Figure 3.

Enzymatic processing of amyloid-β precursor protein (AβPP). (a) Cleavage within the amyloid-β (Aβ) sequence (i.e., at the peptide bond between Lys16 and Leu17) by α-secretase precludes Aβ production while sequential cleavages first by β-secretase, and then by γ-secretase at the sites indicated produce Aβ40 and Aβ42. (b) Amyloidogenic and non-amyloidogenic pathways and their products. Curcumin modulates the amyloidogenic pathway by inhibiting β-secretase. EGCG and curcumin facilitate the non-amyloidogenic pathway by enhancing the activity of α-secretase.