New Indole Alkaloids fromKopsia. Alkaloid Variation inKopsia singapurensis

Chemodiverse monoterpene indole alkaloids from Kopsia teoi, inhibitory potential against α-amylase, and their molecular docking studies

Diabetes mellitus stands as a metabolic ailment marked by heightened blood glucose levels due to inadequate insulin secretion. The primary aims of this investigative inquiry encompassed the isolation of phytochemical components from the bark of Kopsia teoi, followed by the assessment of their α-amylase inhibition. The phytochemical composition of the K. teoi culminated in the discovery of a pair of new indole alkaloids; which are 16-epi-deacetylakuammiline N(4)-methylene chloride (akuammiline) (1), and N(1)-methoxycarbonyl-11-methoxy-12-hydroxy-Δ14-17-kopsinine (aspidofractinine) (2), together with five known compounds i.e. kopsiloscine G (aspidofractinine) (3), akuammidine (sarpagine) (4), leuconolam (aspidosperma) (5), N-methoxycarbonyl-12-methoxy-Δ16, 17-kopsinine (aspidofractinine) (6), and kopsininate (aspidofractinine) (7). All compounds were determined via spectroscopic analyses. The in vitro evaluation against α-amylase showed good inhibitory activities for compounds 5-7 with the inhibitory concentration (IC50) values of 21.7 ± 1.2, 34.1 ± 0.1, and 30.0 ± 0.8 μM, respectively compared with the reference acarbose (IC50 = 34.4 ± 0.1 μM). The molecular docking outputs underscored the binding interactions of compounds 5-7 ranging from -8.1 to -8.8 kcal/mol with the binding sites of α-amylase. Consequently, the outcomes highlighted the anti-hyperglycemic attributes of isolates from K. teoi.

A comprehensive review on phytochemistry and pharmacology of genus Kopsia: monoterpene alkaloids - major secondary metabolites

Kopsia belongs to the family Apocynaceae, which was originally classified as a genus in 1823. Kopsia consists of medicinal plants that can be traditionally used to treat rheumatoid arthritis, pharyngitis, tonsillitis, and dropsy. More than one hundred and twenty-five publications have been documented relating to the phytochemical and pharmacological results, but a systematic review is not available. The goal of this study is to compile almost all of the secondary metabolites from the plants of genus Kopsia, as well as the coverage of their pharmacological research. The document findings were conducted via reliable sources, including Web of Science, Sci-Finder, Science Direct, PubMed, Google Scholar, and publishers, while four words "Kopsia", "monoterpene alkaloids", "Phytochemistry" and "Pharmacology" are key factors to search for references. Most Kopsia secondary metabolites were collected. A total of four hundred and seventy-two, including four hundred and sixty-six monoterpene alkaloids, five triterpenoids, and one sterol, were summarized, along with their resource. Kopsia monoterpene alkaloids presented in various skeletons, but aspidofractinines, eburnamines, and chanofruticosinates are the three major backbones. Mersinines and pauciflorines are new chemical classes of monoterpene alkaloids. With the rich content of monoterpene alkaloids, Kopsia constituents were also the main objects in pharmacological studies since the plant extracts and isolated compounds were proposed for anti-microbial, anti-inflammatory, anti-allergic, anti-diabetic, anti-manic, anti-nociceptive, acetylcholinesterase (AChE) inhibitory, cardiovascular, and vasorelaxant activities, especially cytotoxicity.

Rapid Construction of Hexacyclic Indolines via the Ru(II)-Catalyzed C-H Activation Initiated Cascade Cyclization of Phenidones with Enynones

A highly efficient cascade cyclization of phenidones and enynones has been developed via a Ru(II)-catalyzed C-H activation initiated indole formation/Diels-Alder reaction/iminium ion cyclization sequence, which afforded hexacyclic indolines as single diastereomer in good to excellent yields with a broad substrate scope under mild conditions. The reaction features the simultaneous generation of five new chemical bonds and four new rings in one pot, providing a rapid and concise approach toward polycyclic indoline alkaloids and their analogues.

