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Compounds derived from natural products are becoming promising alternative drugs/tools in Alzheimer's disease (AD) therapeutics. From an in-house natural products library, seventeen hits were selected for their inhibitory effect on the production of amyloid-β (Aβ) with IC50 lower than 10 μM without causing obvious toxicity. Among these compounds, camptothecin (CPT) and its analogs showed inhibitory effects on amyloid-β 1-42 (Aβ42) with the IC50 value in the nanomolar range in HEKsw cells and SHSY5Ysw cells. Further studies showed that CPT and its analogs inhibited Aβ42 via a p53 dependent pathway. Meanwhile, CPT and its analogs could also inhibit Aβ42 induced IL-1β production in the THP-1 cells. Taken together, our results indicate that CPT and its analogs would be a promising therapeutic candidates for AD. [ABSTRACT FROM AUTHOR]

Triptolide, a biologically active natural product from Tripterygium wilfordii, protects neurons from inflammation-mediated damage. Our results showed for the first time that triptolide inhibited the expression of CXCR2 and presenilin in a neuroblastoma cell line SHSY5Ysw. Moreover, triptolide potently inhibited amyloid-β1-42 production with IC50 value of 30 pM in HEK293sw cells or 2 nM in SHSY5Ysw cells, respectively. We also demonstrated that triptolide prevented primary cortical neurons from chemokine CXCL1-induced cytotoxicity. Therefore, our study indicates that the neural protective effect of triptolide is largely mediated by inhibiting CXCR2 activity. [ABSTRACT FROM AUTHOR]