International Journal of Molecular Sciences (Jan 2023)
New Monoterpenoid Indole Alkaloids from <i>Tabernaemontana crassa</i> Inhibit <i>β</i>-Amyloid42 Production and Phospho-Tau (Thr217)
Abstract
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 Aβ42 production and inhibit phospho-tau (Thr217), a new biomarker of Alzheimer’s disease [AD] associated with BACE1-, NCSTN-, GSK3β-, and CDK5-mediated pathways, suggesting these alkaloids’ potential against AD.
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