In the essential oil distilled from aerial parts (flowers, leaves) of ajwain grown in Algeria, however, isothymol (50%) was found to be the dominant constituent before p-cymene, thymol, limonene and γ-terpinene. Note, however, that the name isothymol is not well defined and might refer to both 2-isopropyl-4-methylphenol and 3-isopropyl-6-methylphenol (carvacrol).
From South Indian ajwain fruits, almost pure thymol has been isolated (98%), but the leaf oil was found to be composed of monoterpenoids and sesquiterpenoids: 43% cadinene, 11% longifolene, 5% thymol, 3% camphor and others.
Ajwain (also known as Carom, Ajowan, Bishop's Weed and Seeds Of Bishop's Weed), is an uncommon spice except in certain areas of Asia. It is the small seed-like fruit of the Bishop's Weed plant, (Trachyspermum ammi syn. Carum copticum), egg-shaped and grayish in colour. The plant has a similarity to parsley.
Ajowan contains thymol which is a germicide and antiseptic and is prescribed for diarrhoea, colic and other bowel problems, helping expel wind and mucus. Sometimes used in the treatment of asthma, the seeds being smoked in a pipe to relieve shortness of breath. Water in which ajowan seeds have been boiled is used to 'cleanse the eyes and cure the ears of deafness.' It is said that if ajowan seeds are soaked in the juice of a lemon and dried 7 times, then ingested, they cure impotence.