Mustard oils and mustard oil glucosides occurring in the seed kernels ofPutranjiva roxburghii Wall.

Summary

Besides phenyl mustard oil reported by Gambhir and Dutt two other mustard oils, namelyisopropyl andsec-butyliso-thiocyanates, have been isolated from the steam volatile oil (yield 0·5%) of the wet kernels ofPutranjiva roxburghii Wall. All the three mustard oils (69% isopropyl, 28%sec-butyl and 3% phenyl mustard oils) are derived from glucosides present in the seed kernels and are only liberated from them in the presence of moisture by enzymic hydrolysis along with dextrose and potassium acid sulphate. Under these moist conditions it is found that as much as 35% of the mustard oils are extracted by petroleum-ether from the kernels along with the fatty oil but only to the extent of 1·7% if the kernels are dry. Fatty oil expressed from dry kernels contain only traces of the mustard oils.

Out of these mustard oils onlysec-butyl mustard oil has been previously reported to occur in the plants of the Cruciferæ or mustard family but all the three are now found for the first time in a plant of the Euphorbiaceæ family. The characteristic mustard smell of the moist kernels is due toisopropyl andsec-butyl mustard oils, the principal constituents of the steam volatile oil isolated from them.

While mustard oil glucosides have been isolated in the form of their mixture their individual isolation has not been possible owing to their highly hygroscopic nature and due to the difficulty of obtaining them in the crystalline state.