hydroxyl or methoxy groups on the B ring of 5,7-dihydroxyflavone. The mRNA expression levels of adipogenic and lipogenic genes were suppressed by luteolin treatment in the cells, while the mRNA levels of lipolytic genes were not affected. However, the expression levels of the adipogenic, lipogenic, and lipolytic genes, except for adipocyte protein 2 (aP2), were not affected by the addition of tricetin. Moreover, luteolin suppressed glucose transporter type 4 (GLUT4) gene and protein levels. These results indicate that luteolin decreased triacylglycerol levels in 3T3-L1 cells during adipogenesis through the suppression of adipogenic/lipogenic and GLUT4 genes and GLUT4 protein.

Dioscin Derived from Solanum melongena L. "Usukawamarunasu" Attenuates α-MSH-Induced Melanogenesis in B16 Murine Melanoma Cells via Downregulation of Phospho-CREB and MITF.

This study aimed to chemically isolate and explore an antimelanogenesis inducer in extracts of Solanum melongena L. "Usukawamarunasu" eggplant. We successfully identified dioscin ([25R]-Spirost-5-en-3ß-yl) 2-O-(6-deoxy-α-L-mannopyranosyl) - 4-O-(6-deoxy-α-L-mannopyranosyl)-ß-D-glucopyranoside] in the plant, and examined the effects of α-melanocyte-stimulating hormone (MSH)-induced melanogenesis in B16 murine melanoma cells by this plant-derived dioscin. Immunoblot analysis suggested that dioscin reduced the expression of tyrosinase, tyrosinase-related protein-1 (TRP-1), and TRP-2, resulting in inhibition of intracellular production of melanin. In addition, dioscin caused reduction of phosphorylated cAMP-responsive element binding protein 1 transcription factors (CREB), which led to a reduction of microphthalmia-related transcription factor (MITF) in α-MSH-stimulated cells, but did not affect phosphorylation of extracellular signal-regulated kinase. Furthermore, dioscin significantly downregulated the expression of tyrosinase, TRP-1, and TRP-2, which led to the reduction of α-MSH-induced melanogenesis in B16 cells. These results suggest that dioscin may decrease the level of MITF via inhibition of phosphorylation of CREB in α-MSH-induced melanogenesis in B16 cells.

Melanogenesis-inhibitory activity and cancer chemopreventive effect of glucosylcucurbic acid from shea (Vitellaria paradoxa) kernels.

Two jasmonate derivatives, glucosylcucurbic acid (1) and methyl glucosylcucurbate (2), were isolated from the MeOH extract of defatted shea (Vitellaria paradoxa; Sapotaceae) kernels. These and their deglucosylated derivatives, cucurbic acid (3) and methyl cucurbate (4), were evaluated for their melanogenesis-inhibitory and cancer chemopreventive potencies. Compounds 1, 3, and 4 exhibited potent melanogenesis-inhibitory activities in α-melanocyte-stimulating hormone (α-MSH)-stimulated B16 melanoma cells. Western-blot analysis revealed that compounds 1 and 3 reduced the protein levels of MITF (=microphthalmia-associated transcription factor), tyrosinase, TRP-1 (=tyrosine-related protein 1), and TRP-2 mostly in a concentration-dependent manner. In addition, compound 1 exhibited inhibitory effects against Epstein-Barr virus early antigen (EBV-EA) activation induced with 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells, against TPA-induced inflammation in mice, and against 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.

Triterpene glycosides and other polar constituents of shea (Vitellaria paradoxa) kernels and their bioactivities.

