Constituents of three EtOH extracts of the stem bark of Garcinia assigu LANTB., Garcinia dulcis (ROXB.) KURZ., and Garcinia latissima MIQ., belonging to the Guttiferae, collected in Central Province of Papua New Guinea, were studied. A novel depsidone named garcinisidone-A (1), six new xanthones named assiguxanthone-A (3) and -B (9) and dulxanthone-A (4), -B (6), -C (7), and -D (11), and four new pyranoxanthones named latisxanthone-A (13), -B (14), -C (15), and -D (16) were isolated, as well as some known xanthone, benzophenone, chromone, and biflavanone derivatives, and their structures were elucidated by spectroscopic methods. Among these components, garcinisidone-A (1) is the first example of a depsidone derivative having a five-carbon unit (prenyl) as a substituent to be found in nature. Latisxanthone-B (14) was found to contain a hydroperoxy moiety in the molecule. This is the second example of a xanthone hydroperoxide to be found in nature.