Coumarins from Olea africana and Olea capensis

Esculetin and scopoletin were isolated from the bark of Olea africana while isoscopoletin and scoparone were isolated from the bark of Olea capensis. The distribution of these coumarins in Olea species from South Africa is described.     

Antioxidant Efficacy of Esculetin against Tert-Butyl Hydroperoxide-Induced Oxidative Stress in HEK293 Cells

Esculetin is an antioxidant and anti-inflammatory compound derived from coumarin. Oxidative stress can cause overproduction of reactive oxygen species (ROS), which can lead to the development of chronic kidney failure. In this study, human embryonic kidney 293 (HEK293) cells were treated with tert-butyl hydroperoxide (t-BHP) to determine the antioxidant effects of esculetin. HEK293 cells were treated with t-BHP to validate changes in cell viability, ROS production, and apoptosis, and then treated with esculetin to evaluate the changes. Changes in mRNA and protein levels were analyzed using a proteome kit, PCR, and Western blotting. Esculetin improved HEK293 cell viability and reduced apoptosis caused by t-BHP-induced oxidative stress. At the mRNA and protein levels, esculetin decreased pro-apoptotic factor expression as well as increased anti-apoptotic factor expression. The antioxidant efficacy of esculetin was validated when it inhibited the apoptosis caused by t-BHP-induced oxidative stress in HEK293 cells.     

Les flavonoides des tiges principales de Periploca graeca cultive en conditions uniformes

The level of flavonoids does not change significantly when the main stem of plants cultivated in a controlled environment change from the short upright type to the twining type, but the quantity of cafeic acids derivatives is greater. The flavonoid content changes with temperature and light, with no correlation between the variation in elongation rate and stem type. Nevertheless, stems maintained in the short upright stage at a temperature of 15° are richer in derivatives of esculetin, ferulic acid and p-coumaric acid. The flavonoid content of these short upright main stems resemble that of short upright lateral stems grown under natural conditions. In the controlled environment, the axillary buds of the main stem give rise to short upright lateral stems and twining lateral stems which possess the same flavonoids as lateral stems under natural conditions. There is no evidence of any relationship between the stem type and the flavonol content and this group of compounds are not responsible for circumnutation in Periploca graeca.