Phytoecdysteroids of Silene guntensis and their in vitro Cytotoxic and Antioxidant Activity

Plants are an important source of medicinally potent secondary metabolites with a wide range of biological activities, including anticancer and antioxidant properties. Although many plants have been screened for active compounds, fundamental phytochemical investigations of previously neglected plants are still needed, especially in view of the interest in discovering new bioactive molecules with greater effi cacy and fewer side effects than existing drugs. Many species of the genus Silene (Caryophyllaceae) are abundant sources of ecdysteroids. The genus consists of more than 700 species (Mabberley, 2008) of which 84 grow in Central Asia (Bondarenko, 1971). Ecdysteroids have been recognized in more than 120 species and subspecies of Silene from the 155 species so far tested (Zibareva et al., 2009). Ecdysteroids have anabolic, adaptogenic, tonic (Slama et al., 1996), carcinogenic (El-Mofty et al., 1994), cardiotonic (Kurmukov and Yermishina, 1991), and antioxidant (Kuzmenko et al., 1997) properties. Since plant ecdysteroids are similar in structure to the arthropod moulting hormone, ecdysone, they act as antifeedants and interfere with the growth of insects (Kubo et al., 1983). Some species of Silene exert haemorheologic activity (Plotnikov et al., 1998) and are strongly fungicidal (Vivek et al., 2008). The steroid-containing fractions of some Silene species are immunosuppressive, potentially anti-infl ammatory (Gasiorowski et al., 1999), inhibit the proliferation of cancer cells by inducing apoptosis (Gaidi et al., 2002), and show in vivo anticancer activity in mice (Zibareva, 2003). The potential economic signifi cance and biological value of ecdysteroids encouraged us to search for novel sources of phytoecdysteroids in the genus Silene. Thus, Silene guntensis B. Fedtsch from Uzbekistan, which had not been investigated previously (Vvedenskiy, 1953), is a promising target for phytochemical investigations and determination of its biological activity. We report here the isolation and structural elucidation of three phytoecdysteroids from extracts of this plant together with their cytotoxic and antioxidant activities. These compounds exhibit mild cytotoxic Phytoecdysteroids of Silene guntensis and their in vitro Cytotoxic and Antioxidant Activity Nilufar Z. Mamadalieva, Mahmoud Z. El-Readi, Abdulaziz A. Janibekov, Ahmad Tahrani, and Michael Wink*