María Victoria Rodríguez

Antifungal Activity of Eugenol Analogues. Influence of Different Substituents and Studies on Mechanism of Action

Twenty one phenylpropanoids (including eugenol and safrole) and synthetic analogues, thirteen of them new compounds, were evaluated for antifungal properties, first with non-targeted assays against a panel of human opportunistic pathogenic fungi. Some structure-activity relationships could be observed, mainly related to the influence of an allyl substituent at C-4, an OH group at C-1 and an OCH3 at C-2 or the presence of one or two NO2 groups in different positions of the benzene ring. All active compounds were tested in a second panel of clinical isolates of C. albicans and non-albicans Candida spp., Cryptococcus neoformans and dermatophytes. The eugenol derivative 4-allyl-2-methoxy-5-nitrophenol (2) was the most active structure against all strains tested, and therefore it was submitted to targeted assays. These studies showed that the antifungal activity of 2 was not reversed in the presence of an osmotic support such as sorbitol, suggesting that it does not act by inhibiting the fungal cell wall synthesis or assembly. On the other hand, the Ergosterol Assay showed that 2 did not bind to the main sterol of the fungal membrane up to 250 µg mL−1. In contrast, a 22% of fungal membrane damage was observed at concentrations = 1 × MIC and 71% at 4× MIC, when 2 was tested in the Cellular Leakage assay. The comparison of log P and MICs for all compounds revealed that the antifungal activity of the eugenol analogues would not to be related to lipophilicity.

Antifungal activity of extracts and prenylated coumarins isolated from Baccharis darwinii Hook & Arn. (Asteraceae).

The petroleum ether extract of Baccharis darwinii showed activity against Cryptococcus neoformans and dermatophytes. Bioactivity-guided fractionation of Baccharis darwinii has resulted in the isolation of three coumarins: 5’-hydroxy aurapten (anisocoumarin H, 1), aurapten (7-geranyloxycoumarin, 2) and 5’-oxoaurapten (diversinin, 3). The structures of these compounds were characterized by spectroscopic methods. These compounds were evaluated for their antimicrobial activity against a panel of each, bacteria and fungi. Compound 3 showed the best activities against Microsporum gypseum, Trichophyton rubrum and Trichophyton mentagrophytes with MICs = 15.6 µg/mL, followed by compound 1 whose MICs against the same fungi were 62.5 µg/mL. In addition they showed fungicidal rather than fungistatic activity. Both compounds showed moderate activity (MICs = 125 µg/mL) against Cryptococcus neoformans. This is the first report of the presence of compound 1 in B. darwinii.

Synthesis, antifungal and antitumor activity of novel (Z)-5-hetarylmethylidene-1,3-thiazol-4-ones and (z)-5-ethylidene-1,3-thiazol-4-ones.

New hetaryl- and alkylidenerhodanine derivatives 3a–d, 3e, and 4a–d were prepared from heterocyclic aldehydes 1a–d or acetaldehyde 1e. The treatment of several rhodanine derivatives 3a–d and 3e with piperidine or morpholine in THF under reflux, afforded (Z)-5-(hetarylmethylidene)-2-(piperidin-1-yl)thiazol-4(5H)-ones and 2-morpholinothiazol-4(5H)-ones 5a–d, 6a–d, and (Z)-5-ethylidene-2-morpholinothiazol-4(5H)-one (5e), respectively, in good yields. Structures of all compounds were determined by IR, 1D and 2D NMR and mass spectrometry. Several of these compounds were screened by the U.S. National Cancer Institute (NCI) to assess their antitumor activity against 60 different human tumor cell lines. Compound 3c showed high activity against HOP-92 (Non-Small Cell Lung Cancer), which was the most sensitive cell line, with GI50 = 0.62 μM and LC50 > 100 μM from the in vitro assays. In vitro antifungal activity of these compounds was also determined against 10 fungal strains. Compound 3e showed activity against all fungal strains tested, but showed high activity against Saccharomyces cerevisiae (MIC 3.9 μg/mL).

Detection of synergistic combinations of Baccharis extracts with Terbinafine against Trichophyton rubrum with high throughput screening synergy assay (HTSS) followed by 3D graphs. Behavior of some of their components

Forty four extracts from nine Baccharis spp. from the Caulopterae section were tested in combination with terbinafine against Trichophyton rubrum with the HTSS assay at six different ratios with the aim of detecting those mixtures that produced a ≥50% statistically significant enhancement of growth inhibition. Since an enhanced effect of a combination respective of its components, does not necessarily indicate synergism, three-dimensional (3D) dose-response surfaces were constructed for each selected pair of extract/antifungal drug with the aid of CombiTool software. Ten extracts showed synergistic or additive combinations which constitutes a 22% hit rate of the extracts submitted to evaluation. Four flavonoids and three ent-clerodanes were detected in the active Baccharis extracts with HPLC/UV/ESI-MS methodology, all of which were tested in combination with terbinafine. Results showed that ent-clerodanes but not flavonoids showed synergistic or additive effects. Among them, bacchotricuneatin A followed by bacrispine showed synergistic effects while hawtriwaic acid showed additive effects.

