Toxicity to sea urchin egg development of the quinone fraction obtained from Auxemma oncocalyx

Auxemma oncocalyx Taub. belongs to the Boraginaceae family and is native to the Brazilian northeast where it is known as "pau-branco". We investigated the ability of the water soluble fraction isolated from the heartwood of A. oncocalyx to inhibit sea urchin egg development. This fraction contains about 80 percent oncocalyxone A (quinone fraction), a compound known to possess strong cytotoxic and antitumor activities. In fact, the quinone fraction inhibited cleavage in a dose-dependent manner [IC50 of 18.4 (12.4-27.2) æg/ml, N = 6], and destroyed the embryos in the blastula stage [IC50 of 16.2 (13.7-19.2) æg/ml, N = 6]. We suggest that this activity is due to the presence of oncocalyxone A. In fact, these quinones present in A. oncocalyx extract have strong toxicity related to their antimitotic activity

Taurine modulates chemical nociception in mice

The effect of taurine on nociception was investigated in adult male Swiss mice using the formalin and acetic acid tests. Taurine (50-200 mg/kg) injected sc into the animals (N = 6 per group) 30 min before formalin injection into the right hind paw reduced formalin-induced early phase (0-5 min) licking activity by 30-42 per cent , but had no effect on the late phase (20-25 min) response. Writhing responses induced by acetic acid injected ip were also significantly inhibited by 49 per cent and 56 per cent by doses of 100 and 200 mg/kg taurine, respectively. In both tests taurine demonstrated antinociception which was significantly blocked by naloxone (1 mg/kg, sc, administered simultaneously with taurine). The naloxone-sensitive antinociceptive action of taurine was probably mediated via modulation of endogenous pain-regulatory systems that involve opioid peptides, neuropeptides like substance P and amino acids such as glutamate and aspartate