Tetsuo Kimoto

Cell differentiation and apoptosis of monocytic and promyelocytic leukemia cells (U-937 and HL-60) by tryptanthrin, an active ingredient of Polygonum tinctorium Lour.

Tryptanthrin, a bioactive ingredient of Polygonum tinctorium Lour., is a member of the Indigo plant family and has potent cytocidal effects on various human leukemia cells in vitro. At low concentrations, tryptanthrin enhanced the expression of cell differentiation (CD) markers in human monocytic (U‐937) and promyelocytic (HL‐60) leukemia cells indicative of differentiation to monocytes/macrophages. Furthermore, nitroblue tetrazolium (NBT) reductive and α‐naphthyl butyrate esterase (NBE) activities were markedly increased after treatment. Tryptanthrin was more potent than dimethyl sulfoxide (DMSO) at inducing U‐937 cell differentiation into monocytes/macrophages. After treatment with higher concentrations of tryptanthrin for 24 h, cytoplasmic vacuolation and destruction of mitochondria were observed. The leukemia cells died via apoptosis 48 h after treatment. Cytoplasmic vacuolation and apoptotic changes correlated with the dysfunction of mitochondria. Electron microscopic observations revealed marked swelling and destruction of mitochondria after exposure of the leukemia cells to tryptanthrin. Exposure to tryptanthrin enhanced Fas‐induced apoptosis and increased caspase‐3 activity before induction of apoptosis. These results show that low concentrations of tryptanthrin can induce differentiation of leukemia cells but higher concentrations will kill leukemia cells through apoptosis, possibly through a caspase‐3/Fas antigen pathway.

Renal carcinogenesis induced by ferric nitrilotriacetate in mice, and protection from it by Brazilian propolis and Artepillin C

The protective effect of Brazilian propolis and its extract Artepillin C against ferric nitrilotriacetate (Fe‐NTA)‐induced renal lipid peroxidation and carcinogenesis was studied in male ddY mice. Fe‐NTA‐induced renal lipid peroxidation leads to a high incidence of renal cell carcinoma (RCC) in mice. Administration of propolis by gastric intubation 2 h before or Artepillin C at either the same time, 2 h, or 5 h before the intraperitoneal injection of Fe‐NTA (7 mg Fe/kg) effectively inhibited renal lipid peroxidation. This was evaluated from the measurement of renal thiobarbituric acid‐reactive substances (TBARS) or histochemical findings of 4‐hydroxy‐2‐nonenal (4‐HNE)‐modified proteins and 8‐hydroxy‐2′‐deoxyguanosine (8‐OHdG). Repeated injection of Fe‐NTA (10 mg Fe/kg per day, twice a week for a total of 16 times in 8 weeks) caused subacute nephrotoxicity as revealed by necrosis and pleomorphic large nuclear cells in the renal proximal tubules, and gave rise to RCC 12 months later. A protective effect from carcinogenicity was observed in mice given propolis or Artepillin C. Furthermore, the mice given Fe‐NTA only developed multiple cysts composed of precancerous lesions with multilayered and proliferating large atypical cells. Mice treated with propolis and Artepillin C also had cysts, but these were dilated and composed of flat cells. These results suggest that propolis and Artepillin C prevent oxidative renal damage and the carcinogenesis induced by Fe‐NTA in mice.

The natural plant product tryptanthrin ameliorates dextran sodium sulfate-induced colitis in mice.

The therapeutic effects of tryptanthrin (TRYP), a natural product from the medicinal plant Polygonum tinctorium, were examined in a murine model of inflammatory bowel disease (IBD). Colitis was induced by 5% dextran sodium sulfate (DSS) in drinking water for 7 days from day 0. TRYP (100 mg/kg) was administered orally suspended in 5% arabia gum everyday from day 3 for 5 days. Histopathological analysis showed reduced colon damage in TRYP-treated mice on day 6; however, colon injury resumed after treatment was stopped. The production of prostaglandin E2 (PGE2), tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) by untreated and treated mouse colon tissues cultured in vitro were mostly unchanged by TRYP treatment. However, mitogen-stimulated spleen cells from TRYP-treated colitic mice produced less interleukin 2 (IL-2) and less interferon-gamma (IFN-gamma) than untreated colitic mouse spleen cells, early after induction of colitis. When colitis was induced with 5% DSS for 7 days and TRYP was given to the mice for 8 days from day 3, TRYP enhanced the survival of the mice but results were not significant. A significant reduction of weight loss was observed in TRYP-treated mice with colitis induced by 5% DSS for 4 days as compared to control mice. Remarkably, whereas 90% of the vehicle-treated mice died from wasting disease, all the TRYP-treated mice survived, suggesting that TRYP may have a therapeutic effect on colitis.

Preventive effect of Coriandrum sativum (Chinese parsley) on localized lead deposition in ICR mice

The preventive effect of Coriandrum sativum, Fam. UMBELLIFERAE (Chinese parsley) on lead deposition was investigated in male ICR mice given lead (1000 ppm) as lead acetate trihydrate in drinking water for 32 days. Administration of Chinese parsley to mice by gastric intubation was performed for 25 days from day 7 after the start of lead exposure up to the end of the experiment. The mice were then sacrificed for comparison of lead distribution. The lead reached its highest concentration in the femur but localized lead deposition in the femur was significantly decreased by meso-2,3-dimercaptosuccinic acid (DMSA), a chelating agent used as a positive control to validate this experimental model. Administration of Chinese parsley also significantly decreased lead deposition in the femur and severe lead-induced injury in the kidneys. In addition, urinary excretion of delta-aminolevulinic acid (ALA) which is known to increase with lead intake was significantly decreased after administration of Chinese parsley. The MeOH extract of Chinese parsley also reduced lead-induced inhibition of delta-aminolevulinic acid dehydratase (ALAD) activity in vitro. These results suggest that Chinese parsley has suppressive activity on lead deposition, probably resulting from the chelation of lead by some substances contained in Chinese parsley.

CELL RECOGNITION AND PHAGOCYTOSIS OF SV40 TRANSFORMED CELL

In the course of cell transformation by SV40 the cell membrane undergoes changes, which in turn cause its surface negatively charged, and decrease markedly the phagocytosis of negatively charged substances. The study of the relationship between such transformed cells and allo‐genous hamster red cells as well as lymphocytes has revealed that the rates of adhesion to and ingestion of native cells by the transformed cell, which recognizes the former as self, are low. However, when such native cells are previously treated with half saturated ammonium sulfate and 2.5% glutaraldehyde there occurs a change in the charge of cell membrane and a marked phagocytosis is triggered. In such an instance, when L cells are coated with non‐immune albumin or immune sera (anti‐RBC‐rabbit sera) the phagocytosis is inhibited, but the phagocytosis of transformed cell remains unchanged. The phagocytosis of transformed cells can be inhibited by Concanavalin A treatment of transformed cells and fixed RBC, while be blocking the surface antigen the phagocytosis is enhanced. Therefore, it can be said that the cell recognition of self or non‐self by cancer cell depends upon changes in the cell surface of both cell groups, in other words, upon the changes in cell surface charge due to molecular architecture.