A new pentacyclic guanidine alkaloid, monanchomycalin C (1), along with the earlier known ptilomycalin A (2), were isolated from the Far-Eastern marine sponge Monanchora pulchra. The structure of 1 was elucidated using 1D and 2D NMR spectroscopic and mass spectrometric data. Compounds 1 and 2 exhibited cytotoxic activities against human breast cancer MDA-MB-231 cells with IC 50 values of 8.2 µM and 4.3 µM, respectively.

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New marine natural products, pulchranins B and C (2 and 3), were isolated from the marine sponge Monanchora pulchra and their structures were established using NMR and MS analysis. Compounds 2 and 3 were moderately active as inhibitors of TRPV1 (EC50 value of 95 and 183 μM, respectively) and less potent against TRPV3 and TRPA1 receptors.