The endophytic fungus Penicillium citrinum was isolated from a fresh stem of the Moroccan plant Ceratonia siliqua. Extracts of P. citrinum grown on rice and white bean media yielded five new compounds, namely, citriquinochroman (1), tanzawaic acids G and H (2 and 3), 6-methylcurvulinic acid (4), 8-methoxy-3,5-dimethylisoquinolin-6-ol (5), and one new natural product, 1,2,3,11b-tetrahydroquinolactacide (6), which had previously been described as a synthetic compound. In addition, 13 known compounds including seven alkaloids and six polyketides were isolated. The structures of the new compounds were unambiguously determined on the basis of one- and two-dimensional NMR spectroscopy as well as by high-resolution mass spectrometry. Citriquinochroman (1) features a new skeleton, consisting of quinolactacide and (3S)-6-hydroxy-8-methoxy-3,5-dimethylisochroman linked by a C-C bond. 1,2,3,11b-Tetrahydroquinolactacide (6) may be a biogenetic precursor of quinolactacide. Citriquinochroman (1) showed cytotoxicity against the murine lymphoma L5178Y cell line with an IC50 value of 6.1 μM, while the other compounds were inactive (IC50 >10 μM) in this assay.

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Four new alkaloids, representing the first members of new groups of polyindolinic alkaloids, have been isolated from the aerial parts of CALYCODENDRON MILNEI along with other alkaloids. The names vatine, its stereoisomer vatine A, vatamine, and vatamidine are proposed. They are polymers of six, seven, and eight N(b)-methyltryptamine units, respectively.

Certain genera of the tribe Psychotrieae, specifically Calycodendron and Psychotria, found on Pacific Islands, synthesize a series of Nb-methyltryptamine-derived alkaloids made by linking together 2 to 8 pyrrolidinoindoline units. Nine alkaloids of this class have been isolated from the aerial parts and stem bark of Calycodendron milnei, a species endemic to the Vaté Islands (New Hebrides), and examined for potential application as anti-cancer and anti-infective agents. All members of the series exhibited readily detected cytotoxic activity against proliferating and non-proliferating Vero African green monkey kidney cells in culture, with the most potent activity being exhibited by vatamine and quadrigemine C. Only hodgkinsine A exhibited substantial antiviral activity against a DNA virus, herpes simplex type 1, and an RNA virus, vesicular stomatitis virus. All members of the series showed readily detected anti-bacterial, anti-fungal, and anti-candidal activities using both tube dilution and disc diffusion assay methods. The most potent anti-microbial alkaloids were hodgkinsine A and quadrigemine C, which exhibited minimum inhibitory concentration (MIC) values as low as 5 micrograms/ml.

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