Considering the economic potential of secondary metabolites, researches have been focusing several strategies in order to explore and enhance the accumulation of these metabolites in plant matrices in a broad context. One of those strategies is the development of suitable methodologies for the determination of some elicitors, such as salicylic acid (SA). Since literature presents only a few analytical methods for the quantification of SA in plants, this study developed, validated and evaluated these metabolite contents in Polygala species using capillary zone electrophoresis with ultraviolet-visible detection. The background electrolyte (BGE) consisted of 15 mmol L−1 of hydroxymethyl-aminomethane and 30 mmol L−1 of 2-hydroxy-isobutyric acid, pH = 3.9. The BGE was chosen using a rational procedure to increase selectivity and reduce migration time. The method presented rapid performance, migration time less than 0.76 min for salicylic and phthalic acid (internal standard), precision results for peak area were better than 2.9% (intra-day) and 2.8% (inter-day) and the responses for the analytes were linear (range of 1-5 mg L−1), with limits of detection and quantification of 0.2 and 0.6 mg L−1, respectively. The developed method was applied for 39 samples of plant extracts.

This paper describes the use of a multiple-injection capillary electrophoresis method as a fast strategy to determine the antinitrosating capacity of nine commercial teas through nitrite quantification. The method consists of the injection of the sample followed by the injection of the control solution, employing a fused-silica capillary of 32.0 cm total length (23.5 cm effective length, 50 µm internal diameter) with background electrolyte composed of 4.0 g L-1 β-alanine and 1.5 g L-1 perchloric acid (pH 3.79) and sodium thiocyanate was used as the internal standard. Before the injections the tea samples were maintained by 1 h of incubation, at 37 °C, with sodium nitrite in perchloric acid medium (pH 2.3). In order to avoid nitrite oxidation and nitrate formation, ultra-pure nearly oxygen-free water was used to prepare the solutions. Black tea, green tea and white tea, obtained from Camellia sinensis, showed greater antinitrosating capacity (96, 93 and 89%, respectively).

Uma investigação fitoquímica de Polygala molluginifolia (raiz, caule, folhas e flores) resultou no isolamento de quatro piranoisoflavonas das quais a isoflavona1é desconhecida na literatura. As isoflavonas 2-4: , embora sejam compostos sintéticos conhecidos são descritos neste trabalho como novos produtos naturais. Os compostos isolados foram avaliados em termos do seu efeito antioxidante e o potencial para inibir a enzima acetilcolinesterase. As isoflavonas 1 e 4 inibiram a acetilcolinesterase, exibindo valores de IC50 de 68 µmol L-1 e 84 µmol L-1, respectivamente. No ensaio de DPPH, os mesmos compostos e a rutina 5 apresentaram valores de EC50 de 61 µmol L-1, 55 µmol L-1 e 16 µmol L-1, respectivamente. Além disso, a permeabilidade das compostos 1-4 foi testada através do ensaio de permeabilidade em membrana artificial paralela (PAMPA) com as isoflavona 3 (9.25 × 10-6 cm s-1) e 4 (3.48 × 10-6 cm s-1) exibindo as maiores permeabilidades.

A phytochemical investigation of Polygala molluginifolia (root, stem, leaves and flowers) resulted in the isolation of four pyranoisoflavones, of which isoflavone 1 was previously unknown in the literature. Isoflavones 2-4: , although they are known synthetic compounds, are described in this work as new natural products. The isolated compounds were evaluated for their antioxidant effects and potential for inhibiting the acetylcholinesterase enzyme. Isoflavones 1 and 4 inhibited acetylcholinesterase, displaying IC50 values of 68 µmol L-1 and 84 µmol L-1, respectively. In the DPPH assay, the same compounds and rutin 5 exhibited EC50 values of 61 µmol L-1, 55 µmol L-1 and 16 µmol L-1, respectively. Moreover, the permeability of compounds 1-4: was evaluated using parallel artificial membrane permeability assay (PAMPA) with isoflavones 3 (9.25 × 10-6 cm s-1) and 4 (3.48 × 10-6 cm s-1) exhibiting the highest permeabilities.