The isolation of skimmianine and three new acridone alkaloids from the root bark of Glycosmis pentaphylla (Retz.) Correa is reported. Based on the spectral evidence and chemical correlations, these are shown to be hitherto naturally unknown noracronycine (IIb), des-N-methyl-acrocynine (IXa) and des-N-methylnoracronycine (IXb). Evidence is also presented to show that of the two possible structures, 1-methoxy-2′,2′,10-trimethylpyrano(5′,6′-2,3 or 3,4) acridone (Ia or IIa) for acronycine, the angular structure IIa is correct. © 1964.