The present invention deals with an efficient method of extraction of Carbazole alkoloids including mahanimbine from the leaves of Murraya koenigii and the use the extract as an anti-stress agent .The method of extraction comprises of steps of drying and powdering the leaves of Murraya koenigii, extraction with Methanol, acidifying, evaporating, adjusting the pH, subjecting the filtrate to liquid extraction with Methyl isobutene and collecting and concentrating the alkaloid phase by chromatography etc.