Inhibition of Aβ aggregation by naphtho-γ-pyrone derivatives from a marine-derived fungus, Aspergillus sp. MPUC239

Abstract

Alzheimer's disease (AD) is an important human disease that mainly causes cognitive impairments. Growing evidence has shown that amyloid-β (Aβ) peptide plays a key role in AD pathogenesis in what is known as the Aβ cascade hypothesis. This hypothesis suggests the importance of suppressing Aβ aggregation and Aβ production. The latter process is governed by β-site APP Cleaving Enzyme1 (BACE1) and γ-secretase. We, therefore, focused on Aβ aggregation inhibitory activity, initially assessing numerous extracts derived from our marine-derived fungus collections. One EtOAc extract derived from an Aspergillus sp. exhibited Aβ aggregation inhibitory activity. Eleven known compounds (1-11) were isolated from CHCl₃ and EtOAc extracts derived from the fungus, and the structures were identified based on MS, NMR, and ECD spectra. Compounds 2, 6, and 10 inhibited Aβ aggregation with IC₅₀ values of 2.8, 3.9, and 8.1 μM, respectively. The protective effect on SH-SY5Y cells against Aβ toxicity was also evaluated, and compounds 6 and 10 significantly alleviated Aβ toxicity. BACE1 inhibitory activity was also examined, and compounds 4, 5, 7, 10, and 11 inhibited BACE1 activity with IC₅₀ values of 14.9, 70.0, 36.5, 28.0, and 72.8 μM, respectively. These data suggest that compound 10 could be useful in AD treatment.

Keywords: Alzheimer’s disease; Amyloid beta; Aspergillus; BACE1; Fungus; Naphto-γ-pyrone; Polyketide.