Antioxidative and modifying effects of a tropical plant Azadirachta indica (Neem) on azoxymethane-induced preneoplastic lesions in the rat colon.
The purpose of the present study was to examine whether Neem leaf (Azadirachta indica) has short-term chemopreventive effects on endpoint preneoplastic lesions involved in rat colon carcinogenesis and might also exert antioxidative activity. Forty- two male F344 rats were randomly divided into 6 experimental groups. Groups 1 to 4 were given a subcutaneous injection of azoxymethane (AOM, 20 mg/kg body weight) once a week for 2 weeks. Starting one week before the first injection of AOM, rats in groups 2 to 4 received an aqueous extract of Neem leaf (20, 100, and 250 mg/kg, respectively) by gavage 3 times per week, for 5 weeks. Rats in group 5 also were given the Neem extract by gavage feeding 3 times per week for 5 weeks, while group 6 served as untreated controls. The experiment was terminated 5 weeks after the start. Dietary feeding of the Neem extract at all dose levels significantly inhibited the induction of aberrant crypt foci (ACF) (P<0.0002), when compared to the AOM-treated group (group 1). In groups 2 to 4, treatment of rats with the Neem extract also significantly decreased the proliferating cell nuclear antigen (PCNA) labeling indices (P<0.0006) of colon epithelium and ACF. Moreover, the Neem extract also showed antioxidative activity. The finding that dietary Neem has possible chemopreventive effects in the present short-term colon carcinogenesis bioassay suggests that longer-term exposure may cause suppression of tumor development.
Arakaki
Junya
J
Tumor Pathology, University of the Ryukyus Faculty of Medicine, Okinawa 903-0215, Japan. junya-arakaki@ryukyu-surg1.org
Suzui
Masumi
M
Morioka
Takamitsu
T
Kinjo
Tatsuya
T
Kaneshiro
Tatsuya
T
Inamine
Morihiko
M
Sunagawa
Nao
N
Nishimaki
Tadashi
T
Yoshimi
Naoki
N
D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology*; D031601:Azadirachta / Q000737:chemistry*; D001397:Azoxymethane / Q000008:administration & dosage / Q000633:toxicity*; D002273:Carcinogens / Q000008:administration & dosage / Q000633:toxicity*; D002471:Cell Transformation, Neoplastic; D018890:Chemoprevention; D003110:Colonic Neoplasms / Q000139:chemically induced / Q000517:prevention & control* / Q000662:veterinary; D008297:Male; D008517:Phytotherapy / Q000662:veterinary; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology*; D011230:Precancerous Conditions / Q000139:chemically induced / Q000517:prevention & control* / Q000662:veterinary; D051381:Rats; D011916:Rats, Inbred F344
D000975:Antioxidants; D002273:Carcinogens; D010936:Plant Extracts; D001397:Azoxymethane