Pilar E. López

Solution- and solid-phase synthesis and anti-HIV activity of maslinic acid derivatives containing amino acids and peptides

Maslinic acid (1) has been coupled at C-28 with several alpha- and omega-amino acids by using solution- and solid-phase synthetic procedures. Twelve derivatives (2-13) with a single amino acid residue were prepared in solution phase, whereas a dipeptide (14), a tripeptide (15), and a series of conjugate dipeptides (16-24) were synthesized in solid phase. The anti-HIV activity of these compounds was assessed on MT-2 cells infected with viral clones carrying the luciferase gene as a reporter. While in maslinic acid (1) were present both cytotoxic and antiviral activities, only the derivatives 13 and 24 showed anti-HIV-1 activity and therefore represent a novel class of anti-HIV-1 compounds.

Bioactive Compounds with Added Value Prepared from Terpenes Contained in Solid Wastes from the Olive Oil Industry

Starting from solid wastes from two‐phase olive‐oil extraction, the pentacyclic triterpenes oleanolic acid and maslinic acid were isolated. These natural compounds were transformed into methyl olean‐12‐en‐28‐oate (5), which then was transformed into several seco‐C‐ring triterpene compounds by chemical and photolytic modifications. The triene seco‐products were fragmented through several oxidative procedures to produce, simultaneously, cis‐ and trans‐decalin derivatives, both potential synthons for bioactive compounds. The chemical behavior of the isolated fragments was investigated, and a suitable approach to several low‐molecular‐weight terpenes was performed. These are interesting processes for the value‐addition to solid waste from the olive‐oil industry.

Degradation of triterpenic compounds from olive-pressing residues. Synthesis of trans-decalin type chiral synthons

Three seco-C-ring triterpenic compounds were obtained from oleanolic or maslinic acids from olive-mill solid wastes by photochemical and chemical reactions. From these oleantriene compounds, different remarkable sesquiterpene and nor-sesquiterpene fragments such as 3β-hydroxydrimenol (13) and epoxydecalone (16) were achieved through oxidative cleavages of the double bonds in the opened C-ring.

Different pathways for the deoxygenation of the A-ring of natural triterpene compounds

Some deoxygenation pathways were tested to remove the hydroxyl groups of the natural triterpenes oleanolic acid and maslinic acid to obtain a practical starting material for the semisynthesis of other interesting organic synthons. Different deoxygenation processes were carried out starting from these triterpenic acids or from several derivatives such as methyl esters and epoxy derivatives. The hydroxyl groups were transformed into some intermediate compounds including xanthyl, thiocarbonyl or tosyl derivatives. The opening of the oxirane ring between C-2 and C-3 was also achieved through different methods using deoxygenating reagents such as Me3SiCl/NaI, WCl4/n-BuLi and Cp2TiCl.

Reactivity of Chiral Sesquiterpene Synthons Obtained by the Degradation of Maslinic Acid from Olive‐Pressing Residues

Abstract Maslinic acid, a naturally occurring compound isolated from the solid wastes of olive‐oil pressing, was fragmented through the C‐ring via oxidative procedures to obtain two structural fragments. The chemical behaviors of cis‐decalin, from the D and E rings, and of trans‐decalin fragments, from the A and B rings, were investigated in depth using several chemical and enzymatic reactions. These decalin chiral synthons are interesting intermediates to semisynthesize phenanthrene‐ and drimane‐type compounds and natural tricyclic triterpenes.