Annonaceae family

Solanaceae), acts as competitive inhibitor for ubiquinone in Complex I. Methyl capsaicin is more potent than capsaicin, indicating that the phenolic OH is not essential for the activity [297]. Other natural inhibitors of Complex I are annonaceous acetogenins. These compounds belong to a wide group of natural products isolated from several species of the Annonaceae family, which include more than 250 molecules with diverse chemical structures. Among the various classes, it seems that monotetrahydrofuranic derivatives are less potent than other acetogenins [296, 299]. 

The protoberberine alkaloids are widely distributed, occurring in at least eight botanical families. They occur most frequently in the various genera of the Papaveraceae but are also well represented in the Berber-aceae, Menispermaceae, Ranunculaceae, Rutaceae, and Annonaceae families. Table I shows the additional plant sources of the protoberberines that have been reported since the appearance of the last review in Volume IV. 

Investigation of Xylopia descreta, a member of the Annonaceae family, has resulted in the isolation of four new protoberberine alkaloids— xylopinine, descretine, descretinine, and descretamine, in addition to the aporphine base, xylopine 49). 

Tetrahydrofuran rings. 8,e-Unsaturated alcohols are oxidized by Re207-2,6-lutidine to give 2-(l-hydroxyalkyl)tetrahydrofurans. This method, in conjunction with the asymmetric dihydroxylation, constitutes a versatile synthetic approach to bioactive natural products from plants of the Annonaceae family. ... 

The known chemistry of the Annonaceae is mainly based on the work of Cave and Leboeuf on the benzyhsoquinoline alkaloids. After this work, several papers were published which evidenced the presence of alkaloids derivatives of isoquinolines. Approximately 800 alkaloids of the types isoquinolines, protoberberine, aporphine, and others were isolated from different genera of the Aimonaceae. Previous chemical and pharmacological investigations have indicated that bisbenzylisoquinolines are important bioactive components existing in plants of the Annonaceae family. Other terpenes, flavonoids, Hgnans, acetogenins, and some aromatic compounds are also found in the family but the alkaloids are the major chemical constituents. 

A list of the secobisbenzylisoquinoline alkaloids with their species of origin is included in Table VIII. The secobisbenzylisoquinoline alkaloids have mainly been found among members of the family Berberidaceae, less frequently in the Annonaceae, and in only a single case in the Ranunculaceae. In Table IX some of the physical data and spectral features of secobisbenzylisoquinoline alkaloids are presented. 

Taxonomically close to the Annonaceae, the Lauraceae family abounds with apor-phinoid alkaloids. A remarkable advance in the search for topoisomerase inhibitors from Lauraceae has been provided by Woo et al. (6). Using DNA-unwinding assay and structural modeling, they showed that dicentrine can attain a relatively planar conformation and molecular bulk which allow it to occupy the active site of topoisomerase II which becomes inactive. The requirement of a suboptimal conformation to achieve DNA binding appears to make dicentrine less potent against topoisomerase II than the... 

Whereas the Annonaceae are characterized primarily by benzylisoquinoline alkaloids, two pyrrolidine alkaloids have recently been found in species belonging to this family. Squamolone (29) was isolated from Annona squamosa L. by Chinese workers in 1962 (68). Despite careful spectroscopic investigation and a total synthesis (Eq. 1), squamolone was assigned the incorrect diazepine formula 30. The correct structural formula (29) was later established by an unambiguous synthesis of 30 (Eq. 2). Compounds 29 and 30 proved to have very similar spectroscopic properties, which could justify the early confusion (69). 

Direct methylation through C-bonds appears to be common in the positions 6 and 8 of the flavonoid molecule. Other positions are rarely C-methylated (C7, saltillin C3, a glycoside only compound 23, Table 12.3). Most reports concentrate on species from the family Myrtaceae, where C-methylflavones also occur externally. Desmos cochinchinensis (Annonaceae) was... 

Six new flavanones having one or more C-benzyl groups attached to C-6 or C-8, or both, have been reported from members of the Annonaceae, a family from which many C-benzylated flavanones and dihydrochalcones had previously been described. The new compounds (212-217) are presented in Table 15.6. Macrophyllol (212) and macrophyllol A (213, Figure 15.6) have been isolated from the roots of Uvaria macrophylla. These consist of 5-hydroxy-6,7-dimethoxyflavanone with one 2-hydroxy-5-methoxybenzyl unit attached to C-8 and C-6, respectively. The roots of Xylopia africana yielded isouvarinol (214, Figure 15.6), in which one 2-hydroxybenzyl unit is attached to C-6 and two units to C-8. Its... 

The Annonaceous acetogenins are an important new group of long-chain fatty acid derivatives found exclusively in the plant family, Annonaceae. Nearly 400 compounds from this... 

FAMILY Annonaceae (Custard-Apple Family) SUBFAMILY Annonoideae TRIBE Unoneae GENUS Asimina SPECIES A. triloba... 

Espositi, M.D., Ghelli, A., Batta, M., Cortes, D., and Estornell, E. Natural substances (acetogenins) from the family Annonaceae are potent inhibitors of mitochondrial NADH dehydrogenase (complex I). Biochem.., 301, 161, 1994. 

It is interesting to note that the occurrence of C-7 oxygenated aporphine alkaloids with the C-6a R configuration is limited to the families Annonaceae, Lauraceae, Magnoliaceae, and Menispermaceae. Aporphine alkaloids oxygenated at both C-4 and C-7 have been found in the Annonaceae, but (-)-stephadiolamine /3-A-oxide (48) is the first known alkaloid hydroxyl-ated at both C-4 and C-7 and having a cis relationship between H-6a and H-7. (-)-O-Acetylsukhodianine is the first known example of a naturally occurring 7-acetoxylated aporphine (30). 

Aporphinoids are by far the most abundant alkaloids in this genus and also, generally speaking, in the family Annonaceae. Guatteria has proved to be a rich source of unusual structures of this general type. Aporphines have been reviewed in Volume 24 of this treatise (3) and elsewhere (4-7), and a review on aporphinoids of the Annonaceae has just been published (8). For this reason we address the structures and chemistry of only a few alkaloids of this type that have not been included in the Kametani and Honda review (5). 

Azafluorene alkaloids have been found in a number of Annonaceae and have not yet been reviewed. Three of these compounds (136-138) were first isolated from a Guatteria species (22, 23) while the parent substance of this group, onychine (135), and the other congeners known until now have been found in different genera of the family Annonaceae. 

Benzylisoquinolines, of which more than 2500 structures are known, are found as defence chemicals within the families of the superorder Mag-noliids (comprising Piperales, Laurales and Magnoliales with the families Annonaceae, Eupomatiaceae, Aristolochiaceae, Magnoliaceae, Lau-raceae, Monimiaceae), Nelumbonaceae and Ranunculales (i.e. Berberidaceae,... 

---