An ethanolic extract of Psorospermum febrifugum was fractionated with antileukemic activity in vivo in the P388 lymphocytic leukemia in mice and in vitro in the KB cell culture system used as a guide. The new antileukemic xanthone psorospermin 1 was isolated, and its structure was elucidated. The chlorohydrin of O-methylpsorospermin 2 was also isolated after treatment of the fraction containing psorospermin chlorohydrin 6 with diazomethane. Psorospermin 1 was demonstrated to have significant antitumor activity in the P388 in vivo system as well as cytotoxicity against the KB in vitro system.

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Isolierung und Strukturermittlung der antileukämischen Trichothecene Baccharin (I), Isobaccharin (II), Baccharinol (III), Isobaccharinol (IV) sowie das Acetat (V) werden beschrieben.

Die Struktur des antileukämisch wirksamen Quassimaifins wird zu (I) sichergestellt.