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

Salpratlactones A (1) and B (2), a pair of abietane cis-trans tautomers from Salvia prattii, were identified as the first naturally occurring agonists of T-type calcium channel (TTCC). Structurally, 1 and 2 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 Cav3.1 TTCC peak currents, and 1 had an EC50 value of...