Modulation of Neurogenesis through the Promotion of Energy Production Activity Is behind the Antidepressant-Like Effect of Colonial Green Alga, Botryococcus braunii

Marine natural products: potential agents for depression treatment

Depression is a common psychiatric disorder. Due to the disadvantages of current clinical drugs, including poor efficacy and unnecessary side effects, research has shifted to novel natural products with minimal or no adverse effects as therapeutic alternatives. The ocean is a vast ecological home, with a wide variety of organisms that can produce a large number of natural products with unique structures, some of which have neuroprotective effects and are a valuable source for the development of new drugs for depression. In this review, we analyzed preclinical and clinical studies of natural products derived from marine organisms with antidepressant potential, including the effects on the pathophysiology of depression, and the underlying mechanisms of these effects. It is expected to provide a reference for the development of new antidepressant drugs.

Botryococcus terribilis Ethanol Extract Exerts Anti-inflammatory Effects on Murine RAW264 Cells

The present study aimed to evaluate the effects of Botryococcus terribilis ethanol extract (BTEE) on lipopolysaccharide (LPS)-induced inflammation in RAW264 cells. BTEE significantly attenuated LPS-induced nitric oxide production and inflammatory cytokines release, including Ccl2, Cox2, and Il6. On the other hand, several anti-inflammatory mediators, such as Pgc1β and Socs1, were increased in BTEE-treated cells. Further, we performed an untargeted whole-genome microarray analysis to explore the anti-inflammatory molecular mechanism of BTEE. Enrichment analysis showed BTEE significantly downregulated ‘response to stimulus’, ‘locomotion’, and ‘immune system response’ and upregulated ‘cell cycle’ gene ontologies in both 6- and 17-h post-LPS stimulation conditions. Pathway analysis revealed BTEE could downregulate the expressions of chemokines of the CC and CXC subfamily, and cytokines of the TNF family, TGFβ family, IL1-like, and class I helical. PPI analysis showed AXL receptor tyrosine kinase (Axl), a receptor tyrosine kinase from the TAM family, and its upstream transcription factors were downregulated in both conditions. Node neighborhood analysis showed several Axl coexpressed genes were also downregulated. Further, kinase enrichment and chemical perturbation analyses supported Axl inhibition in BTEE-treated conditions. Altogether, these findings suggest anti-inflammatory effects of BTEE that are mediated via the suppression of pro-inflammatory cytokines and predict its potential as an Axl inhibitor.

Microalgae as a potential therapeutic drug candidate for neurodegenerative diseases

Microalgae are highly photosynthetic unicellular organism that have increased demand in the recent days owing to the presence of valuable cellular metabolites. They are ubiquitous in terrestrial and aquatic habitats, rich in species diversity and are capable of generating significant biomass by efficiently using CO₂, light and other nutrients like nitrogen, phosphate etc., The microalgal biomass has upsurged in economic potential and is used as both food and feed in many countries across the world, accounting for more than 75 % of annual microalgal biomass production in the past decades. The microalgal cells are sustainable resource that synthesize various secondary metabolites such as carotenoids, polysaccharides, polyphenols, essential amino acids, sterols, and polyunsaturated fatty acids (PUFA). Microalgae and its derived compounds possess significant pharmacological and biological effects such as antioxidant, anti-inflammatory, anti-cancer, immunomodulatory and anti-obesity. Because of their potential health promoting properties, the utilization of microalgae and its derived substances in food, pharmaceutical and cosmetic industries has skyrocketed in recent years. In this context, the current review discusses about the benefits of microalgae and its bioactive compounds against several neurodegenerative disorders like Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS).

Elucidation of the Potential Hair Growth-Promoting Effect of Botryococcus terribilis, Its Novel Compound Methylated-Meijicoccene, and C32 Botryococcene on Cultured Hair Follicle Dermal Papilla Cells Using DNA Microarray Gene Expression Analysis

A person’s quality of life can be adversely affected by hair loss. Microalgae are widely recognized for their abundance and rich functional components. Here, we evaluated the hair growth effect of a green alga, Botryococcus terribilis (B. terribilis), in vitro using hair follicle dermal papilla cells (HFDPCs). We isolated two types of cells from B. terribilis—green and orange cells, obtained from two different culture conditions. Microarray and real time-PCR results revealed that both cell types stimulated the expression of several pathways and genes associated with different aspect of the hair follicle cycle. Additionally, we demonstrated B. terribilis’ effect on collagen and keratin synthesis and inflammation reduction. We successfully isolated a novel compound, methylated-meijicoccene (me-meijicoccene), and C32 botryococcene from B. terribilis to validate their promising effects. Our study revealed that treatment with the two compounds had no cytotoxic effect on HFDPCs and significantly enhanced the gene expression levels of hair growth markers at low concentrations. Our study provides the first evidence of the underlying hair growth promoting effect of B. terribilis and its novel compound, me-meijicoccene, and C32 botryococcene.

