Medicinal importance and utilization of Rhododendron- A Review

Rhododendron arboreum is an evergreen shrub or small tree with a showy display of bright red flowers. Rhododendron is the national flower of Nepal and is known as (Laligurans) & the state tree of Uttarakhand. It is called ‘Burans, Bras, Buras or Barahkephool’ in local dialect. Rhododendron arboreum is a wild plant species possesses high ecological importance and the flower of the species having unique medicinal and nutritional value. It is widely popular for the processed juice of its flowers which have gained market popularity as rhodojuice /sharbat. The paper highlighted medicinal value and potential of R. arboreum for bioprospecting by making value added products to improve the livelihood and employment opportunities of hill farmers. Key wordsRhododendron, History, Medicinal uses,Juice preparation, Ornamental uses Introduction The genus Rhododendron (Greek Rhodon= rose and Dendron= tree) belongs to the family Ericaceae. Three major species (Rhododendron arboretum Smith, R. anthopogon D.Don and R. Campanulatum D.Don) have been reported from Western Himalayas (Prakash et al., 2007) however, R. arboretum Smith is the predominating species found in the hills of Uttarakhand state of India (Mehta et al., 2010). Leaves and flowers have got various medicinal uses such as treatment of illness, headache, diabetes, rheumatism etc. (Sharma et al., 2010). In the Indian Himalayan Region (IHR) over 675 wild edibles are known (Samant and Dhar, 1997) of which Rhododendron arboreum, commonly known as “Burans”, is amongst highly valued wild edible flower growing between 1500 and 2400 m asl. The genus forms dominant combination of forest types in the high altitudes (above 1500 m) of the of Garhwal region having ecological significance and economic importance in addition to its graceful flowers. A total of 72 species, 20 subspecies and 19 varieties have been listed from India (Mao et al., 2001). The genus Rhododendron has long been regarded as a rich source of secondary metabolites such as phenols, phenolic acids, flavonoids, terpenoids, resins etc. The ethanol soluble portion of the flower of R. arboretum showed áglucosidase inhibitor and potent diabetic activity (Sharma et al ., 2010). Phenolic acids obtained from its leaves and twings have shown anti-HIV activity (Kashiwada et al., 2001). Recently Verma et al. (2000) investigated the antiinflammatory and antiseptic properties of flowers of R. arboretum. The flowers of R.arboreum are deep scarlet in color, which comes in upto twenty blossoms in a single tree. The fresh flowers which are sweet-sour in taste are used to make a health promoting beverage i.e. squash by local inhabitants. Therefore Rhododendron squash fetches relatively higher prices and preferred for medicinal purposes by consumer in this region. However this squash has a slight bitter taste and consumers did not consuming it. This is the reason that Rhododendron squash has fewer takers beyond this region, despite its high nutritive value. Moreover, Rhododendron squash available in the market are not uniform in their organoleptic and quality attributes owing to arbitrary preparation practices adopted by individuals. A fewer studies have been focused on phytochemical composition of Rhododendron (Prakash et al. 2007; Silies et al. 2010; Sharma et al. 2010; Verma et al; 2010). Until no attempt have been made to estimate the total phenolic content, total antioxidant capacity and other quality parameters. Variations and Sub-Species Dominant species=R. arboreum roseumpink, R.arboreum album Sub species=R. arboreum s. sp. CinnamomeumOrange, pale pink, bi-color (indumentums of a rusty or cinnamon) R. arboreum s. sp. Campbelleaebrown and woolly indumentums on the underside of the leaf. Among all Indian rhododendron species, R. arboreum is widely distributed, occurring from western to eastern Himalayan region and other neighbouring countries (Giriraj et al., 2008). Apart from their worldwide aesthetic and ethnic uses, several species have commercial and medicinal values (Leach 1986). Rhododendron species with high levels of phenols, promising antioxidant and free radical scavenging activities may be utilized in the development of healthcare products (Dhan et al. 2007).