Indole-Mevalonate Metabolites

Most members were isolated from sclerotia of ergot fungus, Claviceps paspali 

C-13 in paspalicine and its replacement by a new signal at 76.6 ppm indicates a hydroxyl group at C-13. The assumed structure has been checked in a singlecrystal X-ray experiment 170). 

Biosynthesis studies with C- and C-labeled precursors were conducted by 

From other fungal species more complex tremorgens, such as the janthitrems (A-G) from Pen. janthinellum (174), the penitrems (A-F) (175,176) from Pen. crustosum and other species, and the lolitrems (A-D) (177) from Acremonium 

The stereochemistry of these compounds is virtually identical, and the configuration of the substituents is 15(S ), 18(5 ), 19(5 ), 22( ), and 23(5 ). The two cyclohexane rings are chair conformations, whereas the cyclohexene ring has a distorted half-chair conformation. The presence of two more hydroxyl groups in dihydroxyaflavinine generates two additional asymmetric centers, 20(1 ) and 24(5 ). 

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Cyclopentanoid Monoterpenoids.—Further studies confirm that mevalonic acid, but not 3-hydroxy-3-methylglutaric acid, is specifically incorporated into loganic acid (27), and methionine or adenosylmethionine into loganin (28). The latter metabolite is a key intermediate in indole alkaloid biosynthesis. ... 

Tryptophan and its relative indolylpyruvic acid (3.42) have been shown to precursors of hinnuliquinone (3.41), which is a pigment of Nodulisporium hin-nuleum. Typical of many fungal indoles in which alkylation by a dimethylallyl or isopentenyl group has occurred, mevalonate was also a precursor. However, the stage at which prenylation of a monomer or a dimer took place was unclear. Asterriquinone (3.43) from Aspergillus terreus and cochliodinol (3.44) from Chaetomium cochliodes are similar metabolites. Fission of the hydroxyquinone in the latter followed by lactonization leads to cochliodinone (3.45) in a sequence that is similar to that which inter-relates the terphenyls and pulvinic acids described in Chapter 7. 

The assignment of the structures of the brevianamides A-E, five closely related diketopiperazine metabolites isolated from the mould Penicillium brevicompactum, was based partly on the results of biosynthetic studies and biogenetic considerations The presence of an indole unit and a diketopiperazine ring in the brevianamides suggested the possibility of the formation of these metabolites from L-tryptophan and L-proline (101) with the additional C5 unit in the molecules originating in mevalonate (102). Biosynthetic evidence to support this conclusion was obtained in the case of brevianamide A (105). Thus DL-3-[ CJ-tryptophan and L-U-[ C -proline were both readily incorporated into the... 

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