Synthetic Route Development for the Laboratory Preparation of Eupalinilide E.

Following the discovery that the guaianolide natural product eupalinilide E promotes the expansion of hematopoietic stem and progenitor cells; the development of a synthetic route to provide laboratory access to the natural product became a priority. Exploration of multiple synthetic routes yielded an approach that has permitted a scalable synthesis of the natural product. Two routes that failed to access eupalinilide E were triaged either as a result of providing an incorrect diastereomer or due to lack of synthetic efficiency. The successful strategy relied on late-stage allylic oxidations at two separate positions of the molecule, which significantly increased the breadth of reactions that could be used to this point. Subsequent to C-H bond oxidation, adaptations of existing chemical transformations were required to permit chemoselective reduction and oxidation reactions. These transformations included a modified Luche reduction and a selective homoallylic alcohol epoxidation.

Synthesis of Eupalinilide E, a Promoter of Human Hematopoietic Stem and Progenitor Cell Expansion.

Improving the ex vivo and in vivo production of hematopoietic stem and progenitor cells (HSPCs) has the potential to address the short supply of these cells that are used in the treatment of various blood diseases and disorders. Eupalinilide E promotes the expansion of human HSPCs and inhibits subsequent differentiation, leading to increased numbers of clinically useful cells. This natural product represents an important tool to uncover new methods to drive expansion while inhibiting differentiation. However, in the process of examining these effects, which occur through a novel mechanism, the natural product was consumed, which limited additional investigation. To provide renewed and improved access to eupalinilide E, a laboratory synthesis has been developed and is reported herein. The synthetic route can access >400 mg in a single batch, employing reactions conducted on useful scales in a single vessel. Key transformations enabling the approach include a diastereoselective borylative enyne cyclization and a late-stage double allylic C-H oxidation as well as adapted Luche reduction and aluminum-mediated epoxidation reactions to maximize the synthetic efficiency. Retesting of the synthetic eupalinilide E confirmed the compound's ability to expand HSPCs and inhibit differentiation.

Vinaxanthone inhibits Semaphorin3A induced axonal growth cone collapse in embryonic neurons but fails to block its growth promoting effects on adult neurons.

Semaphorin3A is considered a classical repellent molecule for developing neurons and a potent inhibitor of regeneration after nervous system trauma. Vinaxanthone and other Sema3A inhibitors are currently being tested as possible therapeutics to promote nervous system regeneration from injury. Our previous study on Sema3A demonstrated a switch in Sema3A's function toward induction of nerve regeneration in adult murine corneas and in culture of adult peripheral neurons. The aim of the current study is to determine the direct effects of Vinaxanthone on the Sema3A induced adult neuronal growth. We first demonstrate that Vinaxanthone maintains its anti-Sema3A activity in embryonic dorsal root ganglia neurons by inhibiting Sema3A-induced growth cone collapse. However, at concentrations approximating its IC50 Vinaxanthone treatment does not significantly inhibit neurite formation of adult peripheral neurons induced by Sema3A treatment. Furthermore, Vinaxanthone has off target effects when used at concentrations above its IC50, and inhibits neurite growth of adult neurons treated with either Sema3A or NGF. Our results suggest that Vinaxanthone's pro-regenerative effects seen in multiple in vivo models of neuronal injury in adult animals need further investigation due to the pleiotropic effect of Sema3A on various non-neuronal cell types and the possible effect of Vinaxanthone on other neuroregenerative signals.

Expedited access to vinaxanthone and chemically edited derivatives possessing neuronal regenerative effects through ynone coupling reactions.

The natural product vinaxanthone has demonstrated a remarkable capability to promote nerve growth following injury or transplantation. In rats following total transection of the spinal cord delivery of vinaxanthone enhanced axonal regeneration, remyelination and angiogenesis at the site of injury all leading to an improved reinstatement of motor function. Through the development of a new ynone coupling reaction, chemically edited derivatives of vinaxanthone have been prepared and studied for improved activity. The coupling reaction allows rapid access to new derivatives, wherein n ynone precursors provide n(2) vinaxanthone analogues. These compounds have been tested for their ability to promote neuronal regrowth using laser axotomy, severing axonal connections in Caenorhabditis elegans. This precise microsurgery using C. elegans allows a new in vivo approach for medicinal chemistry based optimization of neuronal growth promoting compounds.