Alejandro Madrid

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.

Comparative study on the larvicidal activity of drimane sesquiterpenes and nordrimane compounds against Drosophila melanogaster til-til.

Natural compounds from Drimys winteri Forst and derivatives exhibited larvicidal effects against Drosophila melanogaster til-til. The most active compound was isodrimenin (4). The highest lethal concentration to the larvae of D. melanogaster was 4.5 ± 0.8 mg/L. At very low concentrations drimenol (1), confertifolin (3), and drimanol (5) displayed antifeedant and larvae growth regulatory activity. The antifeedant results of nordrimanic and drimanic compounds were better in first instar larvae. The EC50 value of polygodial (2) was 60.0 ± 4.2 mg/L; of diol 15 45.0 ± 2.8 mg/L, and of diol 17 36.9 ± 3.7 mg/L, while the new nordrimane compound 12 presented a value of 83.2 ± 3.5 mg/L.

Study on the cytotoxic activity of drimane sesquiterpenes and nordrimane compounds against cancer cell lines

Twelve drimanes, including polygodial (1), isopolygodial (2), drimenol (3), confertifolin (4), and isodrimenin (5), were obtained from natural sources. Semi-synthetic derivatives 6–12 were obtained from 1 and 2, and cytotoxic activity was evaluated in vitro against cancer cell lines (HT-29, MDA-MB231, DHF, MCF-7, PC-3, DU-145, and CoN). IC50 values were determined at concentrations of 12.5–100 µM of each compound for 72 h. In addition, it was found that polygodial (1), 8, and 12 induced changes in mitochondrial membrane permeability in CoN, MCF-7, and PC-3 cells.

SYNTHESIS AND NMR STRUCTURE DETERMINATION OF NEW LINEAR GERANYLPHENOLS BY DIRECT GERANYLATION OF ACTIVATED PHENOLS

The known geranylhydroquinone 2, geranylorcinol 4 and the derivative (E)-4-(3,7-dimethylocta-2,6-dienyl)-5-methylbenzene-1,3-diol 5, were prepared by Electrophilic Aromatic Substitution (EAS) reactions between the corresponding phenol derivatives containing electron-donor subtituents and geraniol using BF 3 ×OEt 2 as a catalyst. In addition, spectroscopic NMR information for 4 and 5 is complemented. Furthermore, the new (E)-2-(3,7-dimethylocta-2,6-dienyl) benzene-1,3,5-triol (geranylphloroglucinol) 13, (E)-2-(3,7-dimethylocta-2,6-dienyl)-1,3,5-trimethoxybenzene 14, (E)-2-(3,7-dimethylocta-2,6-dienyl)-6methoxyphenol 15, (E)-3-(3,7-dimethylocta-2,6-dienyl)-2-methoxyphenol 16, (E)-5-(3,7-dimethylocta-2,6-dienyl)-2-methoxyphenol 17, (E)-4-(3,7-dimethylocta2,6-dienyl)benzene-1,3-diol 18, (E)-3-(3,7-dimethylocta-2,6-dienyl)benzene-1,2-diol 19, (E)-4-(3,7-dimethylocta-2,6-dienyl)-5-isopropyl-2-methylphenol 20, (E)-2-(3,7-dimethylocta-2,6-dienyl)-4-isopropyl-3-methylphenol 21, (E)-2-(3,7-dimethylocta-2,6-dienyl)-4-isopropyl-5-methylphenol 22, and(E)-2-tert-butyl-4(3,7-dimethylocta-2,6-dienyl)-5-methylphenol 23 were also prepared with this synthesis strategy. All the synthesized compounds were fully characterized and their structures were established by IR, MS and mainly NMR spectroscopic dates.