Cytotoxic monoterpenoid indole alkaloids from the aerial parts of Kopsia officinalis

Three new monoterpenoid indole alkaloids, kopsiaofficines A-D (1-3), were isolated from the 95% EtOH extract of the aerial parts of Kopsia officinalis. Their structures were established on the basis of spectroscopic data. The isolated alkaloids were tested in vitro for cytotoxic activity against seven lung cancer cell lines. Consequently, alkaloids 1 and 3 exhibited some cytotoxic activities against all the tested tumor cell lines with IC₅₀ values less than 20 µM.[Formula: see text].

Indole alkaloids from the aerial parts of Kopsia fruticosa and their cytotoxic, antimicrobial and antifungal activities

A chemical investigation on the 80% EtOH extract of the aerial parts of Kopsia fruticosa led to five new indole alkaloids, kopsifolines G-K (1-5), and one known alkaloid, kopsifoline A (6). Structural elucidation of all the compounds were performed by spectral methods such as 1D and 2D (¹H-¹H COSY, HMQC, and HMBC) NMR spectroscopy, in addition to high resolution mass spectrometry. The isolated components were evaluated in vitro for cytotoxic activities against seven tumor cell lines, antimicrobial activities against two Gram-positive bacteria and five Gram-negative bacteria, and antifungal activities against five pathogens. As a result, alkaloids 3-5 exhibited some cytotoxicity against all of seven tested tumor cell lines (HS-1, HS-4, SCL-1, A431, BGC-823, MCF-7, and W480) with IC₅₀ values of 11.8-13.8, 10.3-12.5, and 7.3-9.5 μM, respectively. Alkaloids 3-5 also possessed significant antimicrobial and antifungal activities which was reported for the first time for the alkaloids isolated from Kopsia genus.

Cytotoxic aspidofractinine alkaloids from Kopsia hainanensis

Five new aspidofractinine-type alkaloids, kopsiahainins A-E (1-5), were isolated from a 80% EtOH extract of the leaves and stems of Kopsia hainanensis. Structural elucidation of all the compounds were performed by spectral methods such as 1D- and 2D-NMR, IR, UV, and HR-ESI-MS. Alkaloids 3 and 4 exhibited some cytotoxic activity against all of six tested tumor cell lines (BGC-823, HepG2, MCF-7, SGC-7901, SK-MEL-2, and SK-OV-3) with IC₅₀ values of 7.3-9.5μM and 9.2-10.6μM, respectively.

Pd(ii)-Catalyzed oxidative dearomatization of indoles: substrate-controlled synthesis of indolines and indolones

A Pd(ii)-catalyzed oxidative dearomatization of indoles provides a straightforward access to diverse fused indolines and indolones bearing C2-oxygenated quaternary stereocenters.

Grandilodines A-C, biologically active indole alkaloids from Kopsia grandifolia

Three new indole alkaloids (1-3), named grandilodines A-C, and five known ones were obtained from the Malayan Kopsia grandifolia. The structures were established using NMR and MS analyses and, in the case of 1 and 2, were confirmed by X-ray diffraction analyses. Alkaloids 1, 3, and lapidilectine B (8) were found to reverse multidrug resistance in vincristine-resistant KB cells.

Aspidospermatan-aspidospermatan and eburnane-sarpagine bisindole alkaloids from Leuconotis

Leucofoline and leuconoline, representing the first members of the aspidospermatan-aspidospermatan and eburnane-sarpagine subclasses of the bisindole alkaloids, respectively, were isolated from the Malayan Leuconotis griffithii. The structures of these bisindole alkaloids were established using NMR and MS analysis, and in the case of leuconoline, confirmed by X-ray diffraction analysis. Both alkaloids showed weak cytotoxicity towards human KB cells.

Titanocene(III)-catalyzed formation of indolines and azaindolines

Reductive cyclization of epoxides tethered to substituted anilines and aminopyridines in the presence of 3 mol % of titanocene dichloride and stoichiometric manganese metal promotes a radical annulation to form 3,3-disubstituted indolines and azaindolines.