Cannabinoids as Antibacterial Agents: A Systematic and Critical Review of In Vitro Efficacy Against Streptococcus and Staphylococcus

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“Background: Two major bacterial pathogens, Staphylococcus aureus and Streptococcus pyogenes, are becoming increasingly antibiotic-resistant. Despite the urgency, only a few new antibiotics have been approved to address these infections. Although cannabinoids have been noted for their antibacterial properties, a comprehensive review of their effects on these bacteria has been lacking.

Objective: This systematic review examines the antibacterial activity of cannabinoids against S. aureus, including methicillin-resistant S. aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) strains, and S. pyogenes.

Methods: Databases, including CINAHL, Cochrane, Medline, Scopus, Web of Science, and LILACS, were searched. Of 3510 records, 24 studies met the inclusion criteria, reporting on the minimum inhibitory concentration (MIC) and minimum bactericidal concentration of cannabinoids.

Results: Cannabidiol (CBD) emerged as the most effective cannabinoid, with MICs ranging from 0.65 to 32 mg/L against S. aureus, 0.5 to 4 mg/L for MRSA, and 1 to 2 mg/L for VRSA. Other cannabinoids, such as cannabichromene, cannabigerol (CBG), and delta-9-tetrahydrocannabinol (Δ9-THC), also exhibited significant antistaphylococcal activity. CBD, CBG, and Δ9-THC also showed efficacy against S. pyogenes, with MICs between 0.6 and 50 mg/L. Synergistic effects were observed when CBD and essential oils from Cannabis sativa when combined with other antibacterial agents.

Conclusion: Cannabinoids’ antibacterial potency is closely linked to their structure-activity relationships, with features like the monoterpene region, aromatic alkyl side chain, and aromatic carboxylic groups enhancing efficacy, particularly in CBD and its cyclic forms. These results highlight the potential of cannabinoids in developing therapies for resistant strains, though further research is needed to confirm their clinical effectiveness.”

https://pubmed.ncbi.nlm.nih.gov/39596719/

“In conclusion, cannabinoids such as CBD, CBG, and Δ9-THC offer significant promise as alternatives or adjuncts to traditional antibiotics, particularly for targeting S. aureus, MRSA, and S. pyogenes. Their favourable safety profile positions them as potential candidates for antibacterial therapies, though rigorous clinical trials, standardised testing, and long-term safety studies are crucial to fully unlock their potential in combating AMR.”

https://www.mdpi.com/2079-6382/13/11/1023

A recent update on the antibacterial effects of distinct bioactive molecules derived from the Cannabis plant

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“The number of human infections with multidrug-resistant (MDR) bacteria is increasing worldwide and constitutes a serious threat to human health. Given the lack of novel antibiotic compounds worsening this dilemma, alternative antibiotic-independent treatment and prevention strategies of infectious diseases applying natural compounds appear highly appreciable.

Given the long-known health-beneficial and disease-alleviating properties of Cannabis, we performed a literature search summarizing current knowledge regarding the antibacterial effects of extracts from different parts of the Cannabis sativa plant and of defined Cannabis-derived molecules and their potential mode of action.

The included studies revealed that various extracts and essential oils of C. sativa as well as major cannabinoids exerted potent activities against a broad spectrum of Gram-positive bacteria and against some Gram-negative bacterial species including MDR strains. Particularly the disruption of the bacterial cytoplasmic membrane by some cannabinoids resulted in potent antibacterial effects against Gram-positive bacteria including methicillin-resistant Staphylococcus aureus. Furthermore, defined cannabinoids inhibited the formation of and eradicated existing bacterial biofilms.

