ACTIVITY OF CANNABIS IN RELATION TO ITS Δ‘-trans-TETRAHYDROCANNABINOL CONTENT
- 1Conditions have been worked out for a reliable estimation of the cataleptic activity of Δ′-trans-tetrahydrocannabinol (THC) after oral administration to mice, using the ring test over a period of 6 h.
- 2By this method, the activity of cannabis herb and 5 crude fractions were measured against THC; at the same time the THC contents were determined chemically.
- 3The B/C ratio (biological activity divided by chemical assay) was calculated for each. With cannabis herb the value was 3.3 and with extracts prepared with ethanol or 70% ethanol the values ranged from 3.2 to 7.1, indicating that in all samples the activity was much higher than would be expected from their THC content.
- 4The cannabinoids were completely extracted from a sample of herb using petroleum spirit and the marc examined for a possible synergist. Surprisingly, it contained a powerful inhibitor of the action of THC, which could be restored by intraperitoneal prostaglandin E2 (3 μg/kg). Some crude fractions had inhibitory activities about 10 times that of aspirin.
- 5In contrast, the petroleum spirit extract (referred to in 4) had a surprisingly high B/C ratio of 23, indicating that a powerful synergist of THC activity is present.
- 6The net effect of the herb and ethanol extracts is probably due to a balance of synergist and inhibitor.