Phlorotannin and Fucoidan Mixture Prevents Cognitive Decline Caused by Aβ

May 1, 2025 Molly

In the United States, the debilitating and progressive neurodegenerative disease known as Alzheimer’s disease (AD) currently impacts the lives of over 5 million individuals. As the proportion of the US population aged 65 years or older increases, the number of patients with Alzheimer’s disease and other dementias continues to increase annually. Alzheimer’s disease (AD) involves several mechanisms of cognitive decline, prominently featuring amyloid-beta (Aβ) in senile plaques and cerebral amyloid angiopathy, but also highlighting the significance of mitochondrial function as a potential therapeutic avenue.

In this blog, I would like to share the following study: “Mixture of Phlorotannin and Fucoidan from Ecklonia cava Prevents the Aβ-Induced Cognitive Decline with Mitochondrial and Cholinergic Activation” by Hye Ju Han et al. The study researched the preventive effect of a mixture (P4F6, phlorotannin: fucoidan derived from E. cava = 4:6) on Aβ-induced cognitive decline was evaluated by using Amyloid β peptide (Aβ)-induced cognitive impairment mice.

First, mice were randomly divided into six groups: normal control (NC) group, Aβ1-42 infusion (Aβ) group (negative group), donepezil 5 mg/kg body weight (DP) group (positive group), and mixture (P4F6) group (5, 10, and 20 mg/kg body weight, M5, M10, and M20, respectively).

To assess and confirm the functionality of spatial learning and memory, a Y-maze test was carried out, with the resulting data displayed in Figure 1a. In all groups, the total entry into the arms showed similar movements. This means that Aβ injection did not affect motor ability. The Aβ group showed a significant decrease in spontaneous alternation behavior by about 10.55% compared with the NC group. (See Figure. 1a) The alternation behavior of the mixed (P4F6) group (M5; 55.35, M10; 60.11, and M20; 67.15%) was improved compared with the Aβ group, as was the DP group used as a positive control.

Short-term learning capabilities and memory retention were assessed using a passive avoidance test, and the resultant data is graphically represented in the accompanying Figure. 1b. The Aβ group showed a reduced latency compared with the NC group. However, the mixed group showed a longer step-through latency compared with the Aβ group (M5; M10, M20).

Long-term memory and learning were evaluated using the Morris water maze test. The escape latencies of all groups were gradually shortened during the hiding test period to learn the location of the platform. (See Figure. 1c) The Aβ group took significantly longer to complete the final hiding test, indicating Aβ-induced cognitive impairment. Figure 1d shows the results obtained from the probe test, which was conducted after the completion of the training test. The Aβ group spent less time in the W zone, where the platform was located, comparing the NC group. In contrast, the DP group, used as a positive control, improved long-term learning and memory impairment with Aβ injection. Notably, the mixed groups (M10 and M20) also showed similar improvements to the NC group. Analysis of brain tissue following behavioral tests revealed that the P4F6 mixture attenuated Aβ-induced oxidative stress, as indicated by decreased SOD activity and TBARS levels.

To evaluate the ameliorative effect of Aβ-induced mitochondrial damage, they investigated the mitochondrial ROS content, MMP, ATP levels, and expression levels of mitochondrial-mediated molecules. (See Figure. 3) Mitochondrial ROS content increased with Aβ compared with the NC group. (See Figure. 2a) In comparison, Aβ infusion remarkably inhibited mitochondrial ROS production in the DP and mixed groups.

MMP levels in the Aβ group were lower than in the NC group in the MMP measurement results; however, the DP and M20 groups showed significantly improved MMP levels compared to the Aβ group. (See Figure. 2b)

In Figure. 2c, Aβ-induced mitochondrial dysfunction reduced ATP levels, which resulted in the Aβ group having a decreased ATP content compared with the NC group. Meanwhile, the DP group promoted ATP production. In addition, the M20 group showed a significant increase in ATP levels.

The findings demonstrate that the mixture stimulated mitochondrial activity; this was achieved by suppressing ROS generation and enhancing MMP and ATP production. BAX, cytoplasmic cytochrome c, and caspase 3 levels were measured to assess mitochondrial apoptosis. (Figure. 2d, e) The Aβ group induced BAX expression, and cytochrome c was released from mitochondria to the cytoplasm. Cytochrome c released into the cytoplasm activated caspase 3. However, administration of the mixture effectively suppressed the expression levels of BAX and cytochrome c released into the cytoplasm compared with the Aβ group. The mixture P4F6 suppressed caspase 3 expression, indicating its effectiveness in activating mitochondria by downregulating molecules involved in mitochondria-mediated apoptosis.

As a result of measuring the Aβ-induced tau hyperphosphorylation signaling pathway, the expression of p-JNK was increased in the Aβ group compared with the NC group, and the expression of p-JNK was suppressed in the DP and M20 groups. The expression of p-Akt and p-GSK-3β was decreased in the Aβ group compared with the NC group, and finally, tau phosphorylation was induced. In contrast, the DP group was shown to inhibit tau hyperphosphorylation in brain tissue by promoting Akt phosphorylation and resulting in GSK-3β inactivation (p-GSK-3β). The expression of p-Akt was increased, and p-Tau was inhibited in the M20 group.

Measurements of ChAT and AChE expression, AChE activity, and acetylcholine content were used to evaluate cholinergic activity within the brain tissue. The expression levels of ChAT and AChE were decreased and the expression level of AChE was increased by Aβ injection compared with the NC group. The M20 group showed similar expression levels compared with the DP group used as a positive control. The ACh content comparison showed that the ACh content in the Aβ group was increased by about 51.32% compared to the NC group. In contrast, the ACh content in the mixed groups (M5, M10, and M20) significantly increased compared to the Aβ group. Also, the AChE activity in the Aβ group was increased by about 118.41% compared to the NC group, while the mixed groups (M5, M10, and M20) showed an increase in AChE activity upon inhibition.

The study’s findings indicate that the P4F6 mixture could improve cognitive function through its effects on cognition-related molecules.