Wen-Guang Li

Amelioration of doxorubicin-induced myocardial oxidative stress and immunosuppression by grape seed proanthocyanidins in tumour-bearing mice.

We have investigated the protective effects of grape seed proanthocyanidins on doxorubicin‐induced toxicity in tumour‐bearing mice. The intraperitoneal administration of doxorubicin (2 mg kg−1 every other day, cumulative dosage for 18 mg kg−1) significantly inhibited the growth of sarcoma 180, and induced myocardial oxidative stress with decreased superoxide dismutase and glutathione peroxidase activity while increasing malondialdehyde formation in the heart or serum. Doxorubicin‐induced myocardial oxidative stress also reduced lactate dehydrogenase and creatine kinase activity in the heart and elevated their levels in the serum. Doxorubicin also affected immune functions of tumour‐bearing mice with significantly decreased interleukin‐2 (IL‐2) and interferon‐γ (INF‐γ) production, and slightly decreased natural killer (NK) cell cytotoxicity, lymphocyte proliferation and CD4+/CD8+ ratio. It markedly increased the percentages of cytotoxic T cells (CD3+CD8+), helper T cells (CD3+CD4+), IL‐2R+CD4+, and IL‐2R+ cells as compared with untreated tumour‐bearing mice. The intragastric administration of proanthocyanidin (200 mg kg−1 daily) significantly inhibited tumour growth, and increased NK cell cytotoxicity, lymphocyte proliferation, CD4+/CD8+ ratio, IL‐2 and INF‐γ production. Moreover, proanthocyanidin strongly enhanced the anti‐tumour effect of doxorubicin and the above immune responses, and completely eliminated myocardial oxidative stress induced by doxorubicin. In conclusion, intragastric administration of proanthocyanidin could enhance the anti‐tumour activity of doxorubicin and ameliorate doxorubicin‐induced myocardial oxidative stress and immunosuppression in tumour‐bearing mice.

Natural Antioxidant-Isoliquiritigenin Ameliorates Contractile Dysfunction of Hypoxic Cardiomyocytes via AMPK Signaling Pathway

Isoliquiritigenin (ISL), a simple chalcone-type flavonoid, is derived from licorice compounds and is mainly present in foods, beverages, and tobacco. Reactive oxygen species (ROS) is a critical factor involved in modulating cardiac stress response signaling during ischemia and reperfusion. We hypothesize that ISL as a natural antioxidant may protect heart against ischemic injury via modulating cellular redox status and regulating cardioprotective signaling pathways. The fluorescent probe H2DCFDA was used to measure the level of intracellular ROS. The glucose uptake was determined by 2-deoxy-D-glucose-3H accumulation. The IonOptix System measured the contractile function of isolated cardiomyocytes. The results demonstrated that ISL treatment markedly ameliorated cardiomyocytes contractile dysfunction caused by hypoxia. ISL significantly stimulated cardioprotective signaling, AMP-activated protein kinase (AMPK), and extracellular signal-regulated kinase (ERK) signaling pathways. The ROS fluorescent probe H2DCFDA determination indicated that ISL significantly reduced cardiac ROS level during hypoxia/reoxygenation. Moreover, ISL reduced the mitochondrial potential (Δψ) of isolated mouse cardiomyocytes. Taken together, ISL as a natural antioxidant demonstrated the cardioprotection against ischemic injury that may attribute to the activation of AMPK and ERK signaling pathways and balance of cellular redox status.

The relationship between structure and antioxidative activity of piperidine nitroxides