The MeOH extract of defatted shea (Vitellaria paradoxa; Sapotaceae) kernels was investigated for its constituents, and fifteen oleanane-type triterpene acids and glycosides, two steroid glucosides, two pentane-2,4-diol glucosides, seven phenolic compounds, and three sugars, were isolated. The structures of five triterpene glycosides were elucidated on the basis of spectroscopic and chemical methods. Upon evaluation of the bioactivity of the isolated compounds, it was found that some or most of the compounds have potent or moderate inhibitory activities against the following: melanogenesis in B16 melanoma cells induced by α-melanocyte-stimulating hormone (α-MSH); generation of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, against Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-teradecanoylphorbol 13-acetate (TPA) in Raji cells; t TPA-induced inflammation in mice, and proliferation of one or more of HL-60, A549, AZ521, and SK-BR-3 human cancer cell lines, respectively. Western blot analysis established that paradoxoside E inhibits melanogenesis by regulation of expression of microphthalmia-associated transcription factor (MITF), tyrosinase, and tyrosinase-related protein-1 (TRP-1) and TRP-2. In addition, tieghemelin A was demonstrated to exhibit cytotoxic activity against A549 cells (IC50 13.5 µM) mainly due to induction of apoptosis by flow cytometry. The extract of defatted shea kernels and its constituents may be, therefore, valuable as potential antioxidant, anti-inflammatory, skin-whitening, chemopreventive, and anticancer agents.

Cytotoxic and nitric oxide production-inhibitory activities of limonoids and other compounds from the leaves and bark of Melia azedarach.

Nine limonoids, 1-9, one apocarotenoid, 11, one alkaloid, 12, and one steroid, 13, from the leaf extract; and one triterpenoid, 10, five steroids, 14-18, and two flavonoids, 19 and 20, from the bark extract of Melia azedarach L. (Chinaberry tree; Meliaceae) were isolated. Among these compounds, three compounds, 4-6, were new, and their structures were established as 3-deacetyl-28-oxosalannolactone, 3-deacetyl-28-oxosalanninolide, and 3-deacetyl-17-defurano-17,28-dioxosalannin, respectively, on the basis of extensive spectroscopic analyses and comparison with literature data. All of the isolated compounds were evaluated for their cytotoxic activities against leukemia (HL60), lung (A549), stomach (AZ521), and breast (SK-BR-3) cancer cell lines. 3-Deacetyl-4'-demethyl-28-oxosalannin (3) against HL60 and AZ521 cells, and methyl kulonate (10) against HL60 cells exhibited potent cytotoxicities with IC50 values in the range of 2.8-5.8 µM. In addition, upon evaluation of compounds 1-13 against production of nitric oxide (NO) in mouse macrophage RAW 264.7 cells induced by lipopolysaccharide (LPS), seven, i.e., trichilinin B (1), 4, ohchinin (7), 23-hydroxyohchininolide (8), 21-hydroxyisoohchininolide (9), 10, and methyl indole 3-carboxylate (12), inhibited production of NO with IC50 values in the range of 4.6-87.3 µM with no, or almost no, toxicity to the cells (IC50 93.2-100 µM). Western blot analysis revealed that compound 7 reduced the expression levels of the inducible NO synthase (iNOS) and COX-2 proteins in a concentration-dependent manner. Furthermore, compounds 5, 6, 13, and 18-20 exhibited potent inhibitory effects (IC50 299-381 molar ratio/32 pmol TPA) against Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cell line.

Three new and other limonoids from the hexane extract of Melia azedarach fruits and their cytotoxic activities.

A defatted fraction obtained from the hexane extract of the fruits of Melia azedarach L. (chinaberry tree; Meliaceae) exhibited cytotoxic activities against leukemia (HL60), lung (A549), stomach (AZ521), and breast (SK-BR-3) cancer cell lines with IC50 values in the range of 2.9-21.9 µg/ml. Three new limonoids, 3-deacetyl-4'-demethylsalannin (5), 3-deacetyl-28-oxosalannin (14), and 1-detigloylohchinolal (17), along with 16 known limonoids, 1-4, 6-13, 15, 16, 18, and 19, and one known triterpenoid, 20, were isolated from the fraction. The structures of new compounds were elucidated on the basis of extensive spectroscopic analyses and comparison with literature. These compounds were evaluated for their cytotoxic activities against the four cancer cell lines mentioned above. 3-Deacetyl-4'-demethyl-28-oxosalannin (16), which exhibited potent cytotoxicity against AZ521 (IC50 3.2 µM) cells, induced typical apoptotic cell death in AZ521 cells upon evaluation of the apoptosis-inducing activity by flow cytometry. This work provided, furthermore, valuable information on the structural features of limonoids of the fruits and/or seeds of Melia azedarach and related Meliaceae plants, M. toosendan and Azadirachta indica.

