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Susceptibility of mammalian cell lines to allicin. Cell cultures were stressed for one hour by exposure to allicin at different concentrations, either in the absence or presence of 1 mM reduced glutathione (GSH). Cell viability was determined with the MTT-(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)-test. The half maximal effective concentration (EC50) for allicin was determined and is marked with a horizontal dashed line (- - - - -). The MIC value for the majority of tested bacteria (390 µM allicin, 64 µg/mL) is marked with a vertical dotted line (………). (a) Beas-2B (SV40-immortalized human bronchial epithelial cells); (b) A549 (human epithelial lung carcinoma); (c) Caco-2 (human epithelial colon tumor) and (d) NIH/3T3 (murine embryonic fibroblast), respectively.
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Garlic (Allium sativum) has potent antimicrobial activity due to allicin (diallylthiosulfinate) synthesized by enzyme catalysis in damaged garlic tissues. Allicin gives crushed garlic its characteristic odor and its volatility makes it potentially useful for combating lung infections. Allicin was synthesized (>98% pure) by oxidation of diallyl disu...
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Garlic has been used as a source of food and medicine for thousands of years.
Given that the garlic contains different biologically active materials and acts as an
antibiotic and a fungicide, the purpose of this research was to estimate the degree of
sensitivity of three different Gram-positive bacteria: Staphylococcus aureus, methicillinresistent...
Citations
... Extensive studies have demonstrated the broad-spectrum biological activities of allicin, including its antimicrobial, antifungal, anti-inflammatory, antioxidant, and anticancer properties (8,9).Allicin has also been studied for its beneficial effects on cardiovascular diseases, specifically through the regulation of blood pressure and lipid concentration (10). ...
Allicin, a natural sulfur-rich compound, is formed when garlic is crushed or chopped. It has been used for centuries as a natural defence against bacteria and fungi. However, we do not fully understand how well it works against viruses, such as SARS-CoV-2. In this study, we investigated the effect of allicin on the expression of the SARS-CoV-2 receptor-binding domain of the spike protein in human primary splenic fibroblasts. These cells were transfected with a plasmid encoding RBD-S protein fused to a superfolder green fluorescent protein (sfGFP), a bright, stable marker. When cells were treated with 50μM allicin, either 30 min before or 6 h after transfection, a pronounced drop in fluorescence was observed, indicating reduced spike protein expression. Interestingly, the cell morphology, growth, and behavior remained normal, indicating that allicin could minimize spike protein levels without being toxic to the cells. These results open the door to the use of allicin as a gentle, natural antiviral agent and raise critical questions regarding the regulation of protein expression after transcription. Further research is required to understand these effects better.
... The bacterial strains were susceptible to the aqueous fresh garlic extract, with the inhibition zones comparable to those observed in the copper-based treatments when tested via antibacterial disc diffusion. However, the MIC was not detectable for the highest concentration in the microdilution testing, and this lack of an effect was likely due to the dilution of the volatile sulphur-containing compounds in garlic known for their antibacterial activity [39,40]. The lack of an effect observed with the seaweed A. nodosum product (Phylgreen) may have been due to the low concentrations applied in this study, which might not have been sufficient to demonstrate antibacterial activity. ...
One of the most persistent and damaging diseases in olive trees is olive knot disease. This disease is caused by an infection by the Gram-negative phytopathogenic bacterium Pseudomonas savastanoi pv. savastanoi that is notoriously difficult to control. The increasing demand for eco-friendly and sustainable agricultural solutions has driven research into plant-based agents. This study investigated the antibacterial properties of essential oils (EOs) and their constituents, olive mill wastewater (OMWW), the phenolic compound hydroxytyrosol (HTyr), and algae and garlic extracts, as well as copper-based and plant-stimulating commercial products against P. savastanoi pv. savastanoi, a significant olive tree pathogen. Antibacterial activity was determined using the Kirby–Bauer disc diffusion and broth microdilution methods. The EOs derived from Thymus vulgaris (thyme) and Origanum compactum (oregano), and their key components thymol and carvacrol, exhibited the strongest antibacterial efficacy. Conversely, the OMWW, plant-stimulating products, and algae and garlic extracts showed limited to no antibacterial activity in vitro, with their antibacterial properties determined using the disc diffusion method. While the EOs were highly effective in vitro, regardless of the testing method, their efficacy in bacterial growth inhibition was strain- and concentration-dependent, possibly highlighting some metabolic or genetic variability in the target pathogen, even though the MIC values against all tested strains of P. savastanoi pv. savastanoi were equal. Bacterial membrane disruption and the consequent leakage of metabolites were determined as the modes of action of carvacrol and oregano EO. Carvacrol also promoted plant growth in lettuce without significant phytotoxic effects, although minor necrotic lesions were observed in young olive leaves at higher concentrations, presenting these agents as potential next-generation green bactericides.
