Memory‐enhancing effects ofIshige foliaceaextract: In vitro and in vivo study

Abstract

Ishige foliacea is used as a functional food in East‐Asian countries. We evaluated the memory‐enhancing effect of an ethanol extract of I. foliacea (EEI) using in vitro and in vivo models. In vitro acetylcholinesterase and β‐secretase inhibitory activities, antioxidant properties, and neuroprotective effects against human neuronal cell death by H2O2 and β‐amyloid (Aβ) were investigated. We explored the memory‐enhancing effect and its underlying mechanism in a mouse model of scopolamine (SCO)‐induced memory deficits. EEI showed free radical scavenging and acetylcholinesterase and β‐secretase inhibition activities. Additionally, EEI significantly decreased neuronal cell death induced by H2O2 or Aβ in human neuroblastoma SH‐SY5Y cells. In behavior tests, SCO‐induced memory deficits was improved by EEI administration. EEI increased the protein expression of brain‐derived neurotrophic factor (BDNF) and tropomyosin receptor kinase B (TrkB) and phosphorylated extracellular signal‐regulated kinase, which are related to synaptic plasticity in the hippocampus. EEI may ameliorate memory deficits and prevent neurodegenerative disorders. Practical applications As the population ages, dementia, a neurodegenerative disease, is becoming an important problem. Various Alzheimer's drugs have been developed based on the disease mechanism, but alternative treatments are required because of the low bioavailability and hepatotoxicity of current medications. Ishige foliacea is a type of brown algae containing various bioactive substances. Phlorotannins, known as brown algae polyphenols, have been studied for their various functionalities such as, anticancer, anti‐obesity, antioxidant, and sleep improvement effects, and have attracted attention as raw materials for developing new natural products. We found that the EEI mitigates SCO‐induced damage by protecting neurons from oxidative stress‐induced cell damage, controlling synthesis mechanisms of the causative agents of AD, and activating BDNF–TrkB–ERK signaling to promote memory function in the hippocampus. The results of this study can serve as a foundation for further research. Additionally, I. foliacea may be useful for treating and improving AD.

Neuroprotective Potentials of Marine Algae and Their Bioactive Metabolites: Pharmacological Insights and Therapeutic Advances

“…In addition, the extracts from some marine algae have shown anti-cholinesterase properties. These include Halimeda cuneata [ 80 ], Padina australis [ 125 ], Botryococcus braunii and Nannochloropsis oculata [ 126 ], Cystoseira tamariscifolia and Cystoseira nodicaulis [ 127 ], Ishige foliacea [ 128 ], and Asparagopsis taxiformis [ 129 ].…”

“…Olasehinde et al reported that four South African macroalgae such as Gracilaria gracilis, Ulva lactuca, Ecklonia maxima , and Gelidium pristoides exhibited anti-cholinesterase, anti-BACE1, and Aβ aggregation inhibitory activities, indicating that these types of seaweed could be potential sources of anti-AD agents [ 35 ]. Ishige foliacea extract showed β-secretase inhibition property [ 128 ].…”

“…In addition, extracts from several marine algae have shown neuroprotective activity in various in vitro models. The neuroprotective algae include Ulva conglobata that protected against glutamate-induced neurotoxicity in murine hippocampal HT22 cell line [ 108 ], Botryococcus braunii , and Nannochloropsis oculata against H 2 O 2 -induced cytotoxicity in dopaminergic SH-SY5Y cells [ 126 ], Padina pavonica, Sargassum muticum, Saccorhiza polyschides, Codium tomentosum , and Ulva compressa [ 214 ], and Bifurcaria bifurcata [ 215 ] against 6-hydroxidopamine-induced cytotoxicity in neuroblastoma cells, Cystoseira tamariscifolia and Cystoseira nodicaulis against H 2 O 2 -induced cytotoxicity in SH-SY5Y cells [ 127 ], Gracilaria corticata against aluminium-induced neurotoxicity in the hippocampus, and cerebral cortexes of rat brains [ 216 ], Australian macroalgae against Aβ 1-42-induced neurotoxicity in PC-12 cells [ 217 ], Ishige foliacea against H 2 O 2 - or Aβ-induced cell death in human neuroblastoma SH-SY5Y cells [ 128 ], Undaria pinnatifida against endoplasmic reticulum stress in hypothalamic neurons [ 218 ] and Gracilariopsis corda [ 219 ] and Gelidium amansii [ 153 ] against H/R-induced oxidative damage in primary hippocampal neurons, indicating that these algae could offer some potential compounds with encouraging neuroprotective activity, and, therefore, demand further investigation.…”

“…In addition, extracts from several marine algae have shown to either ameliorate memory impairment or enhance cognition in various in vivo models. For instance, Gelidiella acerosa attenuated Aβ25-35-induced cytotoxicity and memory deficits in mice [ 223 ], Sargassum swartzii improved memory functions in rats [ 224 ], Ishige foliacea [ 128 ], Undaria pinnatifida [ 225 ] ameliorated scopolamine-induced memory deficits in mice, Haematococcus pluvialis recovered Alzheimer’s disease in rats [ 226 ], and fermented Spirulina maxima prevented memory impairment in mice [ 227 ]. In addition, some marine algae have shown to attenuate ischemic injury in stroke models.…”

Polyphenols from Brown Seaweeds (Ochrophyta, Phaeophyceae): Phlorotannins in the Pursuit of Natural Alternatives to Tackle Neurodegeneration

“…To date, only a few in vivo studies have addressed the neurological activity of phlorotannins and phlorotannin preparations, but their somnogenic [47,[90][91][92] and memory-enhancing [46,[93][94][95] effects have already been demonstrated.…”