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PubMed1990

In vivo effects of single or combined dietary antimutagens on mutagen-induced chromosomal aberrations.

The food components chlorophyllin, beta-carotene and alpha-linolenic acid (in its methyl ester form) were tested in Chinese hamsters for antimutagenic activity on the powerful mutagen thio-tepa. Each of these natural protective compounds inhibited by 70-85% the clastogenic effects induced by the mutagen. When 2 or 3 of these antimutagens were administered simultaneously no additive effects were observed. alpha-Linolenic acid methyl ester was the most effective antimutagen under the experimental conditions.

Animals↗
PubMed1991

Antimutagenicity studies of chlorophyllin using the Salmonella arabinose-resistant assay system.

Studies with the arabinose-resistant Salmonella forward mutation assay system were performed to determine the antimutagenic activity of chlorophyllin against the mutagenic activity of aflatoxin B1 (AFB1), 2-aminoanthracene (2AA), benzo[a]pyrene (BaP), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and solvent extracts of coal dust (CD), diesel emission particles (DE), airborne particles (AP), tobacco snuff (TS), black pepper (BP) and red wine (RW). Various concentrations of each chemical and complex mixture extract were assayed for mutagenic activity with and/or without S9 in a preincubation test. One concentration of each chemical and complex mixture extract was then tested with various concentrations of chlorophyllin. Results showed that chlorophyllin, at concentrations of 2.5 mg/plate or less, completely or almost completely inhibited the mutagenicity of 2AA, AFB1, BaP, MNNG and solvent extracts of CD, DE and RW. With concentrations from 1.25 to 5 mg/plate, chlorophyllin inhibited over 50% of the mutagenicity of AP, TS and BP extracts. These results further substantiate the antimutagenic efficacy of chlorophyllin against chemicals and complex mixtures.

Aflatoxin B1↗
PubMed1993

Differential protection of chlorophyllin against clastogenic effects of chromium and chlordane in mouse bone marrow in vivo.

The anticlastogenic activity of sodium-copper-chlorophyllin was tested against two known clastogens, chromium(VI) oxide and the pesticide chlordane, both of which occur as environmental toxicants. The chemicals were administered to male Swiss albino mice by gavage and chromosomes were studied from bone marrow cells 24 h after the exposure, following colchicine-air drying-Giemsa preparation. The end-points screened were the frequencies of chromosomal aberrations and damaged cells. The clastogenic effects induced by chromium in aqueous solution (20 mg/kg body weight) were reduced to a significant level by chlorophyllin (1.5 mg/kg body weight), when administered both before and simultaneously with the toxicant. The effects of chlordane in olive oil (10 mg/kg body weight) were, however, not reduced by the administration of chlorophyllin (1.5 and 3 mg/kg body weight).

Analysis of Variance↗
PubMed1989

Interactions between native oat phytochrome and tetrapyrroles.

The suggestion, that the increase in the far-UV CD signal of the 124 kDa oat phytochrome upon phototransformation of the Pr to Pfr form is possibly due to the chromophore interaction with the N-terminus segment of the phytochrome protein in the Pfr from (Chai, Y.G., Song, P.S., Cordonnier, M.-M. and Pratt, L.H. (1987) Biochemistry 26, 4947-4952), has been investigated by measuring the circular dichroism in the absence of exogenous tetrapyrrolic chromophores (bilirubin, biliverdin, chlorophyllin and hemin). Open tetrapyrrolic chromophores (bilirubin and biliverdin) did not have any significant effect on the phototransformability of the far-UV CD signal of the phytochrome, whereas closed tetrapyrroles (chlorophyllin and hemin) almost completely blocked the increase in the far-UV CD signal upon Pr to Pfr phototransformation. However, closed tetrapyrroles had no effect on the decrease in the CD signal upon Pfr to Pr photoconversion. Secondary structure analysis showed that the alpha-helix content of both Pr and Pfr forms of phytochrome (with 53 and 56% alpha-helical content, respectively) increased to 62% when a 50-fold molar excess of chlorophyllin was added to them separately. Spectral phototransformation of phytochrome was not affected in the presence of tetrapyrroles, except in the case of hemin. A 50-fold molar mass of hemin caused a significant bleaching of the Pfr form of phytochrome but not that of the Pr form. These results suggest that the chromophore-protein interaction is significantly altered during the phototransformation of phytochrome.

