Revista Chilena de Historia Natural 81 (2): 293-302, 2008
RESEARCH ARTICLE
Effects of natural phenolic compounds from a desert dominant shrub Larrea divaricata
Cav. on toxicity and survival in mice
It is known that generalist herbivores may circumvent intoxication by ingesting small
quantities from a mixture of plant secondary metabolites. However a single chemical, a highly toxic one or the most abundant in the
mixture could cause toxicity. Survivorship and toxicity in Rockland male mice were measured to determine if the toxic effects of the
phenolic resin of creosote bush (Larrea divaricata Cav.) is due to its major constituent, the nordihydroguaiaretic acid
(NDGA) or to the total concentration of phenolic compounds in this resin. This objective was accomplished by exposing mice to
voluntary feeding on resin-treated rat chow and by oral gavaging of mice with the following doses and compounds: Resin-100 mg (n =
7), NDGA- 15 mg (n = 8), and NDGA-100 mg (n = 10) and Control (n = 6). Our hypothesis was that NDGA is responsible for the toxicity
of Larrea divaricata’s phenolic resin. Voluntary resin intake by mice had a pronounced toxic effect, producing body mass
loss and significant reduction of food intake. Mice gavaged with Resin-100 mg, NDGA-100 mg, and NDGA-15 mg showed a significant
reduction in survival probability compared to mice under Control conditions. Animals exposed to NDGA-15 mg had a higher
survivorship compared to the NDGA-100 mg animals, and equivalent survivorship to the Resin-100 mg (containing 15 mg of NDGA)
animals. No significant differences in detoxification, measured as glucuronic acid conjugates in urine, were detected among gavage
treatments. Therefore, given that just 15 mg of NDGA were enough to produce the same effect as the whole resin, we suggest that
NDGA is the main constituent of Larrea divaricata’s resin responsible for the toxic effect of the phenolic resin
of this plant.
Key words:
Larrea divaricata,
phenolic resin, NDGA, survival, mice
