Polyphenolic compounds, encompassing flavonoids (e.g., quercetin, rutin, cyanidin) and non-flavonoids (e.g., gallic acid, resveratrol, curcumin), show several health-related beneficial effects, which include antioxidant, anti-inflammatory, hepatoprotective, antiviral, and anticar-cinogenic properties, as well as the prevention of coronary heart diseases. Polyphenols have been also investigated for their counteraction against adverse effects of common anticancer chemo-therapeutics. This review examines the outcomes of clinical studies (and related preclinical data) over the last ten years, with a focus on the use of polyphenols in chemotherapy as auxiliary agents acting against oxidative stress toxicity induced by antitumor drugs. While further clinical studies are needed to establish adequate doses and optimal delivery systems, the improvement in pol-yphenols’ metabolic stability and bioavailability, through implementation of nanotechnologies currently being investigated, could improve therapeutic applications of their pharmaceutical or nutraceutical preparations in tumor chemotherapy.

The multitarget therapeutic strategy, as opposed to the more traditional ‘one disease-one tar-get-one drug’, may hold promise in treating multifactorial neurodegenerative syndromes, such as Alzheimer’s disease (AD) and related dementias. Recently, combining a photopharmacology approach with the multitarget-directed ligand (MTDL) design strategy, we disclosed a novel donepezil-like compound, namely 2-(4-((diethylamino)methyl)benzylidene)-5-methoxy- 2,3-dihydro-1H-inden-1-one (1a), which in the E diastereomeric form (and about tenfold less in the UV-B photo-induced isomer Z) showed the best activity as dual inhibitor of the AD-related targets acetylcholinesterase (AChE) and monoamine oxidase B (MAO-B). Herein, we investigated further photoisomerizable 2-benzylideneindan-1-one analogs 1b-h with the unconjugated tertiary amino moiety bearing alkyls of different bulkiness and lipophilicity. For each compound the thermal stable E diastereoisomer, along with the E/Z mixture as produced by UV-B light irradia-tion in the photostationary state (PSS, 75% Z), was investigated for the inhibition of human ChEs and MAOs. The pure E-diastereoisomer of the N-benzyl(ethyl)amino analog 1h achieved low nanomolar AChE and high nanomolar MAO-B inhibition potencies (IC50s 39 and 355 nM, re-spectively), whereas photoisomerization to the Z isomer (75% Z in the PSS mixture) resulted in a decrease (about 30%) of AChE inhibitory potency, and not in the MAO-B one. Molecular docking studies were performed to rationalize the different E/Z diastereoselectivity of 1h toward the two target enzymes.

Previous studies showed that some lamellarin-resembling annelated azaheterocyclic carbaldehydes and related imino adducts, sharing the 1-phenyl-5,6-dihydropyrrolo[2,1-a]isoquinoline (1-Ph-DHPIQ) scaffold, are cytotoxic in tumor cells and may reverse multidrug resistance (MDR) mediated by P-glycoprotein (P-gp). Herein, we synthesized and evaluated for their antiproliferative activity in four tumor cell lines (RD, HCT116, HeLa, A549) and ability of inhibiting P-gp-mediated MDR some ten diversely substituted 1-Ph-DHPIQ derivatives bearing at position 2 carboxylate groups (COOH, COOEt), nitriles (CN) and Mannich bases (e.g., morpholinomethyl derivatives). Lipophilicity parametrization and molecular docking calculations improved the understanding of the structure-activity relationships in cytotoxicity and P-gp inhibition of the investigated 1-Ph-DHPIQs, which led us to disclose a novel Mannich base HCl salt (8b’), which proved to be cytotoxic to all the tested tumor cell lines in the low micromolar range (IC50 < 20 M) and to inhibit in-vitro the efflux pumps P-gp and MRP1 responsible for MDR, with IC50s of 0.45 and 12.1 M, respectively.