Triterpenoid saponins from the stem bark of Caryocar villosum

Five triterpenoid saponins, caryocarosides II-22 (3), III-22 (4), II-23 (5), III-23 (6), and II-24 (7), have been isolated from the methanol extract of the stem bark of Caryocar villosum, along with two known saponins (1-2). The seven saponins are glucuronides of hederagenin (II) or bayogenin (III). Caryocaroside II-24 (7) is an unusual galloyl ester saponin acylated on the sugar chain attached to C-28, the 3-O-alpha-L-rhamnopyranosyl-(1 -> 3)-beta-D-galactopyranosyl-(1 -> 3)-beta-D-glueuronopyranosyl hederagenin-28-O-[2-O-galloyi-beta-D-glucopyranosyl] ester. The structures of the saponins were established on the basis of extensive NMR (C-13, H-1, COSY, TOCSY, HSQC, HMBC and ROESY) and ESI-MS studies. The cytotoxic activity of saponins 2 and 3 was evaluated in vitro against human keratinocytes. The DOPA-oxidase inhibition and the lipolytic activities were evaluated ex vivo using an explant of human adipose tissue. (c) 2006 Elsevier Ltd. All rights reserved

Chevalierinoside A: A new isoflavonoid glycoside from the stem bark of Antidesma chevalieri Beille (Euphorbiaceae)

Chevalierinoside A (1), a new isoflavonoid glycoside determined as biochanin A 7-O-[a-L-rhamnopyranosyl-1→6-β-D-apiofuranosyl-1→2-β-D-glucopyranoside], together with the known friedelin (2), friedelan-3b-ol (3) and betulinic acid (4), were isolated from the stem bark of Antidesma chevalieri Beille. Their structures were established by direct interpretation of their spectral data, mainly TOF-HRESIMS, 1D-NMR (1H, 13C and DEPT) and 2D-NMR (COSY, ROESY, TOCSY, HSQC and HMBC), and by comparison with the literature. DOI: http://dx.doi.org/10.4314/bcse.v28i2.1

Synthesis, evaluation and molecular modelling of piceatannol analogues as arginase inhibitors

International audienceArginase is involved in a wide range of pathologies including cardiovascular diseases and infectious diseases whilst it is also a promising target to improve cancer immunotherapy. To date, only a limited number of inhibitors of arginase have been reported. Natural polyphenols, among them piceatannol, are moderate inhibitors of arginase. Herein, we report our efforts to investigate catechol binding by quantum chemistry and generate analogues of piceatannol. In this work, we synthesized a novel series of amino-polyphenols which were then evaluated as arginase inhibitors. Their structure–activity relationships were elucidated by deep quantum chemistry modelling. 4-((3,4-Dihydroxybenzyl)amino)benzene-1,2-diol 3t displays a mixed inhibition activity on bovine and human arginase I with IC50 (Ki) values of 76 (82) μM and 89 μM, respectively