Search

Walnut oil (WO) is widely used in traditional medicine, and it has become a dietary supplement in many countries. We isolated walnut oil from Juglans sigillata and evaluated its protective effects on acute intestinal injury, and Toll‐like receptor 4 (TLR4)/nuclear factor‐κB (NF‐κB) signaling pathway in lipopolysaccharide (LPS)‐induced mice was studied. The results showed that the LPS + WO group significantly decreased serum tumor necrosis factor‐α (TNF‐α), interleukin‐6 (IL‐6), and IL‐1β levels and increased the jejunum superoxide dismutase (SOD) and glutathione peroxidase (GSH‐Px) levels compared with the LPS group. Walnut oil ameliorated the pathological morphology of the LPS‐induced acute jejunum injury and decreased jejunum cells apoptosis rate and TLR4/NF‐κB protein expression. Furthermore, the expression of the TLR4/NF‐κB pathway key gene mRNA significantly reduced after treatment with walnut oil. This study concludes that walnut oil can exert the protective effect on LPS‐induced acute intestinal injury in mice by inhibiting the TLR4/NF‐κB signaling pathway., Walnut oil ameliorated the pathological morphology of the LPS‐induced acute jejunum injury and decreased jejunum cells apoptosis rate and TLR4/NF‐κB protein expression. Walnut oil can exert the protective effect on LPS‐induced acute intestinal injury in mice by inhibiting the TLR4/NF‐κB signaling pathway.

In this study, it was found that fulvic acid (FA) enhanced the contents of astaxanthin and lipids in Haematococcus pluvialis under high light and nitrogen starvation conditions by 2- and 1.2-fold, respectively. Meanwhile, the carbohydrate and chlorophyll contents were decreased by FA induction, whereas the levels of reactive oxygen species (ROS) and glutathione (GSH) as well as the expression of astaxanthin and lipid biosynthetic genes were increased. To further explore the interrelation between FA and the biosynthesis of astaxanthin and lipids, a metabolomics analysis of H. pluvialis by combined FA and abiotic stress exposure was conducted by using LC-MS/MS. The contents of some cytoprotective metabolites and signal molecules, including d-maltose, succinate, malic acid, melatonin (MT), and some amino acids, were increased under FA induction and abiotic stress conditions. These metabolites are intermediates in the TCA cycle and Calvin cycle, providing more precursors for the synthesis of astaxanthin and lipids. Moreover, the signal molecules might contribute to enhancing the abiotic stress tolerance. This study provided new insights into the regulatory mechanism of FA on astaxanthin and lipid accumulation in H. pluvialis.

Ulcerative colitis (UC) has become a global disease and closely related to changes in intestinal oxidative stress, inflammatory factors and gut microbiota. Furthermore, the NLRP3 inflammasome activation is a key cause in the pathogenesis of dextran sulfate sodium (DSS)-induced colitis. Recent data showed the potential antioxidative and anti-inflammatory advantage of walnut oil, which widely used in traditional medicine and has become a dietary supplement for some patients. Therefore, we investigated whether walnut oil exerts an anti-inflammatory effect on DSS-induced colitis mice by targeting NLRP3 inflammasome and gut microbiota. Our data showed that walnut oil ameliorated the pathological morphology, decreased the reactive oxygen species (ROS) production and pro-inflammatory cytokines release, down-regulated the related gene proteins expression of NLRP3/ASC/Caspase-1 inflammatory pathway, inhibited apoptosis, shifted from more pathogens towards probiotics, and increased the levels of short-chain fatty acids (SCFAs) in DSS-induced damaging process. Collectively, our study concludes that walnut oil exerts anti-inflammatory effect on DSS-induced colitis in mice by inhibiting the NLRP3 inflammasome activation and modulating gut microbiota, and may be a prominent functional food candidate for UC treatment.

The effects of γ-aminobutyric acid (GABA) on the biomass and astaxanthin and lipids production in Haematococcus pluvialis under combined salinity stress and high-light stresses were investigated. The results showed that the highest biomass (1.65 g L−1), astaxanthin production (3.86 mg L−1 d−1) and lipids content (55.11%) in H. pluvialis LUGU were observed under the 0.25 mM GABA treatment. Moreover, compared with salinity and high-light stress, GABA treatment also increased the transcript levels of biosynthesis genes, the contents of endogenous GABA and carbohydrates but decreased reactive oxygen species (ROS) levels. Further evidence revealed that intracellular GABA could regulate cell growth, astaxanthin production and lipids synthesis by mediating carotenogenesis, lipogenesis and ROS signalling. Collectively, this study provides a combined strategy for promoting the coproduction of astaxanthin and lipids and sheds light on the regulatory mechanism through which GABA affects cell growth, astaxanthin production and lipids biosynthesis in H. pluvialis under unfavourable conditions.

