Steroids alkaloids, steroidal

Steroid Alkaloids. Steroid alkaloids ate compounds isolated from plants and some higher animals that possess the basic steroidal skeleton with nitrogen(s) incorporated as an integral part of the molecule. The nitrogen can be located within the perhydro-l,2-cyclopenlenoplienanlhrene ring system or in a side chain. 

Buxus steroid alkaloids. Steroid alkaloids with 9)8,19-cyclopregnane or 9(10- 19)-afeeo-pregnane structure, but with 1 to 3 additional methyl groups at C-4 and/or C-14 as well as amino functions at C-3 and/or C-20. They are isolated from numerous species of the Buxaceae genus Buxus. To date about 200 B.s. are known. In order to achieve transparency and especially to reduce the number of incomprehensible trivial names for new compounds it was proposed to ac-... 

According to this classification, actinidine described in this chapter is classified as a monoterpenoid alkaloid, whereas nupharidine and aconitine are classified as sesquiterpenoid and diterpenoid alkaloids, respectively. Batrachotoxin A, which possesses a steroidal skeleton, is classified into steroidal alkaloid. Steroids are derived through the degradation of a triterpenoid skeleton (C30 unit) [2,4]. 

Fonaaldeliyde-pliospliorie acid for steroid alkaloids, steroid sapogenins and... 

Species Steroid alkaloid Steroid sapogenin Reference... 

A major trend in organic synthesis, however, is the move towards complex systems. It may happen that one needs to combine a steroid and a sugar molecule, a porphyrin and a carotenoid, a penicillin and a peptide. Also the specialists in a field have developed reactions and concepts that may, with or without modifications, be applied in other fields. If one needs to protect an amino group in a steroid, it is advisable not only to search the steroid literature but also to look into publications on peptide synthesis. In the synthesis of corrin chromophores with chiral centres, special knowledge of steroid, porphyrin, and alkaloid chemistry has been very helpful (R.B. Woodward, 1967 A. Eschenmoser, 1970). 

The trimer famesyl pyrophosphate (35), in addition to serving as a pregenitor of steroids via squalene (114), is also the pregenitor of the compounds known as sesquiterpenes. It has been suggested that famesyl pyrophosphate (88) similarly serves as the carbon backbone of alkaloids such as deoxynuphatidine (120) ftom Nupharjapomcum (Nymphaceae) (water hhes) and dendrobine (121) Dendrobium nobikl indl. (Orchidaceae) (Table 11). 

The path from squalene (114) to the corresponding oxide and thence to lanosterol [79-63-0] (126), C qH qO, cholesterol [57-88-5] (127), and cycloartenol [469-38-5] (128) (Fig. 6) has been demonstrated in nonphotosynthetic organisms. It has not yet been demonstrated that there is an obligatory path paralleling the one known for generation of plant sterols despite the obvious stmctural relationships of, for example, cycloartenol (128), C qH qO, to cyclobuxine-D (129), C25H42N2O. The latter, obtained from the leaves of Buxus sempervirens E., has apparentiy found use medicinally for many disorders, from skin and venereal diseases to treatment of malaria and tuberculosis. In addition to cyclobuxine-D [2241-90-9] (129) from the Buxaceae, steroidal alkaloids are also found in the Solanaceae, Apocynaceae, and LiUaceae. 

In addition to the alkaloids such as cyclobuxiae-D (129) and solanidine (130) where the stmctural similarities to steroids are clear (although it must be remembered that detailed evidence actually linkiag the compounds is lacking) there are the less obvious (but nonetheless also clearly related) Veratrum alkaloids. These compounds, of which protoverattine A [143-57-7] (131), obtained from the rhizome of Veratrum album L. (LiUaceae), is a... 

Experimental procedures have been described in which the desired reactions have been carried out either by whole microbial cells or by enzymes (1—3). These involve carbohydrates (qv) (4,5) steroids (qv), sterols, and bile acids (6—11) nonsteroid cycHc compounds (12) ahcycHc and alkane hydroxylations (13—16) alkaloids (7,17,18) various pharmaceuticals (qv) (19—21), including antibiotics (19—24) and miscellaneous natural products (25—27). Reviews of the microbial oxidation of aUphatic and aromatic hydrocarbons (qv) (28), monoterpenes (29,30), pesticides (qv) (31,32), lignin (qv) (33,34), flavors and fragrances (35), and other organic molecules (8,12,36,37) have been pubflshed (see Enzyp applications, industrial Enzyt s in organic synthesis Elavors AND spices). 

H. lizuka and A. Naito, MicrobialTransformation of Steroids and Alkaloids, University Park Press, State College, Pa., 1967. 

Steroid alkaloids have been isolated from four famihes of terrestrial plant sources (Soianaceae l iliaceae pOijnaceae and Buxaceae) two animal sources (Saiamandra and Phjllobates) and several marine sources. Steroid alkaloids can be classified based on stmcture and fall into a variety of categories. The spirosolanes contain a cholestane skeleton with a C20 spiroaminoketal moiety, as exemplified by the most abundant members of this class, veramine... 

Biotransformations are carried out by either whole cells (microbial, plant, or animal) or by isolated enzymes. Both methods have advantages and disadvantages. In general, multistep transformations, such as hydroxylations of steroids, or the synthesis of amino acids, riboflavin, vitamins, and alkaloids that require the presence of several enzymes and cofactors are carried out by whole cells. Simple one- or two-step transformations, on the other hand, are usually carried out by isolated enzymes. Compared to fermentations, enzymatic reactions have a number of advantages including simple instmmentation reduced side reactions, easy control, and product isolation. 

As exemplified in the present procedure, the reaction has been optimized and extended in scope it affords functionalized benzocyclobutenes as well as substituted isoquinolines in high yields. Benzocyclobutenes have been used as intermediates in the synthesis of many naturally occurring alkaloids, - steroids,polycyclic terpenoids,and anthracycline antibiotics. The traditional routes leading to the preparation of benzocyclobutenes have been... 

If a molecule contains several asymmetric C atoms, then the diastereomers show diastereotopic shifts. Clionasterol (28a) and sitosterol (28b) for example, are two steroids that differ only in the absolute configuration at one carbon atom, C-24 Differing shifts of C nuclei close to this asymmetric C atom in 28a and b identify the two diastereomers including the absolute configuration of C-24 in both. The absolute configurations of carboxylic acids in pyrrolizidine ester alkaloids are also reflected in diastereotopic H and C shifts which is used in solving problem 54. 

In practice a few iodine crystals are usually placed on the bottom of a dry, closed trough chamber. After the chamber has become saturated with violet iodine vapor the solvent-free plates are placed in the chamber for 30 s to a few minutes. The iodine vapor condenses on the TLC layers and is enriched in the chromatogram zones. Iodine vapor is a universal detector, there are examples of its application for all types of substances, e.g. amino acids, indoles, alkaloids, steroids, psychoactive substances, lipids (a tabular compilation would be too voluminous to include in this section). 

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