Clusiaceae xanthones from

Hypericum perforatum (Clusiaceae), commonly known as SJW, is used in many countries for the treatment of mild-to-moderate forms of depression. Several clinical studies provide evidence that SJW is as effective as conventional synthetic antidepressants (46-51). From a phytochemical point of view, H. perforatum belongs to one of the best-investigated medicinal plants. A series of bioactive compounds have been detected in the crude material, namely phenylpropanes, flavonol derivatives, biflavones, proanthocyani-dins, xanthones, phloroglucinols, some amino acids, naphthodianthrones, and essential oil constituents (Fig. 3) (52-54). 

Djoufack, G. L. Valant-Vetschera, K. M. Schinnerl, J. Brecker, L. Lorbeer, E. Robien, W., Xanthones, biflavanones and triterpenes from Pentadesma grandifolia (Clusiaceae) structural determination and bioactivity, Nat. Prod. Commun., 2010, 5, 1055-1060. 

Benzophenones and xanthones are known to co-occur in the Clusiaceae [1], and the garciduols (74, 75, 84) are three benzophenone-xanthone dimers [27,64]. The cudraphenones (33, 37, 42, 37), a group of benzophenones isolated from the Moraceae family, are prenylated on the A- and B-rings [47], These are the only four compounds that are prenylated on both the A- and B-rings. 

Benzophenones are derived from several pathways. In higher plants, most benzophenones arise by cyclization of a polyke-tide chain of three malonates added to a hydroxybenzoic acid precursor (Manitto, 1981). Cyclization occurs via a Claisen condensation mechanism (Fig. 10.14). These compounds serve as precursors for xanthones in many plants. In some instances [e.g., in the heartwood of Symphonia globulifera (Clusiaceae)], the benzophenone and the corresponding xan-thone co-occur [in this case maclurin (33) and 1,3,5,6-tetra-hydroxyxanthone (34)] (Weiss and Edwards, 1980). 

Several xanthones that possess antidepressant activity inhibit monoamine oxidases. These compounds have in vitro cytotoxicity and in vivo antitumor activity (Hostettmann and Hostettmann, 1989). The xanthone psorospermin (38) from Psorospermum febrifugum (Clusiaceae) exhibited antileukemic activity in several test systems. Other xanthones have tuberculostatic effects (Vermes and Wagner, 1986). 

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