Tyrosinase inhibitors from Rhododendron collettianum and their structure-activity relationship (SAR) studies.
A new coumarinolignoid 8'-epi-cleomiscosin A (1) together with the new glycoside 8-O-beta-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 microM) against the enzyme tyrosinase, as compared to the standard tyrosinase inhibitors kojic acid (IC50=16.67 microM) and L-mimosine (IC50=3.68 microM), indicating its potential used for the treatment of hyperpigmentation associated with the high production of melanocytes.
Ahmad
Viqar Uddin
VU
HEJ Research Institute of Chemistry, University of Karachi, Karachi, Pakistan. vuahmad@cyber.net.pk
Ullah
Farman
F
Hussain
Javid
J
Farooq
Umar
U
Zubair
Muhammad
M
Khan
Mahmud Tareq Hassan
MT
Choudhary
Muhammad Iqbal
MI
D001578:Benzopyrans / Q000737:chemistry / Q000494:pharmacology*; D003374:Coumarins / Q000737:chemistry / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D006027:Glycosides / Q000737:chemistry / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors*; D010936:Plant Extracts / Q000737:chemistry; D029793:Rhododendron / Q000737:chemistry*; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship
C499804:8'-epi-cleomiscosin A; C499806:8-O-beta-D-glucopyranosyl-6-hydroxy-2-methyl-4H-1-benzopyrane-4-one; D001578:Benzopyrans; D003374:Coumarins; D004791:Enzyme Inhibitors; D006027:Glycosides; D010936:Plant Extracts; D014442:Monophenol Monooxygenase