Suppression of the SOS-Inducing Activity of Trp-P-1 and Aflatoxin B₁ by Meso-dihydroguaiaretic Acid from Machilus thunbergii in the Salmonella typhimurium TA1535/pSK1002 umu Test

Abstract

  The methanol extract from Machilus thunbergii showed a suppressive effect on umu gene expression of the SOS response in Salmonella typhimurium TA1535/pSK1002 against the mutagen, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), which requires liver metabolizing enzymes. The methanol extract from M. thunbergii was successively re-extracted with chloroform, butanol and water. A suppressive compound in the chloroform extract fraction was isolated by SiO₂ column chromatography and identified as meso-dihydroguaiaretic acid by GC-MS, and ¹H- and ¹³C-NMR spectroscopy.
  Meso-dihydroguaiaretic acid inhibited of the SOS-inducing activity of Trp-P-1 in the umu test. Gene expression was suppressed by 62% at less than 0.18 μmol/ml, the ID₅₀ value being 0.08 μmol/ml. Compound 1 was also assayed with aflatoxin B₁ (AfB₁) and showed a suppressive effect.