It was synthesized nine polyoxygenated chalcones with a potential and safe use as antioxidant, antimicrobial and anti-inflammatory therapies. Chalcones obtained by Claisen-Schmidt condensation were studied as antioxidant, inhibitors of human 5-lipoxygenase, antifungal, antibacterial and antibiotic resistance modifiers. Two chalcones with catecholic moieties were able to strongly decrease the minimum inhibitory concentration (MIC) of methicillin against methicillin-resistant Staphylococcus aureus, increase the antiradical activity and significantly inhibit the human 5-lipoxygenase. Only one of these chalcones was active synergistically with methicillin. Chalcones with methoxyl substituents at different positions displayed the best activities against Cryptococcus neoformans. Only one chalcone showed good activity against the plant pathogenic bacteria Pseudomonas syringae whose half maximal inhibitory concentration (IC50) value (2.5 µg mL-1) was similar to that observed with the antibiotic streptomycin (2.9 µg mL-1). These simple chalcones have safe potential uses in antioxidant, antimicrobial and anti-inflammatory therapies.

The syntheses of six prenylated acetophenone and benzaldehyde derivatives and their anti-phytopathogenic and antioxidant activities are reported. These compounds were obtained by electrophilic aromatic substitution (S E Ar) of the corresponding arenes and 3-methyl-2-buten-1-ol using ZnCl2 as a Lewis acid catalyst in ethyl acetate. Reasonable to good yields were obtained based on unrecovered aromatic starting material (45-73%). All the synthesized compounds were evaluated against phytopathogenic gram-negative bacteria Agrobacterium tumefaciens, Pseudomonas syringae and Erwinia carotovora and plant fungal pathogens Botrytis cinerea, Phytophthora cinnamomi and Gibberella fujikuroi. The antioxidant activity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity assay and expressed as half maximal inhibitory concentration (IC50) values in μΜ concentrations. The antioxidant activity went from 27.20 μΜ to >100 μΜ. Compound 11 showed statistically significant inhibition of the growth of Botrytis cinerea, and compounds 13 and 15 showed statistically significant inhibition of the growth of Phytophthora cinnamomi, with respect to negative control fungal growth. All six compounds showed bacteriostatic effects against gram-negative plant pathogenic bacteria with IC50 values between 250 and <3.9 μΜ.

A new rapid and efficient method for the synthesis of a series of alkylated phloroglucinols using conventional microwave is reported 4 phloroglucinol derivatives (4, 5, 6 and 7) were synthesized with good yields (~50%) by a Friedel-Crafts reaction through an Electrophilic Aromatic Substitution mechanism between geraniol/prenol and phloroglucinol, using reusable SiO2 and AgNO3 as the best catalyst tested without solvents under microwave irradiation.