Tackling the Cytotoxic Effect of a Marine Polycyclic Quinone-Type Metabolite: Halenaquinone Induces Molt 4 Cells Apoptosis via Oxidative Stress Combined with the Inhibition of HDAC and Topoisomerase Activities

A marine polycyclic quinone-type metabolite, halenaquinone (HQ), was found to inhibit the proliferation of Molt 4, K562, MDA-MB-231 and DLD-1 cancer cell lines, with IC₅₀ of 0.48, 0.18, 8.0 and 6.76 μg/mL, respectively. It exhibited the most potent activity against leukemia Molt 4 cells. Accumulating evidence showed that HQ may act as a potent protein kinase inhibitor in cancer therapy. To fully understand the mechanism of HQ, we further explored the precise molecular targets in leukemia Molt 4 cells. We found that the use of HQ increased apoptosis by 26.23%–70.27% and caused disruption of mitochondrial membrane potential (MMP) by 17.15%–53.25% in a dose-dependent manner, as demonstrated by Annexin-V/PI and JC-1 staining assays, respectively. Moreover, our findings indicated that the pretreatment of Molt 4 cells with N-acetyl-l-cysteine (NAC), a reactive oxygen species (ROS) scavenger, diminished MMP disruption and apoptosis induced by HQ, suggesting that ROS overproduction plays a crucial rule in the cytotoxic activity of HQ. The results of a cell-free system assay indicated that HQ could act as an HDAC and topoisomerase catalytic inhibitor through the inhibition of pan-HDAC and topoisomerase IIα expression, respectively. On the protein level, the expression of the anti-apoptotic proteins p-Akt, NFκB, HDAC and Bcl-2, as well as hexokinase II was inhibited by the use of HQ. On the other hand, the expression of the pro-apoptotic protein Bax, PARP cleavage, caspase activation and cytochrome c release were increased after HQ treatment. Taken together, our results suggested that the antileukemic effect of HQ is ROS-mediated mitochondrial apoptosis combined with the inhibitory effect on HDAC and topoisomerase activities.     

The Protection of Polysaccharide from the Brown Seaweed Sargassum graminifolium against Ethylene Glycol-Induced Mitochondrial Damage

The aim of the present study is to evaluate the protective effect of polysaccharide from the Brown Seaweed Sargassum graminifolium (SGP) on ethylene glycol-induced kidney damage and the mechanism of SGP-mediated protection. Mitochondrial lipid peroxidation, mitochondrial swelling, the activity of succinate dehydrogenase (SDH), ATPases and mitochondrial antioxidant enzymes was observed in hyperoxaluric rats. Administration of SGP (25, 100 and 400 mg·kg⁻¹, intragastrically) increased the activities of antioxidant enzymes, SDH and Na⁺/K⁺-ATPases, Ca²⁺-ATPases, Mg²⁺-ATPases, also decreased mitochondrial lipid peroxidation and mitochondrial swelling. SGP exhibited a protective effect by improving antioxidant enzymes and restoring mitochondrial dysfunction in the kidney of hyperoxaluric rats. It may be used as a promising therapeutic agent to provide superior renal protection.     

纸片型1-MCP处理对采后安溪油柿果实活性氧代谢和细胞膜 透性的影响

研究了纸片型 1-甲基环丙烯（1-MCP）处理对采后安溪油柿果实活性氧代谢和细胞膜透性的影响。采后安溪 油柿果实经 1.35 μL/L 纸片型 1-MCP 处理 12 h 后,在(20±1) ℃、相对湿度 85%条件下贮藏。结果表明,与对照果实相 比,纸片型 1-MCP 处理能有效提高采后安溪油柿果实的超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT） 和抗坏血酸过氧化物酶（APX）等活性氧清除酶活性,保持较高的还原型抗坏血酸（AsA）和还原型谷胱甘肽（GSH） 等内源抗氧化物质的含量;降低超氧阴离子自由基（O2 ? ? ）产生速率和膜脂过氧化产物丙二醛（MDA）含量的积累;延 缓采后安溪油柿果实细胞膜透性增加。因此,1.35 μL/L 纸片型 1-MCP 处理能有效提高采后安溪油柿果实的活性氧清除 能力,降低活性氧积累和抑制膜脂过氧化作用,从而延缓采后安溪油柿果实衰老,延长果实保鲜期。     

Evaluation of antioxidant activities of the edible and medicinal Suaeda species and related phenolic compounds

Antioxidants are the chemical substances that reduce or prevent oxidation. The present study aimed to assess in vitro and ex vivo antioxidant activities of four acetonic extracts Tunisian halophytes (Suaeda fruticosa, Suaeda pruinosa, Suaeda mollis and Suaeda maritima). Various experimental models were used for characterization of antioxidant activities of shoot extracts. Eventually, the promising specie was subjected to phenolic identification using RP-HPLC. The analyzed shoot extracts exhibited that antioxidant activities varied considerably as function of species. The highest DPPH scavenging ability was found in S. mollis with the lowest IC₅₀ value (2.5 μg/ml), followed by S. pruinosa, S. fruticosa and S. maritima. The same tendency was observed with ferric reducing power. Concerning β-carotene bleaching assays and total antioxidant activity, results showed that S. fruticosa exhibited the highest antioxidant ability against the inhibition of β-carotene bleaching, and a better total antioxidant capacity. Moreover antioxidant capacities using ORAC method and a cell based-assay showed that S. mollis, S. fruticosa, and S. pruinosa exhibit statistically similar antioxidant activity. The identification of phenolic compounds in S. mollis extract using RP-HPLC revealed that 2,5-dihydroxybenzoic acid and rutin hydrate were the major molecules. These results suggested that Suaeda species showed a variability of their antioxidant activities.