Biological properties of Sonoran propolis (SP) are influenced by harvest time. Caborca propolis showed cellular protective capacity against reactive oxygen species, which might be implicated in anti-inflammatory effects. However, the anti-inflammatory activity of SP has not been investigated so far. This study investigated the anti-inflammatory activity of previously characterized seasonal SP extracts (SPE) and some of their main constituents (SPC). The anti-inflammatory activity of SPE and SPC was evaluated by measuring nitric oxide (NO) production, protein denaturation inhibition, heat-induced hemolysis inhibition, and hypotonicity-induced hemolysis inhibition. SPE from spring, autumn, and winter showed a higher cytotoxic effect on RAW 264.7 cells (IC₅₀: 26.6 to 30.2 µg/mL) compared with summer extract (IC₅₀: 49.4 µg/mL). SPE from spring reduced the NO secretion to basal levels at the lowest concentration tested (5 µg/mL). SPE inhibited the protein denaturation by 79% to 100%, and autumn showed the highest inhibitory activity. SPE stabilized erythrocyte membrane against heat-induced and hypotonicity-induced hemolysis in a concentration-dependent manner. Results indicate that the flavonoids chrysin, galangin, and pinocembrin could contribute to the anti-inflammatory activity of SPE and that the harvest time influences such a property. This study presents evidence of SPE pharmacological potential and some of their constituents.

Intracellular bacterial infections represent a considerable therapeutic challenge due to the ability of pathogens to invade and replicate within host cells, hampering the action of the immune system and the effectiveness of conventional antibiotics. Bacteria such as Mycobacterium tuberculosis, Listeria monocytogenes, and methicillin-resistant Staphylococcus aureus (MRSA), among others, can persist within host cells, allowing them to evade the immune response and develop resistance to antibacterial treatments. A key factor in the persistence of these infections is the ability of bacteria to enter a dormant state, which reduces their susceptibility to antibiotics that affect the dividing cells. Nanotechnology is emerging as a promising solution as nanoparticle-based systems can improve the intracellular penetration of antibiotics, allow their controlled release, and reduce side effects. This review covers the development and efficacy of nanoparticle-encapsulated antibiotics in models of intracellular infections, highlighting the need to further investigate their potential to overcome the barriers of conventional therapies and improve the treatment of these complex infections.

Bactericidal efficiency of Au and Ag nanoparticles (NPs) is reported with and without photoactivation by white light. Au and Ag NPs were synthesized with an average size of $14\pm 1.2\mathrm{nm}$ and of $4.6\pm 0.5\mathrm{nm}$ , respectively. The size distribution of the Ag colloid was relatively wide. Less than 4$\mathrm{\%}$ of these NPs were largely decahedral, which, based on numerical calculations, determined the position of the optical band. In contrast, the Au colloid had a narrow optical band; a concentration of $1.3\mu \mathrm{g}/\mathrm{ml}$ was determined by theoretical and experimental spectra. Ag and Au NPs showed a superficial charge of $-35\mathrm{mV}$ and $+57\mathrm{mV}$ due to the presence of the citrate ions and cetyltrimethylammonium bromide on their surface, respectively. The effect of the NPs concentration on the viability of Escherichia coli and Staphylococcus aureus strains was investigated. It was found that Ag NPs were more effective against E. coli than Au NPs, whereas Au NPs were more effective against S. aureus than Ag NPs. The induced damage to the bacteria by the NPs was evaluated by AFM. The images show that the bacterial cell wall was changed in shape and in surface roughness, being more noticeable in S. aureus than in E. coli. The bactericidal activity of the photoactivated Ag NPs was almost doubled for both bacteria, whereas for the Au NPs, no bactericidal enhancement was observed for either strain. This can be explained by the high efficiency of Ag NPs to absorb white light and the consequent creation of hot spots that contribute to kill the bacteria.

Urinary tract infections are commonly caused by uropathogenic Escherichia coli (UPEC), which usually presents multiple virulence and resistance mechanisms, making it difficult to treat. It has been demonstrated that silver and polymeric nanoparticles had potential against these pathogens. In this study, we synthesized thiol chitosan-coated silver nanoparticles (SH-Cs-AgNPs) and evaluated their antibacterial, antibiofilm and antiadherence activity against clinical isolates of UPEC. The SH-Cs-AgNPs showed a spherical shape with a size of 17.80 ± 2.67 nm and zeta potential of 18 ± 2 mV. We observed a potent antibacterial and antibiofilm activity as low as 12.5 μg/mL, as well as a reduction in the adherence of UPEC to mammalian cells at concentrations of 1.06 and 0.53 μg/mL. These findings demonstrate that SH-Cs-AgNPs have potential as a new therapeutic compound against infections caused by UPEC.

Multi-drug resistant (MDR) bacteria have gained importance as a health problem worldwide, and novel antibacterial agents are needed to combat them. Silver nanoparticles (AgNPs) have been studied as a potent antimicrobial agent, capable of countering MDR bacteria; nevertheless, their conventional synthesis methods can produce cytotoxicity and environmental hazards. Biosynthesis of silver nanoparticles has emerged as an alternative to reduce the cytotoxic and environmental problems derived from their chemical synthesis, using natural products as a reducing and stabilizing agent. Sonoran Desert propolis (SP) is a poplar-type propolis rich in polyphenolic compounds with remarkable biological activities, such as being antioxidant, antiproliferative, and antimicrobial, and is a suitable candidate for synthesis of AgNPs. In this study, we synthesized AgNPs using SP methanolic extract (SP-AgNPs) and evaluated the reduction capacity of their seasonal samples and main chemical constituents. Their cytotoxicity against mammalian cell lines and antibacterial activity against multi-drug resistant bacteria were assessed. Quercetin and galangin showed the best-reduction capacity for synthesizing AgNPs, as well as the seasonal sample from winter (SPw-AgNPs). The SPw-AgNPs had a mean size of around 16.5 ± 5.3 nm, were stable in different culture media, and the presence of propolis constituents was confirmed by FT-IR and HPLC assays. The SPw-AgNPs were non-cytotoxic to ARPE-19 and HeLa cell lines and presented remarkable antibacterial and antibiofilm activity against multi-drug resistant clinical isolates, with E. coli 34 and ATCC 25922 being the most susceptible (MBC = 25 μg/mL), followed by E. coli 2, 29, 37 and PNG (MBC = 50 μg/mL), and finally E. coli 37 and S. aureus ATCC 25923 (MBC = 100 μg/mL). These results demonstrated the efficacy of SP as a reducing and stabilizing agent for synthesis of AgNPs and their capacity as an antibacterial agent.