Identification of novel metabolites of abiraterone in human serum and their metabolic pathways.

Two novel abiraterone (Abi, 3ß-OH-Abi) metabolites in human serum were identified as 3α-OH-Abi and Δ5-Abi (D5A). Both metabolites were confirmed by their retention times on LC/MS and their product-ion mass spectra on LC-MS/MS compared to those of authentic compounds, which were chemically synthesized. The plausible metabolic pathways of these two metabolites are as follows: Abi is first oxidized to D5A by 3ß-hydroxysteroid dehydrogenase (3ß-HSD) and then irreversibly converted to Δ4-Abi (D4A) by ∆5-∆4 isomerase. Presumably, D5A detection is difficult because of its rapid conversion to D4A and its low concentration in serum samples. In contrast, the low concentration 3α-OH-Abi was generated by reducing the remaining D5A using 3α-hydroxysteroid dehydrogenase (3α-HSD).

Synthesis of 6-Halo-Substituted Pericosine A and an Evaluation of Their Antitumor and Antiglycosidase Activities.

The enantiomers of 6-fluoro-, 6-bromo-, and 6-iodopericosine A were synthesized. An efficient synthesis of both enantiomers of pericoxide via 6-bromopericosine A was also developed. These 6-halo-substituted pericosine A derivatives were evaluated in terms of their antitumor activity against three types of tumor cells (p388, L1210, and HL-60) and glycosidase inhibitory activity. The bromo- and iodo-congeners exhibited moderate antitumor activity similar to pericosine A against the three types of tumor cell lines studied. The fluorinated compound was less active than the others, including pericosine A. In the antitumor assay, no significant difference in potency between the enantiomers was observed for any of the halogenated compounds. Meanwhile, the (-)-6-fluoro- and (-)-6-bromo-congeners inhibited α-glucosidase to a greater extent than those of their corresponding (+)-enantiomers, whereas (+)-iodopericosine A showed increased activity when compared to its (-)-enantiomer.

Enantiomeric composition of natural pericosine A derived from Periconia byssoides and α-glycosidase inhibitory activity of (-)-enantiomer.

Chiral high-performance liquid chromatography (HPLC) analysis of natural pericosine A, which appeared in literature first in 1977, from Periconia byssoides was conducted using a column CHIRALPAK® AD-H to determine the enantiomeric composition of the original mixture which was found to be 68: 32 mixtures of (+)- and (-)-enantiomer, respectively. Furthermore, two independently isolated samples of pericosine A from the same fungus were also analyzed to show the two peaks in the HPLC charts at approximate 1:1 ratio. These results concluded that pericosine A derived from Periconia byssoides was indeed an enantiomeric mixture. Synthesized enantiomers were subjected to evaluation of antitumor activity against three kinds of tumor cells (p388, L1210, HL-60), indicating moderate cytotoxicity against all three kinds of tumor cell lines, but significant difference in potency between the enantiomers was not observed. In contrast, when both the enantiomers of pericosine A were evaluated against five kinds of glycosidases-inhibitory activities (α- and ß-glucosidases, α- and ß-galactosidases, and α-mannosidase), an apparent difference on anti-glycosidase assay was found between the enantiomers: (-)-pericosine A inhibited α-glucosidase at IC50 : 2.25 mM, and ß-galactosidase at IC50 : 5.38 mM, albeit the (+)-enantiomer showed inactivity against these five enzymes.

Design, synthesis, and evaluation of new vanin-1 inhibitors based on RR6.

Fourteen novel vanin-1 inhibitors coded OMP-# were designed from RR6 and successfully synthesized by a nucleophilic addition-elimination reaction of the pantetheinic acid-derived Weinreb amide as a key step under Barbier conditions. The synthesized OMP compounds exhibited inhibitory activity against human serum vanin-1 in vitro. Among the synthesized compounds, OMP-7, which possesses a trifluoromethoxy group at the para-position on the phenyl ring, exhibited the most potent activity, approximately 20 times that of the mother compound RR6. OMP-7 was further subjected to an in vivo assay using a normal hamster. More potent activity was observed than that of RR6 against both serum and renal vanin-1. The activity lasted for 4 h after injection against serum vanin-1 and 1 h after injection against renal vanin-1, whereas RR6 did not show the desired activity.

CuI-Catalyzed Coupling Reactions of 4-Iodopyrazoles and Alcohols: Application toward Withasomnine and Homologs.

