Prenyl bibenzyls

The diprenylated bibenzyl glepidotin D (162) with one substitution at 3-0 was isolated from the leaves of Glycyrrhiza lepidota is responsible for the anti-viral activity [98], Phytochemical investigation of the liverwort Lethocolea glossophylla yielded four new prenylated bibenzyls (163-166) [99], and a lipid extract of the leaves of Sicilian Glycyrrhiza glabra... 

P. E-G are open-chain bisbibenzyls with linear linkages of the two bibenzyl units through an ether bridge. They are considered to be biogenetic precursors of cyclic bisbibenzyls (see riccardins and marchantins). In contrast, the P. A-D are prenylated bibenzyls. The occurrence of P. is limited to liverworts. P. E., isolated from Radula perrottetii (which also contains F and G) and other liverworts, is cytotoxic to KB cells For synthesis, see Lit.. ... 

Kraut L, Mues R, Zinsmeister HD (1997) Prenylated bibenzyl derivatives from Lethocolea glossophylla dmdRadula voluta. Phytochemistry 45 1249-1255... 

Group B prenylated, geranylated and famesylated bibenzyls, regardless of the substitution position. 

Fig. (8). Structures of prenylated, geranylated and famesylated bibenzyls (Group B) Table 6. Simple Bibenzyls (Group A)...

Table 7. Prenylated, Geranyiated and Farnesylated Bibenzyls (Group B)...

Dihydroxy-4-(3-methyl-2-butenyl)-bibenzyl (3,5-2XOH, 4-Prenyl) G. lepidota whole part (360)... 

The bibenzyls are characterized by the presence of one 1,2-diphenylethane structure in their molecules. Similar with the stilbene structures, there are hydroxyls, methyl, methoxy, prenyl, geranyl, etc., located in the structures of bibenzyls. Bibenzyls have been mainly isolated from bryophytes. In addition, a few compounds of this group were reported from the genera of Stemona, Dendrobium, and Polygonum. 

Bibenzyls of this group are characterized by the presence of prenyl, geranyl, and/or famesyl substitutes. Isoprene units in the structures may be branched and/or form five- to seven-member rings. The typical compounds of this group are bauhinols A 110 and B 111 from Bauhinia saccocalyx [64],... 

Stilbenoids represent a group of important natural products in the plant kingdom. The developments of modem analytical methods accelerate the discovery of these compounds, and to this day more than 1,000 stilbenoids have been isolated. For the stilbenes, bibenzyls, and phenanthrenes, these three groups shared the feature of their nucleus with hydroxyls, methyl, methoxy, prenyl, geranyl, glycosyl, etc., substituents. The oligostilbenes and bisbibenzyls are formed by polymerization of stilbene and bibenzyl units, and the diverse polymerized patterns produced their... 

Radula species contain many bibenzyls incorporating prenyl groups. Seven such bibenzyls (612—614,616—618,620) have been isolated from R. variabilis structures were established mainly by detailed analysis of H-NMR and mass spectra (58, 61). In (612) the presence and the location of two phenolic hydroxyls and the geranyl group were settled by comparison of the signal pattern of the aliphatic protons with those of geraniol (3) and by observation of a NOE between two aromatic protons (H-2 and H-6) and the benzylic protons (5 2.93 ppm) of the dimethyl ether. Fragment ions at mjz 91 (100%) and mjz 111 (98%) and formation of a chromane derivative (653) from (612) further supported the proposed structure (612) (Scheme 74). 

---