Roylea cinerea (D.Don) Baillon: Ethnomedicinal uses, phytochemistry and pharmacology: A review

Roylea cinerea (D.Don) Baillon: Roylea cinerea (D.Don) Baillon family Lamiaceae is a shrub of the monotypic genus. Aerial parts of the plant are used traditionally in Indian sub-Himalayas and Nepal for the treatment of jaundice, skin diseases, malaria, diabetes, febrifuge and contusions. Method: This article reviews botanical description, phytochemistry, ethnomedicinal uses and pharmacological activities of R. cinerea to evaluate if the scientifically evaluated pharmacological profile of the plant can corroborate ethnomedicinal uses. A survey was conducted to document ethnomedicinal and folklore uses of the plant in five districts of Himachal Pradesh, India. Results: Phytochemical studies of R. cinerea reveal the presence of glycosides, diterpenes, flavonoids, tannins, steroids, saponins and phenols. R. cinerea extracts. The compounds showed anticancer, antifungal, hepatoprotective, antiperiodic, antiprotozoal, antidiabetic and antioxidant activities on scientific evaluation. A diterpenoid from the plant, precalyone, exhibited antiproliferative activity against P-388 lymphocytic leukemia cell line. Cinereanoid D, a labdane diterpenoid that inhibits ATP binding of heat shock protein Hsp90, is a potential anticancer lead. Two compounds from aerial parts of the plant, 4-methoxybenzo[b]azet-2(/H)-one and 3 beta-hydroxy-35-(cyclohexy1-5'-propan-7'-one)-33-ethy1-34-methylbacteriohop-16-ene, showed antidiabetic activity. Thus, the scientific reports confirm the ethnomedicinal use of this plant in diabetes, malaria and liver diseases. Conclusion: Roylea cinerea is a traditionally used medicinal plant from Western Himalayas. The pharmacological evaluation confirmed the ethnomedically claimed antidiabetic activity using scientifically accepted protocols and controls, although some of the studies require reconfirmation. The bioactivity-guided fractionation attributes the activity to 4-methoxybenzo[b]azet-2(./H)-one and 3/3-hydroxy-35-(cyclohexy1-5'-propan-7'-one)-33ethy1-34-methylbacteriohop-16-ene. Further, cinereanoid D is a potential lead for targeting Hsp90 and its medicinal chemistry studies can lead to a potent anticancer compound. The plant extract also showed antimalarial and hepatoprotective activities. Some of the studies discussed in this review require reconfirmation, as the protocols lacked proper positive and negative controls. Thus, the review of the scientific reports on Roylea cinerea supports ethnomedicinal use as antidiabetic, antimalarial and hepatoprotective. Further studies to prove scientific basis for use in leucorrhea, skin diseases, inflammation and strengthening of claims for liver tonic are required.