Several natural compounds containing a coumarin moiety have been reported. They have multiple biological activities, e.g., as scavengers of reactive oxygen species (ROS) and to reduce the inflammatory processes by inhibition of enzymes like COX or LOX. A study was made of the inhibitory capacity of seven natural coumarins and one derivative of esculetin, against soybean 15-lipoxygenase (15-sLOX). The studied coumarins showed interesting degrees of inhibition compared to quercetin, a known LOX inhibitor. Docking studies of some compounds into the binding site of 15-sLOX and 5-hLOX were also made.

A cromatografia do extrato resinoso das partes aéreas de Haplopappus remyanus conduziu ao isolamento do ácido 18-acetoxilabda-7,13E-dien-15-óico, assim como dos derivados monoterpênicos 9-hidróxi-α-terpineol, 9-benzoilóxi-α-terpineol, 7-hidróxi-9-benzoilóxi-α-terpineole 9-benzoilóxi-(1-formil)-α-terpineol. As estruturas para os novos compostos foram propostas com base em evidências espectroscópicas. A presença de quercetina e de outros cinco flavonóides conhecidos e identificados neste estudo pode ser responsável pela alta atividade antioxidante descrita e pelo moderado efeito tópico anti-inflamatório sobre edema de orelha induzido. Uma avaliação MTT com células tumorais CCRF-CEM mostrou 50% da atividade citotóxica exibida pela doxorubicina nas mesmas condições. Diferenças quantitativas na composição química foram detectadas em comparação com estudos prévios com a mesma espécie, as quais podem ser atribuídas a fatores ambientais.

Chromatography on the resinous extract of aerial parts of Haplopappus remyanus led to the isolation of 18-acetoxy-labda-7,13E-dien-15-oic acid along with the monoterpene derivatives 9-hydroxy-α-terpineol, 9-benzoyloxy-α-terpineol,7-hydroxy-9-benzoyloxy-α-terpineoland 9-benzoyloxy-(1-formyl)-α-terpineol. Structures for the new compounds are proposed on spectroscopic evidence. The presence of quercetin and five other known flavonoids identified in this study could account for the reported high antioxidant activity and the moderate topic anti-inflammatory effect on induced ear oedema. MTT assay with CCRF-CEM tumor cells showed 50% of the cytotoxic activity displayed by doxorubicin under the same conditions. Quantitative differences in chemical composition were detected in comparison with previous studies of the species that could be attributed to environmental factors.