Going Back to Our Roots: Medicinal Plants as Antimicrobials in the Age of Antimicrobial Resistance
Alisa Khoreva, Alana La Mantia, Alexandra Ricci, & Madalyne Webber
Undergraduate Students, University of Guelph
Introduction
Medicinal plants have a long history of preventing and treating illness in traditional medicine (Mickymaray, 2019). Over 50% of synthetic drugs have been sourced from plants, revolutionizing drug discovery and medicine (Ranasinghe et al., 2023). 80% of the developing world still benefit from the use of traditional medicine and medicinal plants (Vaou et al., 2021). Infections caused by bacteria, viruses, fungi and parasites are a threat to human well-being. There are major concerns of regressing to a pre-antimicrobial era due to antimicrobial resistance (Abdallah et al., 2023). Microbes are becoming resistant to synthetic drugs through genetic mutation, gene transfer and defense mechanisms (Habboush & Guzman, 2023). This has resulted in higher treatment failures and higher rates of mortality (SeyedAlinaghi et al., 2025). The overuse of synthetic antimicrobials has resulted in an increasing demand to develop new antimicrobial agents (Vaou et al., 2021). Medicinal plants have antimicrobial properties with high potential in restoring or enhancing synthetic antimicrobial effectiveness against multidrug-resistant microbes.
Cultural Use of Medicinal Plants as Antimicrobials
Synthetic antimicrobials did not always exist. Humans used medicinal plants to treat infections and illnesses before the development of synthetic drugs. Medicinal plants are extensively used in traditional medicine systems dating back thousands of years and seen in practices such as Ayurveda, Traditional Chinese medicine, and Islamic medicine.
Ayurvedic medicine, also referred to as the ‘Science of Life’ is considered the most ancient practice that originated in India 5000 years ago (Ranasinghe et al., 2023). Its main purpose focuses on prevention of disease and optimal health promotion through a holistic approach considering aspects of physical, emotional, mental and spiritual means (Ranasinghe et al., 2023). Several thousand medicinal plants are used in this practice, including garlic, sweet wormwood, and turmeric. (Ranasinghe et al., 2023).
Traditional Chinese medicine is another ancient healing system, practiced for roughly 2000 years in China (Ranasinghe et al., 2023). Fundamental theories include the concept of yin-yang balance, which is crucial for maintaining good health and longevity (Ranasinghe et al., 2023). In addition, the 5 elements are used to explain the workings of the universe including humans, where balance of these elements is necessary for optimal energy flow (Ranasinghe et al., 2023). Traditional Chinese medicine concepts are applied to diagnose and treat diseases, through medicinal herbs like ginseng, ginkgo, Chinese peony, licorice and ginger (Ranasinghe et al., 2023).
The traditional Arabic medical system also known as Unani or Islamic medicine originated in Greece, with practices originating from Greek physicians Hippocrates and Galen (Ranasinghe et al., 2023). In the practice, plants, mineral and animal-origin drugs were used, with great prevalence and use of polyherbal-mineral recipes. Medicinal plants used include onion, saffron, opium poppy and castor. (Ranasinghe et al., 2023)
It is through traditional knowledge and cultural use that we have been able to identify the medicinal and therapeutic properties of many plants. These practices form the foundation of our current knowledge of medicinal plants and have contributed to the development of many of the antimicrobials available in pharmacies today.
Drug Discovery and Plant-Derived Synthetic Medicines
Isolating lead molecules from medicinal plants has led to the development of new drugs (Ranasinghe et al., 2023). For instance, the first naturally derived medicine was reported in 1803 when morphine was isolated from the opium poppy plant (Papaver somniferum), aiding greatly in the terms of pain management (Ranasinghe et al., 2023). Over 50% of synthetic drugs are sourced from plants, revolutionizing drug discovery and medicine as a whole (Ranasinghe et al., 2023).