... The active component of garlic is allicin, which has broad-spectrum antimicrobial properties [79]. Studies has shown that adding allicin to antibiotics (e.g., amoxicillin, ceftriaxone) increases biotics effects against many antibiotic-resistant bacteria, such as methicillin-resistant Staphylococcus aureus [80,81]. Allicin interferes with bacterial cell membranes and enhances the penetration of antibiotics, thus resulting in higher bacterial elimination [81]. ...
... Studies has shown that adding allicin to antibiotics (e.g., amoxicillin, ceftriaxone) increases biotics effects against many antibiotic-resistant bacteria, such as methicillin-resistant Staphylococcus aureus [80,81]. Allicin interferes with bacterial cell membranes and enhances the penetration of antibiotics, thus resulting in higher bacterial elimination [81]. Together, this not only revives the activity of antibiotics but also underscores the utilization of plant bioactives for the pressing challenge of antimicrobial resistance. ...
Background/Objectives: The interaction of bioactive compounds derived from plants with drugs has become a significant area of investigation due to its potential to improve, reduce, or have no effect on therapeutic outcomes. Due to the dual effect of these interactions, elucidating the underlying mechanisms is essential for establishing a therapeutic strategy. This study emphasizes the significant findings, mechanisms, and clinical implications of drug–plant bioactive interactions. It calls for more studies to seek safe and effective incorporation into clinical practice. Methods: To identify relevant studies, we performed a systematic literature search based on various scientific databases from 11 August 2024 to 30 December 2024. The search will be based on relevant keywords such as synergy, antagonism, plant bioactive compounds, and drug interactions supplemented with secondary terms such as phytochemicals, herb-drug interactions, pharmacokinetics, and pharmacodynamics. Results: Plant bioactives, including polyphenols, flavonoids, alkaloids, and terpenoids, display valuable biological activities that can interact with medications in three principal ways: synergy, additive effects, and antagonism. Synergy occurs when the combined effects of plant chemicals and pharmaceuticals outweigh the sum of their separate effects, increasing therapeutic effectiveness or allowing dosage decrease to reduce adverse effects. Additive effects occur when the combined impact equals the total individual effects, resulting in better outcomes without increasing risk. Antagonism occurs when a plant ingredient reduces or counteracts the effects of a medicine, thereby jeopardizing treatment. In addition, specific interactions may have no discernible effect. The chemical makeup of bioactive chemicals, medication pharmacokinetics, and individual patient characteristics such as genetics and metabolism all impact the intricacy of these interactions. Conclusions: Pharmacokinetics and pharmacodynamics of drugs can be considerably modulated through their interactions with plant bioactive components, which may cause a significant decrease in efficacy or increase in toxicity of therapeutic agents. More studies are needed to clarify mechanisms of action, prove clinical relevance, and create guidelines for safe co-administration. This integrative approach can mitigate those risks and allow for therapeutic optimization by introducing pharmacogenomics and personalized medicine approaches.
... Moreover, some drug-resistant strains carry antibiotic-modifying enzymes that can degrade or metabolize antibiotics. Allicin (diallyl thiosulfinate), found in Allium sativum, has been reported to enhance the activity of ciprofloxacin, tobramycin, and cefoperazone against P. aeruginosa by inhibiting sulfhydryl-dependent enzymes such as RNA polymerase, thioredoxin reductase, and alcohol dehydrogenase [103]. Of particular interest is the fact that the primary reservoirs of genes encoding antibiotic resistance in ARB strains are plasmids. ...
The escalating presence of antibiotic-resistant bacteria (ARB) in food systems presents a pressing challenge, particularly in preventing contamination and ensuring food safety. Traditional sanitation methods, such as cooking and chemical disinfectants, provide effective means to reduce ARB, yet there is a growing need for additional preventive measures directly on food surfaces. This review explores the potential of chitosan–phytochemical composites (CPCs) as surface coatings to prevent the initial contamination of food by ARB, thereby offering a novel complementary approach to conventional food safety practices. Chitosan, combined with active plant-derived metabolites (phytochemicals), forms composites with notable antibacterial and antioxidant properties that enhance its protective effects. We examine CPC synthesis methodologies, including chemical modifications, free radical-induced grafting, and enzyme-mediated techniques, which enhance the stability and activity of CPCs against ARB. Highlighting recent findings on CPCs’ antibacterial efficacy through minimum inhibitory concentrations (MIC) and zones of inhibition, this review underscores its potential to reduce ARB contamination risks on food surfaces, particularly in seafood, meat, and postharvest products. The insights provided here aim to encourage future strategies leveraging CPCs as a preventative surface treatment to mitigate ARB in food production and processing environments.
