Salpratlactones A and B: A Pair of <i>cis</i>–<i>trans</i> Tautomeric Abietanes as Ca_v3.1 T-Type Calcium Channel Agonists from <i>Salvia prattii</i>

Abstract

Salpratlactones A (<b>1</b>) and B (<b>2</b>), a pair of abietane <i>cis</i>-<i>trans</i> tautomers from <i>Salvia prattii</i>, were identified as the first naturally occurring agonists of T-type calcium channel (TTCC). Structurally, <b>1</b> and <b>2</b> were featured by unique 6/5 carbocyclic rings bearing a γ-lactone ring through an exocyclic double bond. Moreover, both compounds and their mixture at 10 μM potently and equally increased Ca_v3.1 TTCC peak currents, and <b>1</b> had an EC₅₀ value of 12.48 μM.