The Effect of Maturity Stage on Polyphenolic Composition, Antioxidant and Anti-Tyrosinase Activities of Ficus rubiginosa Desf. ex Vent. Extracts.

Ficus spp. are often used as food and in traditional medicine, and their biological activities as anti-inflammatory and diuretic, for wound healing, and as antimicrobial agents have been largely reviewed. The aim of this work was to investigate the polyphenol content and the antioxidant and anti-tyrosinase properties of the extracts from F. rubiginosa, a very poorly explored Ficus species. For this purpose, F. rubiginosa leaves were collected at three different maturity stages (H1, H2, and H3), and the environmentally sustainable methanolic extracts were evaluated for the total phenolic content (TPC), total flavonoid content (TFC), and total catechins content (TCC). The polyphenolic profile was studied using HPLC-UV/DAD and UHPLC-MS, and the antioxidant activity was determined in vitro using DPPH, FRAP, and ABTS assays. The study showed that the H2 extract had higher TPC and TFC values (113.50 mg GA/g and 43.27 mg QE/g, respectively) and significant antioxidant activity. Therefore, the H2 extract was selected to study the anti-tyrosinase activity. The results also showed that H2 was able to bind and inhibit tyrosinase, with rutin being the compound responsible for the measured activity on the enzyme.

Development of an easy-to-set-up multiple heart-cutting achiral-chiral LC-LC method for the analysis of branched-chain amino acids in commercial tablets.

In this paper, the development and application of a multiple heart-cutting achiral-chiral LC-LC method (mLC-LC) for the analysis of dansylated (Dns) branched-chain amino acids in commercial tablets are described. In the first dimension, a Waters Xbridge RP C18 achiral column was used under gradient conditions with buffered aqueous solution and acetonitrile. The elution order Dns-valine (Dns-Val) < Dns-isoleucine (Dns-Ile) < Dns-leucine (Dns-Leu) turned out with full resolution between adjacent peaks: 7.25 and 1.50 for the Val/Ile and the Ile/Leu pairs, respectively. A "research" validation study was performed, revealing high accuracy (Recovery%) and precision (RSD%) using two external set solutions, respectively, in the range 93.7%-104.1% and 0.4%-3.2%. The C18 column was connected via a two-position six-port switching valve to the quinidine-based Chiralpak quinidine-anion-exchange chiral column. A water/acetonitrile, 30/70 (v/v) with 50 mM ammonium acetate (apparent pH of 5.5) eluent allowed getting the three enantiomers' pairs resolved: RS equal to 4.3 for Dns-Val and Dns-Ile, and 1.7 for Dns-Leu. The application of the mLC-LC method confirmed that the content of Val, Ile, and Leu in the tablets was compliant with that labeled by the producer. Only l-enantiomers were found in the food supplement, as confirmed by LC-MS/MS analysis.

Estimating the hydrophobicity extent of molecular fragments using reversed-phase liquid chromatography.

A fast HPLC method was developed to study the hydrophobicity extent of pharmaceutically relevant molecular fragments. By this strategy, the reduced amount of sample available for physico-chemical evaluations in early-phase drug discovery programs does not represent a limiting factor. The sixteen acid fragments investigated were previously synthesized also determining potentiometrically their experimental log D values. For four fragments it was not possible to determine such property since their values were outside of the instrumental working range (2 < pKa  < 12). An RP-HPLC method was therefore optimized. For each scrutinized method, some derived chromatographic indices were calculated, and Pearson's correlation coefficient (r) allowed to select the so-called "φ0 index" as the best correlating with the log D. The w s p H ${}_w/pH$ was fixed at 3.5 and a modification of some variables [organic modifier (methanol vs. ACN), stationary phase (octyl vs. octadecyl), presence/absence of the additives n-octanol, n-butylamine, and n-octylamine], allowed to select the best correlation conditions, producing a r = 0.94 (p < 0.001). Importantly, the φ0 index enabled the estimation of log D values for four fragments which were unattainable by potentiometric titration. Moreover, a series of molecular descriptors were calculated to identify the chemical characteristics of the fragments explaining the obtained φ0 . The number of hydrogen bond donors and the index of cohesive interaction correlated with the experimental data.