Cytotoxic and apoptosis-inducing activities, and anti-tumor-promoting effects of cyanogenated and oxygenated triterpenes.

Two of each semisynthetic lanostane- and cycloartane-type triterpenes with a cyano-enone functionality, i.e., 13 and 18, and 23 and 28, respectively, sixteen of their synthetic intermediates, 9-12, 14-17, 19-22, and 24-27, along with seven semisynthetic oxygenated triterpene acetates, 29-35, and eight natural hydroxy triterpenes, 1-8, were evaluated for their cytotoxic activities against leukemia (HL60), lung (A549), stomach (AZ521), and breast (SK-BR-3) cancer cell lines. One natural triterpene, 8, and ten semisynthetic triterpenes, 9, 13, 15, 18, 23, 25, 28, 29, 32, and 33, exhibited potent cytotoxicities against one or more cell lines with IC50 values in the range of 1.4-9.9 µM. Two lanostane-type triterpenes with a cyano-enone functionality, 3-oxolanosta-1,8,24-triene-2-carbonitrile (13) and 3-oxolanosta-1,8-diene-2-carbonitrile (18), induced apoptosis in HL60 cells, as observed by membrane phospholipid exposure in flow cytometry. Western blot analysis showed that 13 and 18 significantly reduced procaspases-3, -8, and -9, and increased cleaved caspases-3, -8, and -9. These findings indicated that compounds 13 and 18 induced apoptosis in HL60 cells via both the mitochondrial and the death receptor-mediated pathways. In addition, upon evaluation of the inhibitory effects on EpsteinBarr virus early antigen (EBV-EA) activation induced with 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells, seven natural triterpenes, 1-6 and 8, and ten semisynthetic triterpenes, 9, 10, 14, 15, 19, 20, 24, 25, 29, and 30, exhibited inhibitory effects which were higher than that of ß-carotene, a vitamin A precursor studied widely in cancer-chemoprevention animal models.

Cytotoxic and melanogenesis-inhibitory activities of limonoids from the leaves of Azadirachta indica (Neem).

Seventeen limonoids (tetranortriterpenoids), 1-17, including three new compounds, i.e., 17-defurano-17-(2,5-dihydro-2-oxofuran-3-yl)-28-deoxonimbolide (14), 17-defurano-17-(2ξ-2,5-dihydro-2-hydroxy-5-oxofuran-3-yl)-28-deoxonimbolide (15), and 17-defurano-17-(5ξ-2,5-dihydro-5-hydroxy-2-oxofuran-3-yl)-2',3'-dehydrosalannol (17), were isolated from an EtOH extract of the leaf of neem (Azadirachta indica). The structures of the new compounds were elucidated on the basis of extensive spectroscopic analyses and comparison with literature. Upon evaluation of the cytotoxic activities of these compounds against leukemia (HL60), lung (A549), stomach (AZ521), and breast (SK-BR-3) cancer cell lines, seven compounds, i.e., 1-3, 12, 13, 15, and 16, exhibited potent cytotoxicities with IC50 values in the range of 0.1-9.9 µM against one or more cell lines. Among these compounds, cytotoxicity of nimonol (1; IC50 2.8 µM) against HL60 cells was demonstrated to be mainly due to the induction of apoptosis by flow cytometry. Western blot analysis suggested that compound 1 induced apoptosis via both the mitochondrial and death receptor-mediated pathways in HL60 cells. In addition, when compounds 1-17 were evaluated for their inhibitory activities against melanogenesis in B16 melanoma cells, induced with α-melanocyte-stimulating hormone (α-MSH), seven compounds, 1, 2, 4-6, 15, and 16, exhibited inhibitory activities with 31-94% reduction of melanin content at 10 µM concentration with no or low toxicity to the cells (82-112% of cell viability at 10 µM). All 17 compounds were further evaluated for their inhibitory effects against the EpsteinBarr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells.

Limonoids and flavonoids from the flowers of Azadirachta indica var. siamensis, and their melanogenesis-inhibitory and cytotoxic activities.