... This volatility is the primary cause of the distinctive scent that these plants emit, particularly when they are crushed or mashed. According to Reiter et al. (2017), there aren't many volatile antimicrobials available for clinical use. ...
... However, erythromycin and clindamycin were resistant to S. pneumoniae and showed a high MIC value of >256 μg/mL. Cefotaxime inhibited Streptococcus pneumoniae SNo 68668 and Streptococcus pyogenes SNo 67467 with the same MIC value of ≤0.015 μg/mL [135]. A recent study confirmed that allicin showed antibacterial activity by inhibiting the DNA gyrase activity in E.coli [136]. ...
Sulfur has been used as a medicinal agent by the Greeks since ancient times. Approximately 350 sulfur-containing compounds have been approved as drugs by the Food and Drug Administration (FDA). Generally, sulfur exists as organosulfur in plants and as glucosinolates and isothiocyanates. Metabolic disorders and infectious diseases are becoming worldwide public health problems, directly affecting individuals' quality of life and constitute a robust economic challenge to healthcare systems. Glucosinolates have been reported in several vegetables, bacteria, plants, fungi, and animals. In addition to organosulfur, glucosinolates, and their hydrolyzed products, isothiocyanates have immense therapeutic value. Several studies suggest glucosinolates have a potential role in treating metabolic disorders, including cancer, diabetes, and inflammation. Also, some of the glucosinolates had shown broad-spectrum antimicrobial activity against gram-positive and gram-negative bacteria and antifungal activity against fungal strains. This review discusses recently identified naturally occurring sulfur-containing compounds, including glucosinolates and organosulfur, and their therapeutic potential for treating metabolic disorders and infectious diseases.
... An example of this multi-target behavior is seen with diallylthiosulfinate (allicin), a compound extracted from garlic (A. sativum), which has demonstrated antibacterial activity against K. pneumoniae, P. aeruginosa, and Streptococcus agalactiae (Table 1) [61]. Allicin exerts its antimicrobial effects by inhibiting both protein and DNA synthesis, contributing to its broad-spectrum antibacterial activity. ...
Infectious diseases continue to cause global morbidity and mortality. The rise of drug-resistant pathogens is a major challenge to modern medicine. Plant-based antimicrobials may solve this issue; hence, this review discussed in detail plant-sourced antimicrobial drugs as an alternative toward bacterial, fungal, and viral pathogens. Plant-derived chemicals from various sources such as marine, medicinal, and non-medicinal sources have diverse antimicrobial properties. Complex chemical profiles from these sources allow these molecules to interact with several targets in the microbial pathogens. Due to their multi-component composition, these compounds are more effective and less likely to acquire resistance than single-target antibiotics. Medicinal herbs have long been used for their antimicrobial properties; however, non-medicinal plants have also been identified for their antimicrobial properties. Other interesting new pathways for the identification of antimicrobials include marine plants, which contain a wide variety of metabolites that are both distinct and varied. We have conducted a thorough literature search for the medicinal, non-medicinal, and marine plant-derived molecules with antimicrobial roles from databases which include Scopus, PubMed, Google Scholar, and Web of Science. The review also discussed the synergistic potential of combining these plant-derived compounds with traditional antimicrobial drugs to attenuate the microbial pathogenesis. Based on the existing research and advancements, the review article emphasizes the importance of continuing research into plant-based antimicrobials from these many sources and integrating them with existing therapies to combat the rising threat of drug-resistant infections.
... The antimicrobial effect of GP, evidenced by reduced psychrophilic bacterial counts, can be primarily attributed to allicin and other thiosulfinates. These compounds disrupt bacterial cell membranes and inhibit crucial enzymatic systems, particularly those containing thiol groups (Reiter et al., 2017). Furthermore, garlic's antimicrobial activity extends to both Gram-positive and Gram-negative ...
Dietary supplementation with plant-based products may arise as part of an alternative strategy to using antibiotics as growth promoters in the poultry industry. Garlic powder (GP) possesses antimicrobial and antioxidant properties. The aim was to investigate the effect of dietary supplementation of GP on growth performance, carcass traits and meat quality of the Japanese quail. A total of 240, day-old mixed gender Japanese quail were assigned to 4 treatment groups, each group being replicated 4 times and containing 15 birds in each replication. Birds were provided with either a basal diet (control) or basal diet supplemented with 0.5%, 1% and 2% GP for 5 wk. At slaughter age, birds fed 1% GP had higher (P < 0.05) live weight and body weight gain when compared to the control. Supplementation with different levels of GP had no influence (P > 0.05) on feed intake, feed conversion ratio except 3rd wk, carcass traits and abdominal fat. Thiobarbituric acid, peroxide and pH values in breast meat of birds receiving GP (1% or 2%) after storage (0, 1, 3, 5, and 7 d) were lower (P < 0.05) than the birds in control. Furthermore, total psychrophilic bacteria count was lower in breast meat of birds supplemented with GP at any dose compared to the birds of control. Sensory characteristics such as color, aroma, juiciness and tenderness were observed significantly better (P < 0.05) in GP supplemented groups especially when fed 1% GP. In conclusion, supplementing the diet with 1% to 2% GP demonstrated growth-promoting effects and positively impacted meat quality, including sensory characteristics.
