Penitrems structure

Several other twofold cyclization strategies have been developed by Smith and coworkers, ultimately to obtain access to the cyclic framework of penitrem D with the correct stereochemistry [176]. Williams group has been interested in Stemona alkaloids, which are represented by approximately 50 structurally novel, polycyclic natu-... 

The structures of the penitrems were elucidated156 mainly by extensive n.m.r. studies, both on the natural material and on 13C-enriched material isolated after administration of appropriate 13C-labelled precursors (tryptophan and acetate) to the cultures. Structure (16a) incorporates the proposed relative stereochemistry of penitrem A, but no deductions concerning the stereochemistry of the other metabolites were made. Penitrem A is a powerful toxin, and causes sustained tremors, disco-ordination, and convulsions in laboratory and farm animals. 

Figure 18 Structures of phomopsin A, penitrem A, PR toxin, rubratoxin B, fusarin C, and fusaproliferin.

Species of Penicillium fungi are rich sources of indole metabolites, such as thomitrem A 71 and thomitrem E 72, isolated from Penicillium crustosum <2002P979>. They are structurally similar to previously described penitrem derivatives <1996CHEC-II(2)207> but lack the characteristic penitrem 17(18)-ether linkage. 

Steyn PS Mycotoxins, general view, chemistry and structure. Toxicol Lett 1995 82 843-851. Yamaguchi T, Nozawa K, Hosoc T, Nakajima S, Kawai KL Indoloditerpenes related to tremorgenic mycotoxin penitrems, from Penicillium crustosum. Phytochemistry 1993 32 1177-1181. Penn J, Swift R, Wigley LJ, Mantle PG, Bilton JN, Sheppard RN Janthitrems B and C, two principal indole-diterpenoids produced by Penicillium janthinellum. Phytochemistry 1993 32 1431-1434. 

Similar structural features are also demonstrated by penitrems A to F (Fig. 18), which form a small family of tremorgenic mycotoxins produced by the ergot fungus Penicillium crustosum. The structure of these alkaloids was elucidated by Steyn and co-workers (238-241), and an approach to the total synthesis of penitrem D was also presented (242). 

Penitrem D (226) (Scheme 41) is one member of the penitrem family, which is a small family of structurally complex tremorgenic mycotoxins, and was isolated from the ergot fungus Penicillium crustosum by Steyn and coworkers in 1981 [90]. 

Isoprenoids (isopentenoids). The name for a group of natural products made up of isoprene units (e.g., ses-qui-, di-, and triterpenes, iridoids, carotinoids, steroids, natural rubber, etc.). Many non-isoprenoid compounds, however, do possess isoprenoid side chains, e.g., tocopherols, ubiquinones, chlorophyll, or contain isoprenoid structures incorporated into their skeletons, e.g., monoterpenoid indole alkaloids, penitrems, Cinchona alkaloids. 

---