A new limonoid, 7-O-acetyl-7-O-debenzoyl-22-hydroxy-21-methoxylimocinin (2), and two new flavonoids, 3'-(3-hydroxy-3-methylbutyl)naringenin (7) and 4'-O-methyllespedezaflavanone C (9), along with nine known compounds, including two limonoids, 1 and 3, and seven flavonoids, 4-6, 8, and 10-12, were isolated from a MeOH extract of the flowers of Azadirachta indica A.Juss. var. siamensis Valeton (Siamese neem tree; Meliaceae). The structures of new compounds were elucidated on the basis of extensive spectroscopic analysis and comparison with literature data. All of these compounds were evaluated for their melanogenesis-inhibitory activities in B16 melanoma cells induced with α-melanocyte-stimulating hormone (α-MSH). Compound 2 (16.9% melanin content at 30 µM), 6-deacetylnimbin (3; 49.6% melanin content at 100 µM), and kaempferide (10; 41.7% melanin content at 10 µM) exhibited inhibitory effects with no, or almost no, toxicity to the cells (81.0-111.7% cell viability). In addition, evaluation of their cytotoxic activities against HL60, A549, AZ521, and SK-BR-3 human cancer cell lines, isoazadironolide (1), 4'-O-methyl-8-prenylnaringenin (5), euchrestaflavanone A (8), 9, and 3-methoxy-3'-prenylnaringenin (12) revealed potent cytotoxicities against one or more cell lines with IC50 values in the range of 4.5-9.9 µM.

Glycosidic inhibitors of melanogenesis from leaves of Passiflora edulis.

A new flavonoid glycoside, chrysin 6-C-ß-rutinoside (chrysin α-L-rhamnopyranosyl-(1→6)-C-ß-glucopyranoside; 2), and two new triterpene glycosides, (31R)-31-O-methylpassiflorine (7) and (31S)-31-O-methylpassiflorine (8), along with 14 known glycosides, including three flavonoid glycosides, 1, 3, and 4, six triterpene glycosides, 5, 6, and 9-12, three cyano glycosides, 13-15, and two other glycosides, 16 and 17, were isolated from a MeOH extract of the leaves of Passiflora edulis (passion flower; Passifloraceae). The structures of new compounds were elucidated on the basis of extensive spectroscopic analysis and comparison with literature data. Upon evaluation of compounds 1-17 against the melanogenesis in the B16 melanoma cells induced with α-melanocyte-stimulating hormone (α-MSH), three compounds, isoorientin (1), 2, and (6S,9R)-roseoside (17), exhibited inhibitory effects with 37.3-47.2% reduction of melanin content with no, or almost no, toxicity to the cells (90.8-100.2% cell viability) at 100 µM. Western blot analysis showed that compound 2 reduced the protein levels of MITF, TRP-1, and tyrosinase, in a concentration-dependent manner while exerted almost no influence on the level of TRP-2, 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 TRP-1 and tyrosinase. In addition, compounds 1-17 were evaluated for their inhibitory effects against the EpsteinBarr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells.

Cytotoxic activities of amino acid-conjugate derivatives of abietane-type diterpenoids against human cancer cell lines.

Nine amino acid conjugate derivatives, each 2-10 and 12-20, were prepared from abietic acid (1) and dehydroabietic acid (11), respectively, and they were evaluated for their cytotoxicities against four human cancer cell lines, i.e., leukemia (HL60), lung (A549), stomach (AZ521), and breast (SK-BR-3). All compounds showed cytotoxicities against HL60 with IC50 values in the range of 2.3-37.3 µM. In addition, most of the derivatives exhibited moderate cytotoxicities against the other cancer cell lines. Among the derivatives, methyl N-[18-oxoabieta-8,11,13-trien-18-yl]-L-tyrosinate (19) exhibited potent cytotoxic activities against four cancer cell lines with IC50 values of 2.3 (HL60), 7.1 (A549), 3.9 (AZ521), and 8.1 µM (SK-BR-3). Furthermore, all derivatives were shown to possess high selective cytotoxic activities for leukemia cells, since they exhibited only weak cytotoxicities against normal lymphocyte cell line RPMI1788.