Gustavo Ruiz

Antibacterial activity of extracts from plants of central Argentina--isolation of an active principle from Achyrocline satureioides.

The great increase in bacterial infections is fueling interest in the search for antibacterial products of plant origin. Extracts obtained from 51 native and naturalized plants from central Argentina were therefore evaluated for their IN VITRO inhibitory activity on pathogenic bacteria with the aim of selecting the most active ones as new sources of effective antibiotics. The susceptibility of reference and clinical strains of Enterococcus faecalis, Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella enterica serovar Enteritidis, and Staphylococcus aureus was determined. Extracts from Achyrocline satureioides, Flourensia oolepis, Lepechinia floribunda, and Lithrea molleoides were the most potent, with MIC and MBC values ranging from 0.006 to 2 and 0.012 to 10 mg/mL, respectively, on both gram-positive and negative bacteria. The antibacterial activity-guided isolation of A. satureioides ethanol extract showed 23-methyl-6-O-desmethylauricepyrone (1) to be the most active compound. This compound showed inhibitory effects against gram-positive bacteria with MIC and MBC values of 0.002 and 0.008 mg/mL, respectively, while on gram-negative strains, the MIC and MBC were 0.062-0.250 and 0.062-0.500 mg/mL, respectively. The strong antibacterial activity shown by the four plant extracts or the compound isolated from A. satureioides suggests that they could become part of the arsenal of antibacterial drugs currently used.

Screening for acetylcholinesterase inhibitory activity in plant extracts from Argentina

Plants are a potential source of bioactive compounds and offer a promising strategy for the treatment of neurological disorders such as Alzheimers disease.

The Inhibitory Activity of Plants from Central Argentina on p-Hydroxyphenylpyruvate Dioxygenase. Isolation and Mechanism of Inhibition of a Flavanone from Flourensia oolepis.

The enzyme 4-hydroxyphenylpyruvate dioxygenase catalyzes the second step in the tyrosine degradation pathway. In mammals, this enzyme is the molecular target of drugs used for the treatment of metabolic disorders associated with defects in the tyrosine catabolism, mainly the fatal hereditary disease tyrosinemia type 1. This study evaluated the inhibitory effect of 91 extracts on 4-hydroxyphenylpyruvate dioxygenase from mostly native plants from central Argentina. Flourensia oolepis ethanol extract showed itself to be the most effective, and bioguided fractionation yielded pinocembrin (1) as its active principle. This flavanone, with an IC50 value of 73.1 µM and a KI of 13.7 µM, behaved as a reversible inhibitor of the enzyme and as a noncompetitive inhibitor. Molecular modeling studies confirmed the inhibitory potency of 1 and explained its activity by means of in silico determination of its binding mode in comparison to inhibitors of known activity, cocrystallized with 4-hydroxyphenylpyruvate dioxygenase. The main structural determinants that confer its potency are discussed. Analysis of the binding mode of the flavanone 1 with 4-hydroxyphenylpyruvate dioxygenase revealed the basis of the noncompetitive reversible mechanism of inhibition at the molecular level, which seems to be a common feature in this ubiquitous family of natural compounds. The resulting information may establish the basis for obtaining novel 4-hydroxyphenylpyruvate dioxygenase inhibitors for the treatment of tyrosinemia type 1 and other disorders associated with tyrosinase catabolism.

Cytotoxic Activity of Extracts from Plants of Central Argentina on Sensitive and Multidrug-Resistant Leukemia Cells: Isolation of an Active Principle from Gaillardia megapotamica

Plants are a significant reservoir of cytotoxic agents, including compounds with the ability to interfere with multidrug-resistant (MDR) cells. With the aim of finding promising candidates for chemotherapy, 91 native and naturalized plants collected from the central region of Argentina were screened for their cytotoxic effect toward sensitive and MDR P-glycoprotein (P-gp) overexpressing human leukemia cells by means of MTT assays. The ethanol extracts obtained from Aldama tucumanensis, Ambrosia elatior, Baccharis artemisioides, Baccharis coridifolia, Dimerostemma aspilioides, Gaillardia megapotamica, and Vernonanthura nudiflora presented outstanding antiproliferative activity at 50 μg/mL, with inhibitory values from 93 to 100%, when tested on the acute lymphoblastic leukemia (ALL) cell line CCRF-CEM and the resistant derivative CEM-ADR5000, while 70–90% inhibition was observed against the chronic myelogenous leukemia (CML) cell K562 and its corresponding resistant subline, Lucena 1. Subsequent investigation showed these extracts to possess marked cytotoxicity with IC50 values ranging from 0.37 to 29.44 μg/mL, with most of them being below 7 μg/mL and with ALL cells, including the drug-resistant phenotype, being the most affected. G. megapotamica extract found to be one of the most effective and bioguided fractionation yielded helenalin (1). The sesquiterpene lactone displayed IC50 values of 0.63, 0.19, 0.74, and 0.16 μg/mL against K562, CCRF-CEM, Lucena 1, and CEM/ADR5000, respectively. These results support the potential of these extracts as a source of compounds for treating sensitive and multidrug-resistant leukemia cells and support compound 1 as a lead for developing effective anticancer agents.

Volatile Organic Constituents of Clinopodium gilliesii (Benth.) Kuntze: Analysis by HS-SPME and classic hydrodistillation

In the present research, an analytical methodology to micro scale based on the use of the HS-SPME/GC-MS to determine volatile compounds present in Clinopodium gilliesii (Benth.) Kuntze (Lamiaceae) was employed, and settled differences and similarities with its essential oil obtained by hydrodistillation. A systematic description of the volatile components of flowers, stems, leaves and combined aerial parts (whole plant) was constructed via GC-MS analyses of HS-SPME adsorbed compounds and of essential oils obtained through hydrodistillation of the same tissues. Piperitenone oxide and piperitone oxide were the main components of both the HS-SPME analysis and essential oil analysis. The HS-SPME method can achieve comparable results to those obtained by essential oil analysis, by using very fewer samples, a shorter extraction time and a much simpler procedure. Para citar este articulo Vazquez, A., Aimar, M.,Decarlini, M., Demmel, G., Cantero, J y Ruiz, G. (2016). Volatile Organic Constituents of Clinopodium gilliesii (Benth.) Kuntze: Analysis by HS-SPME and classic hydrodistillation. Rev. Colomb. Investig. Agroindustriales, 3(1), 91-100. DOI: http://dx.doi.org/10.23850/24220582.351