New research on neuro protective effects of certain seaweeds against Alzheimer's disease
Prof. Dr. Dang Diem Hong gave a scientific report on the screening of neuroprotective substances and extracts from Vietnam's seaweed at the ISS 2023 International Conference in Horbat, Tasmania, Australia
Alzheimer's Disease
Alzheimer's disease is one of the most common neurodegenerative disorders, with the number of patients expected to exceed 100 million by 2050 (Bauer et al., 2021). Currently, there is no complete cure for the disease, and treatments mainly focus on early detection and prevention. Prescription drugs used in the treatment and management of Alzheimer's (such as rasagline, rivastigmine and donepezil) are primarily related to inhibiting cholinesterase and β-secretase (BACE-1) enzymes, or inhibiting the N-methyl-D-aspartate (NMDA) receptor with memantine. However, these drugs can have side effects such as nausea, vomiting, dizziness, liver toxicity and gastrointestinal disorders. Consequently, a promising future treatment direction is the use of natural products rich in nutrients, with neuroprotective activity and fewer or no side effects compared to synthetic drugs.
Biological activity of seaweed
Seaweed, a marine organism, is a natural source of high biological activity compounds. Some seaweed species can grow in harsh environments, and extracts and compounds isolated from seaweed biomass have been shown to have strong antioxidant activity, antibacterial and antiviral effects, liver-protective properties, and inhibit the proliferation of Hela cells. Olasehinde et al. (2019a) reported that crude extracts and compounds isolated from seaweed have neuroprotective effects against Alzheimer's disease by inhibiting cholinesterase. Adding Sargassum fusiforme to the diet can slow cognitive decline and the accumulation of β-amyloid peptide plaques (Aβ) in mice (Bogie et al., 2019). Research has demonstrated that seaweed is an important marine resource that can be exploited for high biological activity compounds with neuroprotective effects against neurodegenerative diseases, including Alzheimer's disease.
Seaweed potential in Vietnam
To date, 878 species of seaweed have been recorded in Vietnam (including 439 species of red algae (Rhodophyta), 196 green algae (Chlorophyta), 156 brown algae (Ochrophyta-Phaeophytaceae), 87 species of blue-green algae (Cyanophyta), and 15 species of seagrass (according to data published by Phang et al. (2016); Dang et al. (2019), Dang and Ha (2022), Nguyen et al. 2023). Among them, species from the genera Caulerpa, Sargassum, Gracilaria, Ulva, Kappaphycus, and Eucheuma are economically important, with large reserves, currently being cultivated and naturally harvested in high yields. This provides a rich natural resource for use as food and for extracting high biological activity compounds, including those with neuroprotective effects, enhancing human memory.
Research evidence
To elucidate the molecular mechanism of the neuroprotective effects of extracts/compounds obtained from Vietnamese seaweed, and to exploit the potential seaweed species as health-protective foods, Prof. Dr. Dang Diem Hong and colleagues proposed and were approved by VAST to carry out the project: "Neuroprotective Effects Against Alzheimer's Disease (AD) of Some Vietnamese Seaweed Species" (code: VAST04.10/22-23).
In the study, scientists produced 69 total extracts from 11 species belonging to eight seaweed genera, including Ulva, Kappaphycus, Sargassum, Eucheuma, Gracilariopsis, Caulerpa, Gracilaria, and Palzheimerina (Figure 2) under different extraction conditions and solvents. For the first time, the molecular mechanism of the effects of fucoxanthin extracted from S. oligocystum and ethanol extract from Sargassum spp. was studied (Figures 3 and 4). These were found to have antioxidant activity, AChE (acetylcholinesterase) inhibition, and protective effects against cell toxicity in Alzheimer's models induced by Aß25-35 or H2O2 in C6 neuronal cells. Fucoxanthin achieved this by regulating the activity and expression of genes encoding antioxidant enzymes (such as CAT and GPx) and ER pathways (such as caspase-3 and Bax), as well as promoting the expression of genes related to PI3K/Akt signaling (GSK-3β), autophagy (p62 and ATG5), and acetylcholine biosynthesis (VAChT and ChAT).
Morphological images of the 11 seaweed species used in the study were collected from the waters of Khanh Hoa in 2022.
Experiment summary
The protective effect of ethanol extract on the expression levels of genes related to AChE enzyme activity (A), Alzheimer's disease pathogenesis (B), oxidative reduction (C, D), programmed cell death prevention (E), ER stress pathway (F), autophagy process (G), and antioxidant enzymes (H)
Prof. Dr. Dang Diem Hong shared: The results of this project are an important initial success in the research process, mastering the technology to create functional foods derived from Vietnamese seaweed to support Alzheimer's disease treatment. The research demonstrated that fucoxanthin extracted from S. oligocystum and 96% ethanol extract (with ultrasound) from Sargassum spp. are safe regarding acute and sub-chronic toxicity and can improve cognitive decline caused by scopolamine (similar to donepezil at a dose of 5 mg/kg body weight in mice) in in vivo experimental animal models. The research team published two scientific papers in international SCI-E (Q1) journals, 1 paper in a national journal (VAST02), one presentation at the ISS2023 International Conference, and one full-text report at the 2022 National Biotechnology Conference. The project was evaluated and rated as Excellent by VAST.
With the achieved results, Prof. Dr. Dang Diem Hong hopes to continue researching, testing, and soon perfecting the technology process to create these natural, nutrient-rich health-protective products, contributing to effectively supporting Alzheimer's patients as well as those working in strenuous conditions in Vietnam in the near future.
Translated by Phuong Huyen
Link to Vietnamese version
