Two new furacridone alkaloids have been obtained from tissue culture of Ruta graveolens by DCCC of a crude dichloromethane extract and subsequent CC and TLC. On the basis of spectroscopic data their structures have been determined to be 1-hydroxyrutacridone epoxide (3) and its intramolecular substitution product (5, rutagravin); a third furoacridone has been identified as gravacridonol (4). Recent studies on roots and tissue cultures of Ruta graveolens L. (Rutaceae) have shown the presence of two new furoacridone alkaloids: rutacridone epoxide (1) and 20-hydroxyrutacridone epoxide (2). In the production of larger amounts of 1 using droplet counter current chromatography (DCCC) several minor components were obtained with the main fraction which showed Rf values between 1 and 2 on TLC with silica gel using MeCN/toluene mixtures as solvents. 1 was separated from this fraction by column chromatography; the more polar compounds have been purified subsequently by semipreparative TLC on silica gel to yield a few mgs of compounds 3, 4 and 5 (increasing polarity), which appeared to be acridone alkaloids by their yellow colour in VIS and orange to brown-orange fluorescence at 360 nm. They all showed UV spectra in CH2Cl2 with a maximum at 274—278 nm and minor absorption bands at 390—396, 326—334, 298—300, 264—266 and 250—254 nm, which are very similar in position and intensity to those of 1 and 2. The structure of 3, with a molecular ion of m/z 339 (EI-MS) identical to that of 2, follows from the similarity of the 1H-NMR spectrum (Table I) with those of 1 and 2. The only notable difference is the loss of the characteristic ABX system for the proton signals of the five-membered ring found in the latter and the presence of the 20-CH3 group. The attachment of an hydroxyl group at C-1 in 3 was indicated by the loss of a vicinal coupling to H-1 upon H/D exchange. The high resolution EI mass spectrum of the molecular ion of 4 of 323.1148 confirmed the molecular formula of C19H17NO4 (calculated 323.1158). The absence of the 20-methyl group and characteristic epoxide C-19 methylene signals in the 1H-NMR spectrum of 4 (Table I) and appearance of two new two-proton signals at 5.3 and 4.3 ppm showed the presence of the hydroxymethylethenyl group. The nature of this group was unambiguously confirmed both by the vicinal proton coupling of the hydroxyl at C-20 in dry solvent and by the characteristic 13C shifts of the proton-bearing carbons, whose multiplicities were determined by a DEPT 13C-spectrum (Table II). This compound is identical with gravacridonol and our data agree with published 1H-data apart from the 1H-shifts of the methylene hydrogens at C-20 and C-1 which were poorly characterized previously. The molecular formula of 5 of C19H17NO5 (calculated 339.1107) was deduced from the high resolution EI mass spectrum of the molecular ion of 339.1097. Comparison of the 1H spectrum (Table I) with 1 to 4 indicated the presence of the intact aromatic system and oxygen substituent at C-17. The nature of the groups present in the aliphatic ring systems were evident from the 1H- and 13C-shifts (Table II), while the nOe responses upon irradiation of the two methyl groups indicated the relative positions of these. The same experiments, together with the 13C-shifts of the oxygen-bearing carbons, exclude all structures involving three and four membered ring systems. Of the two remaining possibilities, 5 and 6, the absence of a vicinal coupling to H-2 from a hydroxyl hydrogen either in dry CDCl3 or DMSO-d6 precludes structure 6. Compound 5 represents a new pentacyclic system of acridone alkaloids with a difuranoid moiety for which the trivial name rutagravin is proposed. This compound may be formed from 3 by intramolecular nucleophilic attack of the 1-OH at C-19 of the oxiran ring. The three compounds 3—5 have been tested for antimicrobial activity. Compound 5 showed some antimicrobial activity whereas no inhibition zones could be detected with 3 and 4. In the test system used 40 µg of 5 effected an inhibition which is a rather poor response compared to 1 or 2; The chemical shifts and most of the main coupling constants of seven sarpagine alkaloids 1—7 have been determined in a 400 MHz 1H-NMR study.