Analgesic effects of Stachys turcomanica extract in mice

Pain and inflammation are the complex biological responses to harmful stimulants. In fact, they are a protective attempt by the organism to remove the injurious stimulant. Natural products have long been recognized as an important source of therapeutically effective medicines. Different approaches have been developed to analyze analgesic and anti-inflammatory potential of plants in the past years. Stachys species (Lamiaceae) have been used as medicinal plants because of their biological activities. Some Stachys have been used as remedy for painful or inflammatory conditions in folk medicine [1,2]. In this study, the antinociceptive property of S. turcomanica was investigated by formalin test in mice. Aerial parts of S. turcomanica were collected from its growing area and identified. Dried and milled plant material was extracted by using methanol 80% and different concentrations of the dried extract were prepared. During the test, formalin solution (0.5%) was injected into the plantar surface of the right hind paw of the mice, 15 minutes after peritoneal injection of the plant methanol extract (100, 200 and 400mg/kg). In order to elucidate the probable mechanism of action of the plant extract, naloxone was administered with extract. The results showed that injection of the plant extract at the doses of 100, 200 & 400mg/kg significantly inhibited the chronic phase of formalin- induced pain. Intraperitoneal injection of opioid antagonist (naloxone) significantly reversed the analgesic effect of the extract in chronic phase. This result suggests that analgesic activity of this plant may be partly mediated by opioid system.

References: 1. Rezazadeh, Sh. et al. (2009)J. Med. Plants Res. 3: 368–376.

2. Hajhashemi, V. et al. (2007) Res. Pharmac. Sci. 2: 92–98.