Abstract

The inhibitory effects of rice extract on mutagenicity induced by 3-amino-1,4-dimethyl-5H-pyrido [4,3-b]indole(Trp-P-1), 3-amino-1-methyl-5H-pyrido [4,3-b]indole(Trp-P-2), sodium azide(SA), 2-nitrofluorene(2NF), mitomycin C(MMC), aflatoxin $B_1(AFB_1)$ and 4-nitroquinoline oxide(4-NQO) were investigated using Salmonella typhimurium reversion assay, SOS chromotest and spore rec-assay. In Salmonella typhimurium reversion assay, methanol extract from brown rice (Illpumbyeo, Japonica variety) showed the highest inhibitory effect among other extracting solvent including hexane, chloroform and water. Methanol extract showed stronger inhibitory effect, above 85%, on indirect-acting mutagens(Trp-P-1, Trp-P-2 and $AFB_1$) than those on direct-acting mutagens(4-NQO, 2NF). In SOS chromotest, methanol extracts showed $77.6{\sim}88.9%$ effects on SOS function induced by Trp-P-1, Trp-P-2, $AFB_1$ and 4-NQO. In spore rec-assay, methanol extracts inhibited the mutagenicity induced by $AFB_1$ and MMC. As the concentration of methanol extract increased, inhibitory effect on mutagenicity increased but reached at steady state as inhibition rate of 90% when the concentration was above 5 mg/plate. In inhibitory effects of methanol extracts by various rice varieties, all of 11 varieties turned out to have inhibitory effect on mutagenicity. There was no significant difference (p>0.05) in inhibitory effect of methanol extracts between brown and white rice against Trp-P-1, but showed difference (p<0.05) against 4-NQO.

쌀의 돌연변이 억제초과를 검토하기 위해 여러 돌연변이 유발원(3-amino-1,4-dimethyl-5H-pyrido [4,3-b]indole(Trp-P-1), 3-amino-1-methyl-5H-pyrido [4,3-b]indole(Trp-P-2), sodium azide(SA), 2-nitrofluorene(2NF), mitomycin C(MMC), aflatoxin $B_1(AFB_1)$ 및 4-nitroquinoline oxide(4-NQO))에 대한 쌀 추출물들의 억제효과를 Salmonella typhimurium reversion assay, SOS chromotest 및 spore rec-assay로 조사하였다. S. typhimurium TA 98 및 TA 100을 이용한 Salmonella typhimurium reversion assay에서 현미(일품벼) 메탄올 추출물이 핵산, 클로로포름 및 물 추출물 보다 억제효과가 크게 나타났다. 메탄올 추출물의 경우, 간접변이원(Trp-P-1, Trp-P-2 및 $AFB_1$)에 대한 억제효과가 약 85% 이상으로써, 직접변이원(4-NQO, 2NF)에 대한 효과 보다 크게 나타났다. 메탄올 추출물은 E. coli PQ37을 이용한 SOS chromotest에서도 Trp-P-1, Trp-P-2, $AFB_1$ 및 4-NQO에 의한 SOS유도에 대해 $77.6{\sim}88.9%$의 억제작용을 나타내었고, B. subtilis $H17(rec^+)$과 $M45(rec^-)$를 사용한 spore recassay에서도 양성대조구인 $AFB_1$ 및 MMC에 의한 저지대의 차이를 감소시켜 억제작용을 나타내었다. 현미(일품벼)의 메탄올 추출물은 농도가 증가함에 따라 돌연변이 억제효과가 증가하였으나, 농도가 5 mg/plate(5%) 이상에서는 억제효과가 약 90%로 일정하였다. 쌀 품종별 메탄올 추출물의 억제효과는 조사된 11개 품종 모두에게서 나타나, 직접변이원인 2NF에 대해 $4.1{\sim}75.2%$의 억제를, 간접 변이원인 Trp-P-1에 대해 $99.5{\sim}100.2%$의 억제를 나타내었다. 백미와 현미(일품벼)간의 돌연변이 억제효과를 비교해 볼 경우, Trp-P-1 및 Trp-P-2에 의한 변이에 대해서는 차이가 없었으나(p>0.05), 4-NQO에 의한 변이에 대해서는 현미의 효과가 높았다(p<0.05).

Keywords

• rice;
• methanol extract;
• inhibitory effect on mutagenicity;
• Salmonella typhimurium reversion assay;
• SOS chromotest;
• spore rec-assay