The direct 4-alkoxylation of 4-iodo-1H-pyrazoles with alcohols was achieved by a CuI-catalyzed coupling protocol. The optimal reaction conditions employed excess alcohol and potassium t-butoxide (2 equiv) in the presence of CuI (20 mol%) and 3,4,7,8-tetramethyl-1,10-phenanthroline (20 mol%) at 130 °C for 1 h under microwave irradiation. The present method was efficiently applied to the synthesis of withasomnine and its six- and seven-membered cyclic homologs.

C4-Alkylamination of C4-Halo-1H-1-tritylpyrazoles Using Pd(dba)2 or CuI.

Alkylamino coupling reactions at the C4 positions of 4-halo-1H-1-tritylpyrazoles were investigated using palladium or copper catalysts. The Pd(dba)2 catalyzed C-N coupling reaction of aryl- or alkylamines, lacking a ß-hydrogen atom, proceeded smoothly using tBuDavePhos as a ligand. As a substrate, 4-Bromo-1-tritylpyrazole was more effective than 4-iodo or chloro-1-tritylpyrazoles. Meanwhile, the CuI mediated C-N coupling reactions of 4-iodo-1H-1-tritylpyrazole were effective for alkylamines possessing a ß-hydrogen atom.

Syntheses and Glycosidase Inhibitory Activities, and in Silico Docking Studies of Pericosine E Analogs Methoxy-Substituted at C6.

Inspired by the significant -glucosidase inhibitory activities of (+)- and (-)-pericosine E, we herein designed and synthesized 16 analogs of these marine natural products bearing a methoxy group instead of a chlorine atom at C6. Four of these compounds exhibited moderate -glucosidase inhibitory activities, which were weaker than those of the corresponding chlorine-containing species. The four compounds could be prepared by coupling reactions utilizing the (-)-pericosine B moiety. An additional in silico docking simulation suggested that the reason of reduced activity of the C6-methoxylated analogs might be an absence of hydrogen bonding between a methoxy group with the surrounding amino acid residues in the active site in -glucosidase.

Synthesis of Dihydropyrano[3,2-c]pyrazoles via Double Bond Migration and Ring-Closing Metathesis.

Three types of pyrazole-fused heterobicycles, i.e., 1,5-, 1,7-, and 2,5-dihydropyrano[3,2-c]pyrazoles, were synthesized from 4-allyloxy-1H-pyrazoles. A sequence of the Claisen rearrangement of 4-allyloxy-1H-pyrazoles, ruthenium-hydride-catalyzed double bond migration, O-allylation, and ring-closing metathesis was employed in this study.

Synthesis of Dihydrooxepino[3,2-c]Pyrazoles via Claisen Rearrangement and Ring-Closing Metathesis from 4-Allyloxy-1H-pyrazoles.

Synthesis of novel pyrazole-fused heterocycles, i.e., dihydro-1H- or 2H-oxepino[3,2-c]pyrazoles (6 or 7) from 4-allyloxy-1H-pyrazoles (1) via combination of Claisen rearrangement and ring-closing metathesis (RCM) has been achieved. A suitable catalyst for the RCM of 5-allyl-4-allyloxy-1H-pyrazoles (4) was proved to be the Grubbs second generation catalyst (Grubbs2nd) to give the predicted RCM product at room temperature in three hours. The same reactions of the regioisomer, 3-allyl-4-allyloxy-1H-pyrazoles (5), also proceeded to give the corresponding RCM products. On the other hand, microwave aided RCM at 140 °C on both of 4 and 5 afforded mixtures of isomeric products with double bond rearrangement from normal RCM products in spite of remarkable reduction of the reaction time to 10 min.

Transformation of Carbonyl Compounds into Homologous Alkynes under Neutral Conditions: Fragmentation of Tetrazoles Derived from Cyanophosphates.

Cyanophosphates (CPs) can be easily prepared from either ketones or aldehydes, and their reaction with NaN3-Et3N·HCl results in the formation of azidotetrazoles. Under microwave irradiation, successive fragmentation of the azidotetrazoles generates alkylidene carbenes that undergo [1,2]-rearrangement and are transformed into homologous alkynes. Treatment of ketone-derived CPs with TMSN3 and Bu2SnO as catalyst in toluene at reflux directly yields the corresponding internal alkynes, whereas the reaction of aldehyde-derived CPs with NaN3-Et3N·HCl in THF at reflux or TMSN3-Bu2SnO (cat.) in toluene at reflux provides homologous terminal alkynes in good yields. These reactions take place under neutral conditions and can be successfully extended to obtain alkynes that are not usually accessible from the corresponding carbonyl compounds by the Ohira-Bestmann or Shioiri procedures, which require basic conditions.

Synthesis of Natural O-Linked Carba-Disaccharides, (+)- and (-)-Pericosine E, and Their Analogues as α-Glucosidase Inhibitors.

