Superoxide dismutase (SOD) activity with Fe-chlorin e6-Na and suppression of malignant tumor growth in rats

Efficacy of SXN in the Treatment of Iron Deficiency Anemia: A Phase IV Clinical Trial

Shengxuening (SXN) tablet is extracted from the excrement of the silkworm and has effects on hematopoiesis. The main components of SXN are chlorophyll derivatives and sodium iron chlorophyllin (SIC). The present study aims to investigate the efficiency and safety of SXN on iron deficiency anemia. This phase IV, multicenter, open-label, randomized clinical trial was conducted in 31 hospitals in China from June 2001 to April 2002. Adults and children were randomly divided into low-dose (L-SXN), medium-dose (M-SXN), and high-dose (H-SXN) groups, respectively. The course of treatment was 1 month. Peripheral hemogram levels and iron status were examined before and after treatment. Adults in all three dose groups demonstrated a significant increase in hemoglobin (HGB) concentration. Children who received SXN treatment in medium and high doses also demonstrated increased HGB concentration. Reticulocyte counts increased at the end of treatment in the M-SXN and H-SXN adult groups and in the M-SXN child group. For both children and adults, SXN in the three dose groups was found to significantly elevate red blood cell level, mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration. The total effective rate in the SXN-treated group reached 84.8%. The incidence of adverse events was 4.07%. The most common side effects were nausea (2.83%), diarrhea (0.74%), and rash (0.25%). SXN was proved to be efficient and safe for adults and children with iron deficiency anemia.

Elevated basal reactive oxygen species and phospho-Akt in murine keratinocytes resistant to ultraviolet B-induced apoptosis

Resistance to apoptosis may be a critical phenotype that cells must acquire during skin carcinogenesis. The Akt kinase is a known upstream regulator of apoptosis in many cell types and has been shown to be activated by increased reactive oxygen species (ROS). We have previously demonstrated that two malignant variants (6M90 and 6R90) of the mouse keratinocyte 308 cell line have elevated ROS because of loss of catalase activity, and that this elevated ROS confers a growth advantage. We report here that in addition to a growth advantage, chronically increased ROS in the variants resulted in an increase in resistance to ultraviolet (UV) B-induced apoptosis. This resistance was due to basal increases of Akt phosphorylation in the malignant variants compared to the 308 cells. Modulation of ROS in 6M90 and 6R90 cells by catalase overexpression or antioxidant treatment resulted in decreased levels of Akt phosphorylation and subsequent loss of resistance to UVB-induced apoptosis. Conversely, treatment of 308 cells with hydrogen peroxide caused increases in Akt phosphorylation and increased apoptosis resistance. These results indicate that the chronically elevated ROS often observed in tumors may contribute to a malignant phenotype by keeping Akt in a phosphorylated state, resulting in increased apoptosis resistance.

Iron chlorin e6 scavenges hydroxyl radical and protects human endothelial cells against hydrogen peroxide toxicity

Iron chlorin e6 (FeCe6) has recently been proposed to be potentially antimutagenic and antioxidative. However, the antioxidant property of FeCe6 has not been elucidated in detail. In this study, we investigated the ability of FeCe6 to scavenge hydroxyl radical and to protect biomolecules and mammalian cells from oxidative stress-mediated damage. In electron spin resonance (ESR) experiments, FeCe6 showed excellent hydroxyl radical scavenging activity, whereas its iron-deficient molecule, chlorin e6 (Ce6) showed little effect. FeCe6 also significantly reduced hydroxyl radical-induced thiobarbituric acid reactive substance (TBARS) formation and benzoate hydroxylation in a dose-dependent manner. The rate constant for reaction between FeCe6 and hydroxyl radical was measured as 8.5 x 10(10) M(-1) s(-1) by deoxyribose degradation method, and this value was much higher than that of most hydroxyl radical scavengers. Superoxide dismutase (SOD) activity of FeCe6 was also confirmed by ESR study and cytochrome c reduction assay, but its in vitro activity appeared to be less efficient in comparison with other well-known SOD mimics. In addition, FeCe6 appreciably diminished hydroxyl radical-induced DNA single-strand breakage and protein degradation in Fe-catalyzed and Cu-catalyzed Fenton systems, and it significantly protected human endothelial cells against hydrogen peroxide (H2O2) toxicity. These results suggest that FeCe6 is a novel hydroxyl radical scavenger and may be useful for preventing oxidative injury in biological systems.

Susceptibility of natural killer (NK) cells to reactive oxygen species (ROS) and their restoration by the mimics of superoxide dismutase (SOD)

Natural killer (NK) cells are susceptible to reactive oxygen species (ROS), and lose the activity by the effects of ROS. Cancer bearing hosts usually suffer from oxidative stress (OS), and the NK-activity decreases to a significantly lower level than normal controls. Superoxide dismutase (SOD)-mimicking substances, such as protein-bound polysaccharide of Coriolus versicolor (Fr) QUEL (PSK) and iron-chelating chlorine e6-Na (FeCNa), can restore the NK-activity of cancer bearing hosts, when collaborating with catalase. Incorporation of 3H-thymidine by ROS-treated NK-cells is not affected, indicating that these cells are still active in the nucleic acid metabolism. Intraperitoneal administration of anti-Asialo GM1 antibody extinguished the NK-activity. NK-cells affected by ROS lost the adherence to target cancer cells in both in vitro and in vivo. ROS may change the surface charge of NK-cells to anionic, resulting in an inability of adhesion to target cancer cells which usually show the negative surface charge.

Mitochondrial contributions to cancer cell physiology: redox balance, cell cycle, and drug resistance

Alterations in the biochemistry of mitochondria have been associated with cell transformation and the acquisition of drug resistance to certain chemotherapeutic agents, suggesting that mitochondria may play a supportive role for the cancer cell phenotype. Mitochondria are multifunctional organelles that contribute to the cellular adenosine triphosphate (ATP) pool and cellular redox balance through the production of reactive oxygen intermediates (ROI). Our laboratory has focused on these mitochondrial functions in the context of cancer cell physiology to evaluate the potential role of mitochondria as controllers of tumour cell proliferation. Low concentrations of ROI have been implicated as messengers in intracellular signal transduction mechanisms; thus an imbalance of ROI production from the mitochondria may support cancer cell growth. In addition, suppression of mitochondrial ATP production can halt cell cycle progression at two energetic checkpoints, suggesting that the use of tumor-selective agents to reduce ATP production may offer a therapeutic target for cancer growth control.

Cationic chlorophyl derivatives with SOD mimicking activity suppress the proliferation of human ovarian cancer cells

Derivatives of chlorophyl, e.g. Fe-chlorin e6-Na, alpha, beta, gamma, delta-Tetraphenylporphine-tetrasulfonic acid disulfonic acid salt tetrahydrate (Fe-TPPTS) and alpha, beta, gamma, delta-Tetrakis (4-N-trimethylaminophenyl) porphine, tetra (p-toluensulfonate (Fe-TTMAPP), express SOD mimicking activity. Examination was made of suppressive effects of human cancer cell lines by derivatives of chlorophyl. Fe-TPPTS and Fe-TTMAPP suppressed proliferation of the human ovarian cancer cell lines but Fe-chlorin e6-Na failed to suppress the proliferation. Lipid peroxide was increased by application of Fe-TPPTS and Fe-TTMAPP, but decreased by application of Fe-chlorin e6-Na. SOD activity of the cancer cells did not change by application of these drugs. TPPTS and TTMAPP have a cationic charge but Fe-chlorin e6-Na has an anionic charge. It is suggested that charge of these drugs relates to the suppressive effects of the cancer cell proliferation.