Monoterpenoid indole alkaloids (MIAs) comprise an important class of molecules for drug discovery, and they have variant carbon skeletons with prominent bioactivities. For instance, in spite of limitations to their use, camptothecins are the only clinically approved topoisomerase I (Top1) inhibitors. The enzyme strictosidine synthase, which is key for MIA biosynthesis, was applied to the enantioselective preparation of three N-substituted (S)-3,14,18,19-tetrahydroangustine (THA) derivatives. These non-camptothecin MIAs were shown to have moderate in vitro HepG2 cytotoxicity and Top1 inhibition activities. The (S)-configured MIAs had stronger cytotoxicity and Top1 inhibition than their chemically synthesized (R)-enantiomers, which aligned with the results of molecular dynamics simulations. A series of N-substituted (S)-THAs were then chemoenzymatically synthesized to investigate structure–activity relationships. The most active analogue observed was the N-(2-Cl benzoyl)-substituted derivative (7i). Insight into the binding mode of 7i and a Top1–DNA covalent complex was investigated by molecular dynamics simulations, which will facilitate future efforts to optimize the Top1 inhibitory activities of non-camptothecin MIAs.

Simple and practical reactions of pyrrole-2-carbaldehydes with nitroethylenes provide either the 5,6-dihydroindolizines or the indolizines in one pot, depending on the reaction temperature. Additionally, a plausible mechanism for the entire sequence is proposed.Download high-res image (108KB)Download full-size image

Five series of heterocycles with extraordinary structural diversity have been regiospecifically synthesized from the same Morita–Baylis–Hillman Acetates (MBHAs). All four potential electrophilic sites (α, β, γ, δ) of MBHAs are proved to be reactive.

The Pictet–Spenglerase strictosidine synthase (STR1) has been recognized as a key enzyme in the biosynthesis of some 2000 indole alkaloids in plants, some with high therapeutic value. In this study, a novel function of STR1 has been detected which allows for the first time a simple enzymatic synthesis of the strictosidine analogue 3 harboring the piperazino[1,2-a]indole (PI) scaffold and to switch from the common tryptoline (hydrogenated carboline) to the rare PI skeleton. Insight into the reaction is provided by X-ray crystal analysis and modeling of STR1 ligand complexes. STR1 presently provides exclusively access to 3 and can act as a source to generate by chemoenzymatic approaches libraries of this novel class of alkaloids which may have new biological activities. Synthetic or natural monoterpenoid alkaloids with the PI core have not been reported before.

A new synthetic protocol for efficient and regiospecifc assembly of indolizines and pyrido[1,2-a]indoles by coupling of substituted methyl bromides and alkynes with corresponding pyrrole-2-carboxaldehyde and 1H-indole-2-carboxaldehyde has been developed. Additionally, a possible mechanism for the reaction is proposed.

A domino synthesis of pyrrolo[1,2-α]pyrazine from 1H-2-pyrrolecarbaldehyde and readily synthesized vinyl azides was developed. This reaction proceeded under relatively mild conditions in the presence of base. Additionally, a possible mechanism for the entire sequence is proposed.

MBHA resin-supported tripeptide catalyst system containing l-proline unit has been developed for use in the direct asymmetric aldol reaction of acetone and aldehydes, which afford the corresponding products with satisfactory isolated yields and enantiomeric excesses.

•Compound XW4.4 can differentiate rat mesenchymal stem cells toward insulin-producing cells in vitro.•Differentiated cells had characteristics of insulin-producing cells.•HNF 3β may be involved in pancreatic differentiation of rMSCs in pancreatic differentiation of rat mesenchymal stem cells.Type 1 diabetes mellitus (T1DM), a multisystem disease with both biochemical and anatomical/structural consequences, is a major health concern worldwide. Pancreatic islet transplantation provides a promising treatment for T1DM. However, the limited availability of islet tissue or new sources of insulin producing cells (IPCs) that are responsive to glucose hinder this promising approach. Though slow, the development of pancreatic beta-cell lines from rodent or human origin has been steadily progressing. Bone marrow-derived mesenchymal stem cells (MSCs) are multipotent, culture-expanded, non-hematopoietic cells that are currently being investigated as a novel cellular therapy. The in vitro differentiation potential of IPCs has raised hopes for a treatment of clinical diseases associated with autoimmunity.We screened for small molecules that induce pancreatic differentiation of IPCs. There are some compounds which showed positive effects on the DTZ staining. The aminopyrrole derivative compound XW4.4 which shows the best activity among them was found to induce pancreatic differentiation of rat MSCs (rMSCs). The in vitro studies indicated that treatment of rMSCs with compound XW4.4 resulted in differentiated cells with characteristics of IPCs including islet-like clusters, spherical, grape-like morphology, insulin secretion, positive for dithizone, glucose stimulation and expression of pancreatic endocrine cell marker genes. The data has also suggested that hepatocyte nuclear factor 3β (HNF 3β) may be involved in pancreatic differentiation of rMSCs when treated with XW4.4. Results indicate that XW4.4 induced rMSCs support the efforts to derive functional IPCs and serve as a means to alleviate limitations surrounding islet cell transplantation in the treatment of T1DM.Download full-size image

Five series of heterocycles with extraordinary structural diversity have been regiospecifically synthesized from the same Morita–Baylis–Hillman Acetates (MBHAs). All four potential electrophilic sites (α, β, γ, δ) of MBHAs are proved to be reactive.