Antifungal study of the resinous exudate and of meroterpenoids isolated from Psoralea glandulosa (Fabaceae)

ETHNOPHARMACOLOGICAL RELEVANCE Psoralea glandulosa L. (Fabaceae) is a medicinal resinous shrub used in Chilean folk medicine as antiseptic in treatment of infections and skin diseases caused by bacteria and fungus. AIM OF THE STUDY To evaluate the in vitro antifungal activity of the resin and the active components from P. glandulosa against clinical yeast isolates. MATERIALS AND METHODS Active compounds were obtained of the resinous exudate from aerial parts of P. glandulosa. Eight species of yeast were exposed to the resin and two major compounds. Minimum inhibitory concentration (MIC(80)) was determined according to the standard broth microdilution method. RESULTS Bakuchiol and 3-hydroxy-bakuchiol demonstrated potent activity with the MIC(80) ranging from 4 to >16 and 0.125 to 16 μg/mL, respectively. The resin had some degree of antifungal activity. CONCLUSIONS The overall results provided important information for the potential application of the 3-hydroxy-bakuchiol from P. glandulosa in the therapy of serious infection and skin diseases caused by clinical yeast.

Psoralea glandulosa as a Potential Source of Anticancer Agents for Melanoma Treatment

With the aim of identifying novel agents with antigrowth and pro-apoptotic activity on melanoma cancer, the present study was undertaken to investigate the biological activity of the resinous exudate of aerial parts from Psoralea glandulosa, and its active components (bakuchiol (1), 3-hydroxy-bakuchiol (2) and 12-hydroxy-iso-bakuchiol (3)) against melanoma cells (A2058). In addition, the effect in cancer cells of bakuchiol acetate (4), a semi-synthetic derivative of bakuchiol, was examined. The results obtained show that the resinous exudate inhibited the growth of cancer cells with IC50 value of 10.5 μg/mL after 48 h of treatment, while, for pure compounds, the most active was the semi-synthetic compound 4. Our data also demonstrate that resin is able to induce apoptotic cell death, which could be related to an overall action of the meroterpenes present. In addition, our data seem to indicate that the apoptosis correlated to the tested products appears, at least in part, to be associated with an increase of reactive oxygen species (ROS) production. In summary, our study provides the first evidence that P. glandulosa may be considered a source of useful molecules in the development of analogues with more potent efficacy against melanoma cells.

Synthesis and Evaluation of Novel Oxyalkylated Derivatives of 2′,4′-Dihydroxychalcone as Anti-Oomycete Agents against Bronopol Resistant Strains of Saprolegnia sp.

A series of novel oxyalkylchalcones substituted with alkyl groups were designed and synthesized, and the antioomycete activity of the series was evaluated in vitro against Saprolegnia strains. All tested O-alkylchalcones were synthesized by means of nucleophilic substitution from the natural compound 2′,4′-dihydroxychalcone (1) and the respective alkyl bromide. The natural chalcone (1) and 10 synthetic oxyalkylchalcones (2–11) were tested against Saprolegnia parasitica and Saprolegnia australis. Among synthetic analogs, 2-hydroxy,4-farnesyloxychalcone (11) showed the most potent activity against Saprolegnia sp., with MIC and MOC values of 125 µg/mL (similar to bronopol at 150 µg/mL) and 175 µg/mL, respectively; however, 2′,4′-dihydroxychalcone (1) was the strongest and most active molecule, with MIC and MOC values of 6.25 µg/mL and 12.5 µg/mL.

Chemical Characterization and Anti-Oomycete Activity of Laureliopsis philippianna Essential Oils against Saprolegnia parasitica and S. australis

