Search Results (5)

Giardiasis is a parasitosis caused by Giardia lamblia with significant epidemiological and clinical importance due to its high prevalence and pathogenicity. The lack of optimal therapies for treating this parasite makes the development of new effective chemical entities an urgent need. In the search for new inhibitors of the adenylyl cyclase gNC1 obtained from G. lamblia, 14 extracts from Argentinian native plants were screened. Lepechinia floribunda and L. meyenii extracts exhibited the highest gNC1 inhibitory activity, with IC₅₀ values of 9 and 31 µg/mL, respectively. In silico studies showed rosmarinic acid, a hydroxycinnamic acid present in both mentioned species, to be a promising anti-gNC1 compound. This result was confirmed experimentally, with rosmarinic acid showing an IC₅₀ value of 10.1 µM. Theoretical and experimental findings elucidate the molecular-level mechanism of rosmarinic acid, pinpointing the key interactions stabilizing the compound–enzyme complex and the binding site. These results strongly support that rosmarinic acid is a promising scaffold for developing novel compounds with inhibitory activity against gNC1, which could serve as potential therapeutic agents to treat giardiasis. Full article

In this study, we developed a novel offline high-performance liquid chromatography (HPLC) method based on 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) radicals for antioxidant screening in 20 polyphenolic compounds and used the Trolox equivalent antioxidant capacity assay to evaluate their antioxidant activity. Compared to the existing offline HPLC methods based on 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH), the offline HPLC method based on the AAPH radical is more sensitive. Additionally, we applied this method to Lepechinia meyenii (Walp.) Epling extract and screened out seven antioxidants, caffeic acid, hesperidin, rosmarinic acid, diosmin, methyl rosmarinate, diosmetin, and n-butyl rosmarinate, which are known antioxidants. Therefore, this study provides new insights into the screening of antioxidants in natural extracts. Full article

In the present investigation, an ethanolic fraction (EF) of Lepechinia meyenii (salvia) was prepared and fractionated by gradient column chromatography, and the main secondary metabolites present in the EF were identified by HPLC-MS. Silver nanoparticles (AgNPs) were synthesized and conjugated with the EF of Lepechinia meyenii (salvia). The AgNPs synthesis was optimized using Plackett-Burman design and response surface methodology (RSM), considering the following independent variables: stirring speed, synthesis pH, synthesis time, synthesis temperature and EF volume. The AgNPs synthesized under the optimized conditions were characterized by UV visible spectroscopy (UV-VIS), Fourier Transform Infrared Spectroscopy (FT-IR), Dynamic Light Scattering (DLS) and Scanning Transmission Electron Microscopy (STEM). The antibacterial activity of the AgNPs against Staphylococcus aureus (ATCC^® 25923) was evaluated. The following flavonoids were identified: rosmarinic acid, diosmin and hesperetin-7-O-rutinoside. The optimized conditions for the synthesis of nanoparticles were pH 9.45, temperature 49.8 °C, volume of ethanolic fraction 152.6 µL and a reaction time of 213.2 min. The obtained AgNPs exhibited an average size of 43.71 nm and a resonance plasmon of 410–420 nm. Using FT-IR spectroscopy, the disappearance of the peaks between 626.50 and 1379.54 cm⁻¹ was evident with the AgNPs, which would indicate the participation of these functional groups in the synthesis and protection of the nanoparticles. A hydrodynamic size of 47.6 nm was obtained by DLS, while a size of 40–60 nm was determined by STEM. The synthesized AgNPs conjugated with the EF showed a higher antibacterial activity than the EF alone. These results demonstrate that the AgNPs synthesized under optimized conditions conjugated with the EF of the Lepechinia meyenii (salvia) presented an increased antibacterial activity. Full article

We previously reported that Lepechinia meyenii (Walp.) Epling has antioxidant and aldose reductase (AR) inhibitory activities. In this study, L. meyenii was extracted in a 50% MeOH and CH₂Cl₂/MeOH system. The active extracts of MeOH and 50% MeOH were subjected to fractionation, followed by separation using high-speed counter-current chromatography (HSCCC) and preparative HPLC. Separation and identification revealed the presence of caffeic acid, hesperidin, rosmarinic acid, diosmin, methyl rosmarinate, diosmetin, and butyl rosmarinate. Of these, rosmarinic acid, methyl rosmarinate, and butyl rosmarinate possessed remarkable antioxidant and AR inhibitory activities. The other compounds were less active. In particular, rosmarinic acid is the key contributor to the antioxidant and AR inhibitory activities of L. meyenii; it is rich in the MeOH extract (333.84 mg/g) and 50% MeOH extract (135.41 mg/g) of L. meyenii and is especially abundant in the EtOAc and n-BuOH fractions (373.71–804.07 mg/g) of the MeOH and 50% MeOH extracts. The results clarified the basis of antioxidant and AR inhibitory activity of L. meyenii, adding scientific evidence supporting its traditional use as an anti-diabetic herbal medicine. The HSCCC separation method established in this study can be used for the preparative separation of rosmarinic acid from natural products. Full article

Enzymes MurA and MurF, involved in bacterial cell wall synthesis, have been validated as targets for the discovery of novel antibiotics. A panel of plant-origin antibacterial diterpenes and synthetic analogs derived therefrom were investigated for their inhibitory properties on these enzymes from Escherichia coli and Staphylococcus aureus. Six compounds were proven to be effective for inhibiting MurA from both bacteria, with IC₅₀ values ranging from 1.1 to 25.1 µM. To further mechanistically investigate the nature of binding and to explain the activity, these compounds were docked into the active site of MurA from E. coli. The aromatic ring of the active compounds showed a T-shaped π–π interaction with the phenyl ring of Phe328, and at least one hydrogen bond was formed between the hydroxy groups and Arg120 and/or Arg91. The results disclosed here establish new chemical scaffolds for the development of novel entities targeting MurA as potential antibiotics to combat the threat of pathogenic bacteria, particularly resistant strains. Full article