Continuing to 1928, the accidental discovery of the first antibiotic penicillin was by scientist Alexander Fleming (American Chemical Society, 2025). Leaving a bacterial culture plate out while going on vacation, he returned to mold grown on it (American Chemical Society, 2025). He discovered that the bacteria around the mold was dead, which led to the development of penicillin, revolutionizing synthetic drug synthesis (American Chemical Society, 2025).
Propagation Techniques
When using conventional propagation techniques, some medicinal plants do not germinate, produce seed, and have long growth periods (Shatnawi et al., 2021). Using in vitro propagation provides uniform plants with high multiplication rates (Shatnawi et al., 2021). This method uses axillary buds, somatic embryos, callus or suspension culture (Shatnawi et al., 2021). Standardizing propagation is essential when isolating bioactive compounds, as it needs to be reliable and under controlled environment conditions. By promoting propagation protocols and standardizing the quality of the plant, developing new antimicrobial agents becomes more of a reality.
Extraction Techniques
Extraction of bioactive compounds is an important process when studying the medicinal properties of plants. Solvents such as water, alcohol, chloroform, ether and ionic liquid are commonly used (Abubakar & Haque, 2020). When choosing an extraction method, it is important to consider the heat stability of the plant, nature of solvent, cost of plant, duration of extraction, final volume required and intended use (Abubakar & Haque, 2020). Methods of extraction include maceration, infusion, digestion, and percolation among others (Abubakar & Haque, 2020). Ethanol is the preferred solvent when extracting medicinal compounds as it is highly effective (Abubakar & Haque, 2020). It is considered safe, versatile, and has high extraction yields (Lee et al., 2024). After extraction is performed, tests to determine the antimicrobial activity can be performed.
Determining the Antimicrobial Properties of Medicinal Plants
Researchers have used traditional knowledge of medicinal plants to guide them in discovering over 1,300 plants and 30,000 plant-derived compounds with antimicrobial activity (Vauo et al., 2021). Bioactive chemicals such as coumarins, flavonoids, phenolics, alkaloids, terpenoids, tannins, essential oils, lectins, polypeptides, and polyacetylenes serve as precursors for antibiotic synthesis (Balouiri et al., 2015). These naturally occurring phytochemicals have demonstrated advantageous qualities, including antibacterial, antiviral, antifungal, antiparasitic, antioxidant, and anti-inflammatory activity (Vaou et al., 2021).
Antimicrobial Susceptibility Testing
Antimicrobial susceptibility tests (AST) can be utilized in vitro to determine the antimicrobial activity of plant extracts. While many laboratory methods exist, the two most widely used are disk diffusion and broth or agar dilution. Other methods such as time-kill test and flow cytofluorometric methods are recommended for in-depth studies, however they require specific equipment and lack reproducibility and standardization (Vaou et al., 2021).
Agar Disk Diffusion
Agar disk diffusion is routinely used and standardized to test specific fastidious bacterial pathogens such as streptococci, Haemophilus influenzae, Haemophilus parainfluenzas, Neisseria gonorrhoeae and Neisseria meningitidis (Balouiri et al., 2015). Filter paper discs are saturated with the test compound at a certain concentration and placed on an agar plate with a standardized inoculum of the test microorganism (Balouiri et al., 2015). The petri dishes are intubated, and in positive results of antimicrobial activity, the test compound will diffuse into the agar, inhibiting the germination and growth of the test microorganism (Balouiri et al., 2015). Areas free of bacterial cultures are referred to as the zones of inhibition and measured in diameter to determine efficacy (Balouiri et al., 2015). This method is qualitative and indicates the presence or absence of bioactive compounds (Vaou et al., 2021). It does not indicate bacterial death; therefore, it cannot determine the bactericidal or bacteriostatic effects and minimum inhibitory concentration (MIC) (Balouiri et al., 2015). It is widely utilized due to its simplicity, repeatability, ability to test large quantities of antimicrobial agents, easier interruption and low cost. However, it is time-consuming, impossible to quantify data, and only standardized for a narrow range of microorganisms.
