d-Val22 containing human big endothelin-1 analog, [d-Val22]Big ET-1[16–38], inhibits the endothelin converting enzyme

AbstractEndothelin converting enzyme (ECE) is essential for generation of the biological effects of endothelin-1 (ET-1) from a precursor, big endothelin-1 (Big ET-1). We synthesized four analogs of human Big ET-1[16–38], substituted with single d-amino acids at P1, P2, P1′and P2′ positions. ECE activity was determined using an ET-1 specific radioimmunoassay system. None of the d-amino acid containing Big ET-1 analogs were apparently cleaved by ECE, however, one of the synthetic peptides, [d-Val22]Big ET-1[16–38], strongly inhibited the ECE activity. Furthermore, when this d-Val22 containing peptide was preadministrated to rat striatum, it was found to inhibit the dopamine release induced by Big ET-1. This result suggests that the d-Val22 containing peptide inhibits the ECE activity in vivo. The d-Val22 containing inhibitor offers hope of developing more potent and highly specific ECE inhibitors of therapeutic significance

Black tea aroma inhibited increase of salivary chromogranin-A after arithmetic tasks

Abstract Background Growing attention has been paid to the effects of food flavor components on alleviating negative brain functions caused by stressful lifestyles. In this study, we investigated the alleviating effect of two kinds of black tea aromas on physical and psychological stress induced by the Uchida-Kraepelin test, based on salivary chromogranin-A (CgA) levels as a stress marker and subjective evaluations (Profile of Mood States). Results Compared with the water exposure control, inhaling black tea aroma (Darjeeling and Assam in this study) induced lower salivary CgA concentration levels after 30 min of mental stress load tasks. This anti-stress effect of black tea aroma did not differ between the two tea types even though the concentration of the anti-stress components in the Darjeeling tea aroma was higher than that in the Assam aroma. However, Darjeeling tea aroma tended to decrease the tension and/or anxiety score immediately after the first exposure. Conclusions Inhaling black tea aroma may diminish stress levels caused by arithmetic mental stress tasks, and Darjeeling tea aroma tended to improve mood before mental stress load