Síntese de derivados halogenados e glicosilados do ácido acantoico de annona amazonica

Abstract

Acanthoic acid (AA) is a pimaradiene-like diterpene isolated from many plants, especially those belonging to Annonaceae family. In Amazon rainforest, AA is massively isolated from the n-hexane extract of Annona amazonica stems, reaching up to 65% of the extract total mass. Taking it into account, this abundant and renewable resource represents an important opportunity for the development of semisynthetic based bioactive and complex new compounds. In this way, the present study aimed to perform structural modifications on the AA molecule, specially oxigenations, halogenations and glycosylations. The starting material was isolated from the hexane extract of A. amazonica stems by column chromatography. Chemical transformations were carried out on AA structure through epoxidation, halogenations and carboxyl reduction. The epoxide was identified by NMR 1H, 13C, DEPT-135, HSQC, HMBC and NOESY techniques, as well as mass spectrometry. The product also was evaluated for acetylcholinesterase inhibition activity. In respect to halogenated products, just the brominated product was isolated and identified through NMR and MS spectrometry, while the chlorination and iodation crude products resulted in a complex matrix of compounds, we found unable to purify. However, the success of these protocols of halogenation was verified by mass spectrometry. The reduction product of AA was isolated and identified by spectroscopic techniques.