Amyloid-β (Aβ) is one of the major causative agents of Alzheimer's disease (AD), the most common neurodegenerative disorder characterized by progressive cognitive impairment. While effective drugs for AD are currently limited, identifying anti-Aβ compounds from natural products has been shown as a promising strategy which may lead to breakthroughs for new drug candidate discovery. We have previously reported that 7-(4-hydroxyphenyl)-1-phenyl-4E-hepten-3-one (AO-1), a diarylheptanoid extracted from the plant Alpinia officinarum, has strong effects on neuronal differentiation and neurite outgrowth in vitro and in vivo. The present study further uncovers that AO-1 exerts neuroprotective effects against the neurotoxicity caused by Aβ. Under the damage of Aβ oligomers, the major pathological forms of Aβ, dendrites of neurons become atrophic and simplified, but such impairments were substantially alleviated by AO-1 treatment. Moreover, AO-1 reduced apoptotic levels and oxidative stress triggered by Aβ. Further analysis showed that the anti-caspase and dendrite protective effects of AO-1 were dependent on activation of phosphatidylinositol 3-kinase (PI3K)-mammalian target of rapamycin (mTOR) pathways. These findings collectively identify AO-1 as a beneficial compound to ameliorate the deleterious effects of Aβ on dendrite integrity and cell survival, and may provide new insights on drug discovery of AD.