IN VITRO ANTIOXIDANT AND CYTOTOXIC POTENTIAL OF COSTUS SPECIOSUS (KOEN.) SMITH RHIZOMEAbstract
This study evaluated the in vitro antioxidant and cytotoxic potential of methanolic extract of the rhizome of Costus speciosus (Zingiberaceae). The different antioxidants assays including total antioxidant activity, DPPH, nitric oxide (NO) scavenging, total phenolic content and flavonoid content were studied. Costus speciosus exhibited potent total antioxidant activity which was expressed as an equivalent of ascorbic acid mg/g plant extract. In addition, Costus speciosus had effective free radical scavenging, nitric oxide scavenging activity, total phenolic content and flavonoid content depending on concentration. These various antioxidant activities were compared with the standard antioxidants ascorbic acid and quercetin. The extract of the rhizome of Costus speciosus also demonstrated a strong cytotoxic activity against brine shrimp nauplii with an LC50 value of 31.55 µg/ml.