Preventive effect of a Kampo medicine, kososan, on recurrent depression in a mouse model of repeated social defeat stress

Depression is deemed a mood disorder characterized by a high rate of relapse. Therefore, overcoming of the recurrent depression is globally expecting. Kososan, a traditional Japanese herbal medicine, has been clinically used for mild depressive mood, and our previous studies have shown some evidence for its antidepressive-like efficacy in experimental animal models of depression. However, it remains unclear whether kososan has beneficial effects on recurrent depression. Here, we examined its effect using a mouse model of modified repeated social defeat stress (SDS) paradigm. Male BALB/c mice were exposed to a 5-min SDS from unfamiliar aggressive CD-1 mice for 5 days. Kososan extract (1.0 kg/kg/day) or an antidepressant milnacipran (60 mg/kg/day) was administered orally for 26 days (days 7-32) to depression-like mice with social avoidant behaviors on day 6. Single 5 min of SDS was subjected to mice recovered from the social avoidance on day 31, and then the recurrence of depression-like behaviors was evaluated on day 32. Hippocampal gene expression patterns were also assayed by DNA microarray analysis. Water- or milnacipran-administered mice resulted in a recurrence of depression-like behaviors by re-exposure of single SDS, whereas kososan-administered mice did not recur depression-like behaviors. Distinct gene expression patterns were also found for treating kososan and milnacipran. Collectively, this finding suggests that kososan exerts a preventive effect on recurrent depression-like behaviors in mice. Pretreatment of kososan is more useful for recurrent depression than that of milnacipran.

Marine algae as emerging therapeutic alternatives for depression: A review

Depression is a complex heterogeneous brain disorder characterized by a range of symptoms, resulting in psychomotor and cognitive disabilities and suicidal thoughts. Its prevalence has reached an alarming level affecting millions of people globally. Despite advances in current pharmacological treatments, the heterogenicity of clinical response and incidences of adverse effects have shifted research focus to identification of new natural substances with minimal or no adverse effects as therapeutic alternatives. Marine algae-derived extracts and their constituents are considered potential sources of secondary metabolites with diverse beneficial effects. Marine algae with enormous health benefits are emerging as a natural source for discovering new alternative antidepressants. Its medicinal properties exhibited shielding efficacy against neuroinflammation, oxidative stress, and mitochondrial dysfunction, which are indicated to underlie the pathogenesis of many neurological disorders. Marine algae have been found to ameliorate depressive-like symptoms and behaviors in preclinical and clinical studies by restoring monoaminergic neurotransmission, hypothalamic-pituitary-adrenal axis function, neuroplasticity, and continuous neurogenesis in the dentate gyrus of the hippocampus via modulating brain-derived neurotrophic factors and antineuroinflammatory activity. Although antidepressant effects of marine algae have not been validated in comparison with currently available synthetic antidepressants, they have been reported to have effects on the pathophysiology of depression, thus suggesting their potential as novel antidepressants. In this review, we analyzed the currently available research on the potential benefits of marine algae on depression, including their effects on the pathophysiology of depression, potential clinical relevance of their antidepressant effects in preclinical and clinical studies, and the underlying mechanisms of these effects.

Physical Stress Induced Reduction of Proliferating Cells and Differentiated Neuroblasts Is Ameliorated by Fermented Laminaria japonica Extract Treatment

Laminaria japonica is widely cultivated in East Asia, including South Korea. Fucoidan, a main component of L. japonica, protects neurons from neurological disorders such as ischemia and traumatic brain injury. In the present study, we examined the effects of extract from fermented L. japonica on the reduction of proliferating cells and neuroblasts in mice that were physically (with electric food shock) or psychologically (with visual, auditory and olfactory sensation) stressed with the help of a communication box. Vehicle (distilled water) or fermented L. japonica extract (50 mg/kg) were orally administered to the mice once a day for 21 days. On the 19th day of the treatment, physical and psychological stress was induced by foot shock using a communication box and thereafter for three days. Plasma corticosterone levels were significantly increased after exposure to physical stress and decreased Ki67 positive proliferating cells and doublecortin immunoreactive neuroblasts. In addition, western blot analysis demonstrated that physical stress as well as psychological stress decreased the expression levels of brain-derived neurotrophic factor (BDNF) and the number of phosphorylated cAMP response element binding protein (pCREB) positive nuclei in the dentate gyrus. Fermentation of L. japonica extract significantly increased the contents of reduced sugar and phenolic compounds. Supplementation with fermented L. japonica extract significantly ameliorated the increases of plasma corticosterone revels and decline in the proliferating cells, neuroblasts, and expression of BDNF and pCREB in the physically stressed mice. These results indicate that fermented L. japonica extract has positive effects in ameliorating the physical stress induced reduction in neurogenesis by modulating BDNF and pCREB expression in the dentate gyrus.