Laureliopsis philippiana (Looser) R. Schodde (Monimiaceae) is a native tree widespread in the forest areas in the south of Chile and Argentina, known for its medicinal properties and excellent wood. The aim of this study was to evaluate the chemical composition of L. philippiana leaf and bark essential oils (EOs) using gas chromatography-mass spectrometry (GC-MS), and to quantify its anti-oomycete activity, specifically against Saprolegnia parasitica and S. australis. Only six components were identified in leaf EO, 96.92% of which are phenylpropanoids and 3.08% are terpenes. As for bark EO, 29 components were identified, representing 67.61% for phenylpropanoids and 32.39% for terpenes. Leaf EO was characterized mainly by safrole (96.92%) and β-phellandrene (1.80%). Bark EO was characterized mainly by isosafrole (30.07%), safrole (24.41%), eucalyptol (13.89%), methyleugenol (7.12%), and eugenol (6.01%). Bark EO has the most promising anti-Saprolegnia activity, with a minimum inhibition concentration (MIC) value of 30.0 µg/mL against mycelia growth and a minimum fungicidal concentration (MFC) value of 50.0 μg/mL against spores; for leaf EO, the MIC and MFC values are 100 and 125 µg/mL, respectively. These findings demonstrate that bark EO has potential to be developed as a remedy for the control of Saprolegnia spp. in aquaculture.

EVALUATION OF THE ANTIOXIDANT CAPACITY OF Psoralea glandulosa L. (Fabaceae) EXTRACTS

The antioxidant properties of different extracts of culen (Psoralea glandulosa L., Fabaceae) herb from Gran Valparaiso location in Chile were evaluated. Antioxidant capacity was assessed in four different model systems. Antioxidant models were examined by measuring the scavenging activity of extracts on 2,2-diphenyl-1-pycrylhydrazil (DPPH●) as well as on hydrogen peroxide (H 2 O 2 ), the oxidant species. In addition, extracts were evaluated by ferric reducing antioxidant power (FRAP) and the total peroxyl radical-trapping potential (TRAP). The amount of dried extract, the content of total phenolics, flavonoids and hydrolyzed sugar were also determined. The leaves extracts from culen expressed very strong scavenging activity, reducing the DPPH● (IC 50 = 1.00 mg/mL to 1.61 mg/mL) and neutralizing H 2 O 2 (IC 50 = 34.29 mg/mL to 64.87 mg/mL). Also, dichloromethane extract of the leaves showed notable index of FRAP (2.71 mM) and TRAP (1.19 mM). The results suggest strong antioxidant potential of dichloromethane and ethyl acetate extracts of leaves of P. glandulosa that could be partially explained by the levels of phenolics (1.65 mg GAE/g dry extract) and flavonoids (55.34 mg QE/g dry extract) respectively.

ANTIOXIDANT EFFECTS OF MUEHLENBECKIA HASTULATA J. (POLYGONACEAE) EXTRACTS

The antioxidant properties of different extracts of quilo (Muehlenbeckia hastulata J., Poligonaceae) herb from Valparaiso region in Chile were evaluated. Antioxidant activity was assessed in three different model systems. Antioxidant models were examined by measuring the scavenging activity of extracts on 2,2-diphenyl-1-pycrylhydrazil (DPPH●). Moreover extracts were evaluated by ferric reducing antioxidant power (FRAP) and the total peroxyl radical-trapping potential (TRAP). The amount of dried extract, the content of total phenolics, flavonoids, hydrolyzed sugar and anthraquinones were also determined. Extracts pertaining to stem and root of the plants were the significant activities DPPH radical scavenging (IC 50 0.74 mg/mL to 1.33 mg/mL the more active extracts). The activities and TRAP and FRAP high values in extracts of EtOAc (1.423 and 1.540 mM TEAC) and ethanol (245.26 and 309.04 mM TEAC) stem and root of the plant are higher.The observed differences in antioxidant activity among the different parts of quilo could be partially explained by the levels of phenolics compounds present in the root extract of EtOAc (0.023 mg GAE/g dry extract), flavonoids in the leaves of EtOAc extract (99.12 mg QE/g dry extract), hydrolyzed sugar in the ethanol extract (21.87, 14.85 and 14.32 mg GES/ g dry extract of leaf, stem and roots, respectively) and anthraquinones in the EtOAc extracts (2.50, 1.43 and 0.84 mg EE/ g dry extract of leaf, stem and roots, respectively) .