Broth and Agar Dilution
Dilution methods are quantitative and able to determine the minimum inhibitory concentration (MIC) values against bacteria and fungi (Balouiri et al., 2015). MIC values are the lowest concentration of a bioactive compound that inhibits the growth of a microorganism (Balouiri et al., 2015). Guidelines are available; however, they are less standardized than agar disk diffusion. Dilution can be categorized into broth microdilution and agar dilution.
Broth dilution involves the preparation of two-fold dilutions of an antimicrobial agent in a liquid growth medium in tubes (Balouiri et al., 2015). Each tube is inoculated with a microbial inoculum, mixed and incubated. Agar dilution involves the incubation of an agar medium with a concentration of the antimicrobial agent and microbial inoculum (Balouiri et al., 2015). Both methods are examined for signs of microbial growth, such as cloudiness and bacterial colonies, and the lowest concentration of antimicrobial agent used that inhibits the growth of the microorganism is determined at the MIC. Dilution methods are faster than agar disk diffusion; however, there is extensive handling during the preparation of the inoculum that could result in human error, contamination, and skewed results (Vaou et al., 2021).
Antimicrobial Gradient Method (Etest)
The Etest combines the principles of diffusion and dilution methods. It is a commercial test that can determine the MIC value of antimicrobial agents. The test involves creating a concentration gradient of the antimicrobial agent on an agar medium (Balouiri et al., 2015). Positive correlation between the MIC values obtained from an Etest and those obtained from dilution and diffusion methods has been shown in many studies (Balouiri et al., 2015). This method can also investigate the antimicrobial interaction between two drugs ref). Synergy can be measured by a decrease in the MIC when two dilutions are tested simultaneously (Balouiri et al., 2015). This method has low variability, highly reproducible results, and is considered equivalent to standard MIC methods (Vaou et al., 2021).
Mechanisms and Compounds
Medicinal plants derive their antimicrobial properties from various secondary metabolites. Secondary metabolites are compounds produced by plants that are not directly involved in their basic growth and survival but provide adaptive advantages, such as defense against diseases and pathogens (Allemailem, 2021). Antimicrobials from plants can exist in many different parts of the plant, including roots, stems, leaves, flowers, fruits, and seeds; however, they are generally concentrated in the outer layers, such as the skin of fruits and the epidermis of leaves, as they are meant to protect from external stressors (Fialová et al., 2021). Certain plants produce particularly effective secondary metabolites, which can be extracted and used for human benefit. These secondary metabolites fall into three main categories: phenols, terpenes, and alkaloids.
Phenols
Phenols contain a hydroxyl group on an aromatic ring. The antimicrobial effectiveness of phenols can be attributed to this hydroxyl group, and its ability to delocalize pi bonds on the aromatic ring, allowing it to interact with microbial membranes and proteins (De Rossi et al., 2025). Previous studies have shown that certain phenols, such as quercetin, have fewer free hydroxyl groups making them hydrophobic, thus increasing the molecule’s chemical affinity for the lipid membrane (De Rossi et al., 2025). Phenols bind to the proteins in bacterial cell walls, disrupting cell membranes and weakening them, causing lysis. Lysis is the leakage of intracellular components resulting in cell death which kills the microbes (Allemailem, 2021). Phenols may also interact with hydrophobic parts of microbial proteins located outside of the cell, disrupting metabolism and thus inhibiting bacterial activity. Furthermore, the hydroxyl groups form hydrogen bonds with DNA and RNA nucleotides, proteins, and other charged molecules, inhibiting the synthesis of DNA and RNA (De Rossi et al., 2025). Phenols possess remarkable antibacterial and antiviral traits due to these diverse abilities.
