Triterpenoids and steroids

Triterpenoids are quite rare in the Hepaticae. Ursolic acid (557), friedelinol (559) and epifriedelinol (660) have been found in Gymnocolea inflata 166). Friedelin (558) was isolated from Porella (164), Frullania (175, 

Campesterol (566), stigmasterol (568) and sitosterol (569) are distributed in most of the liverworts. Cholesterol (564) and brassicasterol (565) were also found in the Hepaticae however, their distribution is restricted to a few species. Calypogeia species contain campesteryl behenate (567) as the major component 80, 154). 

Structure Number Name of Compound Formula m.p.°C [ajp Plant Source Order References Comments  

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The in vitro EBV-EA activation inhibition assay uses EBV genome-carrying lymphoblastoid cells (Raji cells derived from Burkitt s lymphoma). Many compounds which inhibit EBV-EA induction by tumor promoters have been demonstrated to act as inhibitors of tumor promotion in vivo [16,22,42,66-68]. This assay has an advantage since it obtaines the information on die cytotoxicity from the viability of Raji cells. High viability of these cells is an important factor in developing a compound for the chemoprevention of cancer [16]. So far, a number of triterpenoids and steroids from plants and their derivatives have been shown to possess... 

Figure 12 Triterpenoid and steroid skeletons common in plants and structures of some saponins.

These studies firmly establish the role of 2,3-epoxysqualene (32) as progenitor of the polycyclic triterpenoids and steroids. However, a number of triterpenoids lack an oxygen function at C(3). In these cases, it has been suggested that a plausible biogenesis mechanism would involve the proton-initiated cyclization of squalene rather than of the terminal epoxide. An alternative hypothesis... 

Saccharum officinarum L. -cana-de-afucar Insomnia Culm (suco) Caboclos [56] Flavonoids [344,345] long-chain aliphatic acids [347] fatty acids [346,348] phenolic compounds [349] glycans [350] triterpenoids and steroids [351] Anti-inflammatory and analgesic effects [348] antidiabetes [350]... 

Yang C-R, Li X-C (1996) Bioactive Triterpenoid and Steroid Saponins from Medicinal Plants in Southwest China. Adv Exp Med Biol 404 225... 

A number of alkaloids containing steroid and triterpene skeleta are discussed under Triterpenoid and Steroid Alkaloids in Chapter 36. 

When macerated plant material or plant extracts containing saponins is shaken with water, a thick stable foam usually results (Hostettmann et al, 1991). This is the basis of a simple, reasonably specific test for the general presence of these compounds. Saponins also are detected by the Lieber-mann-Burchard test, which is useful for distinguishing between triterpenoid and steroidal saponins (Chandel and Ras-togi, 1980). 

A neat method for cleaving acid-sensitive triterpenoid and steroid aglycones from L-arabinopyranosides and D-galactopyranosides involved oxidation (DMSO-acetic anhydride) of the corresponding 3,4-0-isopropylidene derivative to the glycopyranosidulose, which can be cleaved on u.v.-irradiation in t-but-anol. Photolysis of the model acetals (61) gave, depending on the substituents... 

Rao AV, Gurftnkel DM (2000) The bioactivity of saponins triterpenoid and steroidal glycosides. Drug Metab Dmg Interact 17 211-235... 

Barton D H R, Jarman T R, Watson K C, Widdowson D A, Boar R B, Damps K 1975 Investigations on the biosynthesis of steroids and terpenoids. Part XII. Biosynthesis of 3fi-hydroxy-triterpenoids and -steroids from (3S)-2,3-epoxy-2,3-dihydrosqualene. J Chem Soc Perkin Trans I 1134-1138... 

A number of saponins and triterpenoid and steroid aglycones have been tested for antitumour activity and cytotoxicity in an attempt to establish structure-activity relationships [351]. These tests showed that saponins do not display cytotoxicity to any appreciable extent, and that in the 13 compounds which are active against W 256, no common structural element occurs. Acer saponin P is particularly interesting both chemically and biologically. 

Further combination of GPP with another IPP gives the G15 unit farnesyl diphosphate (FPP), and so on, up to G25. Terpenoids with more than 25 carbons—that is, triterpenoids (G30) and tetraterpenoids (G40)—are synthesized by dimerization of C15 and G20 units, respectively. Triterpenoids and steroids, in particular, arise from dimerization of farnesyl diphosphate to give squalene (Figure 23.10). 

The biogenetic-type synthesis of a number of naturally occurring penta-cyclic triterpenoids and steroids from acyclic olefinic epoxide precursors has been achieved. Thus the epoxide (501) is transformed into dl-d-amynn (502) (8%) by SnCl4-MeN02 at 0 °C. ... 

In addition to the above mentioned hydrocarbons, oils also contain alkenes and monoterpenic and sesquiterpenic hydrocarbons. For example, the amount of alkenes in olive oils range from 0.5 to 2 mg/kg and includes a series of alk-9-enes from C22 to C27, heptadec-8-ene and 6,10-dimethyl-undec-l-ene. An important compound is the linear triterpenic (C39) hydrocarbon squalene (3-81), aIl-tra s-2,6,10,15,19,23-hexamethyltetracosa-2, 6,10,14,18,22-hexaene, which is the universal precursor of all triterpenoids and steroids. It was given this name because it was discovered in the Hver of sharks (Squalidae). Shark Hver oil contains about 30% squalene, about 7% pristane (2,6,10,14-tetramethylpentadecane) and smaller amounts of phytane (2,6,10,14-tetramethylhexadecane). Squalene occurs in small amounts in edible oils and especially in oHve oil, where its content is in the tenths of a percent (1-7 g/kg). 

Triterpenoids and steroids are the major group of the lipid-accompanying substances in all natural lipids. Triterpenoids and steroids belong to a large group of compounds known as terpenoids or isoprenoids (through the oxidation or rearrangement modified terpenes). Six isoprene (2-methylbuta-1,3-diene) units... 

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