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Solid-Phase Synthesis of Triostin A Using a Symmetrical Bis(diphenylmethyl) Linker System
Sable, Ganesh A.,Lim, Dongyeol American Chemical Society 2015 Journal of organic chemistry Vol.80 No.15
<P>Triostin A is a symmetric bicyclic depsipeptide with very potent antitumoral activity because of its bisintercalation into DNA. In this study, we report a new synthetic strategy that exploits a structural symmetry of triostin A. First, we prepared a novel symmetric linker molecule that is labile under mildly acidic conditions and suitable for a solid-phase synthesis procedure. Two Cys units were attached to a linker-resin conjugate via their free thiol groups, and double deprotection and double coupling reactions were then applied to synthesize linear tetradepsipeptides. Subsequently, the key biscyclization of the tetradepsipeptides was performed on the resin, and the resulting cyclic octapeptide was detached from the linker-resin conjugate to give a peptide with two free thiols. Finally, triostin A was obtained by oxidizing the free thiols in solution to produce a disulfide. The yield was improved through exploration of two different solid-phase synthetic approaches under similar strategy. Mainly, this strategy was developed to enable the ease and rapid preparation of libraries of symmetric bicyclic depsipeptides. It also addresses several synthetic problems with our synthesis, including diketopiperazine (DKP) formation, poor cyclization yields and preparation of noncommercial <I>N</I>-methyl amino acids in good yields.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/joceah/2015/joceah.2015.80.issue-15/acs.joc.5b01055/production/images/medium/jo-2015-010555_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jo5b01055'>ACS Electronic Supporting Info</A></P>
Sable, Ganesh A.,Park, Jaekwan,Kim, Hyunsik,Lim, Soo‐,Jeong,Jang, Soonmin,Lim, Dongyeol WILEY‐VCH Verlag 2015 European Journal of Organic Chemistry Vol.2015 No.32
<P>The solid-phase total synthesis of the proposed structure of cyclic depsipeptide coibamide A and its derivative O-desmethyl coibamide A is reported. In this study, we demonstrate the solid-phase synthetic strategy and final solution-phase O-methylation for highly N-methylated cyclic depsipeptides. On-resin macrocyclization, N,N-dimethylation and solution-phase O-methylation were the key steps of these syntheses. The mass of synthetic coibamide A is consistent with that of the natural product according to liquid chromatography-mass spectroscopy (LCMS) analysis but significant differences are observed upon H-1 and C-13 NMR analysis. The 2D NMR analysis and modeling studies of the synthetic compound compared with the isolated natural compound revealed that either they are conformationally different or the stereochemistry of the natural product was incorrectly assigned.</P>
Submonomer Strategy toward Divergent Solid-Phase Synthesis of α-ABpeptoids
Sable, Ganesh A.,Lee, Kang Ju,Shin, Min-Kyung,Lim, Hyun-Suk American Chemical Society 2018 ORGANIC LETTERS Vol.20 No.9
<P>A novel submonomer solid-phase synthetic method for α-ABpeptoid oligomers is reported. Iterative submonomer coupling and Fukuyama-Mitsunobu alkylation enable facile, divergent synthesis of α-ABpeptoid oligomers substituted with chemically diverse side chains in excellent yields.</P> [FIG OMISSION]</BR>
Ganesh A. Sable,Jaekwan Park,임수정,임동렬 대한화학회 2016 Bulletin of the Korean Chemical Society Vol.37 No.3
Solid-phase total syntheses of highly methylated cyclic azacoibamide A and its O-desmethyl analogue were achieved. Two ester linkages of natural coibamide A were replaced by amide bonds to improve its pharmacokinetic properties. The synthetic strategy consists of the key on-resin macrocyclization, N,N-dimethylation, and final solution phase O-methylation reactions. Compared to the naturally occurring coibamide A, azacoibamide A and its O-desmethyl analogue displayed low micromolar activities against tested cancer cell lines.
Amar Udare,Nilesh Sable,Rajiv Kumar,Meenakshi Thakur,Shashikant Juvekar 대한영상의학회 2015 Korean Journal of Radiology Vol.16 No.1
Solitary metastases from colorectal carcinoma in the absence of hepatic or pulmonary metastases are rare. These can have a diverse imaging appearance, particularly after chemotherapy. It is important identify patients with solitary skeletal metastases, as they have a better prognosis than those with multiple skeletal or visceral metastases. We describe an unusual case of a solitary metastasis to the femur in a case of colon carcinoma that went undiagnosed and later presented with imaging features of osteogenic sarcoma.
Ray, Manisha,Rath, Surya Narayan,Sarkar, Saurav,Sable, Mukund Namdev Korea Genome Organization 2022 Genomics & informatics Vol.20 No.1
Non-syndromic hearing loss (NSHL) is a common hereditary disorder. Both clinical and genetic heterogeneity has created many obstacles to understanding the causes of NSHL. The present study has attempted to ravel the genetic aetiology in NSHL progression and to screen out potential target genes using computational approaches. The reported NSHL target genes (2009-2020) have been studied by analyzing different biochemical and signaling pathways, interpretation of their functional association network, and discovery of important regulatory interactions with three previously established miRNAs in the human inner ear as well as in NSHL such as miR-183, miR-182, and miR-96. This study has identified SMAD4 and SNAI2 as the most putative target genes of NSHL. But pathogenic and deleterious non-synonymous single nucleotide polymorphisms discovered within SMAD4 is anticipated to have an impact on NSHL progression. Additionally, the identified deleterious variants in the functional domains of SMAD4 added a supportive clue for further study. Thus, the identified deleterious variant i.e., rs377767367 (G491V) in SMAD4 needs further clinical validation. The present outcomes would provide insights into the genetics of NSHL progression.