RESUMO

The fact that alkaloids are bases has been the most explored chemical feature of their extraction and purification procedures. The main drawback of these procedures is that they employ undesirable chemicals, with HCl and CH2Cl2 probably being the most commonly employed chemicals in their subsequent steps. This work tested the hypothesis that advantages in recovery efficiency support this common practice. Experiments were conducted in three laboratories, monitoring the alkaloids harmine (1), boldine (2), vincamine (3), and mescaline (4) extracted from Banisteriopsis caapi, Peumus boldus, Vinca minor, and Trichocereus macrogonus var. pachanoi, respectively. The research demonstrated that HCl could be replaced with citric acid (CA) without loss or even better extraction performance. The recommended EtOAc could completely replace CH2Cl2 in three out of four study cases and partially in the fourth case without harming the extraction efficiency. In addition, the alternative solvents tert-amyl methyl ether (TAME) and n-butyl acetate (BuOAc) could enhance the extraction of alkaloids. These results might incentivize natural products laboratories to consider sustainability more routinely, thus being closer to current practices in the pharmaceutical industry, which has been replacing solvents and processes with greener ones.

Assuntos

Alcaloides , Extratos Vegetais , Mescalina , Solventes

RESUMO

The oleoresin of Copaifera reticulata Ducke, Fabaceae, is a traditional Brazilian remedy used for a wide range of applications. Commonly named copaiba, the oleoresin has been found to exhibit strong antimicrobial effects in our previous study, which could be attributed to some of its diterpenoid constituents. In order to find new biological activities and to eventually enhance the before observed effects, (-)-polyalthic acid (1) and kaurenoic acid (2), together with eight prepared semi-synthetic derivatives (1a-1c and 2a-2e) were evaluated for their cytotoxic, antibacterial and antifungal properties. Regarding the gram-positive bacteria Enterococcus faecium and methicillin-resistant Staphylococcus aureus, we found that both the exocylic methylene group and the carboxyl group were crucial for the activity against these two clinically relevant bacterial strains. Investigation of the antifungal activity, in contrast, showed that the carboxyl group is unnecessary for the effect against the dermatophytes Trichophyton rubrum and Cryptococcus neoformans, indicated by low micromolar IC50 values for both (-)-polyalthic acid diethylamide (1a) as well as (-)-polyalthic acid methyl ester (1b). Apart from studying the biological activity, the structure of one semi-synthetic derivative, compound 1c, is being reported for the first time. During the course of the structure elucidation of the new compound, we discovered inconsistencies regarding the stereochemistry of polyalthic acid and its stereoisomers, which we clarified in the present work. Graphical Abstract.