16,24-Cyclo-13,14-secoergost-2-ene-18,26-dioic acid, 5-chloro-14,17:14,27-diepoxy-6,13,20,22-tetrahydroxy-1,15-dioxo-, .gamma.-lactone .delta.-lactone 70241-09-7 NSC688074 Physalin H