Pericosine E (6), a metabolite of Periconia byssoides OUPS-N133 was originally isolated from the sea hare Aplysia kurodai, which exists as an enantiomeric mixture in nature. The enantiospecific syntheses of both enantiomers of Periconia byssoides OUPS-N133 has been achieved, along with six stereoisomers, using a common simple synthetic strategy. For these efficient syntheses, highly regio- and steroselective processes for the preparation of bromohydrin and anti-epoxide intermediates were applied. In order to access the unique O-linked carbadisaccharide structure, coupling of chlorohydrin as a donor and anti-epoxide as an acceptor was achieved using catalytic BF3·Et2O. Most of the synthesized compounds exhibited selectively significant inhibitory activity against α-glycosidase derived from yeast. The strongest analog showed almost 50 times the activity of the positive control, deoxynojirimycin.

Histamine H3 receptor antagonist OUP-186 attenuates the proliferation of cultured human breast cancer cell lines.

Histamine is involved in various physiological functions, including its neurotransmitter actions in the central nervous system and its action as a causative agent of inflammation, allergic reactions, and gastric acid secretions. Histamine expression and biosynthesis have been detected in breast cancer cells. It was recently suggested that the histamine H3 receptor (H3R) plays a role in the proliferation of breast cancer cells. We recently developed the non-imidazole H3R antagonist OUP-186 which exhibited a potent and selective human H3R antagonistic activity as well as no activity against the human histamine H4 receptor (H4R). In this study, we compared the effects of OUP-186 on the proliferation of estrogen receptor negative (ER-) breast cancer cells (MDA-MB-231) and ER+ breast cancer cells (MCF7) to the effects of clobenpropit (potent imidazole-containing H3R antagonist). OUP-186 and clobenpropit suppressed the proliferation of breast cancer cells. The IC50 values at 48 h for OUP-186 and clobenpropit were approximately 10 µM and 50 µM, respectively. Furthermore, OUP-186 potently induced cell death by activating caspase-3/7, whereas cell death was only slightly induced by clobenpropit. In addition, OUP-186 treatment blocked the proliferation increase triggered by 100 µM (R)-(-)-α-methylhistamine (H3R agonist). The use of 4-methylhistamine (H4R agonist) and JNJ10191584 (selective H4R antagonist) did not affect breast cancer proliferation. These results indicate that OUP-186 potently suppresses proliferation and induces caspase-dependent apoptotic death in both ER+ and ER-breast cancer cells.

Synthesis of marine natural product (-)-pericosine E.

The first synthesis of (-)-pericosine E (6), a metabolite of the Periconia byssoides OUPS-N133 isolated originally from the sea hare Aplysia kurodai, has been achieved. Efficient and regioselective synthetic procedures for the synthesis of key intermediates, anti- and syn-epoxides 9 and 10, were developed using an anti-epoxidation of diene 12 with TFDO and a bromohydrination of 12 with NBS in CH(3)CN/H(2)O (2:3), respectively. In addition, comparison of the specific optical rotations between synthetic 6 and natural 6 elucidated that the naturally preferred enantiomer of pericosine E had the same absolute configuration as (-)-6 synthesized from chlorohydrin (-)-8 and anti-epoxide (+)-9.

Synthesis and evaluation of N-alkyl-S-[3-(piperidin-1-yl)propyl]isothioureas: high affinity and human/rat species-selective histamine H(3) receptor antagonists.

S-Alkyl-N-alkylisothiourea compounds containing various cyclic amines were synthesized in the search for novel nonimidazole histamine H3 receptor (H3R) antagonists. Among them, four N-alkyl S-[3-(piperidin-1-yl)propyl]isothioureas 18, 19, 22, and 23 were found to exhibit potent and selective H3R antagonistic activities against in vitro human H3R, but were inactive against in vitro human H4R. Furthermore, three alkyl homologs 18-20 showed inactivity for histamine release in in vivo rat brain microdialysis, suggesting differences in antagonist affinities between species. In addition, in silico docking studies of N-[4-(4-chlorophenyl)butyl]-S-[3-piperidin-1-yl)propyl]isothiourea 19 and a shorter homolog 17 with human/rat H3Rs revealed that structural differences between the antagonist-docking cavities of rat and human H3Rs were likely caused by the Ala122/Val122 mutation.

Divergent synthesis and evaluation of inhibitory activities against cyclooxygenases-1 and -2 of natural withasomnines and analogues.

