Chemical and Pharmaceutical Bulletin
Online ISSN : 1347-5223
Print ISSN : 0009-2363
ISSN-L : 0009-2363
Tyrosinase Inhibitors from Rhododendron collettianum and Their Structure–Activity Relationship (SAR) Studies
Viqar Uddin AhmadFarman UllahJavid HussainUmar FarooqMuhammad ZubairMahmud Tareq Hassan KhanMuhammad Iqbal Choudhary
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2004 Volume 52 Issue 12 Pages 1458-1461


A new coumarinolignoid 8′-epi-cleomiscosin A (1) together with the new glycoside 8-O-β-D-glucopyranosyl-6-hydroxy-2-methyl-4H-1-benzopyrane-4-one (2) have been isolated from the aerial parts of Rhododendron collettianum and their structures determined on the basis of spectroscopic evidences. Tyrosinase inhibition study of these compounds and their structure–activity relationship (SAR) were also investigated. The compounds exhibited potent to mild inhibition activity against the enzyme. Especially, the compound 1 showed strong inhibition (IC50=1.33 μM) against the enzyme tyrosinase, as compared to the standard tyrosinase inhibitors kojic acid (IC50=16.67 μM) and L-mimosine (IC50=3.68 μM), indicating its potential used for the treatment of hyperpigmentation associated with the high production of melanocytes.

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© 2004 The Pharmaceutical Society of Japan
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