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Vascular endothelial cell senescence is a leading cause of age-associated diseases and cardiovascular diseases. Interventions and therapies targeting endothelial cell senescence and dysfunction would have important clinical implications. This study evaluated the effect of 10 resveratrol analogues, including pterostilbene (Pts) and its derivatives, against endothelial senescence and dysfunction. All the tested compounds at the concentrations from [10.sup.-9] M to [10.sup.-6] M did not show cytotoxicity in endothelial cells by MTT assay. Among the 10 resveratrol analogues, Pts and Pts nicotinate attenuated the expression of senescence-associated [beta]-galactosidase, downregulated p21 and p53, and increased the production of nitric oxide (NO) in both angiotensin II - and hydrogen peroxide - induced endothelial senescence models. In addition, Pts and Pts nicotinate elicited endothelium-dependent relaxations, which were attenuated in the presence of endothelial NO synthase (eNOS) inhibitor L-NAME or sirtuin 1 (SIRT1) inhibitor sirtinol. Pts and Pts nicotinate did not alter SIRT1 expression but enhanced its activity. Both Pts and Pts nicotinate have high binding activities with SIRT1, according to surface plasmon resonance results and the molecular docking analysis. Inhibition of SIRT1 by sirtinol reversed the anti-senescent effects of Pts and Pts nicotinate. Moreover, Pts and Pts nicotinate shared similar ADME (absorption, distribution, metabolism, excretion) profiles and physiochemical properties. This study suggests that the Pts and Pts nicotinate ameliorate vascular endothelial senescence and elicit endothelium-dependent relaxations via activation of SIRT1. These two compounds may be potential drugs for the treatment of cardiovascular diseases related to endothelial senescence and dysfunction. Key words: endothelial cells, senescence, pterostilbene, sirtuin 1. La senescence des cellules endotheliales vasculaires et l'une des principales causes de maladies associees au vieillissement et de maladies cardiovasculaires. Des interventions et des traitements ciblant la senescence et le dysfonctionnement des cellules endotheliales auraient d'importantes repercussions en clinique. Cette etude visait a evaluer l'effet de 10 analogues du resveratrol, y compris le pterostilbene (Pts) et ses derives, sur la senescence et le dysfonctionnement endotheliaux. Aucun des composes evalues a des concentrations de [10.sup.-9] M a [10.sup.-6] M n'ont montre de cytotoxicite dans les cellules endotheliales soumises au test du MTT. Parmi les 10 analogues du resveratrol, le Pts et le nicotinate de Pts ont permis d'attenuer l'expression de la [beta]-galactosidase associee a la senescence, de reguler a la baisse p21 et p53, ainsi que de faire augmenter la production d'oxyde nitrique (NO) dans des modeles de senescence endotheliale engendree par l'angiotensine II comme le [H.sub.2][O.sub.2]. De plus, le Pts et le nicotinate de Pts ont suscite des relaxations dependantes de l'endothelium, lesquelles s'attenuaient en presence de L-NAME, inhibiteur de la NO synthase endotheliale (eNOS), ou de sirtinol, inhibiteur de la sirtuine 1 (SIRT1). Ni le Pts ni le nicotinate de Pts n'ont altere l'expression de la SIRT1, mais ils ont entraine une augmentation de son activite. Tant le Pts que le nicotinate de Pts ont des activites de liaison elevees avec la SIRT1, selon les resultats de resonance plasmon de surface (SPR) et d'analyses d'arrimage moleculaire. L'inhibition de la SIRT1 par le sirtinol entrainait une inversion des effets anti-senescent du Pts et du nicotinate de Pts. En outre, le Pts et le nicotinate de Pts ont des profils d'ADME et des proprietes physiochimiques similaires. En conclusion, cette etude laisse entendre que le Pts et le nicotinate de Pts permettraient d'attenuer la senescence de l'endothelium vasculaire et de susciter des relaxations dependantes de l'endothelium par l'intermediaire de l'activation de la SIRT1. Ces deux composes pourraient constituer des medicaments eventuels pour le traitement de maladies cardiovasculaires liees a la senescence et au dysfonctionnement de l'endothelium. [Traduit par la Redaction] Mots-cles: cellules endotheliales, senescence, pterostilbene, sirtuine 1., Introduction Vascular endothelial cells play a pivotal role in regulating vascular hemostasis, vascular tone and permeability, angiogenesis, as well as vascular inflammation (Vanhoutte et al. 2017); however, the endothelial cells [...]

Inducible resistance to the phytoalexin, pisatin, in Dictyostelium discoideum was examined, and tested for associations with the nystatin resistance genotype. Pretreatment with a sublethal concentration of pisatin resulted in nondegradative pisatin resistance. Mutations in nysC, which confersnystatin resistance, resulted in suppression of pisatin resistance. However, loss of pisatin resistance by transfer to nystatin medium did not result in loss of nystatin resistance. This was explained by a model wherein pisatin resistance is conferred by membrane alterations which are not maintained in theabsence of pisatin.

The role of jasmonic acid in plant defense reactions involving the synthesis of phytoalexins was elucidated.Plant cell suspension cultures were treated with a yeast elicitor to induce thedefense system. The treatment resulted in the rapid synthesis of jasmonic acid.When cells were treated with exogenous methyl jasmonate, de novo transcription of genes involved in the chemical defense reaction was induced. These results indicate that jasmonates are key signal compounds involved in the synthesis of secondary metabolites in plant cell cultures.

The role of phytoalexin detoxification in the virulence interaction of Nectria haematococca on chickpeawas examined. Genetic analysis was facilitated by the recent identification of Mak genes involved in the metabolism of maakiain. The presence of two genes, Mak1 and Mak2, was linked to high virulence on chickpea. The results were inconclusive for a third gene, Mak3, because progeny segregating for this gene were low in virulence. The results suggest that phytoalexin detoxification is required, but insufficient per se, for high levels of virulence.

Plants defend themselves from pathogen infections or mechanical injury by the induced biosynthesis of phenalenone derivatives called phytoalexins which represent a very economical way to counteract hazard. The occurrence of phenalenone chromophores in phytoalexins suggests that these plants respond to pathogen attacks by biosynthesizing singlet oxygen photosensitizes able to use solar energy for defense.

In recent years, agricultural scientists have begun to explore novel strategies for isolating plant compounds of potential medicinal value. One such strategy involves exploiting the defense mechanisms of the plant [...]