Chrysin 7-O-ß-d-glucopyranoside increases hepatic low-density lipoprotein receptor expression through AMP-activated protein kinase activation.

Elevated plasma low-density lipoprotein (LDL) cholesterol level is a risk factor for developing atherosclerosis. Increased LDL receptor (LDLR) expression is expected to reduce the risk of atherosclerotic disease since hepatic LDLR is essential for clearing plasma LDL cholesterol. Here, we screened human LDLR promoter effectors and observed that extracts from peduncles of sweet cherry (Prunus avium) 'Sato-Nishiki' induce LDLR gene promoter activity. We used several analytical and chemical methods to show that chrysin 7-O-ß-d-glucopyranoside (chrysin-7G) is one of the compounds that stimulate LDLR gene promoter activity in cherry peduncle extracts. Furthermore, synthetic chrysin-7G increased the expression and activity of LDLR. The chrysin-7G-mediated increase in LDLR expression and activity was completely abolished by treatment with an AMP-activated protein kinase (AMPK) inhibitor, compound C. These results indicate that chrysin-7G increases LDLR expression through AMPK activation and may be a useful compound that can be recycled from waste parts of agricultural products.

Isolation of phenolic acids and tannin acids from Mangifera indica L. kernels as inhibitors of lipid accumulation in 3T3-L1 cells.

Mango (Mangifera indica L.) kernels are usually discarded as waste, but they contain many pharmacological properties and bioactivities. In this study, we isolated antiobesity agents from mango kernels that inhibit intracellular lipid formation in 3T3-L1 adipocytes. Two phenolic acids, ethyl gallate and ethyl digallate, and 2 tannin acids, 1,2,3,4,6-penta-O-galloyl-ß-d-glucose (PGG) and 3-O-digalloyl-1,2,4,6-tetra-O-ß-d-glucose (HGG), were identified from mango kernels and were found to be suppressed lipid accumulation as evidenced by Oil Red O staining. Furthermore, ethyl digallate, PGG, and HGG significantly downregulated the mRNA expression of adipogenic transcription factors such as C/EBPα and PPARγ. However, ethyl gallate did not affect the expression of these transcription factors. Our findings reveal the presence of antiobesity compounds in mango kernels, implying its therapeutic role against obesity.

Androgen receptor antagonists produced by Streptomyces overcome resistance to enzalutamide.

Prostate cancer (PC) is a leading cause of cancer-related death in men in Western countries. Androgen receptor (AR) signaling is a major driver of PC; therefore, androgen deprivation by medical and surgical castration is the standard treatment for patients with PC. However, over time, most patients will progress to metastatic castration-resistant PC. Enzalutamide is the only AR antagonist approved by the Food and Drug Administration for the treatment of metastatic castration-resistant PC. However, resistance to enzalutamide also develops in most patients with castration-resistant PC. Thus, there is an urgent need to develop new AR antagonists with new structures. For this purpose, we conducted both in silico and natural product screenings. From the in silico screening, we obtained T5853872 and more potent compound, STK765173. From the natural product screening, the novel compound arabilin was isolated from Streptomyces sp. MK756-CF1. Unlike STK765173, arabilin could overcome resistance to enzalutamide. Furthermore, we also extracted a novel compound, antarlide A, and its geometric isomers from Streptomyces sp. BB47. Antarlides A-F have novel 22-membered-ring macrocyclic structures, while antarlides G and H have 20-membered-ring structures. Both antarlides B and G showed potent AR antagonist activity in prostate cancer cells and could overcome resistance to enzalutamide.

Increased benzoxazinoid (Bx) levels in wheat seedlings via jasmonic acid treatment and etiolation and their effects on Bx genes including Bx6.

Wheat accumulates benzoxazinoid (Bx) as a defensive compound. While Bx occurs at high concentrations, particularly in the early growth stages, its mechanism of regulation remains unclear. In the present study, we first examined the effects of several plant hormones on Bx concentrations in wheat seedlings. Among the compounds tested, jasmonate (JA) elevated the concentrations of DIMBOA-Glc (2-ß-D-glucoside of 2,4-dihydroxy-7-methoy-1,4-benzoxazin-3-one), the primary Bx species in intact wheat seedlings, without a significant increase in HDMBOA-Glc (4-O-methyl-DIMBOA-Glc), which is known to be upregulated by stresses. In addition, growing the plants in the dark increased DIMBOA-Glc levels. Quantification of the Bx-biosynthetic genes showed that TaBx8 (UDP-Glc:Bx glucosyltrasferase) was influenced by neither JA nor etiolation, indicating that TaBx8 is under the regulation mechanism distinct from the mechanisms influencing the others. In addition, none of the other gene expression patterns exhibited considerable correlation with DIMBOA-Glc accumulation. Since there was no correlation between transcript levels of the genes involved in Bx biosynthesis and Bx accumulation, other factors may control the levels of Bx in wheat. In the course of gene analyses, we isolated TaBx6, one of the last two genes that had not been identified in wheat in the DIMBOA-Glc biosynthetic pathway. All the four TaBx6 genes cloned in the present study were expressed in Escherichia coli and characterized their activity.

