Chemical examination of plant insecticides. Part III. Chemical components of Derris Robusta

Abstract

A detailed examination of D. robusta has now been made and two crystalline components isolated. The main component (D.R.I.) melts at 205-6° and agrees, in general, with the properties of robustic acid described by Harper except in melting point and analytical values. The same substance (D.R.I) was also obtained from the crude sample of robustic acid supplied by the Forest Research Institute, Dehra Dun, from where Dr. Harper also got his material. The name robustic acid has been retained for it. The molecular formula, C₂₂H₂₀O₆ agrees with the results more closely. The molecule contains two methoxyls and one hydroxyl group. The acid nature of robustic acid has now been shown to be due to a phenolic hydroxyl just as in the case of scandenin and lonchocarpic acid. These three compounds seem to form a new type not having any simple relationship with rotenone. The second component now named 'robustenin' melts at 188-89°, is neutral in nature and has the probable molecular formula C₂₁H₂₀O₆. It contains two methoxyls.