Lorena Luna

Main flavonoids, DPPH activity, and metal content allow determination of the geographical origin of propolis from the Province of San Juan (Argentina).

The chemical characterization as well as the assessment of geographical origin of propolis from several areas of the Provincia de San Juan (Argentina) is reported. Chemical characterization of propolis was performed by measuring total phenolic (TP), total flavonoids (FL), free radical scavenging capacity (DPPH bleaching), and metal content in samples of six different districts. Methanolic propolis extracts (MEP) showed TP ranging from 25.7 to 39.3 g of gallic acid equivalents per 100 g of MEP, whereas flavonoids ranged from 6.6 to 13.3 g of quercetin equivalents per 100 g of MEP. Six main flavonoids were isolated and identified from the propolis samples, comprising the flavanones 7-hydroxy-8-methoxyflavanone (1), pinocembrin (2), and pinobanksin (3), the flavones chrysin (4) and tectochrysin (5), and the flavonol galangin (6). Compounds 1-6 were quantified by HPLC-PDA. Free radical scavenging activity, measured as percent DPPH bleaching, ranged from 46.6 to 89.5 at 10 mug/mL. Moreover, propolis samples presented high contents of Ca, K, Fe, Na, and Mg, but low amounts of Mn and Zn. Linear discriminant analysis affords eight descriptors, galangin, pinocembrin, pinobanksin, chrysin, tectochrysin, DPPH, K, and Na, allowing a clear distinction with 100% accuracy among different origins within the Provincia de San Juan. A direct relationship of DPPH free radical scavenging activity with TP or with compounds 1-6 was not found, showing the need of further evaluation on the origin of free radical activity in propolis samples.

Essential Oils of Medicinal Plants from the Central Andes of Argentina: Chemical Composition, and Antifungal, Antibacterial, and Insect-Repellent Activities

The antifungal, antibacterial, and insect‐repellent activities of the essential oils (EOs) of Acantholippia seriphioides, Artemisia mendozana, Gymnophyton polycephalum, Satureja parvifolia, Tagetes mendocina, and Lippia integrifolia, collected in the Central Andes area, province of San Juan, Argentina, were investigated. The dermatophytes Microsporum gypseum, Trichophyton mentagrophytes, and T. rubrum were inhibited by the EOs of G. polycephalum, L. integrifolia, and S. parvifolia, with minimum inhibitory concentrations (MICs) between 31.2 and 1000 μg/ml. Moreover, all EOs presented moderate activity against the bacteria tested, and the L. integrifolia and G. polycephalum EOs showed excellent repellent properties against Triatoma infestans, the Chagas disease vector, with repellency values between 60 and 100%. The A. seriphioides, G. polycephalum, and L. integrifolia EOs, obtained by hydrodistillation, were characterized by GC‐FID and GC/MS analyses. The highest number of components (40) was identified in L. integrifolia EO, which, along with that of A. seriphioides, contained important amounts of oxygenated monoterpenes (44.35 and 29.72%, resp.). Thymol (27.61%) and carvacrol (13.24%) were the main components of A. seriphioides EO, and borneol, lippifoli‐1(6)‐en‐5‐one, and terpinen‐4‐ol (>8.5%) were the principal compounds of L. integrifolia EO. These results support the idea that oxygenated monoterpenes are the bioactive fractions of the EOs. Finally, the study shows that these Andean species might be used to treat superficial fungal infections and to improve the local Chagas disease situation by vector‐control.

Chemical Composition and Antibacterial Activity of Satureja parvifolia (Phil.) Epling Essential Oil

Abstract Chemical composition, GC and GC-MS analysis and in vitro antibacterial activity of the essential oils of the aerial parts of Satureja parvifolia (Phil.) Epling collected in San Juan Province Argentine were performed. Twenty six compounds were identified accounting for 94.1% (area %) of the essential oil. The major constituents were piperitone (34.9%), piperitenone (27.3%), cis-piperitenone epoxide (15.0%) and piperitenone oxide (6.0%). The in vitro antimicrobial activity of the essential oil was investigated by the microdilution method, with Cefotaxime as the standard antibiotic against seven Gram-negative and three Gram-positive bacteria. A strongest activity was observed for the essential oil against all Gram negative bacteria assayed, principally Yersinia enterocolítica-PI and Salmonella enteritidis-MI with a MIC value equal to 0.82 mg/ml.

UHPLC-MS Metabolome Fingerprinting: The Isolation of Main Compounds and Antioxidant Activity of the Andean Species Tetraglochin ameghinoi (Speg.) Speg.

