Comparative antimutagenicity of chlorophyllin and five other agents against aflatoxin B₁‐induced reversion in Salmonella typhimurium strain TA98

Abstract

Chlorophyllin was studied for its antimutagenic activity against aflatoxin B1 in Salmonella typhimurium strain TA98 using the plate-incorporation test in the presence of S9 activation. Comparative antimutagenicity between chlorophyllin and certain commonly studied antimutagens (i.e., vitamins A, C, and E, retinoic acid, and beta-carotene) was also examined. A dose-related inhibition of aflatoxin B1 mutagenicity by chlorophyllin was observed, with the mutagenicity being abolished by 860 nmole chlorophyllin per plate. The inhibitory activity of chlorophyllin occurred only when cells were treated concurrently with chlorophyllin and aflatoxin B1. The antimutagenic potency of chlorophyllin was comparable to that of vitamin A and higher than that of retinoic acid and beta-carotene. Vitamins C and E had no effect on aflatoxin B1 mutagenicity under the conditions used. The results of toxicity tests and a reconstruction experiment showed that inhibition of the mutagenicity of aflatoxin B1 by chlorophyllin and the other active agents was due to antimutagenicity.

Chemopreventive properties of chlorophylls towards aflatoxin B1: a review of the antimutagenicity and anticarcinogenicity data in rainbow trout

“…The first studies with CHL in our laboratory used the Salmonella assay, and were based on preliminary experiments which examined the antimutagenic activity of CHL vs. AFB 1 [3]. A key observation in the studies by Whong et al [3] was that the inhibitory activity occurred only when CHL and AFB 1 were incubated concurrently in the assay, suggesting that direct interaction between the inhibitor and mutagen might be important for antimutagenic activity.…”

“…A key observation in the studies by Whong et al [3] was that the inhibitory activity occurred only when CHL and AFB 1 were incubated concurrently in the assay, suggesting that direct interaction between the inhibitor and mutagen might be important for antimutagenic activity. We observed the antimutagenic activity of CHL vs. AFB 1 using trout liver microsomes as the source of metabolic activation [4], but showed the inhibitor to be more effective against the direct-acting mutagen AFB 1 -8,9-epoxide (Fig.…”

Aflatoxin B1 - Prevention of Its Genetic Damage by Means of Chemical Agents

“…However, very soon afterwards most research on the matter was focused on the effect of chlorophyllin (CHL) (Figure 4), mostly because this chemical is a water-soluble, sodium and copper salt, chlorophyll derivative. In regard to its protective effect on AFB1 damage, one of the first studies with CHL was made by quantifying the number of revertants of specific base-pair mutants in Neurospora crassa (Whong et al, 1988). The study showed strong inhibition of the antimutagen on the AFB1-mutagenicity determined in growing cultures of the mold, a result which prompted the group to continue their studies but now in Salmonella typhimuriun, strain TA98, as a model (Whong et al, 1988).…”

“…In regard to its protective effect on AFB1 damage, one of the first studies with CHL was made by quantifying the number of revertants of specific base-pair mutants in Neurospora crassa (Whong et al, 1988). The study showed strong inhibition of the antimutagen on the AFB1-mutagenicity determined in growing cultures of the mold, a result which prompted the group to continue their studies but now in Salmonella typhimuriun, strain TA98, as a model (Whong et al, 1988). The authors used the plateincorporation test in this bacteria and found a concentration-dependent inhibition of AFB1 mutagenicity when the cells were treated with the tested substances, concurrently; in their assay they observed that 860 nmol/plate of CHL completely abolished the mutagenicity of the toxin.…”

Study of the forces stabilizing complexes between chlorophylls and heterocyclic amine mutagens

“…Chlorophyllin (CHL) is a sodium-copper salt of chlorophyll that exhibits antimutagenic activity in several shortterm genotoxicity assays [Katoh et al, 1983;Tenvel and van der Hoeven, 1985;Ong et al, 1986;Whong et al, 1988;Negishi et al, 1989;Dashwood et al, 1991;Warner et al, 1991;Tachino et al, 19941. Studies in vitro indicate that CHL acts via multiple mechanisms, including the following: 1) inhibition of mutagen activation, 2) degradation of electrophilic ultimate carcinogens [Tachino et al, 19941, and 3) molecular complex formation with the promutagen [Negishi et al, 1989;Dashwood and Guo, 1992;Breinholt et al, 1995al.…”