Efficient synthesis of novel 3-aryl-5-(4-chloro-2-morpholinothiazol-5-yl)-4,5-dihydro-1H-pyrazoles and their antifungal activity alone and in combination with commercial antifungal agents.

The α,β‐unsaturated carbonyl compounds 5a–f were prepared by reaction between 2‐chloro‐4‐morpholinothiazol‐5‐carbaldehyde 3 and substituted acetophenones 4a–f. Treatment of compounds 5a–f with hydrazine hydrate employing mild reaction conditions led to the formation of 4,5‐dihydro‐1H‐pyrazoles 6a–f. Then the treatment with acetic anhydride or formic acid afforded the expected 4,5‐dihydro‐1H‐pyrazoles 7a–f and 8a–f. The antifungal activity of each series of synthesized compounds was determined against the clinically important fungi Candida albicans and Cryptococcus neoformans. In addition, the most active compounds 7e and 7f were tested in combination with the commercial antifungal agents: fluconazole, itraconazole, and amphotericin B. Compound 7e showed a synergistic effect with fluconazole against C. albicans while 7f showed synergistic activities with all tested antifungal drugs against the same yeast.

Isolation of Major Components from the Roots of Godmania aesculifolia and Determination of Their Antifungal Activities

From the methanol root extract of Godmania aesculifolia, a species selected in a multinational OAS program aimed at discovering antifungal compounds from Latin American plants, a new chavicol diglycoside (1), the known 3,4-dihydroxy-2-(3-methylbut-2-en-1-yl)-3,4-dihydronaphthalen-1(2H)-one (2), and lapachol (3) were isolated and characterized by 1D and 2D NMR and MS techniques. Only 3 exhibited fairly good activity against a panel of clinical isolates of Cryptococcus neoformans (MIC50 between 7.8 and 31.2 µg/mL) and moderate activities against Candida spp. and non-albicans Candida spp.

Novel micromorphological features of wood and bark of Argentinean Simaroubaceae

ABSTRACT Simaroubaceae is a family of about 22 genera and 100 species of mainly tropical and subtropical trees and shrubs and it is generally considered to be a heterogeneous group. In Argentina, Simaroubaceae is represented by three genera and four species, one of these is exotic: Ailanthus altissima (Mill.) Swingle while the other three are native: Castela coccinea Griseb., C. tweedii Planch. and Picrasma crenata (Vell.) Engl. Wood and bark anatomies of the Argentinean species were studied in an effort to find distinctive features for the genera and species within this family. Transverse, tangential and radial sections of the specimens were prepared and macerated according to conventional techniques; microscopic examination was performed by light microscopy and scanning electron microscopy. It was possible to make a key for the species and genera using a combination of qualitative (presence/absence of wood growth rings, porosity, abundance of parenchyma, occurrence of crystals, etc.), and quantitative features (vessels per square millimetre, tangential diameter of vessel lumina, etc.). The wood and bark characteristics obtained provide new evidence of the heterogeneous nature of the family. From an ecological point of view, according to vessel size, vessel number, mesomorphy and vulnerability index, the wood of the studied species belonging to Castela genus were characterised as xeromorphic, while the other genera were characterised as mesomorphic.

Quality Control of Herbal Medicines with Spectrophotometry and Chemometric Techniques - Application to Baccharis L. Species Belonging to Sect - Caulopterae DC. (Asteraceae)

Medicinal plants constitute a rich cultural and biological heritage in many countries, which could be very useful in meeting the therapeutic needs of the population (Rodriguez, 2010a). Traditional herbal medicines have been widely used for many years in many eastern countries (Liang et al., 2004). However, little work has been done to validate and standardize these products properly in order to match phytotherapy to chemotherapy which currently receives almost unconditional support from formal systems of health care. For several years now activities have been undertaken to systematize the identification, validation, production and use of medicinal plants, for both primary health care as well as a semi-industrial or industrial process, which implies their transformation into safe, reliable and stable phytopharmaceutical products. Therefore it is suggested that medicinal plants and their derived products would be a viable option for national development as an agricultural and therapeutic alternative, but standardization and industrialization, involving sustained yields, a quality control system and honest and reliable marketing would be needed for widespread implementation and official support. Consequently, on account of the above, education and research should be in agreement if any advance is to be made in this area (Rodriguez, 2010a). However, the necessary criteria for data quality, safety and efficacy of traditional medicine that would support its use in the world do not exist. Appropriate, accepted research methodology for evaluating traditional medicine is also lacking (Liang et al., 2004).