Terpenes
Terpenes are active against bacteria, fungi, viruses, and protozoa. Characteristically, terpenes include a wide range of compounds with structures containing characteristic 5-carbon isoprene units, extensive branching, and cyclization (Huang et al., 2022). Their structures consist mainly of hydrogen and carbon atoms, making them largely non-polar and hydrophobic. Terpenes use this feature to exhibit antimicrobial activity in cells. They use lipophilicity to enter the phospholipid bilayer of bacterial cells, compromising the integrity of the cell membrane, affecting normal physiological activities, resulting in cell death (Huang et al., 2022). Moreover, terpenes interfere with bacterial communication systems, inhibiting the coordination of bacterial cells with one another, reducing the development of antibacterial resistance. Furthermore, they inhibit ATP and its enzymes used for synthesis, and protein synthesis, halting bacterial growth altogether (Huang et al., 2022). These mechanisms may be used separately, or in combination with other compounds, making terpene-containing plants very useful as antimicrobials.
Alkaloids
Alkaloids are synthesized from amino acids and contain nitrogen atoms within their heterocyclic ring (Leclerc & Fournier, 2024). Many alkaloids exhibit diverse medicinal properties and several impeccable antibacterial effects. These properties are due to the nitrogen atom, as it can interact with bacterial cells through hydrogen bonding and ionic interactions (Leclerc & Fournier, 2024). For example, some alkaloids have been shown to block nucleic acid synthesis and interfere with bacterial cell division through the inhibition of bacterial enzymes such as dihydrofolate reductase and pyruvate kinase (Allemailem, 2021). Nitrogen binds to specific receptors in the central nervous system, blocking neurotransmitters, which sends chemical messages through the body to signal the production of these enzymes. Furthermore, some alkaloids cause direct cell damage and death through hydrogen bonding, disrupting the infectious cell’s bacterial membrane or inhibiting efflux pumps. This process compromises the integrity of the bacteria (Huang et al., 2022). Alkaloids can control disease by preventing bacteria from activating their pathogenic genes and boost the immune system to help fight off infection (Allemailem, 2021), making them effective antimicrobial agents.
Examples of Medicinal Plants with Antimicrobial Properties
Antibacterial – Goldenseal (Hydrastis canadensis)
Goldenseal (Hydrastis canadensis) has powerful antifungal properties due to the presence of the alkaloid berberine. Berberine is abundant in the leaves and roots of goldenseal. Root extracts tend to be stronger as they have higher quantities of berberine; however, leaf extracts are still effective when used at high concentrations (Gao et al., 2024). Leaf extracts have shown promising results in the treatment of the highly resistant bacteria Staphylococcus aureus. In vitro studies have found that goldenseal extract directly interferes with bacterial efflux pumps. By blocking these pumps, berberine concentrations were able to build up inside the cell, making it more effective at killing the bacteria (Ettefagh et al., 2011). These results highlight the potential of goldenseal as an effective antibacterial against an otherwise resistant bacterium.
Antiviral – Purple Coneflower (Echinacea purpurea)
The purple coneflower (Echinacea purpurea) exhibits immunomodulatory, anti-inflammatory, antioxidant and antimicrobial properties. Its antiviral properties come from compounds such as alkamides, glycoproteins, polysaccharides and polyphenols, including caffeic acid derivatives such as chicoric acid, caftaric acid and cholorogenic acid (Peraccio et al., 2023). These compounds are found in varying quantities throughout the plant (Peraccio et al., 2023). Twice the amount of caftaric acid is found in the top of the plant, while C12 diene-diyne alkamides is heavily concentrated in the roots (Peraccio et al., 2023). Extracts of E.purpurea have been effective in treating HSV-1 and HSV-2 strains of herpes simplex virus in vitro (Ahmadi, 2024). Chicoric acid, found in the echinacea plant inhibited HSV-1 and the integrase enzyme of human immunodeficiency virus type 1 (HIV-1) (Ahmadi, 2024). It has also been shown to enhance the efficacy of the influenza vaccine in immunodepressed mice by preventing the release of pro-inflammatory cytokines (Peraccio et al., 2023). Antiviral plants inhibit viral entry and the replication of the virus, inhibit protein synthesis, and disrupt cell signalling pathways used by the virus to expel the virus from the body (Mukktar et al., 2007). These results suggest that the purple coneflower exhibits antiviral activity against HSI-1 and HSV-2 and contribute to improved efficacy of the influenza vaccine.
