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Synthesis of the C9-C25 Subunit of Spirastrellolide B.

ABSTRACT: The synthesis of the C9-C25 subunit of the marine natural product spirastrellolide B is reported. The key synthetic features included the union of the two key fragments 5 and 6 via a Suzuki-Miyaura coupling reaction and a late-stage, one-pot sequential deprotection/cascade Achmatowicz rearrangement-spiroketalization to install the key spirocyclic intermediate present in the C9-C25 fragment of spirastrellolide B. The synthesis of the C9-C16 fragment 6 was accomplished via a phosphate tether mediated ring-closing metathesis (RCM), a subsequent hydroboration-oxidation protocol, followed by other stereoselective transformations in a facile manner. The spirocyclic intermediate was further functionalized utilizing a Lindlar/NaBH4 reduction protocol to furnish the C9-C25 subunit 3.

SUBMITTER: Maitra S

PROVIDER: S-EPMC4943334 | biostudies-literature | 2016 Jul

REPOSITORIES: biostudies-literature

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Synthesis of the C9-C25 Subunit of Spirastrellolide B.

Maitra Soma S Bodugam Mahipal M Javed Salim S Hanson Paul R PR

Organic letters 20160614 13

The synthesis of the C9-C25 subunit of the marine natural product spirastrellolide B is reported. The key synthetic features included the union of the two key fragments 5 and 6 via a Suzuki-Miyaura coupling reaction and a late-stage, one-pot sequential deprotection/cascade Achmatowicz rearrangement-spiroketalization to install the key spirocyclic intermediate present in the C9-C25 fragment of spirastrellolide B. The synthesis of the C9-C16 fragment 6 was accomplished via a phosphate tether media ...[more]

PMID: 27300267

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Project description:Cis-9, trans-11-conjugated linoleic acid (c9, t11-CLA), a functional fatty acid, is one of the research hotspots in the fields of functional dairy products development because of its multiple beneficial effects in humans and animals. In milk, most c9, t11-CLA is de novo synthesized from trans-11-octadecenoic acid (TVA) and it is confirmed that genes such as stearoyl-coA desaturase 1 (SCD1) play a key role in the synthesis. However, few studies have been reported to deeply elucidate the SCD1-dependent molecular mechanism of cis9, trans11-CLA synthesis and its relationship with the pathways of energy metabolism and lipid metabolism. Therefore, in the present study, MAC-T cells were divided into three groups: CAY group (SCD1-inhibited MAC-T cell model with the addition of CAY, TVA), TVA group (only TVA), and Control group (without CAY, TVA). The relative mRNA expression of SCD1 was measured using real-time PCR, while TVA accumulation and c9, t11 -CLA synthesis were analyzed using gas chromatography (GC). The SCD1-related proteins were firstly screened in MAC-T cells by Tandem Mass Tag (TMT)-based quantitative proteomics analysis, then their functions were annotated by bioinformatic analysis, and finally their relationships with SCD1 were evaluated by parallel reaction monitoring (PRM) analysis and small RNA interference. The results showed that the deficiency of SCD1 led by CAY10566 blocked the synthesis of c9, t11-CLA in MAC-T cells. Sixty-one SCD1-associated proteins were screened and found to be mainly involved in the pathways of energy metabolism and lipid metabolism, such as glycolytic pathway, pentose phosphate pathway, fatty acid elongation pathway, and unsaturated fatty acid biosynthesis. Among these genes, 17 proteins were validated under the PRM analysis. PGAM1 (phosphoglycerate mutase 1), TPI1 (triosephosphate isomerase 1), LDHB (lactate dehydrogenase B), and ALDOA (aldolase, fructose-bisphosphate A) were verified to have a negative relationships with SCD1. This study furthered our understanding of the molecular mechanisms of c9, t11-CLA synthesis in the mammary glands of dairy cows.

Project description:BackgroundThe global prevalence of vitamin D (VitD) deficiency associated with numerous acute and chronic diseases has led to strategies to improve the VitD status through dietary intake of VitD-fortified foods and VitD supplementation. In this context, the circulating form of VitD3 (cholecalciferol) in the human body, 25-hydroxy-VitD3 (calcifediol, 25OHVitD3), has a much higher efficacy in improving the VitD status, which has motivated researchers to develop methods for its effective and sustainable synthesis. Conventional monooxygenase-/peroxygenase-based biocatalytic platforms for the conversion of VitD3 to value-added 25OHVitD3 are generally limited by a low selectivity and yield, costly reliance on cyclodextrins and electron donor systems, or by the use of toxic co-substrates.ResultsIn this study, we used a whole-cell approach for biocatalytic 25OHVitD3 synthesis, in which a molybdenum-dependent steroid C25 dehydrogenase was produced in the denitrifying bacterium Thauera aromatica under semi-aerobic conditions, where the activity of the enzyme remained stable. This enzyme uses water as a highly selective VitD3 hydroxylating agent and is independent of an electron donor system. High density suspensions of resting cells producing steroid C25 dehydrogenase catalysed the conversion of VitD3 to 25OHVitD3 using either O2 via the endogenous respiratory chain or externally added ferricyanide as low cost electron acceptor. The maximum 25OHVitD3 titer achieved was 1.85 g L-1 within 50 h with a yield of 99%, which is 2.2 times higher than the highest reported value obtained with previous biocatalytic systems. In addition, we developed a simple method for the recycling of the costly VitD3 solubiliser cyclodextrin, which could be reused for 10 reaction cycles without a significant loss of quality or quantity.ConclusionsThe established steroid C25 dehydrogenase-based whole-cell system for the value-adding conversion of VitD3 to 25OHVitD3 offers a number of advantages in comparison to conventional oxygenase-/peroxygenase-based systems including its high selectivity, independence from an electron donor system, and the higher product titer and yield. Together with the established cyclodextrin recycling procedure, the established system provides an attractive platform for large-scale 25OHVitD3 synthesis.

Dataset Information

Synthesis of the C9-C25 Subunit of Spirastrellolide B.

Publications

Synthesis of the C9-C25 Subunit of Spirastrellolide B.

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