In vivo and in vitro antiplasmodial activity of extracts, fractions and an isolated compound from silk of zea mays (corn silk)

This study has investigated antiplasmodial activity of extracts, fractions and an isolated compound from corn silk using both in vivo and in vitro assays. Also, safety studies were carried out on the extract. Pharmacologically, both aqueous and methanolic extracts demonstrated remarkable in vivo antiplasmodial activity of 78.9 ± 1.59 % and 77.3 ± 0.92 % reduction in parasitaemia respectively. The bioassay guided fractionation indicated that ethyl acetate fraction of the methanolic extract of corn silk exhibited highest antiplasmodial activity among the fractions investigated. Employing column chromatography and other chromatographic methods on the ethyl acetate fraction of the methanolic extract of corn silk led to isolation of norbergenin. Spectroscopic methods such as infrared, one-dimensional, two-dimensional nuclear magnetic resonance and others were used in characterization and identification of the compound. Antiplasmodial investigation of the compound using in vitro SYBR Green 1 fluorescent-based assay on the chloroquine-sensitive based plasmodial 3D7 strain showed that it possessed antiplasmodial activity of IC50 value of 15.31±2.10 µg/mL and could be linked to the bioactive compounds in ethyl acetate fraction. The results of this study have granted support to the local use of corn silk for the treatment of malaria. It is the first report of these pharmacological studies. It is also the first report of isolating norbergenin from corn silk.