Antihyperuricemic Effect of Urolithin A in Cultured Hepatocytes and Model Mice

Hyperuricemia is defined as a disease with high uric acid (UA) levels in the blood and a strong risk factor for gout. Urolithin A (UroA) is a main microbial metabolite derived from ellagic acid (EA), which occurs in strawberries and pomegranates. In this study, we evaluated antihyperuricemic effect of UroA in both cultured hepatocytes and hyperuricemic model mice. In cultured hepatocytes, UroA significantly and dose-dependently reduced UA production. In model mice with purine bodies-induced hyperuricemia, oral administration of UroA significantly inhibited the increase in plasma UA levels and hepatic xanthine oxidase (XO) activity. In addition, DNA microarray results exhibited that UroA, as well as allopurinol, a strong XO inhibitor, induced downregulation of the expression of genes associated with hepatic purine metabolism. Thus, hypouricemic effect of UroA could be, at least partly, attributed to inhibition of purine metabolism and UA production by suppressing XO activity in the liver. These results indicate UroA possesses a potent antihyperuricemic effect and it could be a potential candidate for a molecule capable of preventing and improving hyperuricemia and gout.

Antidepressant-Like Effect of Ferulic Acid via Promotion of Energy Metabolism Activity

SCOPE

Ferulic acid (FA), a natural phenolic phytochemical abundantly present in whole grains, herbs, and dried fruits, exhibits anti-inflammatory, antioxidant, and neuroprotective effects. In the present study, the antidepressant-like effects of FA in male ICR mice using tail suspension test (TST) are investigated and its molecular mechanisms are explored.

METHODS AND RESULTS

Oral administration of FA at a dose of 5 mg kg-1 for 7 days significantly reduces immobility of mice compared to vehicle-administered control group. Microarray and real-time PCR analyses reveal that FA upregulates the expression of several genes associated with cell survival and proliferation, energy metabolism, and dopamine synthesis in mice limbic system of brain. Interestingly, it is found that FA, unlike antidepressant drug bupropion, strongly promotes energy metabolism. Additionally, FA increases catecholamine (dopamine and noradrenaline), brain-derived neurotrophic factor, and ATP levels, and decreases glycogen levels in the limbic system of the mice brain.

CONCLUSION

The research provides the first evidence that FA enhances energy production, which can be the underlying mechanism of the antidepressant-like effects of FA observed in this study.

Modulation of the neurotransmitter systems through the anti-inflammatory and antidepressant-like effects of squalene from Aurantiochytrium sp

Although algae have been the focal point of biofuel research, studies on their biological activities have been limited. In recent years, however, the importance of algae as sources of functional ingredients has been recognized due to their health beneficial effects. In this study, we evaluated the antidepressant-like activities of ethanol extract of Aurantiochytrium sp. (EEA) in the forced swimming test (FST)-induced depression in ICR mice. Imipramine, a commercially available tricyclic antidepressant drug, was used as positive control. Animals were administered EEA orally for 14 consecutive days and were subjected to the locomotor activity testing. Additionally, changes in gene expression in mice brain were assessed by real-time PCR and microarray assays to understand the molecular mechanisms underlying the effect of EEA. We found that the immobility time in FST was significantly reduced in the EEA-treated mice compared to that of in the control mice. Microarray and real-time PCR results revealed that EEA treatment induced changes in several genes in mice brain associated with pro-inflammation and dopaminergic, cholinergic, glutamatergic, and serotonergic synapses. It has previously been reported that several cytokines, such as IL-6 and TNF-α, which mediate neuroinflammation, are also responsible for indirectly altering brain neurotransmitter levels in neuropsychiatric disorders. Therefore, the regulation of the expression of pro-inflammatory genes in EEA-administered mice brain is considered to contribute to the enhancement of neurotransmitter systems-related gene expression in our study. Moreover, our in vitro study suggested that squalene, a component produced by Aurantiochytrium, was one of the active substances in EEA. In conclusion, our study provides the first evidence that Aurantiochytrium sp. can reduce neuroinflammation that may contribute to the modulation of the neurotransmitter systems, which could underlie its antistress and antidepressant effects.

Anti-Inflammatory Effects of Aurantiochytrium limacinum 4W-1b Ethanol Extract on Murine Macrophage RAW264 Cells

Aurantiochytrium limacinum 4W-1b (AL4W-1b) is a newly discovered microalgal strain with unique features. In the present study, we investigated the effects of ethanol extracts of AL4W-1b on lipopolysaccharide- (LPS-) induced inflammatory responses in RAW264 murine macrophage cells. Pretreatment of RAW264 cells with the AL4W-1b extract significantly reduced the production of LPS-induced nitric oxide (NO) and the expression of proinflammatory cytokine genes, including tumor necrosis factor α, interleukin- (IL-) 1β, and IL-6. Treatment with the AL4W-1b extract also decreased the production of IL-1β and IL-6. These results suggest that AL4W-1b might have anti-inflammatory effects in RAW264 cells. The NF-κB inhibitor, BAY 11-7082, synergistically prevented LPS-induced NO production after pretreatment with the AL4W-1b extract. Thus, the AL4W-1b extract may affect not only the NF-κB pathway but also other inflammatory pathways. To the best of our knowledge, this is the first study to report the anti-inflammatory effects of AL4W-1b extract and its mechanism of action in LPS-stimulated murine macrophage cells.