Anti-nociceptive and anti-hyperprolactinemia activities of Fructus Viticis and its effective fractions and chemical constituents

Vitex rotundifolia L. is widely distributed along the sea coast of China. The aim of this study was to investigate the anti-nociceptive and anti-hyperprolactinemia activities of substances isolated from Fructus Viticis (the fruit of Vitex rotundifolia), which may be effective in the treatment of pre-menstrual symptoms, using acetic-acid-induced writhing and metoclopramide-dihydrochloride-induced hyperprolactinemia in mice. The fractions effective in terms of anti-nociceptive and anti-hyperprolactinemia activities were obtained from Fructus Viticis by elution through macro-porous resin, and polyamide and silica gel column chromatography. The standardization of the fractions obtained from the separation procedures was carried out by means of high-performance liquid chromatography (HPLC)-fingerprint. In this study, the flavone-enriched fraction (Fraction 6) showed a higher inhibitory rate than indomethacin (69.4% vs. 56.4%) at a dose of 50 mg/kg body wt., and significantly reduced the prolactin level as compared to HPRL-treated mice (8.2 ng/ml vs. 25.5 ng/ml). Furthermore, this fraction showed anti-nociceptive activity in a dose-dependent manner (10-50 mg/kg body wt., i.g.). On further purification with silica gel, Casticin was isolated from this fraction and it decreased abnormal serum levels of prolactin by approximately 50% (p < 0.01). Using bioassay-screening methods, our results indicate that the presence of flavonoids such as Casticin in this plant may be responsible for the activity effects. Casticin has potent analgesic and anti-hyperprolactinaemia properties, is likely to be one of the active components of Fructus Viticis, and may have a role in treating PMS (premenstrual syndrom).