Bilirubin↗
PubMed1991

Effect of chlorophyllin on mercuric chloride-induced clastogenicity in mice.

The effect of chlorophyllin (1.5 mg/kg body weight) on the clastogenicity of mercuric chloride (HgCl2) was studied in vivo in mouse bone marrow cells. HgCl2 (3.0, 6.0 and 12.0 mg/kg body weight) administered by gavage induced chromosomal aberrations at frequencies directly proportional to the dose. Chlorophyllin was not clastogenic, and significantly reduced the mitotic index when given alone. Chlorophyllin administered simultaneously with HgCl2 significantly reduced the frequencies of chromosomal aberrations in a dose-dependent manner. When given simultaneously with the lowest HgCl2 concentration tested (3.0 mg/kg body weight), chlorophyllin provided total protection. A lower degree of protection was given by chlorophyllin administered 2 hr before HgCl2. The data demonstrate the potential of green plant components to modify the genotoxic activity of HgCl2 when administered orally.

Administration, Oral↗
PubMed1989

Porphyrin-proteinoid complexes as models of prebiotic photosensitizers.

Photochemical activity as well as some spectral properties of various porphyrins and their model complexes with proteinoids were studied. Photochemical activity increased from the less advanced biosynthetic chlorophyll precursors to the more advanced compounds. The significant increase was detected as a result of the formation of complexes of phytol-containing porphyrins with proteinoids, which brings about the disaggregation of the pigment clusters formed in the aqueous environment. Hemin is photochemically inactive, either alone or in complex with proteinoid. Although hemoproteinoid was demonstrated to be able to catalyse photochemical electron transfer, its activity is about 20 times lower when compared with the chlorophyll a-proteinoid complex. Experimental results are discussed in context of the early evolution of photosynthesis.

Chlorophyll↗
PubMed1994

Inhibitory activity of chlorophyllin on the genotoxicity of carcinogens in Drosophila.

Antimutagenic activity of copper chlorophyllin against various carcinogenic mutagens was assayed with Drosophila genotoxicity tests, i.e., the wing spot test for detecting somatic cell mutations and the DNA repair test for detecting DNA damage. In these tests, Drosophila larvae were fed carcinogens together with chlorophyllin. Polycyclic aromatic compounds, including heterocyclic amines, polycyclic aromatic hydrocarbons, aromatic amines and aromatic nitro compounds, were subject to inhibition, with a few exceptions. The results support the view that chlorophyllin traps carcinogens by forming complexes, thereby inhibiting the absorption of these compounds from the digestive tract. Consistent with this mechanism, Sepharose-supported chlorophyllin in the feed inhibited the Trp-P-2-induced wing spot formation, while Sepharose itself was ineffective.

Animals↗
PubMed1995

Chemoprotective properties of chlorophyllin against vinyl carbamate, p-nitrophenyl vinyl ether and their electrophilic epoxides.

Chlorophyllin (CHL), a water-soluble sodium and copper derivative of chlorophyll, has been shown to be a strong antimutagen in several test systems, but its mechanism of antimutagenic action is largely unknown. In the present study, we have found the protective properties of CHL against vinyl carbamate, p-nitrophenyl vinyl ether and their electrophilic epoxides. CHL exhibited dose-related inhibition of his+ reversion in Salmonella typhimurium TA 1535 induced by these mutagens. Formation of DNA adducts from vinyl carbamate epoxide (VCO) and 2'-(4-nitrophenoxy)oxirane (NPO) was also markedly attenuated in the presence of CHL. Oral administration of CHL prior to the topical application of each of the above carcinogens resulted in significant reduction in both incidence and multiplicity of skin tumors in mice. The effective protection by CHL against VCO and NPO suggest that its formation of inactive complexes with these carcinogens is mediated by mechanisms other than pi-pi interactions.

Animals↗
PubMed1995

Inhibition by chlorophyllin of 2-amino-3-methylimidazo-[4,5-f]quinoline-induced tumorigenesis in the male F344 rat.

