title: Tyrosinase inhibitory cycloartane type triterpenoids from the methanol extract of the whole plant of Amberboa ramosa Jafri and their structure-activity relationship.
abstract: New tyrosinase inhibitory cycloartane triterpenoids have been discovered from the methanol extract of the whole plant of Amberboa ramosa (Roxb.) Jafri, which is a member from the Compositae family. Utilizing the conventional spectroscopic techniques, including 1D and 2D NMR analysis, and also by comparing the experimental with literature data, the isolated compounds proved to be cycloartane type triterpenoids. These cycloartanes are: (22R)-cycloart-20, 25-dien-2alpha3beta22alpha triol (1), (22R)-cycloart-23-ene-3beta, 22alpha, 25-triol (2), cycloartenol (3), cycloart-23-ene-3beta, 25-diol (4), cycloart-20-ene-3beta, 25-diol (5), cycloart-25-ene-3beta, (22R) 22-diol (6), 3beta, 21, 22, 23-tetrahydroxy-cycloart-24 (31), 25 (26)-diene (7), and (23R)-5alpha-cycloart-24-ene-3beta, 21, 23-triol (8). Out of these eight compounds, compound 3 did not show any activity against the enzyme tyrosinase. Among them compound 7 was found to be the most potent (1.32 microM) when compared with the standard tyrosinase inhibitors kojic acid (16.67 microM) and L-mimosine (3.68 microM). Finally in this paper, we have discussed the structure-activity relationships of these molecules.
authors.affiliation: Pharmacology Research Laboratory, Faculty of Pharmaceutical Sciences, University of Science and Technology, Chittagong, Bangladesh. khnmmd@unife.it
authors.forename: Mahmud Tareq Hassan
authors.initials: MT
authors.lastname: Khan
authors.forename: Sher Bahadar
authors.initials: SB
authors.lastname: Khan
authors.forename: Arjumand
authors.initials: A
authors.lastname: Ather
mesh_terms: D019659:Asteraceae / Q000737:chemistry*; D000432:Methanol; D015394:Molecular Structure; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry*; D013329:Structure-Activity Relationship; D013729:Terpenes / Q000737:chemistry* / Q000494:pharmacology*; D014315:Triterpenes / Q000737:chemistry*
chemical_list: D010936:Plant Extracts; D013729:Terpenes; D014315:Triterpenes; C085352:cycloartane; D014442:Monophenol Monooxygenase; D000432:Methanol