Test for alkaloids

Around 200mg plant material was boiled in 10mL methanol and filtered. Then, 1% HCl was added followed by 6 drops of Dragendorff reagent. The brownish-red precipitate was taken as a piece of evidence for the presence of alkaloids. Towards the end, an alkaloids test was applied on few plant materials by diluting 2.5mg of the extract with 2.5ml of 1% HCl in a tube and boiled. Then, 1ml of the filtrate was added to 1ml of dilute ammonia. Finally, 1ml of chloroform (CHCl₃) was added and shaken gently to reveal the alkaloid base. Test for anthraquinones (Borntrager’s Test): About 1mg of each extract was reacted with 2ml benzene, shaken properly, and filtered through Whatman’s no. 1 filter paper. Then, the filtrates were allowed to reacted with 2.5ml of 10% ammonia solution and shaken properly. The presence of pink, red, or violet color in ammonia solution in the lower phase indicates a positive result. Test for cardiac glycosides (Keller-Kiliani test): About 1.25mg of each extract was allowed to react with 0.5ml chloroform and mixed carefully. About 0.5ml of concentrated sulfuric acid was then carefully added to form a lower layer. The reddish-brown color at the interface indicates the presence of a steroidal ring, the glycone portion of cardiac glycosides. Test for flavonoids: About 7.5mg of each dry extract was dissolved in 0.5ml of ethanol, concentrated HCl, and magnesium turnings. A yellowish coloration indicates the presence of flavonoids.