No abstract

Volatile compounds of cajá and taperebá fruits, both classified as Spondias mombin, but from different geographic origins, were extracted (and analyzed) using solid phase microextraction (SPME) and simultaneous distillation and extraction (SDE). Forty-eight compounds were identified in taperebá and 47 in cajá by SPME using a DVB/CAR/PMDS fiber. (E)-Caryophyllene (18.7%), ethyl butyrate (10.0%), and ethyl hexanoate (7.0%) were the most abundant components in taperebá volatiles extracted by SPME, whereas myrcene (41.1%) and beta-phellandrene (8.5%) were the major compounds in cajá. In the taperebá SDE extract, 46 substances were identified, and (Z)-caryophyllene (13.2%) and limonene (9.5%) were predominant. From the 42 substances found in the SDE extract of cajá, the major components were myrcene (38.0%) and p-cymene (6.2%). The two fruits showed similar chromatograms upon the use of SDE and SPME. These methods made it possible to determine 30 identical components in both fruits by using SDE and 32 by using SPME.

A técnica de HPLC por troca de ligante foi utilizada para a separação de racematos de amino ácidos com cadeia lateral alifática. Para tanto, o seletor quiral escolhido foi o complexo de Cu(II) combinado com a L-fenilalananina. Os resultados mostram que o primeiro enanciômero a eluir foi a forma D, seguido da forma L. Segundo o conceito de interação de 3 pontos, foi proposto um mecanismo de reconhecimento quiral, no qual não há evidências de mudança de configuração após a formação dos complexos pseudo-homo e heteroquiral. Cálculos DFT-B3LYP para energia e espectro vibracional confirmaram a viabilidade deste mecanismo, pois mostram a que a configuração trans do complexo homoquiral é mais estável do que a forma cis.Ligand exchange HPLC technique was applied to resolve chiral separation of aliphatic side chain aminoacid racemates. Chiral selector was copper L-phenylalaninate (II) and the results showed the elution of D enantiomer followed by L form. Considering the 3-point interaction concept, a mechanism of chiral recognition was proposed, in which no change of configuration would follow the formation of pseudo-homochiral and heterochiral complexes. To prove the reliability of this mechanism, the trans configuration of homochiral complex had to be more stable than the cis form, which was confirmed by DFT-B3LYP calculation in gas phase. The infrared frequencies were also calculated and the comparison with the subtracted and deconvoluted spectrum of the in-solution complex also pointed to the presence of the trans diasteroisomer.