title: Inhibition by licorice flavonoid oil of glutathione S-transferase-positive foci in the medium-term rat hepatocarcinogenesis bioassay.
abstract: Licorice flavonoid oil (LFO) is a new functional food ingredient consisting of hydrophobic licorice polyphenols in medium-chain triglycerides. Recently, it was reported that licorice and its derivatives have anticarcinogenic activity in some types of tumors. However, the anticarcinogenic activity has not been identified in the liver, which is a major target organ for carcinogenesis in human. Therefore, we hypothesized that LFO has antihepatocarcinogenic activity, and we tested this hypothesis using the rat medium-term liver bioassay for carcinogens. Six-week-old male F344 rats (15 animals/group) received N-diethylnitrosamine (200 mg/kg by intraperitoneal injection) to initiate carcinogenesis. From the second week after initiation, animals received a 6-week regimen of either LFO concentrate solution (0, 150, 300, or 600 mg/kg) intragastrically or phenobarbital sodium salt in the diet (500 ppm) as a positive control. During the third week after initiation, animals were subjected to a two-thirds partial hepatectomy. During the eighth week of the treatment period, liver samples were taken from animals and examined immunohistochemically for expression of glutathione S-transferase placental form. No increase in the number of glutathione S-transferase placental form-positive liver foci was observed in all LFO groups compared with the negative control (solvent) group, and the number of foci in the 600 mg/kg LFO group was significantly lower than that in the negative control group. These results indicate that LFO concentrate solution has a significant inhibitory effect on liver carcinogenesis at 600 mg/kg.
authors.affiliation: QOL Division, Kaneka Corporation, Kita-ku, Osaka, Japan.
authors.forename: Kaku
authors.initials: K
authors.lastname: Nakagawa
authors.forename: Kazunori
authors.initials: K
authors.lastname: Hosoe
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Hidaka
authors.forename: Kyoko
authors.initials: K
authors.lastname: Nabae
authors.forename: Mayumi
authors.initials: M
authors.lastname: Kawabe
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Kitano
mesh_terms: D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology / Q000627:therapeutic use*; D004052:Diethylnitrosamine; D005419:Flavonoids / Q000494:pharmacology / Q000627:therapeutic use*; D055951:Functional Food; D005982:Glutathione Transferase / Q000378:metabolism*; D006035:Glycyrrhiza / Q000737:chemistry*; D008099:Liver / Q000378:metabolism*; D008113:Liver Neoplasms / Q000517:prevention & control*; D008297:Male; D010634:Phenobarbital; D010636:Phenols / Q000494:pharmacology / Q000627:therapeutic use; D008517:Phytotherapy; D028321:Plant Preparations / Q000494:pharmacology / Q000627:therapeutic use*; D051381:Rats; D011916:Rats, Inbred F344; D014280:Triglycerides
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D005419:Flavonoids; D010636:Phenols; D028321:Plant Preparations; D014280:Triglycerides; D004052:Diethylnitrosamine; D005982:Glutathione Transferase; D010634:Phenobarbital