Alzheimer's disease (AD) is a progressive age-related brain disorder that slowly destroys memory, with no cure for AD currently available. Plants from the Lamiaceae have been used traditionally for improving memory. Nineteen Mentha taxa were screened for in vitro antioxidant and acetyl- (AChE) and butyryl-cholinesterase (BuChE) and histone deacetylase (HDAC) inhibition activities. Total phenolic content was assessed, together with chromatographic determination of the phenolic composition. Two species, Mentha diemenica and M. requienii, were investigated for the first time. Mints showed strong antioxidant and moderate AChE and BuChE inhibition activities. Mint extracts exhibited good HDAC inhibition activity which was strongly correlated to their biophenol content. Apigenin-7-O-β-D-diglucuronide, chicoric acid and isosakuranetin were tentatively identified as new compounds in Mentha. Our results suggest that mints provide a substantial basis for future research into AD treatment. Furthermore, we highlight that biophenol composition and bioactivity can vary according to several factors within a single taxon.