Trimeric and dimeric Aspidosperma-type alkaloids from leaves of Tabernaemontana divaricata 'Dwaft'

New monoterpenoid indole alkaloids from the stems of Tabernaemontana bovina Lour (Apocynaceae)

Two new monoterpenoid indole alkaloids, named taberibogines E and F (1 and 2), together with three known ones (3-5) were isolated from the stems of Tabernaemontana bovina Lour (Apocynaceae). Their structures including absolute configurations were elucidated from a combination of NMR and HRESIMS data and NMR calculations as well as DP4+ probability analyses. Compounds 1 and 2 exhibited inhibitory effects on LPS-induced nitric oxide (NO) production in RAW 264.7 macrophages.

Gelselegine-gelsedine type bisindoles as well as the units from Gelsemium elegans with promoting proliferation of oral mucosa fibroblast cells

Two undescribed bisindole alkaloids, gelseginedine A (1) and its rearranged gelseginedine B (2), and seven unreported gelselegine-type oxindole alkaloids (3-9) were isolated from the stems and leaves of Gelsemium elegans, together with five known alkaloids (10-14). Compounds 1 and 2 represented the first examples of gelselegine-gelsedine type alkaloids which bridged two units by a double bond. Their structures with absolute configurations were elucidated by means of HRESIMS, NMR and calculational chemistry. The performed bioassay revealed that 14 could promote the proliferation of human oral mucosa fibroblast cells.

Insecticidal bisindole alkaloids from leaves of Tabernaemontana divaricata 'Dwaft'

Six undescribed bisindole alkaloids, namely taberdisines A-F (1-6), were isolated from the leaves of Tabernaemontana divaricata 'Dwaft'. Among them, alkaloids 1 and 2 were the first examples of strychnos-iboga type alkaloid with both C-C linkage patterns. Alkaloid 3, a new type of aspidosperma-iboga with a furan-ring, as well as other three undescribed ones was disclosed. Their structures were elucidated by comprehensive spectroscopic analyses. Alkaloids 1 and 5 showed insecticide activity on Sf9 cell and eggs of Spodoptera frugiperda in vivo, which might explain the potential of the plants for insect resistance.

Combination of Machine Learning and Empirical Computation for the Structural Validation of Trirosaline, a Natural Trimeric Monoterpene Indole Alkaloid from Catharanthus roseus

Chemical investigation of the emblematic Catharanthus roseus led to the discovery of trirosaline (1), the first example of a tris-ajmalicine-type monoterpene indole alkaloid and the first natural trimeric MIA ever reported from this deeply dug plant species. Its structure was primarily elucidated based on NMR and HRESIMS analyses, and the nature of its unique intermonomeric linkages was firmly confirmed based on a combination of empirical computation and ML-J-DP4 study. Its absolute configuration was mitigated by comparison of experimental and TDDFT-simulated electronic circular dichroism (ECD) spectra. A possible biosynthetic pathway for trirosaline (1) was postulated.

Diverse aspidosperma-type alkaloids from the leaves of Tabernaemontana bovina with anti-hepatoma activity

Seventeen undescribed Aspidosperma-type alkaloids (ASPs), along with nine known ones were isolated from the leaves of Tabernaemontana bovina. Taberbovermines A and B were assigned to tabersonine-type with a contracted A- and E-ring, respectively. Taberbovermine C was attributed to tabersonine without D ring. These structures of the ASPs were established on the basis of comprehensive spectroscopic data, electronic circular dichroism calculations and X-ray diffraction. The summaries of structure-activity relationship of tabersonine class were discussed based on hepatoma cells screening.

The current scenario of naturally occurring indole alkaloids with anticancer potential

Naturally occurring indole alkaloids are ubiquitously present in nature and possess extensive biological properties and structural diversity. Mechanistically, naturally occurring indole alkaloids have the potential to inhibit cancer cell proliferation, arrest cell cycle and induce apoptosis. Accordingly, naturally occurring indole alkaloids exhibit promising activity against both drug-sensitive and drug-resistant cancers including multidrug-resistant forms. Therefore, naturally occurring indole alkaloids constitute an important source of anticancer drug leads and candidates. The goal of this review is to highlight the current scenario of naturally occurring indole alkaloids with anticancer potential, covering articles published from 2018 to present. The names, sources, and antiproliferative activity are discussed to continuously open up a map for the remarkable exploration of more effective candidates.

Bisindole natural products: A vital source for the development of new anticancer drugs

Currently, the number of new cancer cases and deaths worldwide is increasing year on year. In addition to the requirement for cancer prevention, the top priority is still to seek the effective cure of cancer. In over a half century of constant exploration, increasing attention has been paid to the excellent anticancer activity of natural products, with more and more natural products isolated, identified and detected. For this study, the focus lies the natural products of bisindole, where two indole molecules are indirectly linked or directly polymerized, developing the diversity of structure and mechanism, accompanied with the better anticancer activity than monomers. There has been a long history of applying indirubin and vincristine in cancer treatment, verifying the anticancer effect of bisindoles. Vincribine, midostaurin and other anticancer drugs have also been developed and commercialized. In this paper, a review regarding the potential therapeutic effect of bisindole alkaloids extracted from various natural products was carried out, in which the progress made in research of 242 bisindole alkaloids for cancer treatment was introduced. These compounds may be applicable as medicinal products for clinical research in the future.