Antifungal – Turmeric (Curcuma longa)
Turmeric (Curcuma longa) has antifungal properties through the bioactive compounds found in its rhizomes. The phenol curcumin and terpene turmerones work in tandem with other compounds to weaken fungi. These compounds can damage cell membranes, reduce ergosterol, disrupt cellular processes, and interfere with the fungus’s ability to maintain structure and survive (Chen et al., 2018). Turmeric extract has been tested on several fungal isolates, and clear zones of inhibition have been recorded, even at low concentrations. Higher concentrations of turmeric can strengthen the antifungal effect, proving it to be effective in different environments depending on the quantity of extract used. Turmeric does not depend on just one compound but instead uses multiple active ingredients to fight fungal infections (Ogbonna & Umedum, 2022). Turmeric has broad antifungal activity that can act on multiple species, making it a promising natural option for the management of fungal infections.
Antiparasitic – Ginger (Zingiber officinale)
Ginger (Zingiber officinale) has been proven to display antiparasitic activity on a variety of parasites when tested in laboratory. The primary active phytochemicals of ginger are phenolic compounds consisting of gingerols, shogaols, and parasols. In a study using rodents, mice were infected with cryptosporidium, a protozoan parasite with few effective drugs against it (Abdelgelil et al., 2023). Ginger powder was soaked in distilled water and given to the treatment group. Treated mice showed improvement of pathological symptoms without side effects and decreased oocyst shedding (Abdelgelil et al., 2023). Therapeutic effects were recorded as ginger decreased the secretion of proinflammatory cytokines, while increased secretion of anti-inflammatory cytokines (Abdelgelil et al., 2023). These compounds disrupt cell membranes, inhibit key parasitic enzymes, and paralyze parasites such as gastrointestinal worms (helminths), increasing the likelihood of expulsion or death (Ranasinghe et al., 2023). Ginger demonstrates potential as a therapeutic agent against Cryptosporidium and may also confer additional benefits by mitigating inflammation.
Broad-spectrum – Garlic (Allium sativum)
While the preceding sections categorize plants as treating individual microbes, the majority of medicinal plants display activity against a broad spectrum of pathogens. Medicinal plants also have many therapeutic benefits such as anti-inflammatory, antioxidant, anticancer, and general immunity support due to the synergistic effect of their bioactive compounds (Li et al., 2025). Garlic (Allium sativum) is a prime example of a broad-spectrum antimicrobial with therapeutic properties.
Benefits from consuming garlic are attributed to various organosulfur compounds such as allicin, ajoene and vinyl-dithiin (Verma et al., 2023). Garlic exhibits antimicrobial, antioxidant, anti-anaemic, anticarcinogenic, and other immunomodulatory properties (Verma et al., 2023). Garlic has over 200 unique chemicals that can strengthen the immune system and fight against a wide range of pathogens (Verma et al., 2023). Demonstrations of preclinical testing have proven garlic extracts and essential oils to exhibit antiviral properties. In Africa, it has been used to cure sexually transmitted diseases, tuberculosis, wounds, and pneumonia (Verma et al., 2023). Compounds within garlic can prevent bacterial proliferation and cause apoptosis, with remarkable antimicrobial activity against Staphylococcus aureus, Salmonella enterica, E. coli (Escherichia coli), and Listeria monocytogenes, and a wide spectrum of gram-negative and gram-positive bacteria (Verma et al., 2023). It is reported to be more effective with fewer adverse effects than commercial antibiotics (Verma et al., 2023). Extracts also possess broad-spectrum antifungal activity against Candida, Trichophyton, Aspergillus, and Rhodotorula spp (Verma et al., 2023). Garlic oil can be applied externally to cure ringworm, warts, and skin parasites (Verma et al., 2023). Garlic has significant research supporting its use as an antimicrobial alongside its therapeutic benefits.
