Coleus (Coleus forskohlii Briq.)

What is Coleus?

Coleus forskohlii Briq. is a small, branched, aromatic perennial herb of the family Labiatae (the mint family, Lamiaceae). Like its relatives it carries the characteristic aromatic foliage of the mints, but its value lies below ground: the fleshy, tuberous root is the part that yields the plant's defining diterpene. It is the only known natural source of forskohlin, and it is on this single marker compound that the botanical is identified and standardized.

Where does it grow?

Geographical distribution

Coleus is distributed across the subtropical Himalayas of Kumaon and Nepal, ascending to about 8,000 ft, and southward through the Deccan peninsula, Gujarat and Bihar. Its range therefore spans both the temperate Himalayan foothills and the warmer plains of central and western India.

Ideal growing conditions

The plant favours the well-drained, sun-exposed slopes typical of the subtropical Himalayan belt and the open, seasonally dry terrain of the Deccan. As a hardy perennial it tolerates the higher elevations of the Kumaon and Nepal hills while remaining at home across the plains of Gujarat and Bihar.

Parts used

The root is the part used. The tuberous root concentrates the plant's characteristic diterpene and forms the basis of the standardized extract.

Chemical constituents

The principal chemical constituent of Coleus is forskohlin (also written forskolin), a labdane diterpene found in the root. Forskohlin is the marker compound by which the botanical is identified and standardized, and it defines the profile of a quality-assured Coleus extract.

Ayurvedic profile

Coleus belongs to the aromatic mint family and has a place in the traditional Indian materia medica, where its pungent, warming character underlies its classical use. It is conventionally characterised through the Ayurvedic attributes below.

• Rasa (taste): Katu (pungent), Tikta (bitter)
• Virya (potency): Ushna (heating)
• Vipaka (post-digestive effect): Katu (pungent)
• Dosha action: Pacifies Kapha and Vata, in keeping with its warming, aromatic nature