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A novel cytotoxic Annonaceous acetogenin, the first member of this class of compounds having a tri-tetrahydrofuran (THF) moiety, has been isolated from Goniothalamus giganteus. The structure was elucidated by spectral data, and the absolute configuration was determined by advanced Mosher's methodology.

Annonaceous acetogenins are waxy substances consisting of C32 or C34 long chain fatty acids which have been combined with a propan-2-ol unit at C-2 to form a gama-lactone. They are only found in several genera of the plant family, Annonaceae. Their diverse bioactivities as antitumour, immunosuppressive, pesticidal, antiprotozoal, antifeedant, anthelmintic and antimicrobial agents have attracted more and more interest worldwide. Recently, we reported that the Annonaceous acetogenins can selectively inhibit the growth of cancerous cells and also inhibit the growth of adriamycin resistant tumour cells. As more acetogenins have been isolated and additional cytotoxicity assays have been conducted, we have noticed that, al(hough most acetogenins have high potencies among several solid human tumour cells lines, some of the derivatives within the different structural types and some positional isomers show remarkable selectivities among certain cell lines, e.g. against prostate cancer (PC-3).

Using the brine shrimp lethality test (BST) to direct fractionation, two additional Annonaceous acetogenins, bullacin (1) and parviflorin (2), were isolated from the ethanol extract of the bark of Annona bullata Rich. Their absolute stereochemistries were revealed by the use of Mosher's methodology. Compound (1) is a new adjacent bis-tetrahydrofuran (THF) acetogenin possessing a relatively rare C 35 skeleton and an unprecedented C-6 hydroxyl group. The absolute configuration of 1 was assigned as 6S, 13R, 14R, 17R, 18R, 21R, 22R, and 34S. Compound (2) is a known acetogenin but is new to this plant. The absolute configuration of 2 was concluded to be 4R, 13R, 14R, 17R, 18R, 21R, 22R, and 34S. This is the first paper in which the absolute stereochemistry of a new acetogenin is published with the hew structure. 1 showed 10 to 1000 times the cytotoxic potency of adriamycin when tested in huam tumor cell lines