This report describes a 1-year carcinogenicity bioassay in which male F344 rats received 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) by gavage 2-3 times per week throughout the first 35 weeks of study, while 0.1% sodium/copper chlorophyllin (CHL) was given concomitantly in the drinking water. The carcinogen dose was calculated to provide an average exposure of 4.2 mg IQ/rat per day, equivalent to that reported in previous carcinogenicity study in which rats were given 0.03% IQ in the diet. Adjusted for length of follow-up, inhibition was highly significant for total tumor burden (P < 0.001), and for specific sites was significant in the small intestine and Zymbal's gland (P < or = 0.1), and in the liver (P < 0.01). In rats given CHL, the first onset of tumors in the Zymbal's gland was delayed from week 20 to 36, but was shortened from week 31 to 26 in the skin (P < 0.05). These results support a chemopreventive role for CHL in several of the major target organs for IQ tumorigenesis in the rat, but raise concerns over possible deleterious effects in the skin.

Animals↗
PubMed1996

Chemopreventive activity of chlorophyllin against mouse skin carcinogenesis by benzo[a]pyrene and benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide.

Chlorophyllin (CHL), the sodium and copper salt of chlorophyll, was tested for its chemopreventive activity against tumorigenesis induced by benzo[a]pyrene (B[a]P) and its ultimate electrophilic and carcinogenic metabolite, benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide(BPDE). Administration of CHL (15 mg/kg body wt) by gavage to female ICR mice 30 min prior to a topical application of B[a]P or BPDE resulted in significant reduction in both incidence and multiplicity of skin tumors initiated by these carcinogens. CHL was rapidly distributed in the skin and other tissues of mice after oral administration. Taken together, these results suggest that CHL is a potential chemopreventive agent.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1996

Chemopreventive effect of chlorophyllin on mutagenicity and cytotoxicity of 6-sulfooxymethylbenzo[a]pyrene.

The chemopreventive activity of chlorophyllin (CHL) was monitored by using 6-sulfooxymethylbenzo[a]pyrene (SMBP) which is an ultimate metabolite of benzo[a]pyrene (B[a]P). CHL was quite effective in reducing both cytotoxicity and mutagenicity for SMBP in dose dependent manner up to 12.5 mM CHL in Chinese hamster V79 cells. The inhibitory patterns of CHL for SMBP were also confirmed in Salmonella typhimurium strains TA98 and TA100. Mutation frequency caused by SMBP was diminished almost to a control level at a 50 nmol CHL. A similar but less effective prevention of CHL was indicated in the mammalian and the bacterial mutagenicity assays with 6-hydroxymethylbenzo[a]pyrene (HMBP). The inhibitory effect of CHL against assault of SMBP on V79 cells was found to be related to the reduced cellular uptake of SMBP and further the remarkably lowered DNA adducts.

Animals↗
PubMed1995

Selective laser-activated lesioning of prelabeled fetal hippocampal grafts by intracellular photolytic chromophore.

Selective removal of grafted tissue is critical to assess the functional role of that tissue in the host, yet is technically difficult for well-dispersed neural grafts. We labeled fetal hippocampal cells with both a nuclear marker (5'-bromodeoxyuridine) and a cytoplasmic marker (latex microspheres) before grafting into normal adult hippocampus. A nontoxic chromophore, chlorin e6, was conjugated on to the surface of latex microspheres of the treatment group. Chlorin e6 produces cytotoxic singlet oxygen only during photoactivation. Grafted animals received transcranial exposure to various intensities of near-infrared laser light. Following laser exposure, grafts were observed in all groups except in transplants prelabeled with chlorin e6 latex microspheres. An optimal laser exposure of 50-100 J/cm2 (4-8 min) was found to selectively remove only the chlorin e6-containing grafted cells. With increasing doses of laser illumination, non-specific lesions of the host tissue surrounding the graft were induced. Quantitative graft analysis, in the absence of laser exposure, indicated that the survival of grafted cells was similar between control transplants labeled with latex microspheres alone and grafts labeled with latex microspheres plus chlorin e6. This is further evidence that chlorin e6 by itself was not toxic without laser exposure. The results clearly demonstrate that singlet oxygen-induced cell photolysis can result in selective, non-invasive removal of dispersed grafted cells located in adult hippocampus. This technique may facilitate defining specific mechanisms of action of grafted cells which mediate functional recovery in different host conditions.