... Various compounds, including allicin, ajoene, dialkenyl and dialkyl sulfides, S-allyl cysteine, S-allyl-mercapto cysteine, and isothiocyanates, have demonstrated significant antibacterial properties against a wide range of bacteria, both Gram-positive and Gram-negative [114,115]. Research indicates that plants with high polysulfide content exhibit broad-spectrum antimicrobial properties [116,117]. ...
Antibiotic resistance emerged shortly after the discovery of the first antibiotic and has remained a critical public health issue ever since. Managing antibiotic resistance in clinical settings continues to be challenging, particularly with the rise of superbugs, or bacteria resistant to multiple antibiotics, known as multidrug-resistant (MDR) bacteria. This rapid development of resistance has compelled researchers to continuously seek new antimicrobial agents to curb resistance, despite a shrinking pipeline of new drugs. Recently, the focus of antimicrobial discovery has shifted to plants, fungi, lichens, endophytes, and various marine sources, such as seaweeds, corals, and other microorganisms, due to their promising properties. For this review, an extensive search was conducted across multiple scientific databases, including PubMed, Elsevier, ResearchGate, Scopus, and Google Scholar, encompassing publications from 1929 to 2024. This review provides a concise overview of the mechanisms employed by bacteria to develop antibiotic resistance, followed by an in-depth exploration of plant secondary metabolites as a potential solution to MDR pathogens. In recent years, the interest in plant-based medicines has surged, driven by their advantageous properties. However, additional research is essential to fully understand the mechanisms of action and verify the safety of antimicrobial phytochemicals. Future prospects for enhancing the use of plant secondary metabolites in combating antibiotic-resistant pathogens will also be discussed.
... However, when compared to the copper-based treatment, HTyr exhibited only a moderate effect. Similarly, the application of GE exhibited a nearly equivalent effect to copper-based treatments in a disc diffusion study but low efficiency in microdilution testing, potentially due to the volatile nature and consequent evaporation of plant extracts, specifically allicin as the major sulfur-containing volatile compound, responsible for the antibacterial effect of garlic [45,46]. Another study conducted to determine the antibacterial potential of HTyr and HTyr-enriched OMWW extract showed inhibitory effects against P. savastanoi pv. ...
Olive knot disease, caused by the bacterium Pseudomonas savastanoi pv. savastanoi, causes great damage in olive orchards. While control measures of P. savastanoi pv. savastanoi in olive orchards primarily rely on pruning and copper-based treatments, the use of antibiotics as bactericidal preparations in agriculture is limited and highly restricted. However, plants are naturally endowed with protective molecules, such as phenolic compounds, which defend them against herbivores, insects, and microorganisms. This research aimed to test the virulence of five strains of P. savastanoi pv. savastanoi isolated from different growing regions and olive varieties, and to examine whether there is a difference in plant susceptibility based on the variety. An additional goal was to test the antimicrobial activity of olive mill wastewater, known for its high content of phenolic compounds, and aqueous garlic hydrolysate, as well as to compare them with a commercial copper-based product, pure hydroxytyrosol, and a standard antibiotic as references. Analysis of knot characteristics showed variations in the virulence of the P. savastanoi pv. savastanoi strains, with the highest virulence being observed for the strain I7L and the lowest virulence for the strain B45C-PR. The olive cultivar Rosinjola displayed higher susceptibility compared to Frantoio, Buža, and Leccino, while cv. Istarska bjelica exhibited the least susceptibility compared to the other investigated olive cultivars. In an attempt to explore alternative solutions for disease control, in vitro tests revealed that the phenol HTyr, GE, and the wastewater with the highest total phenolic content (cv. Istarska bjelica) possess the highest antibacterial activity. This supports the role of polyphenols in host defense, aligning with previous field observations of lower susceptibility of cv. Istarska bjelica to olive knot disease. These findings highlight the complex nature of olive knot interactions with bacterial strains and olive cultivars, simultaneously accentuating and underscoring the importance of considering the host’s defenses as well as bacterial virulence in disease management strategies.
