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. Here, BACE1 is linked to early-onset autosomal dominant Alzheimer disease.