The seriated extracts of petroleum ether (PE-E), dichloromethane (DCM-E) and methanol extracts (MeOH-E) from the aerial parts of the native South American plant Tetraglochin ameghinoi (Rosaceae), were evaluated regarding their antioxidant and antibacterial activities. The antioxidant properties were evaluated by free radical scavenging methods (DPPH and TEAC), ferric-reducing antioxidant power (FRAP) and lipoperoxidation in erythrocytes (LP), while the antibacterial activity was performed against Gram-positive and Gram-negative bacteria according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The chemical and biological analyses of this plant are very important since this bush is currently used in traditional medicine as a cholagogue and digestive. The polar MeOH-E showed the highest antioxidant activities (17.70 µg/mL in the DPPH assay, 381.43 ± 22.38 mM TE/g extract in the FRAP assay, 387.76 ± 91.93 mg TE/g extract in the TEAC assay and 93.23 + 6.77% in the LP assay) and it was selected for chromatographic isolation of its components. These components were found to be four acetophenones, including the new phloracetophenone glucoside: 4′,6′,-dihydroxy-2′-O-(6″-acetyl)-β-d-glucopyranosylacetophenone or IUPAC name: (6-(2-acetyl-3,5-dihydroxyphenoxy)-3,4,5-trihydroxytetrahydro-2H-pyran-2-yl)methyl acetate, whose structure was elucidated by NMR and MS methods. In addition, twenty-six compounds, including five of these acetophenone derivatives, two sugars, six flavonoids, eleven phenolic acids and two triterpenes, were identified based on UHPLC-OT-MS and PDA analysis on the MeOH-E. The results support the medicinal use of the plant.

The activity of propolis in the scavenging of vitamin B2-photogenerated ROS

Objectives: The study was focused on the activity of propolis from Amaicha del Valle, Argentina (ProAV) as a promoter and scavenger of Riboflavin (Rf) – photogenerated reactive oxygen species (ROS). Methods: Through a kinetic and mechanistic study, employing stationary and time-resolved photochemical and electrochemical techniques, the protecting activity of ProAV was investigated. Results: In the absence of light and Rf, ProAV exerted a relatively efficient inhibitory effect on 1,1-diphenyl-2-picrylhydrazyl radicals and acts as a protector of artificially promoted linoleic acid oxidation. Under aerobic visible-light-irradiation conditions, in the presence of Rf as the only light-absorber species, a complex picture of competitive processes takes place, starting with the quenching of singlet and triplet electronically excited states of Rf by ProAV. The species O2(1 g), O2•−, H2O2, and OH• are generated and interact with ProAV. Discussion: ProAV behaves as an efficient ROS scavenger. It is scarcely photo-oxidized by interaction with the mentioned ROS. Quantitative results indicate that ProAV is even more resistant to photo-oxidation than the recognized antioxidant trolox. Two dihydroxychalcones, mostly present in the ProAV composition, are responsible for the protecting activity of the propolis.

Antimicrobial and antioxidant activities of Gentianella multicaulis collected on the Andean Slopes of San Juan Province, Argentina.

The infusion of the aerial parts of Gentianella multicaulis (Gillies ex Griseb.) Fabris (Gentianaceae), locally known as ‘nencia’, is used in San Juan Province, Argentina, as stomachic and as a bitter tonic against digestive and liver problems. The bioassay-guided isolation of G. multicaulis extracts and structural elucidation of the main compounds responsible for the antifungal and free radical scavenging activities were performed. The extracts had strong free radical scavenging effects in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay (45 - 93% at 10 μg/mL) and ferric-reducing antioxidant power (FRAP) assay at 200 μg/mL. Demethylbellidifolin (4) had high antioxidant activity in the DPPH and FRAP assay. The dermatophytes Microsporum gypseum, Trichophyton mentagrophytes, and T. rubrum were moderately inhibited by the different extracts (MIC values of 125 - 250 μg/mL). Demethylbellidifolin (4), bellidifolin (5), and isobellidifolin (6) showed an antifungal effect (MIC values of 50 μg/mL), while swerchirin (3) was less active with a MIC value of 100 μg/mL. In addition, oleanolic acid (1) and ursolic acid (2) were also isolated. These fi ndings demonstrate that Gentianella multicaulis collected in the mountains of the Province of San Juan, Argentina, is an important source of compounds with antifungal and antioxidant activities.