Animals↗
PubMed1991

Inhibition of clastogenic effects of cesium chloride in mice in vivo by chlorophyllin.

The antagonistic effect of chlorophyllin was tested in reducing the clastogenic action of cesium chloride (CsCl) in vivo on mice bone marrow cells. CsCl induced chromosomal aberration in frequencies directly proportional to the dose administered. Chlorophyllin, when given alone, was not clastogenic even at a concentration of 1.5 mg/kg body wt. of the animal. Simultaneous administration of chlorophyllin and CsCl reduced chromosomal aberrations significantly at 24 h. Exposure to the same dose of chlorophyllin 2 h before exposure to CsCl also decreased clastogenic effects but to a lesser extent. These findings are of importance in view of the uptake of radioactive Cs by green plants after nuclear fallout.

Animals↗
PubMed1990

Chlorin e6-liposome interaction. Investigation by the methods of fluorescence spectroscopy and inductive resonance energy transfer.

On the basis of spectral fluorescence and polarization measurements and results obtained on the luminescence quenching of the membrane fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH) by incorporated chlorin e6 (chl e6) molecules, it is shown that the interaction of the water-soluble pigment with smaller unilamellar lipid vesicles occurs by a mechanism of partition between the aqueous and lipid phases (partition coefficient Kp = 6.7 x 10(3) and provides rigid fixing of chl e6 monomers at the boundary between the polar and non-polar parts of the lipid membrane. In terms of inductive resonance electronic excitation energy transfer between DPH and chl e6 (R0 = 36.2 A), we have analysed data on DPH fluorescence quenching under different conditions of chl e6 localization in the lipid bilayer and have concluded that the incorporation of the pigment molecules into the vesicles from the aqueous phase occurs mainly into the external monolayer.

Chlorophyllides↗
PubMed1991

Photodynamic therapy with chlorin e6. A morphologic study of tumor damage efficiency in experiment.

Morphological changes in rat sarcoma M-1 after photodynamic treatment with chlorin e6 were studied. The frequency of necrosis appearance and the depth of its spreading in tumor tissue were evaluated after intraperitoneal injection of chlorin e6 in doses of 1-10 mg kg-1 and subsequent irradiation by a krypton laser with light energy density 22.5-135 J cm-2, using the method of vital staining with Evans blue. It was found that the antitumoral effect of photodynamic treatment was strengthened by increasing the dose of the agent and light and reduced by increasing the time interval between chlorin e6 injection and light irradiation. The treatment being given in the parameters mentioned produced a depth of tumor necrosis which varied from 4.0 mm to 16.6 mm. The mechanisms of tumor tissue damage after photodynamic treatment in vivo are discussed.

Animals↗
PubMed1992

The laws of delayed photohaemolysis sensitized by chlorin e6.

The relationships between the rate of post-irradiated photohaemolysis sensitized by chlorin e6 and parameters such as the light fluence (time of irradiation) and sensitizer concentration were studied. On the basis of the single-parametric approach proposed by Valenzeno and Pooler, it was found that the haemolytic rate varies with the square of both the light fluence and the sensitizer concentration. Thus it can be concluded that, in a single erythrocyte lesion, two chlorin e6 molecules participate, each absorbing one photon. The possibility of suppression of post-irradiation haemolysis was also studied using the lipophilic antioxidant, butylated hydroxytoluene (BHT), and scavengers of 1O2, O2.- and HO. radicals. It was found that BHT inhibits, to a considerable extent, the post-irradiation lysis of cells, by about a factor of 2.5 at a BHT concentration of 9 microM. The addition to the medium of NaN3 (a scavenger of 1O2), superoxide dismutase (a scavenger of O2.- radicals), ethanol and D-mannitol (scavengers of HO. radicals), when irradiation was interrupted, did not produce a marked influence on the kinetics of subsequent haemolysis. On the basis of the results obtained, the nature of erythrocyte targets, which are crucial for the photodynamic effect of chlorin e6, is discussed.

Biological Transport↗