Gallic Acid as a Non-Selective Inhibitor of α/β-Hydrolase Fold Enzymes Involved in the Inflammatory Process: The Two Sides of the Same Coin

Assessing the Potential of Gallic Acid and Methyl Gallate to Enhance the Efficacy of β-Lactam Antibiotics against Methicillin-Resistant Staphylococcus aureus by Targeting β-Lactamase: In Silico and In Vitro Studies

Methicillin-resistant Staphylococcus aureus (MRSA), a global health concern, has prompted research into antibiotic adjuvants as a potential solution. Although our group previously reported the enhancing effects of gallic acid (GA) and methyl gallate (MG) on penicillin G activity against MRSA, the synergistic potential with other β-lactam antibiotics and the underlying mechanism have not been fully explored. Therefore, this study primarily aimed to investigate the antibacterial synergism with β-lactam antibiotics through disc diffusion, checkerboard, and time-kill assays. The β-lactamase inhibition was also examined through both molecular modeling and in vitro experiments. Additionally, bacterial morphology changes were studied using a scanning electron microscopy (SEM). The results revealed that both GA and MG exhibited anti-MRSA activity and showed indifferent effects when combined with β-lactam antibiotics against methicillin susceptible S. aureus (MSSA). Interestingly, MG demonstrated synergism with only the β-lactamase-unstable antibiotics against MRSA with the lowest fractional inhibitory concentration (FIC) indexes of ≤3.75. However, GA and MG exhibited weak β-lactamase inhibition. Furthermore, GA, MG, and the combination with ampicillin induced the morphological changes in MRSA, suggesting a possible mechanism affecting the cell membrane. These findings suggest that MG could potentially serve as an adjunct to β-lactam antibiotics to combat MRSA infections.

Theoretical evaluation of the malathion and its chemical derivatives interaction with cytosolic phospholipase A2 from zebrafish

Cytosolic phospholipase A2 (cPLA2) belongs to a large family of proteins and plays a crucial role in the regulation of arachidonic acid metabolism and inflammation cascade in zebrafish (Danio rerio). This enzyme with a molecular weight of 85 kDa, has two distinct domains. One is the regulatory and calcium-dependent (Ca²⁺) domain called C2, the other is the catalytic α/β hydrolase Ca²⁺-independent domain, where serine and aspartic acid catalytic dyad residues are present. We investigated the interaction of malathion and their organophosphate metabolites in the cPLA2 using in silico tools. Molecular docking results showed hydrophobic interactions with the paraoxon and catalytic site residue (Ser 223). Malathion increases intracellular Ca²⁺ due to endoplasmic reticulum influx which in turn activities phospholipase A2 and arachidonic acid release. Molecular docking and homology modelling of proteins and ligands could be a complementary tool for ecotoxicology and environment pollution assessment.

Mass Spectrometric Identification of Licania rigida Benth Leaf Extracts and Evaluation of Their Therapeutic Effects on Lipopolysaccharide-Induced Inflammatory Response

Licania rigida Benth has been evaluated as an alternative drug to treat diseases associated with inflammatory processes. This study evaluated the anti-inflammatory effects of aqueous and hydroalcoholic leaf extracts of L. rigida with inflammation induced by lipopolysaccharides in in vitro and in vivo inflammation models. The phytochemical profile of the extracts, analyzed by ultra-fast liquid chromatography coupled with tandem mass spectrometry, revealed the presence of gallic and ellagic acids in both extracts, whereas isovitexin, ferulate, bulky amino acids (e.g., phenylalanine), pheophorbide, lactic acid, and pyridoxine were detected in the hydroalcoholic extract. The extracts displayed the ability to modulate in vitro and in vivo inflammatory responses, reducing approximately 50% of pro-inflammatory cytokine secretion (TNF-α, IL-1β, and IL-6), and inhibiting both NO production and leukocyte migration by approximately 30 and 40% at 100 and 500 µg/mL, respectively. Overall, the results highlight and identify, for the first time, the ability of L. rigida leaf extract to modulate inflammatory processes. These data suggest that the leaf extracts of this plant have potential in the development of herbal formulations for the treatment of inflammation.

Utilization of gallic acid to inhibit some toxic activities caused by Bothrops jararaca or B. jararacussu snake venoms

Snake bite envenoming is a serious public health issue, affecting thousands of people worldwide every year, especially in rural communities of tropical and subtropical countries. Injection of venom into victims may cause hemorrhaging, blood coagulation imbalance, inflammation, pain, edema, muscle necrosis, and eventually, death. The official validated treatment recommended by governments is the administration of antivenom that efficiently prevents morbidity and mortality. However, this therapy does not effectively neutralize the local effects of Viperidae venoms which constitute one of the leading causes of disability or amputation of the affected limb. Thus, bioprospecting studies seeking for alternative therapies to complement antivenom should be encouraged, especially those investigating the blockage of local venomic toxicity. Plants produce a great diversity of metabolites with a wide range of pharmacological and biological properties. Therefore, the objective of this study was to assess the utilization of gallic acid, which is widely found in plants, against some toxic in vitro (coagulation, proteolytic, and hemolytic) or in vivo (edematogenic, hemorrhagic, and lethal) activities of Bothrops jararaca or B. jararacussu venom. Gallic acid was incubated with B. jararaca or B. jararacussu venom (incubation protocol), after which, in vitro or in vivo assays were performed. Additionally, a gel containing gallic acid was developed and topically applied over the skin of mice after injection of B. jararaca or B. jararacussu venom (treatment protocol), and then, a hemorrhagic assay was carried out. As a result, gallic acid inhibited the toxic activities, with variable efficacy, and the gallic acid gel neutralized B. jararaca or B. jararacussu venom-induced hemorrhagic activity. Gallic acid was devoid of in vitro toxicity as shown through a hemocompatibility test. Thus, these findings demonstrate the potential of gallic acid in the development of an alternative agent to treat victims of snake bites inflicted by Bothrops species.