Isolation of proanthocyanidins from red wine, and their inhibitory effects on melanin synthesis in vitro.

The red wines made from Vitis vinifera were identified as skin-whitening effectors by using in vitro assays. OPCs in the wine were evaluated for tyrosinase activity and melanogenesis. Strong tyrosinase inhibitory activity was observed in fractions with high oligomeric proanthocyanidin (OPC) content. Among OPC dimers, a strong inhibitory effect on tyrosinase was observed with OPCs which contain (+)-catechin as an upper unit. Melanogenesis inhibitory effect was observed with OPCs which have (-)-epicatechin as upper units. Also, OPC trimers, upper and middle units joined with 4 → 8 bonds, showed stronger effects compared to trimers with 4 → 6 linkages. Interestingly, (-)-epicatechin-(4ß → 8)-(-)-epicatechin 3-O-gallate, which is a unique component of grapes has potent inhibitory effects on both tyrosinase and melanogenesis. Our data provide structural information about such active compounds. These results suggest that red wines containing OPC, have high melanogenesis inhibitory effect and are supposed to have skin-whitening effect.

Antarlides F-H, new members of the antarlide family produced by Streptomyces sp. BB47.

Castration-resistant prostate cancer (CRPC) is the most aggressive form of this disease. CRPC remains dependent on androgen receptor (AR) signaling. Therefore, a novel AR antagonist, enzalutamide, is used clinically for the treatment of men with metastatic CRPC. However, enzalutamide-resistant AR has appeared, and a new type of AR antagonist is desired. Previously, in the course of screening for a new type of AR antagonist, we isolated a series of compounds, designated antarlides A-E, that share a novel 22-membered-ring macrocyclic structure and are produced by Streptomyces sp. BB47. In the present study, we found that this strain also produces antarlides F-H as minor components. Antarlide F is a novel geometric isomer of known antarlides. On the other hand, antarlides G and H are new members of the antarlide family that have a 20-membered-ring macrocyclic structure. Antarlides G and H inhibited the binding of androgen to AR in vitro at concentrations similar to those observed with antarlides A-E. In addition, antarlide G inhibited the transcriptional activity of not only wild-type AR but also enzalutamide-resistant AR, suggesting that antarlides with either 22- or 20-membered rings may serve as potent third-generation AR antagonists capable of overcoming resistance to enzalutamide.

Antarlides: A New Type of Androgen Receptor (AR) Antagonist that Overcomes Resistance to AR-Targeted Therapy.

Prostate cancer is treated with androgen receptor (AR) antagonists but most patients experience disease progression after long-term treatment with these compounds. Therefore, new AR antagonists are required for patient follow-up treatment. In the course of screening for a new AR antagonist, we isolated the novel compounds antarlides A-E (1-5) from Streptomyces sp. BB47. Antarlides are mutually isomeric with respect to the double bond and have a 22-membered-ring macrocyclic structure. The full stereostructure of 1 was established by chemical modifications, including methanolysis, the Trost method, acetonide formation, and the PGME method. 1-5 inhibited the binding of androgen to ARs in vitro. In addition, 2 inhibited the transcriptional activity of not only wild-type AR but also mutant ARs, which are seen in patients with acquired resistance to clinically used AR antagonists. Therefore, antarlides are a potent new generation of AR antagonists that overcome resistance.

Apoptosis induction associated with the ER stress response through up-regulation of JNK in HeLa cells by gambogic acid.

BACKGROUND: Gambogic acid (GA) was extracted from the dried yellow resin of gamboge (Garcinia hanburyi) which is traditionally used as a coloring material for painting and cloth dying. Gamboge has been also used as a folk medicine for an internal purgative and externally infected wound. We focused on the mechanisms of apoptosis induction by GA through the unfold protein response (ER stress) in HeLa cells. METHODS: The cytotoxic effect of GA against HeLa cells was determined by trypan blue exclusion assay. Markers of ER stress such as XBP-1, GRP78, CHOP, GADD34 and ERdj4 were analyzed by RT-PCR and Real-time RT-PCR. Cell morphological changes and apoptotic proteins were performed by Hoechst33342 staining and Western blotting technique. RESULTS: Our results indicated a time- and dose-dependent decrease of cell viability by GA. The ER stress induction is determined by the up-regulation of spliced XBP1 mRNA and activated GRP78, CHOP, GADD34 and ERdj4 expression. GA also induced cell morphological changes such as nuclear condensation, membrane blebbing and apoptotic body in Hela cells. Apoptosis cell death detected by increased DR5, caspase-8, -9, and -3 expression as well as increased cleaved-PARP, while decreased Bcl-2 upon GA treatment. In addition, phosphorylated JNK was up-regulated but phosphorylated ERK was down-regulated after exposure to GA. CONCLUSIONS: These results suggest that GA induce apoptosis associated with the ER stress response through up-regulation of p-JNK and down-regulation of p-ERK in HeLa cells.

Identification of licopyranocoumarin and glycyrurol from herbal medicines as neuroprotective compounds for Parkinson's disease.