The divergent synthesis of natural withasomnines and analogues was achieved from 4-hydroxypyrazoles, which was prepared via alkaline hydrolysis of the Baeyer-Villiger oxidation products from 4-formylpyrazoles. Key steps of this synthesis are regioselective Claisen rearrangement of 4-allyloxypyrazoles and the Suzuki-Miyaura coupling of 5,6-dihydro-4H-pyrrolo[1,2-b]pyrazol-3-yl trifluoromethanesulfonate and commercially available arylboronic acids. The Suzuki-Miyaura coupling at the final step of this strategy enabled facile access to natural withasomnines and their analogues. The biological activities of the twelve synthesized compounds against cyclooxygenases-1 and -2 (COX-1 and COX-2) were evaluated.

New class azaphilone produced by a marine fish-derived Chaetomium globosum. The stereochemistry and biological activities.

Four new metabolites, chaetomugilins P-R and 11-epi-chaetomugilin I, were isolated from a strain of Chaetomium globosum originally obtained from the marine fish Mugil cephalus, and their absolute stereostructures were elucidated on the basis of spectroscopic analyses, including 1D and 2D NMR techniques and various chemical transformations. Particularly, the skeleton of chaetomugilin P is different from that of other azaphilones isolated from this fungal strain to date. In addition, these compounds significantly inhibited the growth of cultured P388, HL-60, L1210 and KB cell lines.

Stereostructure reassignment and determination of the absolute configuration of pericosine D(o) by a synthetic approach.

A combination of chemical synthesis and NMR methods was used to reassign the structure of pericosine D(o) (8), a cytotoxic marine natural product produced by the fungus Periconia byssoides OUPS-N133 that was originally derived from the sea hare Aplysia kurodai. Chemical synthesis was used to prepare pericoisne D(o) (8) from a known chlorohydrin that was in turn derived from (-)-quinic acid. The absolute configuration of natural pericosine D(o) (8) was determined to be methyl (3R,4S,5S,6S)-6-chloro-3,4,5-trihydroxy-1-cyclohexene-1-carboxylate. HPLC analyses using a chiral-phase column indicated that pericosine D(o) (8) exists in an enantiomerically pure form in nature.

Natural pericosines B and C as enantiomeric mixtures: direct evidence by chiral HPLC analysis.

Pericosines are carbasugar-type metabolites of Periconia byssoides OUPS-N133, a fungus that was originally separated from the sea hare Aplysia kurodai. It has been reported that pericosines C and E are enantiomeric mixtures. The difference in specific rotation between natural pericosine C and the synthetic one led to the conclusion that natural pericosine C is an enantiomeric mixture. Meanwhile, the small specific rotation of natural pericosine B compared to that of the synthetic one led to the deduction that natural pericosine B might also be an enantiomeric mixture. Then, racemic pericosines B and C were synthesized, and the direct enantioseparation of these racemic carbasugars was conducted with CHIRALPAK® IA and CHIRALPAK® AY-H, which are suitable columns for racemic pericosines B and C, respectively. Using chiral HPLC, we conclude that natural pericosines B and C exist as enantiomeric mixtures. A rare example of the application of direct chiral HPLC analysis to intact sugars or carbasugars was provided.

A new class of rhodamine luminophores: design, syntheses and aggregation-induced emission enhancement.

A new class of rhodamine luminophores, 3',3''-bis(oxospiroisobenzofuran)-3,7-bis(dialkylamino)benzopyrano-xanthene derivatives (ABPX), have been successfully developed. The emission behavior of ABPX series is directly opposite to the concentration quenching of conventional rhodamine dyes. ABPX series exhibit aggregation-induced emission enhancement (AIEE).

Antitumor Agents. 282. 2'-(R)-O-acetylglaucarubinone, a quassinoid from Odyendyea gabonensis as a potential anti-breast and anti-ovarian cancer agent.

A new quassinoid, designated 2'-(R)-O-acetylglaucarubinone (1), and seven known quassinoids (2-8) were isolated, using bioactivity-guided separation, from the bark of Odyendyea gabonensis (Pierre) Engler [syn. Quassia gabonensis Pierre]. The structure of 1 was determined by spectroscopic analysis and by semisynthesis from glaucarubolone. Complete (1)H and (13)C NMR assignments of compounds 1-8 were also established from detailed analysis of two-dimensional NMR spectra, and the reported configurations in odyendene (7) and odyendane (8) were corrected. Compound 1 showed potent cytotoxicity against multiple cancer cell lines. Further investigation using various types of breast and ovarian cancer cell lines suggested that 1 does not target the estrogen receptor or progesterone receptor. When tested against mammary epithelial proliferation in vivo using a Brca1/p53-deficient mice model, 1 also caused significant reduction in mammary duct branching.