A Potential Alternative against Neurodegenerative Diseases: Phytodrugs

Figure 1

Representative polyphenol compounds. (a) Benzoic acids: -hydroxybenzoic acid R₁ = R₃ = R₄ = H, R₂ = OH; protocatechuic acid R₁ = R₄ = H, R₂ = R₃ = OH; gallic acid R₁ = R₂ = R₃ = OH, R₄ = H; and salicylic acid R₁ = R₂ = R₃ = H, R₄ = OH. (b) Hydroxycinnamic acids: coumaric acid R₁ = R₂ = H; caffeic acid R₁ = OH, R₂ = H; ferulic acid R₁ = OMe, R₂ = H; and sinapic acid R₁ = R₂ = OMe. (c) Stilbenes: resveratrol R₁ = H; oxyresveratrol R₁ = OH. (d) Hydroxycinnamoyl ester: chlorogenic acid. (e) Hydroxycinnamoyl derivatives: gingerol; (f) Chavicol R₁ = H; eugenol R₁ = OMe; (g) curcumin; (h) magnolol; and (i) echinacoside. Flavonoid compounds. (j) Nobiletin; (k) Flavones: apigenin R₁ = R₄ = H, R₂ = R₃ = R₅ = OH; baicalein R₁ = R₂ = H, R₃ = R₄ = R₅ = OH; chrysin R₁ = R₂ = R₄ = H, R₃ = R₅ = OH; and luteolin R₄ = H, R₁ = OMe, R₂ = R₃ = R₅ = OH. (l) Flavonols: kaempferol R₁ = R₄ = H, R₂ = R₃ = R₅ = OH; quercetin R₄ = H, R₁ = R₂ = R₃ = R₅ = OH. (m) Flavanols (+)-catechin R₁ = H; (+)-gallocatechin R₁ = OH. (n) Flavanones: hesperetin R₄ = H, R₁ = R₃ = R₅ = OH, R₂ = OMe; naringenin R₁ = R₄ = H, R₂ = R₃ = R₅ = OH; pinocembrin R₁ = R₂ = R₄ = H, R₃ = R₅ = OH. (o) Anthocyanins: aurantinidin R₁ = R₂ = H, R₃ = R₄ = OH; cyanidin R₂ = R₄ = H, R₁ = R₃ = OH; pelargonidin R₁ = R₃ = R₄ = H, R₂ = OH; and peonidin R₂ = R₄ = H, R₁ = OMe, R₃ = OH. (p) Flavonolignans: silydianin.

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