Isolation of bisindole alkaloids that inhibit the cell cycle from Myxomycetes Arcyria ferruginea and Tubifera casparyi

From a myxomycete Arcyria ferruginea, dihydroarcyriarubin C (1), a new bisindole alkaloid, has been isolated together with two known bisindoles, arcyriarubin C (2) and arcyriaflavin C (3), and arcyriaflavin C (3) was also isolated from Tubifera casparyi together with arcyriaflavin B (4). Arcyriaflavin C (3) exhibited cell cycle inhibition effect at G1 and G2/M stage at 10 and 100 ng/mL, respectively.