Antibiotic Resistant Modifying Properties
Phytochemicals have shown promising results in combating antimicrobial resistance when combined with the use of antibiotics (Kumar et al., 2025). They are thought to synergize the bacteriostatic or bactericidal effects of antibiotics and enhance their therapeutic impact. Research has shown a decrease in MIC when used together, resulting in resistant bacteria becoming more susceptible (Kumar et al., 2025). There is evidence in phytochemicals affecting the main determinants of antibiotic resistance which include antibiotic modification, altered cell permeability, active efflux pumps, target modification, and gene transfer (Khare et al., 2021).
Antibiotic Modification
Enzymes produced by bacteria modify and degrade the active compounds of antibiotics preventing the interaction with their target (Kumar et al., 2025). Quercetin, berberine, tannic acid, and eugenol can bind and block the enzymes, restoring antibiotic activity (Kumar et al., 2025).
Cell Permeability and Efflux Pumps
Bacteria limit antibiotic uptake by pumping it back out with efflux pumps and protect themselves with a biofilm (Kumar et al., 2025). The terpenoid carvacrol can disrupt the integrity of bacterial membranes by preventing the formation of biofilm or degrading preexisting biofilm (Kumar et al., 2025). By destabilizing the membrane, phytochemicals increase the permeability of antibiotics into bacteria cells (Kumar et al., 2025). Alkaloids and phenolic compounds block or reduce pump expression, allowing a higher concentration of antibiotics to accumulate (Kumar et al., 2025).
Target Modification
Sites targeted by antibiotics can be modified by bacteria to prevent optimal interaction (Kumar et al., 2025). The flavonoids quercetin and alkaloid berberine bind alternative sites, destabilize altered sites, and can inhibit modifying enzymes (Kumar et al., 2025). This allows antibiotics to bind as intended.
Gene Transfer
Resistance can be acquired through horizontal gene transfer. Some phytochemicals inhibit conjugation, disrupt plasmic replication, and suppress competence, which limits the spread of resistance traits (Kumar et al., 2025).
Application to Clinical Practice and Wellness
Many medicinal plants have undergone extraction and processing methods to produce natural health products such as teas, supplements, tinctures and essential oil extracts for self-aid in the treatment of certain illnesses. For instance, the oregano plant (Origanum vulgare) can be processed into oregano oil that was used in traditional medicine for respiratory diseases and fungal infections (National Library of Medicine, 2025). Oil of oregano is available over the counter as capsules or in liquid form, used prevalently to aid with common colds (National Library of Medicine, 2025). However, not all natural health products and supplements are of the highest safety and quality. Safety concerns include interactions between herbal medicine with prescription drugs due to lack of available information for herbal composition and pharmacological pathways, as well as individual self-prescription without consultation of a medical professional prior to use (National Library of Medicine, 2025). There are also issues surrounding the adulteration of natural health products, meaning there are undeclared substances in the product, which can be unsafe and potentially harmful to health (Health Canada, 2019). Other examples of issues with adulterated products include a dose that exceeds the maximum daily recommended dose, undeclared side effects, unauthorized products by Health Canada due to health concerns, and concerns for interaction with the undeclared ingredient with other foods, natural health products or pharmaceutical drugs (Health Canada, 2019). In addition, there are issues surrounding the quality of the herb in these extractions and natural health products (Zhang et al., 2011). For instance, from a variety of selected ginseng products in North America, 26% of the products did not meet label claims of the ginsenoside content (Zhang et al., 2011).
