Abstract:Three annonaceous acetogenins of monotetrahydrofuran type, S2, S5 and S13. were isolated {rom the seeds of Annona muricata L. Based on spectral analysis (IR, MS, NMR) and preparation of the derivative, they were identified as howiicin A (S13), howiicin B (S5) and 4-desoxyhowiicin B (S2). S2 is a new compound.