Steroid alkaloids structures

RELATIVE TERATOGENIC POTENCIES OF STEROIDAL ALKALOIDS Fig. (11). Correlation of relative teratogenic potencies (from Table 2) with steroidal alkaloid structure. For example, values for jervine (100), dihydrojervine (65), cyclopamine (47), and tetrahydrojervine (40) are shown adjacent to the tetrahydrojervine structure that represent jervanes, in general. 

Saponins are glycosylated secondary metabolites that are widely distributed in the Plant Kingdom.3,4 They are a diverse and chemically complex family of compounds that can be divided into three major groups depending on the structure of the aglycone, which may be a steroid, a steroidal alkaloid, or a triterpenoid. These molecules have been proposed to contribute to plant defense.3 6 Saponins are also exploited as drugs and medicines and for a variety of other purposes.4 Despite the considerable commercial interest in this important group of natural products, little is known about their biosynthesis. This is due in part to the complexity of the molecules, and also to the lack of pathway intermediates for biochemical studies. 

Atta-ur-Rahman and Choudhary, M.I., 1988, Structural studies on new steroidal alkaloids of Buxus papillosa. In Studies in Natural Products Chemistry (Atta-ur-Rahman ed.), Elsevier Science, Amsterdam, Vol. 2, pp 175-189. 

The structural features of the solanum alkaloids are based on two primary skeletal configurations solanidane, with or without glycoside functionalities, as featured by the toxic and teratogenic steroidal alkaloids a-chaconine and a-solanine with the indolizidine type E-F ring (Figure 2.7a) and the spirosolane... 

The three most important groups of steroids are the sterols, bile acids, and steroid hormones. Particularly in plants, compounds with steroid structures are also found that are notable for their pharmacological effects—steroid alkaloids, digitalis glycosides, and saponins. 

Khalid A, Zaheer-ul-Haq Anjum S, Khan MR, et al. Kinetics and structure-activity relationship studies on pregnane-type steroidal alkaloids that inhibit cholinesterases, BioorgMed Chem 12 1995—2003, 2004. 

Much practical interest has arisen from steroidal alkaloids, called squalamines, from sharks of the western Atlantic coast (Chart 7.8.A/P/PO). Although imexceptional in structure, these steroids, as a rare example from higher organisms, are precursors or models for new drugs (Tables 13.3 and 15.1). 

Steroidal alkaloids These alkaloids have a core steroidal skeleton as part of the molecule, e.g. solanine. There are a number of structural varieties that exist in steroidal alkaloids. Following discussion is just on a few selected steroidal alkaloids. 

Tomatine is a steroid alkaloid glycoside consisting of an aglycone moiety (tomatidine), and a tetrasaccharide moiety (p-lycotetraose) composed of two molecules of glucose and one each of galactose and xylose the four monosaccharides form a branched structure that is attached at the C-3 position of the aglycone (reviewed by Roddick [7], see also references therein). The structure of tomatine is shown in Fig (1). 

Fukuzawa, S., Matsunaga, S., and Fusetani, N., Isolation and structure elucidation of ritterazines B and C, highly cytotoxic dimeric steroidal alkaloids, from the tunicate Ritterella tokioka, J. Org. Chem., 60, 608, 1995. 

This chapter discusses some of the more important natural products terpenes, steroids, alkaloids, fats, and prostaglandins. (Fats are primary natural products, but it is convenient to include them in this chapter.) The structures and various aspects of their biosynthesis and chemical reactions are presented in subsequent sections. Because entire books have been written on each of these groups of compounds, the coverage here is necessarily incomplete. However, the intent is to present some of the flavor of their chemistry. Many other classes of naturally occurring organic compounds are not included for reasons of space. 

The fission mechanisms assigned were proved by labeling.168 The proposed structure of a-hydroxyconnessine was confirmed by mass spectrometry166 and several steroidal alkaloids occurring in Holarrhena could be detected and identified.170... 

Unique structural features of this steroidal alkaloid are the cis junctions between rings A/B and C/D, the ether linkage between C-3 and C-9, the OH group on C-11, and the alkaloid function in a seven-membered ring formed by a methylethylamine moiety bridging the methyl on C-13 and OH on C-14 of a steroid nucleus. A reanalysis of the spectral data showed that batrachotoxin is the 20-a-dimethylpyrrole carboxylate and homobatrachotoxin the 20-a-ethylmethylpyrrolc carboxylate of batrachotoxinin A (31). 

Figure 6.4 Chemical structures of estranes, androstanes, cardiac glycosides steroid saponins and steroid alkaloids mentioned in the text.

Most of the work reported with amino-substituted steroids has been concerned with the removal of the nitrogen function from the molecule. Interest has centred mainly on the peculiarities of the reaction between nitrous acid and steroidal primary amines. The naturally-occurring steroidal alkaloids have been studied mainly with a view to establishing their structures and usefulness as sources of nitrogen-free steroids, and are not included in the present survey. 

---