Antileishmanial polyphenols from Corymbia maculata

An activity-guided fractionation was used to identify the antileishmanial compounds of Corymbia maculata. The hexane, ethyl acetate and methanol extracts were active in in vitro antileishmanial assay. Twelve polyphenols including 8-demethyl eucalyptin (1), eucalyptin (2), myrciaphenone A (3), myrciaphenone B (4), quercetin-3-O-β-d-xylopyranoside (5), myricetin-3-O-α-l- rhamnopyranoside (6), quercetin-3-O-β-d-galactopyranoside (7), quercetin-3-O-β-d-glucopyranoside (8), quercetin-3-O-α-l- rhamnopyranoside (9), syringic acid (10), gallic acid-3-methyl ether (11), gallic acid-4-methyl ether (12) and gallic acid (13) were isolated from the active extracts. All the tested compounds except 8-demethyleucalyptin and myrciaphenone B showed strong to moderate (6.9-24.5 μM) antileishmanial activity against Leishmania donovani promastigotes. An HPLC-PDA method has been developed to detect/quantify 29 compounds in the extracts of C. maculata leaves. This validated method allows simultaneous quantitation of seven flavonoids, fourteen phloroglucinols and eight other polyphenols and can be applied for qualitative as well as quantitative determination of phytoconstituents in Eucalyptus matrices. [Figure not available: see fulltext.]