Inhibition of cholinesterase activity by extracts, fractions and compounds from Calceolaria talcana and C. integrifolia (Calceolariaceae: Scrophulariaceae)

Extracts, fractions and compounds from Calceolaria talcana and C. integrifolia exhibited strong inhibitory effects of the activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes using the in vitro Ellman's method. The most active samples were from the ethyl acetate extract, which caused a mixed-type inhibition against AChE (69.8% and 79.5% at 100 and 200 pg/ml, respectively) and against BChE (98.5% and 99.8% at 100 and 200 lig/ml, respectively) and its major components verbascoside 8 (50.9% and 70.0% at 200 pg/ml, against AChE and BODE, respectively), martynoside 9, and fraction F-7 (which corresponds to a mixture of 8, 9, and other phenylethanoids and phenolics that remain unidentified) (80.2% and 85.3% at 100 and 200 pg/ml, against AChE, respectively and 99.1% and 99.7% at 100 and 200 1.tg/ml, against BChE, respectively) inhibited the acetylcholinesterase enzyme competitively. The most polar fraction F-5 from n-hexane extract (a mixture of naphthoquinones: 2-hydroxy-3(1,1-dimethylallyl-1,4-naphthoquinone) 6, ot-dunnione 7 and other polar compounds that remain unidentified) showed a mixed-type inhibition (71.5% and 72.1% against AChE and BChE at 200 pg/ml, respectively). Finally, the methanol-soluble residue presented a complex, mixed-type inhibition (39.9% and 67.9% against AChE and BChE at 200 pg/ml, respectively). The mixture F-3 with diterpenes was obtained from the n-hexane extract: (1,10-cyclopropyl-9-epi-ent-isopimarol) 1, 19-a-hydroxy-abietatriene 2, and F-4 a mixture of triterpenes ot-lupeol 3, ii-sitosterol 4, ursolic acid 5 together with a complex mixture of terpenes that did not show activity. In summary, extracts and natural compounds from C talcana and C. integrifolia were isolated, identified and characterized as cholinesterase inhibitors. (C) 2013 Elsevier Ltd. All rights reserved.