Aims: To evaluate the antibacterial and free‐radical scavenging (FRS) activities of propolis collected from three different areas of Sonoran Desert in northwestern Mexico [Pueblo de Alamos (PAP), Ures (UP) and Caborca (CP)]. Methods and Results: The antibacterial and FRS activities of Sonoran propolis were determined by the broth microdilution method and the DPPH (1,1‐diphenyl‐2‐picrylhydracyl) assay, respectively. Propolis samples had antibacterial activity against only Gram‐positive bacteria. The UP sample showed the highest antibacterial activity against Staphylococcus aureus [minimal inhibitory concentration (MIC) 100 μg ml−1] in a concentration‐dependent manner (UP > CP > PAP). Caffeic acid phenethyl ester (CAPE), a UP propolis constituent, had very high growth‐inhibitory activity towards Gram‐positive bacteria, particularly against S. aureus (MIC 0·1 mmol l−1). To our knowledge, this is the first study showing a strong antibacterial activity of CAPE against S. aureus. Additionally, propolis CP exhibited high FRS activity (86% ± 0·3 at 100 μg ml−1) comparable with those of the reference antioxidants vitamin C (87·4% ± 1·7 at 70 μmol l−1) and BHT (66·07% ± 0·76 at 140 μmol l−1). The propolis compounds CAPE and rutin showed high FRS activity (90·4% ± 0·2 and 88·5% ± 0·8 at 70 μmol l−1, respectively). Conclusions: Sonoran propolis UP and CAPE had strong antibacterial activity against S. aureus. In addition, propolis CP showed potent FRS activity comparable with those of vitamin C and BHT. Significance and Impact of the study: The strong antibacterial and antioxidant properties of Sonoran propolis and some of its constituents support further studies on the clinical applications of this natural bee product against S. aureus and several oxidative damage‐related diseases.
In this study, we have analyzed the chemical composition and antiproliferative activity of propolis from three different arid and semiarid regions of Sonora, Mexico. We identified and quantitated the main chemical constituents of propolis by HPLC-MS. The most abundant constituents of propolis were pinocembrin, pinobanksin 3-acetate, and chrysin. Sonoran propolis had a strong antiproliferative activity on both murine and human cancer cell lines in a concentration-dependent manner. The propolis constituents CAPE, galangin, xanthomicrol and chrysin showed significant antiproliferative activity on most of the cancer cells tested. DNA harvested from cancer cell cultures treated with Sonoran propolis exhibited a ladder of internucleosomal DNA cleavage characteristic of apoptosis. In summary, we have identified and quantitated the main constituents of Sonoran propolis. These propolis samples possess a strong antiproliferative activity on cancer cell lines.
A chelating cyclophane has been synthesized by cyclocondensation of two ethylenediaminetetraacetic (EDTA) units with two p-phenylenediamine units: the resulting cyclophane is 2,9,18,25-tetraoxo-4,7,20,23-tetrakis(carboxymethyl)-1,4,7,10,17,20,23,26-octaaza[10.10]paracyclophane, abbreviated as (bis-edtapdn)H(4). Cyclocondensation of two EDTA and two 1,5-diaminonaphthalene units has given the naphthalenophane, 2,9,22,29-tetraoxo-4,7,24,27-tetrakis(carboxymethyl)-1,4,7,10,21,24,27,30-octaaza[10.10](1,5)naphthalenophane, (bis-edtanap)H(4). Studies of electronic and EPR spectra have been carried out on the binuclear Cu(2+) complexes of these new ligands and of related chelating cyclophanes, 2,9,25,32-tetraoxo-4,7,27,30-tetrakis(carboxymethyl)-1,4,7,10,24,27,30,33-octaaza[10.1.10.1]paracyclophane, abbreviated as (bis-edtabpm)H(4), and 2,9,25,32-tetraoxo-4,7,27,30-tetrakis(carboxymethyl)-1,4,7,10,24,27,30,33-octaaza-17,40-dioxa[10.1.10.1]paracyclophane, abbreviated as (bis-edtabpe)H(4). Common features of these chelating cyclophanes are as follows: (1) amino, amide, and pendant carboxymethyl donor groups are substituents in the cyclophane ring, and (2) the amide groups are directly bound to the aromatic groups. These ligands formed neutral binuclear Cu(2+) chelates [Cu(2)L](0) that are water-insoluble. In alkaline solutions, these Cu(2+) complexes were converted to anionic chelates [Cu(2)(LH(-)(4))](4)(-) in which deprotonated amide nitrogens coordinated Cu(2+) ions. These anionic metal chelates of (bis-edtapdn)H(4), (bis-edtabpm)H(4), and (bis-edtabpe)H(4) exhibited three pi-pi transition bands in the spectral range 240-340 nm, in contrast to the uncoordinated cyclophanes, which showed a single band in this spectral range. The unusual pi-pi transition spectra of the [Cu(2)(LH(-)(4))](4)(-) complexes originate from the combined effect of metal-ligand charge transfer and proximity of the pi systems. The absorption and emission spectra of (bis-edtanap)H(4) were also influenced by coordination with copper. The EPR spectrum of [Cu(2)(bis-edtanapH(-)(4))](4)(-) in a methanol glass matrix showed a hyperfine structure due to the spin exchange between two Cu(2+) ions. These unusual spectral and magnetic properties arise from the strong coordination between Cu(2+) ions and deprotonated amide nitrogens that are bound to the pi systems.
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