The Cytoprotective Effect of Petalonia binghamiae Methanol Extract against Oxidative Stress in C2C12 Myoblasts: Mediation by Upregulation of Heme Oxygenase-1 and Nuclear Factor-Erythroid 2 Related Factor 2

This study was designed to examine the protective effects of the marine brown algae Petalonia binghamiae against oxidative stress-induced cellular damage and to elucidate the underlying mechanisms. P. binghamiae methanol extract (PBME) prevented hydrogen peroxide (H₂O₂)-induced growth inhibition and exhibited scavenging activity against intracellular reactive oxygen species (ROS) induced by H₂O₂ in mouse-derived C2C12 myoblasts. PBME also significantly attenuated H₂O₂-induced comet tail formation in a comet assay, histone γH2A.X phosphorylation, and annexin V-positive cells, suggesting that PBME prevented H₂O₂-induced cellular DNA damage and apoptotic cell death. Furthermore, PBME increased the levels of heme oxygenase-1 (HO-1), a potent antioxidant enzyme, associated with the induction of nuclear factor-erythroid 2 related factor 2 (Nrf2). However, zinc protoporphyrin IX, a HO-1 competitive inhibitor, significantly abolished the protective effects of PBME on H₂O₂-induced ROS generation, growth inhibition, and apoptosis. Collectively, these results demonstrate that PBME augments the antioxidant defense capacity through activation of the Nrf2/HO-1 pathway.     

Two Novel Hepatocellular Carcinoma Cycle Inhibitory Cyclodepsipeptides from a Hydrothermal Vent Crab-Associated Fungus Aspergillus clavatus C2WU

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.     

Induction of Apoptosis, G0/G1 Phase Arrest and Microtubule Disassembly in K562 Leukemia Cells by Mere15, a Novel Polypeptide from Meretrix meretrix Linnaeus

Mere15 is a novel polypeptide from Meretrix meretrix Linnaeus with cytotoxicity in solid cancer cells. In this study, we investigated its activity on human K562 chronic myelogenous leukemia cells. Mere15 inhibited the growth of K562 cells with IC₅₀ values of 38.2 μg/mL. Mere15 also caused concentration dependent induction of apoptosis, with overproduction of reactive oxygen species and loss of mitochondrial membrane potential. Moreover, Mere15 arrested cell cycle progression at G₀/G₁ phase of K562 cells in a concentration dependent manner. In addition, Mere15 caused the disassembly of the microtubule cytoskeleton in K562 cells and inhibited the polymerization of tubulin in a cell free system via interaction with tubulin. We concluded that Mere15 was cytotoxic to K562 leukemia cells and the cytotoxicity was related to the apoptosis induction, cell cycle arrest and microtubule disassembly. These results implied that Merer15 was a broad spectrum anticancer polypeptide, not only cytotoxic to various solid cancer cells but also to the chronic myelogenous leukemia cells. Mere15 may have therapeutic potential for the treatment of leukemia.     

Inhibitory Effect of N,N-Didesmethylgrossularine-1 on Inflammatory Cytokine Production in Lipopolysaccharide-Stimulated RAW 264.7 Cells

N,N-Didesmethylgrossularine-1 (DDMG-1), a compound with a rare α-carboline structure, was isolated from an Indonesian ascidian Polycarpa aurata as responsible for the observed inhibitory activity against TNF-α production in lipopolysaccharide-stimulated murine macrophage-like RAW264.7 cells. DDMG-1 inhibited the mRNA level of mTNF-α, IκB-α degradation, and binding of NF-κB to the target DNA site in LPS-stimulated RAW 264.7 cells. Moreover, DDMG-1 had an inhibitory effect on the production of IL-8, which is produced in CD14⁺-THP-1 cells stimulated by LPS. DDMG-1 is thus a promising drug candidate lead compound for the treatment of chronic inflammatory diseases, such as rheumatoid arthritis.     

The Anti-Inflammatory Effect of Algae-Derived Lipid Extracts on Lipopolysaccharide (LPS)-Stimulated Human THP-1 Macrophages

