Processing of nux vomica. VII. Antinociceptive effects of crude alkaloids from the processed and unprocessed seeds of Strychnos nux-vomica in mice.

We examined the antinociceptive effects of the crude alkaloid fractions (CAF) of nux vomica (the dried seeds of Strychnos nux-vomica L.) and the influences of various processing methods upon their antinociception in three analgesic tests in mice. In the tail-pressure test, the CAF (0.01--1 micrograms/kg, i.p.) of nux vomica that was unprocessed or treated with sand-, licorice-, oil- or vinegar and sand-processing showed clear antinociception. The CAF (1 microgram/kg, i.p.) of vinegar-processed nux vomica showed antinociception, without effects at lower doses of 0.01 and 0.1 microgram/kg and those treated with urine- or urine and sand-processing were without effects at doses of 0.01--1 microgram/kg. Morphine (2 mg/kg, s.c.) showed short-lasting antinociception, without effects at a dose of 1 microgram/kg. In the hot-plate test, the CAF (100 microgram/kg, i.p.) of nux vomica having undergone sand-processing produced a significant antinociception, without effects at lower doses of 0.01 and 1 microgram/kg. The CAF (0.01--100 microgram/kg, i.p.) of nux vomica that was unprocessed or treated with oil- or vinegar and sand-processing and morphine (1 and 100 micrograms/kg, s.c.) were without effects. In the acetic acid-induced writhing test, the CAF (1 microgram/kg, i.p.) of nux vomica that was treated with sand-processing significantly inhibited the writhing behavior, while those of nux vomica that was unprocessed or treated with oil- or vinegar and sand-processing and morphine were without effects at a dose of 1 microgram/kg. The present results demonstrate the antinociceptive effects of the CAF of nux vomica and suggest that sand-processing is good for the analgesic potency of nux vomica. It is also suggested that the CAF of nux vomica has distinct antinociceptive potency, even after treatment with licorice-, oil-, vinegar and sand-processing.