In the course of screening for the anti-Parkinsonian drugs from a library of traditional herbal medicines, we found that the extracts of choi-joki-to and daio-kanzo-to protected cells from MPP+-induced cell death. Because choi-joki-to and daio-kanzo-to commonly contain the genus Glycyrrhiza, we isolated licopyranocoumarin (LPC) and glycyrurol (GCR) as potent neuroprotective principals from Glycyrrhiza. LPC and GCR markedly blocked MPP+-induced neuronal PC12D cell death and disappearance of mitochondrial membrane potential, which were mediated by JNK. LPC and GCR inhibited MPP+-induced JNK activation through the suppression of reactive oxygen species (ROS) generation, thereby inhibiting MPP+-induced neuronal PC12D cell death. These results indicated that LPC and GCR derived from choi-joki-to and daio-kanzo-to would be promising drug leads for PD treatment in the future.

Novel isoflavone glucosides in groundnut (Apios americana Medik) and their antiandrogenic activities.

Isoflavone glucosides (2'-hydroxy,5-methoxy genistein-7-O-glucoside (1), 2'-hydroxy genistein-7-O-gentibioside (2), 5-methoxy genistein-7-O-glucoside (3), 3',5-dimethoxy genistein-7-O-glucoside (4), 2'-hydroxy genistein-7-O-glucoside (5), genistein-7-O-gentibioside (6), 2'-hydroxy,5-methoxy genistein-4',7-O-diglucoside (7), and 2'-hydroxy genistein-4',7-O-diglucoside (8)) were isolated from the groundnut of Apios americana Medik. Their structures were elucidated on the basis of HR-ESI-MS and 1D- and 2D-NMR analyses. Compounds 1, 2, 4, and 7 are new compounds presented here for the first time. Compounds 2 and 5 were proven to be androgen receptor antagonists due to their binding activities for androgen receptors (IC50 280 and 160 µM, respectively) and the inhibitory activity of androgen-induced expression of prostate-specific antigen (PSA) mRNA in LNCaP (prostate adenocarcinoma) cells (IC50 20 and 18 µM, respectively).

Caffeine induces apoptosis by enhancement of autophagy via PI3K/Akt/mTOR/p70S6K inhibition.

Caffeine is one of the most frequently ingested neuroactive compounds. All known mechanisms of apoptosis induced by caffeine act through cell cycle modulation or p53 induction. It is currently unknown whether caffeine-induced apoptosis is associated with other cell death mechanisms, such as autophagy. Herein we show that caffeine increases both the levels of microtubule-associated protein 1 light chain 3-II and the number of autophagosomes, through the use of western blotting, electron microscopy and immunocytochemistry techniques. Phosphorylated p70 ribosomal protein S6 kinase (Thr389), S6 ribosomal protein (Ser235/236), 4E-BP1 (Thr37/46) and Akt (Ser473) were significantly decreased by caffeine. In contrast, ERK1/2 (Thr202/204) was increased by caffeine, suggesting an inhibition of the Akt/mTOR/p70S6K pathway and activation of the ERK1/2 pathway. Although insulin treatment phosphorylated Akt (Ser473) and led to autophagy suppression, the effect of insulin treatment was completely abolished by caffeine addition. Caffeine-induced autophagy was not completely blocked by inhibition of ERK1/2 by U0126. Caffeine induced reduction of mitochondrial membrane potentials and apoptosis in a dose-dependent manner, which was further attenuated by the inhibition of autophagy with 3-methyladenine or Atg7 siRNA knockdown. Furthermore, there was a reduced number of early apoptotic cells (annexin V positive, propidium iodide negative) among autophagy-deficient mouse embryonic fibroblasts treated with caffeine than their wild-type counterparts. These results support previous studies on the use of caffeine in the treatment of human tumors and indicate a potential new target in the regulation of apoptosis.

Total synthesis of incednam, the aglycon of incednine.

The first total synthesis of incednam (1), the aglycon of antibiotic incednine (2), is described. Incednine has been reported to exhibit significant inhibitory activity against the antiapoptotic oncoproteins Bcl-2 and Bcl-xL. The synthesis of 1 commenced with the preparation of the C1-C13 subunit 3 and the C14-C23 subunit 4. The construction of the novel 24-membered macrocycle was achieved by the application of a Stille coupling between 3 and 4, followed by macrolactamization.

Isolation and structure elucidation of a novel androgen antagonist, arabilin, produced by Streptomyces sp. MK756-CF1.

In the course of screening for a new type of androgen receptor (AR) antagonist, we isolated a novel compound, arabilin, with two structural isomers, spectinabilin and SNF4435C, produced by Streptomyces sp. MK756-CF1. Structure elucidation on the basis of the spectroscopic properties showed that arabilin is a novel polypropionate-derived metabolite with a p-nitrophenyl group and a substituted γ-pyrone ring. Arabilin competitively blocked the binding of androgen to the ligand-binding domain of AR in vitro. In addition, arabilin inhibited androgen-induced prostate-specific antigen mRNA expression in prostate cancer LNCaP cells.