Anticlastogenicity and Anticarcinogenicity of Purple Rice Extract in Rats.
Oryza sativa L. var. indica cv. Kum Doi Saket is a pigmented rice variety grown in northern Thailand. Our previous study found that the methanol extract of purple rice seed had the highest level of antimutagenicity in a Salmonella mutation assay. The present study was designed to evaluate its in vivo anticlastogenic and anticarcinogenic potentials. The purple rice extract had no acute toxicity on rats. The oral administration of 1,000 mg/kg body weight (bw) of the extract for 28 days did not increase the number of micronucleated hepatocytes. Interestingly, it significantly reduced the amount of micronucleus formation in the liver of diethylnitrosamine (DEN)-treated rats. The inhibitory mechanism involved the induction of hepatic glutathione S-transferase (GST) activity. In addition, oral administration of 500 mg/kg bw extract for 10 weeks significantly decreased the number of hepatic GST placental form positive foci, but did not modulate the number of colonic aberrant crypt foci in DEN- and dimethylhydrazine-initiated rats. In conclusion, the methanol extract of purple rice seed showed no toxicity, clastogenicity, or carcinogenicity in laboratory rats. It did display chemopreventive activity against the early stages of rat hepatocarcinogenesis.
a Department of Biochemistry , Faculty of Medicine, Chiang Mai University , Chiang Mai , Thailand.
Charatda
C
Punvittayagul
a Department of Biochemistry , Faculty of Medicine, Chiang Mai University , Chiang Mai , Thailand.|b Wanghin Wittayakom School , The Secondary Education Service Area Office 42, Uthai Thani , Thailand.
Paweena
P
Sankam
a Department of Biochemistry , Faculty of Medicine, Chiang Mai University , Chiang Mai , Thailand.
Sirinya
S
Taya
a Department of Biochemistry , Faculty of Medicine, Chiang Mai University , Chiang Mai , Thailand.
Rawiwan
R
Wongpoomchai
D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D016587:Antimutagenic Agents / Q000737:chemistry / Q000494:pharmacology*; D015197:Carcinogenicity Tests; D004798:Enzymes / Q000378:metabolism; D015162:Micronucleus Tests; D012275:Oryza / Q000737:chemistry*; D010936:Plant Extracts / Q000494:pharmacology*; D017208:Rats, Wistar; D012639:Seeds / Q000737:chemistry; D023382:Toxicity Tests, Acute
D016588:Anticarcinogenic Agents; D016587:Antimutagenic Agents; D004798:Enzymes; D010936:Plant Extracts