Ursolic acid methyl ester

Ursolic acid methyl ester (ursene triterpene) Semi-synthetic from Ursolic acid HIV-1 protease (14 pM) [53]... 

Using the same Nocardia sp. NRRL 5646 already utilized for the biotransformation of betulinic acid (see Section 28.1). Zhang et al. [42] showed that the same meth-ylation reaction of the C-28 carboxylic group occurred with oleanolic acid and ursolic acid (see Section 28.3). Interestingly, the ursolic acid methyl ester was also irreversibly rearranged to oleanolic methyl ester by migration of the C-19 methyl group to the C-20 position. 

Five FT acids, ursolic acid, oleanolic acid, betulinic acid, 23-hydroxybetulinic acid, and glycyrrhetinic acid were metabolized by Nocardia sp. NRRL 5646 to selectively furnish their corresponding 28-methyl esters. Notably, ursolic acid (87) was converted to oleanolic acid methyl ester via ursolic acid methyl ester as intermediate (Figure 28.30). The oleanolic ester is formed by participation of a "refrobiosynfhetic" methyl migration from C-19 to C-20 [42]. 

Nocardia strains were used by Leipold et al. [86] to generate the following ursolic acid derivatives (Figure 28.35) Nocardia sp. 45077 synthesized ursonic acid (103) and 3-oxoursa-l,12-dien-28-oic acid (104). Nocardia sp. 46002 produced only ursonic acid and Nocardia sp. 43069 showed no metabolism at all. Nocardia sp. NRRL 5646 (previously used for the methylation of lupane and olean families PTs [42,43]), Nocardia sp. 44822, and Nocardia sp. 44000 generated ursolic acid methyl ester (105), ursonic acid (103) and its methyl ester (106), and 3-oxoursa-l,12-dien-28-oic acid (104) and its me yl ester (107). 

Ursolic acid methyl ester Asiatic acid (113)... 

In the Croteau and Fogerson study, the triperpenic alcohols and sterols were derivatized into their trimethylsilyl ether derivatives using bis-trimethylsilylacetamide. The isopropanol-chloroform extract contained higher amounts of sterols and triteipenic alcohols such as p-sitosterol and amyrin compared to the SF extract. This could be due to the high polarity of the extracting liquid solvent as opposed to the supercritical fluid, and the increased volatility of the silylated sterols and triteipenic compounds relative to our fatty acid methyl esters, in addition to these compounds, the isopropanol-chloroform extract reported earlier also contained ursolic acid, a polar triteipenic acid, which was not extracted with pure CO2. 

Biotransformation of ursolic acid to oleanolic acid methyl ester by Nocardia sp. NRRL 5646 [42]. 

Methyl ursolate, 3p,28-dihydroxy-urs-12-ene (100), and the 3p,28-bis (dimethylcarbamoxy) derivative of 100 were incubated with Mucor plumbeus ATCC 4740 by Collins et al. [85]. Only methyl ursolate xmderwent hydroxylation to give the novel compoxmd 3p,7p,2ip-trihydrox30irsa-9(ll),12-dien-28-oic acid methyl ester as the sole product (Figure 28.34). 

Other common plant-derived triterpenoid acids, such as oleanolic and ursolic acid, exhibit weak antiinflammatory and antitumor activities, and studies have been directed at the synthesis of new analogues having increased potencies. These studies have led to the synthesis of 2-cyano-3,12-dioxoolean-l,9-dien-28-oic acid (CDDO) (54) and its methyl ester (55), which exhibit potent in vitro and in vivo antitumor activity against a wide range of tumors, including breast and pancreatic carcinomas and leukemias. ... 

Photolysis of solutions of C6o(OH)ig at low solute concentration leads to [C6o(OH)i8] by electron transfer from Me2C(OH) radicals or from hydrated electrons, and this has enabled the reduction potential of the C6o(OH)ig/ [C6o(OH)ig] couple to be estimated. The kinetics of the photoreduction of hexanal using RhCl(PMe3)2CO as catalyst have been measured and the feasibility of a photocatalytic synthesis of hexanol from pentane, CO, and H2 in the presence of rhodium complexes has been demonstrated. Irradiation of a chiral bimolecular crystal of acridine and R-(-)- or S-(+)-2-phenylpropionic acid induces photodecarboxylation followed by stereoselective condensation to give a mixture of three optically active products, and the 3-0-S-methyl dithiocarbo-nate derivatives of oleanolic and ursolic methyl esters have been used as models for the photodeoxygenation of alcohols. ... 

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