4'-Hydroxy-6,7-methylenedioxy-3-methoxyflavone: A novel flavonoid from Dulacia egleri with potential inhibitory activity against cathepsins B and L.

A new flavone, 4'-hydroxy-6,7-methylenedioxy-3-methoxyflavone 1, and two other nucleosides, ribavirin 2 and adenosine 3, were isolated from the leaves of Dulacia egleri. The nucleosides were identified by spectroscopic techniques (1D, 2D-NMR) while the structure of the flavonoid was established by 1D, 2D-NMR analysis, including HRESIMS data. The results obtained in the biological assays showed that the compound 1 was able to inhibit cathepsins B and L with IC50 of 14.88 ±â€¯0.18 µM and 3.19 ±â€¯0.07 µM, respectively. The mechanism of inhibition for both enzymes were determined showing to be competitive at cathepsin B with Ki = 12.8 ±â€¯0.6 µM and non-linear non-competitive with positive cooperativity inhibition at cathepsin L with Ki = 322 ±â€¯33 µM, αKi = 133 ±â€¯15 µM, ßKi = 5.14 ±â€¯0.41 µM and γKi = 13.2 ±â€¯13 µM.

Chemical constituents and antileukemic activity of Eugenia dysenterica.

The study about Eugenia dysenterica led to the isolation of 3-acetyl-urs-12-en-28-oic (1), 3-acetyl-olean-12-en-28-oic acid (2) and isoquercetin (3) from the stem barks, and of 3-O-ß-glucopyranosyl-ß-sitosterol (4), methyl 3-hydroxy-4-methoxybenzoate (5), methyl 4-hydroxyphenyl propionate (6), E-methyl-4-hydroxycinnamate (7), quercetin-3-O-(6ꞌꞌ-O-galloyl)-ß-d-glucopyranoside (8) and quercetin-3-O-ß-d-galactopyranoside (9) from the leaves. The structures 1-9 were set through the analysis of their NMR spectroscopic data. Compounds 2, 3 and 5-8 were reported for the first time in the Eugenia genus. Compound 8 reduced cell viability and presented IC50 values 40.3 and 36.7 µM, for the CCRF-CEM and the Kasumi-1 cells, respectively.