Fucoxanthin, a natural carotenoid abundant in edible brown seaweeds, has been shown to possess anti-cancer, anti-oxidant, anti-obesity and anti-diabetic effects. In this study, we report for the first time that fucoxanthin effectively protects against scopolamine-induced cognitive impairments in mice. In addition, fucoxanthin significantly reversed the scopolamine-induced increase of acetylcholinesterase (AChE) activity and decreased both choline acetyltransferase activity and brain-derived neurotrophic factor (BDNF) expression. Using an in vitro AChE activity assay, we discovered that fucoxanthin directly inhibits AChE with an IC₅₀ value of 81.2 μM. Molecular docking analysis suggests that fucoxanthin likely interacts with the peripheral anionic site within AChE, which is in accordance with enzymatic activity results showing that fucoxanthin inhibits AChE in a non-competitive manner. Based on our current findings, we anticipate that fucoxanthin might exhibit great therapeutic efficacy for the treatment of Alzheimer’s disease by acting on multiple targets, including inhibiting AChE and increasing BDNF expression.

Alzheimer’s disease (AD), the most common neurodegenerative disorder, is characterized by neurofibrillary tangles, synaptic impairments, and loss of neurons. Oligomers of β‐amyloid (Aβ) are widely accepted as the main neurotoxins to induce oxidative stress and neuronal loss in AD. In this study, we discovered that fucoxanthin, a marine carotenoid with antioxidative stress properties, concentration dependently prevented Aβ oligomer‐induced increase of neuronal apoptosis and intracellular reactive oxygen species in SH‐SY5Y cells. Aβ oligomers inhibited the prosurvival phosphoinositide 3‐kinase (PI3K)/Akt cascade and activated the proapoptotic extracellular signal‐regulated kinase (ERK) pathway. Moreover, inhibitors of glycogen synthase kinase 3β (GSK3β) and mitogen‐activated protein kinase (MEK) synergistically prevented Aβ oligomer‐induced neuronal death, suggesting that the PI3K/Akt and ERK pathways might be involved in Aβ oligomer‐induced neurotoxicity. Pretreatment with fucoxanthin significantly prevented Aβ oligomer‐induced alteration of the PI3K/Akt and ERK pathways. Furthermore, LY294002 and wortmannin, two PI3K inhibitors, abolished the neuroprotective effects of fucoxanthin against Aβ oligomer‐induced neurotoxicity. These results suggested that fucoxanthin might prevent Aβ oligomer‐induced neuronal loss and oxidative stress via the activation of the PI3K/Akt cascade as well as inhibition of the ERK pathway, indicating that further studies of fucoxanthin and related compounds might lead to a useful treatment of AD.

Inflammation is a generalized, nonspecific, and beneficial host response of foreign challenge or tissue injury. However, prolonged inflammation is undesirable. It will cause loss function of involve organs, such as heat, pain redness, and swelling. Marine natural products have gained more and more attention due to their unique mechanism of anti-inflammatory action, and have considered a hotspot for anti-inflammatory drug development. Marine-derived fungi are promising sources of structurally unprecedented bioactive natural products. So far, a plethora of new secondary metabolites with anti-inflammatory activities from marine-derived fungi had been widely reported. This review covers 133 fungal metabolites described in the period of 2000 to 2018, including the structures and origins of these secondary metabolites.

Marine cyanobacteria are significant sources of structurally diverse marine natural products with broad biological activities. In the past 10 years, excellent progress has been made in the discovery of marine cyanobacteria-derived peptides with diverse chemical structures. Most of these peptides exhibit strong pharmacological activities, such as neurotoxicity and cytotoxicity. In the present review, we summarized peptides isolated from marine cyanobacteria since 2007.

Two novel cyclodepsipeptides containing an unusual anthranilic acid dimer and a d-phenyllactic acid residues, clavatustides A (1) and B (2), were identified from cultured mycelia and broth of Aspergillus clavatus C2WU isolated from Xenograpsus testudinatus, which lives at extreme, toxic habitat around the sulphur-rich hydrothermal vents in Taiwan Kueishantao. This is the first example of cyclopeptides containing an anthranilic acid dimer in natural products, and the first report of microbial secondary metabolites from the hydrothermal vent crab. Clavatustides A (1) and B (2) suppressed the proliferation of hepatocellular carcinoma (HCC) cell lines (HepG2, SMMC-7721 and Bel-7402) in a dose-dependent manner, and induced an accumulation of HepG2 cells in G1 phase and reduction of cells in S phase.