EFFECTS OF SOYA BEAN FLAKES AND LICORICE ROOT EXTRACT ON ENZYME-INDUCTION AND TOXICITY IN B6C3F(1) MICE

Both soya bean flakes (SBF) and liquorice root extract (LRE) have prev iously been reported to have anticarcinogenic properties, which have b een thought to be related to an increased activity of specific enzymes responsible for the detoxification of chemical carcinogens. 30- and 9 0-day studies were conducted in male B6C3F1 mice to determine which, i f any, of several detoxification enzymes are induced by SBF or LRE. Mi ce fed 8 and 25% LRE showed a variety of adverse clinical signs, poor weight gain and 30% mortality. Significant increases in liver:body wei ght ratios were observed in both the SBF and LRE groups. No significan t treatment-related gross autopsy findings were observed in any of the SBF groups. A number of abnormalities were observed in the LRE groups , including lesions of the kidney, liver. spleen and thymus. Liver sam ples from the 90-day study were analysed for 7-ethoxycoumarin O-deethy lase (7-ECOD), benzo[a]pyrene hydroxylase (BPH), superoxide dismutase (SOD), glutathione S-transferase (GST) and UDP-glucuronyl transferase (UDPGT) at 90 days, and at an interim 30-day autopsy. No treatment-rel ated increases were observed for BPH or SOD. Both SBF and LRE induced modest increases in UDPGT activity. SBF induced modest increases in GS T activity, but LRE decreased this activity. 7-ECOD activity was signi ficantly increased by LRE and decreased by SBF. Samples from a 30-day study in which both LRE and SBF were administered at various dose leve ls were examined for UDPGT activity: all dose groups showed decreases in UDPGT activity relative to controls. The results suggest that both SBF and LRE may alter the activities of specific enzymes involved in t he detoxification of chemical carcinogens: however, the combination of these two foodstuffs may not produce an additive effect in B6C3F1 mic e.