Limitations
Clinical Trials
There is significant evidence of antimicrobial properties of medicinal plants; however, it is largely seen in vitro. These promising results may not translate to in vivo experiments and clinical trials. Factors such as tissue penetration, maximum plasma concentration, and bioavailability can impact the efficacy of phytochemicals within the human body (Khameneh et al., 2019). Current technology is not developed enough to study this (Khameneh et al., 2019). Conducting in vivo experiments and clinical trials is essential in determining the effectiveness and safety of medicinal plants as antimicrobials, and if they can be used to synthetic new antimicrobial drugs.
Standardization
Currently, there are no universal protocols for the cultivation, harvest, storage and testing of phytochemicals. The production of compounds within plants can be affected by environmental conditions, season of harvest, region of cultivation, parts of the plant used which can result in varying consistency between extractions (Vaou et al., 2021). This makes comparing literate data difficult, as results need to be reliable and repeatable under the same conditions. The standardization of the propagation and cultivation could result in “medical grade” plants, which may be necessary when synthesizing new antimicrobial drugs. Medical grade plants would ensure bioactive compounds exist in the plant at consistent levels ensuring high quality extraction. Standardising may take a substantial amount of time and effort, but it is feasible and an essential step in discovering new antimicrobial agents.
Toxicity
There are limited studies concerning the toxicity of plant extracts (Vaou et al., 2021). There is also limited knowledge on interactions between current pharmaceuticals and interactions with other phytochemicals due to their complexity. The synergistic, additive, and antagonistic characteristics of medicinal plants needs to be researched further. There is some evidence that when compounds are combined, antagonism is produced resulting in a cancellation of their therapeutic effect (Vaou et al., 2021). Currently, there is caution surrounding the use of medicinal plants as treatment, and no extracts have been evaluated by the U.S. Food and Drug Administration (Vaou et al., 2021).
Funding
There is limited financial support for the research and development of medicinal plants as antimicrobial agents (Vaou et al., 2021). Research is essential if we want to discover new antimicrobial agents and the true potential of medicinal plants. All four of these limitations are interconnected. Funding is needed for research, and more research is required to standardize processes and determine the safety and pharmacology of these extracts before initiating clinical trials. Antimicrobial resistance is a major challenge in modern medicine, making dedicated funding essential to address it.
Disclaimer
Traditional knowledge is the main source of identifying medicinal plants, therefore proper acknowledgement must be granted to indigenous practices during the search and discovery of new antimicrobial agents.
Conclusion
Based on the material presented, medicinal plants have significant antimicrobial properties with the ability to enhance synthetic antimicrobial effectiveness against multidrug-resistant microbes. Medicinal plants have been used extensively in traditional medicine for the treatment of infections before the development of synthetic drugs. New antimicrobial agents are needed as the improper use of current antimicrobials has resulted in antimicrobial resistance. The antimicrobial properties of medicinal plants can be quantified and qualified through antimicrobial susceptibility testing. The main methods include agar disk diffusion, broth and agar dilution, and the Etest. Medicinal plants consist of many bioactive compounds, the most common ones contributing to antimicrobial properties include phenols, terpenes and alkaloids. These compounds act to attack microbes by disrupting cell membranes, inhibit enzyme functions, block protein synthesis, and interfere with bacterial communication among other mechanisms. Through extraction and processing, medicinal plants are transformed into products such as teas, supplements, tinctures and essential oils. Goldenseal, purple coneflower, turmeric, ginger and garlic all exhibit promising results in treating infections of bacteria, viruses, fungi and parasites. Not only do these plants fight pathogens, but they also possess therapeutic effects with little or no side effects when compared to synthetic antimicrobial drugs. Medicinal plants also show encouraging results in combatting antimicrobial resistance when used in conjunction with antibiotics. With antimicrobial resistance on the rise, these findings provide some relief to the worry of regressing to a pre-antimicrobial era. Before new antimicrobial drugs can be synthesized from medicinal plants, limitations such as the lack of clinical trials, standardization, unknown toxicity and funding must be addressed. Antimicrobial resistance will only get worse, and in a world filled with unknowns and doubt, this topic provides some hope when addressing this concern.
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