Molucidine and desmethylmolucidine as immunostimulatory lead compounds of morinda lucida (Rubiaceae)

Abstract

Morinda lucida is of great demand in ethnomedicine for treating different kinds of sicknesses. This research work was directed towards validation of the immunostimulatory potentials of M. lucida in immunocompromised animal model as well as filling the gap in knowledge on the bioactive compounds responsible for this effect. The methanol leaf extract was separated into n-hexane, ethyl acetate and butanol fractions. The extract and fractions were tested on cyclophosphamide immunosuppressed mice at doses ranging from 50 – 200 mg/kg with levamisole as positive control. The chromatographic methods were used in purification and isolation of the major bioactive compounds and their structures elucidated by 1D NMR spectroscopy. Other minor compounds present in the fractions were determined by dereplication using HPLC-DAD analysis. The isolated Compounds 1 and 2 were elucidated as molucidine and desmethylmolucidine respectively. Other minor compounds present in the fractions were luteolin, kaempferol-3-O-glucoside, quercetin, cinnamic acid, hyperoside, and cyclopenol. The extract and fractions showed significant (p < 0.05) increase in cellular immunity with ethyl acetate fraction being the most active fraction. The identification and isolation of these compounds as lead compounds responsible for the immunostimulatory activity constitute additional knowledge in the medicinal properties of M. lucida.