Figure 4.

Effects of phlorotannins in Alzheimer’s and Parkinson’s disease. (A) In AD, phlorotannins inhibit AChE and BuChE and combat the loss of cholinergic transmission. Phlorotannins also reduce the formation of Aβ plaques. Aβ-induced spikes in intracellular ROS and Ca²⁺ levels, as well as microglial activation, recruitment, and pro-inflammatory signaling, are suppressed. Adapted from Lee and Stein (2004) and Choi et al. (2015). (B) In PD, phlorotannins may inhibit MAOs to counteract the loss of dopamine. In mitochondria, phlorotannins reduce mitochondrial loss, glutamate-induced membrane flickering, ROS levels, and Ca²⁺. Phlorotannins also reduce cytoplasmic ROS and O₂⁻ levels, while rescuing ATP levels and the number of TH-positive cells in the substantia nigra. Flat-ended arrows indicate direct inhibition, upward arrows indicate upregulation, and downward arrows indicate downregulation. AChE, acetylcholinesterase; BuChE; butyrylcholinesterase, ACh, acetylcholine; ROS, reactive oxygen species; Aβ, beta amyloid; GSK-3β, glycogen synthase kinase-3 beta; P, phosphorylation; MAO, monoamine oxidase; DA, dopamine; ATP, adenosine triphosphate. Adapted from Choi et al. (2015), Cui et al. (2019), and Seong et al. (2019).