In the present study, the effects of four different culture media on the growth, astaxanthin production and morphology of Haematococcus pluvialis LUGU were studied under two-step cultivation. The interactions between astaxanthin synthesis and secondary messengers, reactive oxygen species (ROS) and mitogen-activated protein kinases (MAPK) were also investigated. In the first green vegetative cell stage, maximal biomass productivity (86.54 mg L−1 day−1) was obtained in BBM medium. In the induction stage, the highest astaxanthin content (21.5 mg g−1) occurred in BG-11 medium, which was higher than in any other media. The expressions of MAPK and astaxanthin biosynthetic genes in BG-11 were higher than in any other media, whereas the ROS content was lower. Biochemical and physiological analyses suggested that the ROS, MAPK and astaxanthin biosynthetic gene expression was involved in astaxanthin biosynthesis in H. pluvialis under different culture media conditions. This study proposes a two-step cultivation strategy to efficiently produce astaxanthin using microalgae.

In this study, it was found that fulvic acid (FA) enhanced the contents of astaxanthin and lipids in

The major goal of this study was to explore the functions of butylated hydroxyanisole (BHA) combined with abiotic stress on the cultivation of the microalga Haematococcus pluvialis for astaxanthin and lipid production. Here, the effect of BHA on astaxanthin and lipid accumulation and physiological and metabolomic profiles was investigated. These results suggested that astaxanthin content was increased by 2.17-fold compared to the control. The lipid content was enhanced by 1.22-fold. BHA treatment simultaneously reduced carbohydrates and protein and delayed the decay of chlorophyll. Furthermore, metabolomic analysis demonstrated that BHA upregulated and activated the bioprocesses involved in cellular basal metabolism and signalling systems, such as glycolysis, the TCA cycle, amino acid metabolism and the phosphatidylinositol signalling system, thus enhancing astaxanthin and lipid accumulation. Altogether, this research shows the dramatic effects of BHA on algal metabolism in the regulation of key metabolic nodes and provides novel insights into microalgal regulation and metabolism.

The current study examined the effect of walnut shell extracts (WSE) on simultaneous astaxanthin and lipid production by Haematococcus pluvialis under abiotic stress. After supplementation with 15% WSE, the contents of astaxanthin and lipids were enhanced by 77.57% and 23.39%, respectively, compared with the control. The chlorophyll, carbohydrate and protein contents decreased, and the transcription levels of carotenogenic and lipogenic genes, as well as the levels of the reactive oxygen species (ROS), glutathione (GSH) and light‑oxygen-voltage histidine kinase (LOV-HK), all increased. Further investigation showed that LOV-HK regulated astaxanthin and lipid biosynthesis by mediating carotenogenesis, lipogenesis and ROS signalling. Overall, the present study demonstrated that microalgae cultivation coupled with walnut shell recycling is an effective strategy for hyper-accumulation of astaxanthin and lipids and that there is a pivotal interaction between LOV-HK and ROS in WSE-induced regulation of astaxanthin and lipid synthesis in H. pluvialis.

The effect of melatonin (MT) on the coproduction of astaxanthin and lipids was studied in Haematococcus pluvialis under inductive stress conditions. The contents of astaxanthin and lipids were enhanced by 1.78- and 1.3-fold, respectively. MT treatment upregulated the transcription levels of carotenogenic, lipogenic and antioxidant system-related genes and decreased the levels of abiotic stress-induced reactive oxidative species (ROS). Further metabolomic analysis suggested that the intermediates in glycolysis and TCA cycle facilitate the accumulation of astaxanthin and lipids in algae treated with MT. Meanwhile, MT treatment upregulated the metabolite levels of the γ-aminobutyric acid (GABA) shunt, which might regulate the carbon-nitrogen balance and the antioxidant system. After MT treatment, exogenous linoleic acid, succinate, and GABA further increased the astaxanthin content. This study may help to elucidate the specific responses to MT induction in H. pluvialis and to identify novel biomarkers that may be employed to further promote astaxanthin and lipids coproduction.

To utilize waste walnut shells and to enhance the production of biomass and lipid by microalgae, cultivation of Monoraphidium sp. QLZ-3 in a photobioreactor under different proportions of walnut shell extracts (WSE) was investigated. The highest biomass productivity (534.7 mg L−1 d−1) and lipid content (55.42%) were obtained using 40% WSE as part of the growth medium. Meanwhile, application of WSE increased the protein content and nutrient removal efficiency and upregulated the transcription levels of lipid biosynthetic genes but decreased the carbohydrate and γ-aminobutyric acid (GABA) contents. WSE also increased the levels of reactive oxygen species (ROS) and glutathione (GSH). After supplementation of WSE, further evidence indicated that GABA could further promote biomass, lipid and GABA accumulation by regulating ROS signalling and increase the levels of lipogenic gene expression and GSH. The systemic GABA content was 24.22 mg g−1. Collectively, the cultivation of microalgae in WSE has great feasibility for biofuel and GABA production and solid waste treatment, and the present study provides insights into the regulatory mechanism of cytosolic GABA in the modulation of cell growth, lipid synthesis and oxidative stress in QLZ-3 by the addition of WSE.