O novo flavan-3-ol contendo um substituinte fenilpropanoide apocinina E, juntamente com oito substâncias conhecidas, epicatequina, procianidina B2, procianidina B4, procianidina C1, cinchonaína Ia, cinchonaína Ib, cinchonaína IIb e cinchonaína IIa foram isoladas a partir do extrato acetona-H2O das cascas secas de Trichilia catigua. As substâncias cinchonaína Ib e cinchonaína IIb foram reavaliadas em relação à sua estereoquímica. Todas as substâncias foram caracterizadas por análises espectroscópicas incluindo ressonância magnética nuclear (NMR) 1D e 2D e espectrometria de massa (MS) de seus derivados acetilados. A configuração absoluta do substituinte fenilpropanoide foi determinada por espectropolarimetria de dicroísmo circular (CD) e pela análise do efeito anisotrópico empregando modelo de Dreiding, e por experimento de espectroscopia de efeito nuclear Overhauser (NOESY NMR). As nove substâncias mostraram maior atividade sobre o sequestro de radical livre e poder de redução do que o ácido ascórbico e Trolox frente ao radical livre 2,2-difenil-1-picrilhidrazila e no sistema do teste de redução do ferro (Fe3+-Fe2+).

The new phenylpropanoid substituted flavan-3-ol apocynin E, together with eight known compounds, epicatechin, procyanidin B2, procyanidin B4, procyanidin C1, cinchonain Ia, cinchonain Ib, cinchonain IIb, and cinchonain IIa were isolated from an acetone-H2O extract of the air-dried stem bark of Trichilia catigua. The cinchonain Ia e Ib were reevaluated to its estereochemistry. All the compounds were characterized by spectroscopic analysis including 1D and 2D nuclear magnetic resonance (NMR) and mass spectrometry (MS) of their peracetate derivatives. The absolute configuration of the phenylpropanoid moiety was determined by circular dichroism (CD) spectra and by analyzing the anisotropic effects in the Dreiding model and nuclear Overhauser effect (NOESY NMR) experiments. The nine isolated compounds showed higher radical scavenging activity and reducing power than ascorbic acid and Trolox in the free-radical 2,2-diphenyl-1-picrylhydrazyl and Fe3+-Fe2+ reduction assay systems.

Maytenus ilicifolia (Celastraceae) is a native plant of South America and popularly known as "espinheira-santa". The aim of this study was to evaluate the antioxidant capacity of extracts and isolated compounds from this plant. The antioxidant activity of the crude and semipurified extracts and isolated compounds was evaluated through DPPH-radical and phosphomolybdenum-complex assays. By both methods, the ethyl-acetate fraction demonstrated better antioxidant capacity compared with vitamin C and trolox. In the compounds, the higher the number of hydroxyls, the greater the antioxidant activity. In addition, stereochemistry influenced antioxidant activity, i.e., compounds with 2R,3R showed greater activity than those with 2R,3S.