RESUMEN
Uncarialines A-E (1-5), five undescribed monoterpene indole alkaloids, together with five known analogues were obtained from the stems of Uncaria rhynchophylla. Alkaloids 1-3 were unique 3,4-seco-tricyclic alkaloids with a 6/5/10 ring system, while 4 and 5 possessed a rare rearranged scaffold originated from corynantheine-type alkaloids with C-2/C-7 oxidation. Their structures were characterized by a comprehensive analysis of MS, NMR, and ECD. Their effects on blood clotting times of human plasma were evaluated and alkaloid 5 had a slight prolongation effect on both thrombin time and activated partial thromboplastin time (p < 0.001).
RESUMEN
Eleven monoterpenoid indole alkaloids, including three new ones, tabercrassines A-C (1-3), were isolated from the seeds of Tabernaemontana crassa. Tabercrassine A (1) is an ibogan-ibogan-type bisindole alkaloid which is formed by the polymerization of two classic ibogan-type monomers through a C3 unit aliphatic chain. Their structures were established by extensive analysis of HRESIMS, NMR, and ECD spectra. Cellular assays showed that alkaloids 1-3 all reduce Aß42 production and inhibit phospho-tau (Thr217), a new biomarker of Alzheimer's disease [AD] associated with BACE1-, NCSTN-, GSK3ß-, and CDK5-mediated pathways, suggesting these alkaloids' potential against AD.
Asunto(s)
Antineoplásicos Fitogénicos , Alcaloides de Triptamina Secologanina , Tabernaemontana , Alcaloides de Triptamina Secologanina/farmacología , Alcaloides de Triptamina Secologanina/química , Alcaloides Indólicos/farmacología , Tabernaemontana/química , Secretasas de la Proteína Precursora del Amiloide , Antineoplásicos Fitogénicos/farmacología , Ensayos de Selección de Medicamentos Antitumorales , Ácido Aspártico Endopeptidasas , Estructura MolecularRESUMEN
Two new monoterpenoid indole alkaloids, (2 R, 7 R, 16 R, 20 R, 21S)-12-hydroxypleiocarpine (1) and (2S, 7 R, 16S, 20 R, 21S)-N-methoxycarbonyl-11,12-methylenedioxy-Δ14,15-kopsinaline (2), along with six known alkaloids were isolated from the methanol extract of the kernels of Kopsia arborea. Their structures including the absolute configurations were elucidated by HRESIMS, NMR spectroscopy, and quantum computational methods. Their cytotoxicity against two human cancer cell lines were also evaluated.
Asunto(s)
Apocynaceae , Alcaloides de Triptamina Secologanina , Humanos , Alcaloides de Triptamina Secologanina/farmacología , Alcaloides de Triptamina Secologanina/química , Alcaloides Indólicos/farmacología , Alcaloides Indólicos/química , Estructura Molecular , Espectroscopía de Resonancia Magnética , Apocynaceae/químicaRESUMEN
Two new alkaloids, taberdines L (1) and M (2), together with six known alkaloids, were isolated from the twigs and leaves of Tabernaemontana divaricata. Taberdine L (1) represents the first optically active natural member of the allo iboga class of alkaloids with the ethyl side chain in a bridgehead position. Their structures including absolute configuration were elucidated by a combination of MS, NMR, and ECD calculation. The in vitro cytotoxic activities of 1 and 2 against five human cancer cell lines were also evaluated.