Algae contain a number of anti-inflammatory bioactive compounds such as omega-3 polyunsaturated fatty acids (n-3 PUFA) and chlorophyll a, hence as dietary ingredients, their extracts may be effective in chronic inflammation-linked metabolic diseases such as cardiovascular disease. In this study, anti-inflammatory potential of lipid extracts from three red seaweeds (Porphyra dioica, Palmaria palmata and Chondrus crispus) and one microalga (Pavlova lutheri) were assessed in lipopolysaccharide (LPS)-stimulated human THP-1 macrophages. Extracts contained 34%–42% total fatty acids as n-3 PUFA and 5%–7% crude extract as pigments, including chlorophyll a, β-carotene and fucoxanthin. Pretreatment of the THP-1 cells with lipid extract from P. palmata inhibited production of the pro-inflammatory cytokines interleukin (IL)-6 (p < 0.05) and IL-8 (p < 0.05) while that of P. lutheri inhibited IL-6 (p < 0.01) production. Quantitative gene expression analysis of a panel of 92 genes linked to inflammatory signaling pathway revealed down-regulation of the expression of 14 pro-inflammatory genes (TLR1, TLR2, TLR4, TLR8, TRAF5, TRAF6, TNFSF18, IL6R, IL23, CCR1, CCR4, CCL17, STAT3, MAP3K1) by the lipid extracts. The lipid extracts effectively inhibited the LPS-induced pro-inflammatory signaling pathways mediated via toll-like receptors, chemokines and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling molecules. These results suggest that lipid extracts from P. lutheri, P. palmata, P. dioica and C. crispus can inhibit LPS-induced inflammatory pathways in human macrophages. Therefore, algal lipid extracts should be further explored as anti-inflammatory ingredients for chronic inflammation-linked metabolic diseases.     

Enzyme-Assisted Extraction of Bioactive Material from Chondrus crispus and Codium fragile and Its Effect on Herpes simplex Virus (HSV-1)

Codium fragile and Chondrus crispus are, respectively, green and red seaweeds which are abundant along the North Atlantic coasts. We investigated the chemical composition and antiviral activity of enzymatic extracts of C. fragile (CF) and C. crispus (CC). On a dry weight basis, CF consisted of 11% protein, 31% neutral sugars, 0.8% sulfate, 0.6% uronic acids, and 49% ash, while CC contained 27% protein, 28% neutral sugars, 17% sulfate, 1.8% uronic acids, and 25% ash. Enzyme-assisted hydrolysis improved the extraction efficiency of bioactive materials. Commercial proteases and carbohydrases significantly improved (p ≤ 0.001) biomass yield (40%–70% dry matter) as compared to aqueous extraction (20%–25% dry matter). Moreover, enzymatic hydrolysis enhanced the recovery of protein, neutral sugars, uronic acids, and sulfates. The enzymatic hydrolysates exhibited significant activity against Herpes simplex virus (HSV-1) with EC₅₀ of 77.6–126.8 μg/mL for CC and 36.5–41.3 μg/mL for CF, at a multiplicity of infection (MOI) of 0.001 ID₅₀/cells without cytotoxity (1–200 μg/mL). The extracts obtained from proteases (P1) and carbohydrases (C3) were also effective at higher virus MOI of 0.01 ID₅₀/cells without cytotoxity. Taken together, these results indicate the potential application of enzymatic hydrolysates of C. fragile and C. crispus in functional food and antiviral drug discovery.     

Effect of salinity on yield and 2-acetyl-1-pyrroline content in the grains of three fragrant rice cultivars (Oryza sativa L.) in Camargue (France)

Aromatic quality of rice grains is known to vary greatly with environmental factors and cultivation methods. Among the environmental factors, soil salinity is thought to have a positive impact on the content of 2-acetyl-1-pyrroline (2AP) in grains, the key volatile compound of rice aroma. This study compared 2AP content in grains of three improved fragrant rice (Oryza sativa L.) varieties grown in two fields, differing mainly in their soil salinity level. The impact of salinity on yield and main yield components was also investigated to understand the relationship between aromatic quality and yield build-up. Soil salinity was monitored by measuring the electrical conductivity (EC) of soil solution samples extracted every week. 2AP content in grains was determined by a newly developed stable isotope dilution method involving solid-phase microextraction (SPME) and GC MS/MS analysis. The results showed an increase of 2AP content in grains with salinity for the three varieties. The relationship between 2AP and mean EC of the crop fitted a single model for the three varieties (R² = 0.728). In contrast, the impact of salinity on yield and yield components differed greatly between the three varieties. One variety appeared to be very sensitive to salt stress, with significant yield loss up to 40%, while the two other varieties proved to be resistant to the salinity levels experienced by the plants, with no significant yield loss or even higher yields in saline conditions. Nevertheless, the three varieties presented a significant negative correlation between 1000 grain weight (TGW) and the mean EC of the crop, and between TGW and 2AP content. It was concluded that the increase of 2AP content with salinity resulted partially from a 2AP concentration mechanism in smaller size grains. The direct effect of salinity on 2AP synthesis through stimulation of the proline metabolism is further discussed.