We have investigated the relationship between structure and antioxidative activity of piperidine nitroxides which were substituted by different groups at the 4‐position. All of the tested piperidine nitroxides inhibited malondialdehyde (MDA) generation caused either spontaneously or by a hydroxyl free radical generation system (Fe2+‐ascorbic acid) in homogenates of liver, heart and kidney of rats, and antagonized H2O2‐induced haemolysis from rat erythrocytes in a concentration‐dependent manner. The same rank was followed: Bis‐(4‐amino‐2,2,6,6‐tetramethyl piperidinooxyl) (4‐BIS‐Tempo) and 4‐azido‐2,2,6,6‐tetramethyl piperidinooxyl (4‐N3‐Tempo) >4‐isothiocyanate‐2,2,6,6‐tetramethyl piperidinooxyl (4‐ISO‐Tempo), 4‐2′,4′‐dinitrophenyl‐hydrazone‐2,2,6,6‐tetramethyl piperidinooxyl (4‐D‐Tempo), 4‐sulfonate‐2,2,6,6‐tetramethyl piperidinooxyl (4‐S‐Tempo) and 4‐amino‐2,2,6,6‐tetramethyl piperidinooxyl (4‐NH2‐Tempo) > 4‐acetate ester‐2,2,6,6‐tetramethyl piperidinooxyl (4‐A‐Tempo) and 4‐benzoate‐2,2,6,6‐tetra‐methyl piperidinooxyl (4‐B‐Tempo). With the exception of 4‐A‐Tempo and 4‐D‐Tempo, the tested piperidine nitroxides inhibited superoxide anion (O2.‐) release from neutrophils stimulated by zymosan. The concentration required for inhibiting O2.‐ release was higher than that of inhibiting MDA formation and haemolysis. However, 4‐amino‐2,2,6,6‐tetramethyl piperidine (4‐NH2‐TempH) and other 4‐position substitutes, such as NaN3 and isothiocyanate, had no effects on MDA formation, haemolysis or O2.‐ release. The results indicated that nitroxides have a wide range of scavenging reactive oxygen species (ROS) actions. The nitroxide moiety was the essential group while the 4‐position substitutes could influence the activity of nitroxides on scavenging ROS.

Preclinical safety evaluation of IFNα2a-NGR

IFNalpha2a-NGR is an antitumor agent of bacterial origin. The report presents the preclinical toxicity studies with IFNalpha2a-NGR in mice, rats and monkeys. The single-dose toxicity study showed no effect on general signs, body weight, food consumption, ophthalmology, hematology and clinical chemistry and necropsy analysis. In repeated-dose toxicity studies, increase in HB was noted both in rat and monkey, showed that IFNalpha2a-NGR may not cause the suppression of hematopoiesis. Decrease in AST, A/G, GLU, T-Bil in rat and AST, TP, GLO in monkey were noted, accompanied by increase in TP and GLB in rat and BUN in monkey. All the clinical chemistry changes were mild, reversible and considered to be incidental, since no related abnormal parameters or results were found. Increase in spleen and thymus organ-to-body weight ratios and decrease in menses were mild, reversible and likely related to pharmacology activity of IFNalpha2a. Ames, chromosomal aberration and bone marrow micronulecus test were conducted and the results were negative. The degree of irritation caused by various concentration of IFNalpha2a-NGR was determined to be the same as that induced by normal saline. In conclusion, preclinical safety studies that IFNalpha2a-NGR was well tolerated at pharmacologically active doses in mice, rats and monkeys.

Anti-osteosarcoma Effects and Mechanisms of 4-o-amino-phenol-4＇ - demethylepipodophyllotoxin Ether

The purpose of this study was to investigate the anti‐osteosarcoma effects and mechanisms of 4‐O‐amino‐phenol‐4′‐demethylepipodophyllotoxin ether (ODE), a new derivative of podophyllotoxin. The results showed that ODE inhibited proliferation of K562, OS‐9901, CNE, BGC‐823 and Tca‐8113 cells in a time‐ and concentration‐dependent manner as determined by microculture tetrazolium (MTT) assay. OS‐9901 and K562 cells treated with ODE for 24h showed cell cycle arrest at G2/M and a parallel decrease in G0/G1 and S phase as detected by flow cytometry (FCM). Meanwhile, a fraction of cells with hypodiploid DNA content representing apoptosis were detected by FCM. Morphology observation also revealed typical apoptotic features, including shrinkage of cellular and nuclear membranes, condensed heterochromatin around the nuclear periphery and cytoplasmic vacuolation in OS‐9901 cells. Under a confocal laser scanning microscope, intracellular Ca2+ and Mg2+ concentrations were greatly increased whereas the pH value, mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) were markedly reduced in OS‐9901 cells after treatment with ODE. Taken together, these results suggest that the anti‐osteosarcoma mechanisms of ODE are attributed to apoptosis through increasing intracellular Ca2+ and Mg2+ concentrations, and reducing pH value, MMP and ROS.