Triterpene derivatives

III. VIRUS-CELL FUSION INHIBITORS LECTINS, ALBUMINS, AND TRITERPENE DERIVATIVES... 

Figure 3 Triterpene derivative betulinic acid RPR103611 N - N-[3p-hydroxyl-up-20(29-ene-28-oyl]-8-aminooctanoyl -L-statine. 

Mayaux J-F, Bousseau A, Pauwels R, Huet T, Henin Y, Dereu N, Evers M, Soler F, Poujade C, De Clercq E, Le Pecq J-B. Triterpene derivatives that block entry of human immunodeficiency virus type 1 into cells. Proc Natl Acad Sci USA 1994 91 3564-3568. 

Hauke V, Graff R, Wehrung P, Trendel JM, Albrecht P, Schwark L, Keely BJ, Peakman TM, Novel triterpene-derived hydrocarbons of arborane/fernane series in sediments. Part I, Tetrahedron 48 3915—3924, 1992. 

The synthesis of 4-aza triterpenic derivative 362 (ring A modification) made use of the oxime rearrangement to promote the lactam formation (equation 141). Again, only one isomer of the product was observed. 

By using betulin as substrate, some mechanistic studies were performed and it was demonstrated that these reactions are catalyzed by Brpnsted acid species generated in situ from the hydrolysis of Bi(0Tf)3-.vH20. This process was also applied to other terpenic compounds. The sesquiterpene ( )-caryophyllene oxide originated clov-2-en-9a-ol by a cariophyllene-clovane rearrangement (Scheme 41) whereas 3-oxo- l 8a-olean-28- l 3(3-olide was obtained from oleanonic acid (Scheme 42). With this triterpene derivative, only 28,13(3-lactonization occurred, with inversion of the configuration of the stereocenter at C18 [133],... 

FIGURE 32. Constitution formula of triterpene-derived hydroperoxide 78 ... 

Navarro, et al. Antioxidant activity of maslnic acid, a triterpene derivative obtained from Olea europaea. Planta... 

Hauke, V. Graff, R. Wehrung, P. Trendel, J.M. Albrecht, L. Keefy, B.J. Peakman, T.M. (1992) Novel triterpene-derived hydrocarbons of arborane/femane series m sedim its. Tetrahedron, 48,3915-24. 

Mayaux, J. F, Bousseaux, A, Panwels, R, De Clerq, E, Pecq, J. B. (1994). Triterpenes derivatives that block the entry of human immunodeficiency virus type I into cells. Proceedings National Academy Sciences, 91, 3564-3568. 

In green plants, which contain little or no cholesterol, cydoartenol is the key intermediate in sterol biosynthesis.161-1623 As indicated in Fig. 22-6, step c, cydoartenol can be formed if the proton at C-9 is shifted (as a hydride ion) to displace the methyl group from C-8. A proton is lost from the adjacent methyl group to close the cyclopropane ring. There are still other ways in which squalene is cyclized,162/163/1633 including some that incorporate nitrogen atoms and form alkaloids.1631 One pathway leads to the hop-anoids. These triterpene derivatives function in bacterial membranes, probably much as cholesterol does in our membranes. The three-dimensional structure of a bacterial hopene synthase is known.164 1643 Like glucoamylase (Fig. 2-29) and farnesyl transferase, the enzyme has an (a,a)6-barrel structure in one domain and a somewhat similar barrel in a second domain. 

The practical use and the advantage of proton off-resonance decoupling - less multiplet overcrowding and more signal noise relative to coupled spectra - is illustrated in Fig. 2.47. for a triterpene derivative in comparison to modern and more accurate methods for determination of CH multiplicity. An unequivocal assignment of the number of directly attached hydrogens may be possible for all carbons. 

Limonoids are a group of chemically related triterpene derivatives found in the Rutaceae and Meliaceae. Limonin, a bitter member of the group, occurs widely in citrus juices. It has commercial significance because bitterness (excessive bitterness in the case of grapefruit) reduces juice quality. Dreyer (1) and Connolly et al. (2) have reviewed the chemistry and biochemistry of limonoids. 

In the early days the most direct method for the preparation of [m.n.l]propellanes was not yet known. Therefore the early methods involved solvolysis of suitable substrates. The first cases appear to be the preparation of derivatives of [4.4.1 ]propellanes (i.e. m = n = 4) from a compound containing a good leaving group and a suitably situated double bond. Thus the triterpene derivative (1) was used which gave a [4.4.1]propellane involving rings C and D of the educt 2. ... 

Steroids are degraded triterpene derivatives, and the different nuclei are classified based on carbon number. 

Many triterpene derivatives (some of them being new compounds) were isolated from the AcOEt fraction of Brazilian medicinal plant Camcaa, Cordia multispicata... 

Hydrocarbons Bile acids Sapogenins N-Aryl-N, N -dialkyl-urea herbicides [79] [81,82] [84] [86] rooi Cholestanone, a-cholestanol Triterpene derivatives CycltAexanol Sulfur-containing polysaccharides [80] [83] [85] [87]... 

Limonoids are a group of chemically related triterpene derivatives found in the plant families, Rutaceae and Meliaceae. Among 37 limonoids reported to occur in citrus and hybrids, four are known to be bitter. They are limonin, nomilin, ichangin and nomilinic acid. Limonin is the major cause of citrus juice bitterness and is widely distributed. Nomilin is also known to contribute to limonoid bitterness in grapefruit juice (4). 

Dimers are a class of compounds isolated from only seven species of Celastraceae family [8,88]. These triterpene dimers were found to be composed of one quinoid type and one aromatic type of triterpene derived from pristimerin, tingenone and / or their congeners joined together by two ether linkages formed between the two A rings or between the A and B rings. From the methylene chloride soluble portion of a methanolic extract of Maytenus chuchuhuasca, four dimeric compounds were isolated by Shirota et al. [88]. 

Table 2. Anti-inflammatory Triterpenes Derived from Olean-12-ene...

A86. Yasukawa, K., M. Takido, T. Matsumoto, M. Takeuchi, and S. Nagakawa Sterol and triterpene derivatives from plants inhibit the effects of tumor promoters and sitosterol and betulic acid inhibit tumor formation in monse skin two-stage carcinogenesis Oncology 48 (1991) 72-76. 

S. Nakagawa Sterol and triterpene derivatives from plants inhibit the effects of a tumor promoter and sitosterol and 27A15. 

A novel interpretation of the chiroptical properties of cyclopropyl ketones has been proposed. " In addition to the two natural planes of symmetry of the carbonyl group, a third nodal surface is considered to be curved in a manner similar to that postulated last year for other carbonyl compounds, with its convex face towards oxygen. Cyclopropyl groups are then considered to obey a reversed octant rule i.e. one which reverses the signs of the original octant rule) with respect to the three boundary surfaces. O.r.d. and c.d. data are reported for a variety of pentacyclic triterpene derivatives with oxo-groups at C-3, C-12, and C-16, and for a series of compounds in the A-nor-2-oxo-series, including a,j8-epoxy-ketones and some lactones. ... 

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