In conclusion, given their antibacterial properties distinct Cannabis-derived molecules expand the repertoire of antibiotics-independent treatment options in the combat of bacterial infectious diseases which should be further addressed in future studies including clinical trials.”

https://pubmed.ncbi.nlm.nih.gov/39470741/

“Collectively, results from the here reviewed studies open future perspectives for cannabis-derived molecules as alternative antibiotic-independent treatment and prevention strategies in the combat of bacterial infectious diseases which should be further addressed in future studies including clinical trials.”

https://akjournals.com/view/journals/1886/aop/article-10.1556-1886.2024.00098/article-10.1556-1886.2024.00098.xml

Antifungal properties of Abnormal Cannabinoid derivatives: Disruption of Biofilm Formation and Gene Expression in Candida Species

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“Abnormal cannabinoids (including comp 3) are a class of synthetic lipid compounds with non-psychoactive properties and regioisomer configurations, but distinct from traditional cannabinoids since they do not interact with the established CB1 and CB2 receptors. Previous research showed the cardioprotective and anti-inflammatory potentials of comp 3 and more recently its antimicrobial effect on methicillin-resistant Staphylococcus aureus (MRSA).

Given the escalating challenges posed by Candida infections and the rise of antifungal drug resistance, the exploration of novel therapeutic avenues is crucial. This study aimed to assess the anti-Candida properties of newly synthesized AbnCBD derivatives. AbnCBD derivatives were synthesized by acid catalysis-induced coupling and further derivatized. We evaluated the potential of the AbnCBD derivatives to inhibit the growth stages of various Candida species.

By in vitro colorimetric assays and in vivo mice experiments, we have shown that AbnCBD derivatives induce differential inhibition of Candida growth. The AbnCBD derivatives, especially comp 3, comp 10, and comp 9 significantly reduced the growth of C. albicans, including FLC-resistant strains, and of C. tropicalis and C. parapsilosis but not of C auris compared to their controls (FLC and 0.5% DMSO). Comp 3 also disrupted C. albicans biofilm formation and eradicated mature biofilms. Notably, other derivatives of AbnCBD disrupted the biofilm formation and maturation of C. albicans but did not affect yeast growth. In a murine model of VVC, comp 3 demonstrated significant fungal clearance and reduced C. albicans burden compared to vehicle and FLC controls.

These findings highlight the potential of AbnCBDs as promising antifungal agents against Candida infections.”

https://pubmed.ncbi.nlm.nih.gov/39368567/

https://www.sciencedirect.com/science/article/pii/S1043661824003864?via%3Dihub

Rooted in therapeutics: comprehensive analyses of Cannabis sativa root extracts reveals potent antioxidant, anti-inflammatory, and bactericidal properties

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“Following the legalization of recreational Cannabis in Canada in 2018, the associated waste, including Cannabis roots, has significantly increased. Cannabis roots, comprising 30%-50% of the total plant, are often discarded despite their historical use in Ayurvedic medicine for treating inflammatory and infectious disorders.

This study evaluates the phytochemical and therapeutic properties of Cannabis root extracts from a high tetrahydrocannabinolic acid, low cannabidiolic acid cultivar (variety Alien Gorilla Glue).

We performed ultra high-performance liquid chromatography coupled with mass spectrometry (UPLC-QTOF-MS) to identify the chemical components of the Cannabis roots. Extracts using water, ethanol and acid-base solvents were tested for antioxidant activity through free radical scavenging, metal chelation, and lipoperoxidation inhibition assays. Mitochondrial membrane protection was assessed using flow cytometry with the MitoPerOx probe in THP-1 monocytic leukemia cells. Anti-inflammatory potential was evaluated by measuring interleukin-6 levels in lipopolysaccharide-stimulated THP-1 cells. Bactericidal/fungicidal efficacy against Escherichia coliStaphylococcus aureus, and Candida albicans was determined using the p-iodonitrophenyltetrazolium assay. Additionally, we investigated the anticholinesterase activity of Cannabis root extracts, given the potential role of plant alkaloids in inhibiting cholinesterase, an enzyme targeted in Alzheimer’s disease treatments. UPLC-QTOF-MS analysis suggested the presence of several phenolic compounds, cannabinoids, terpenoids, amino acids, and nitrogen-containing compounds.

Our results indicated significant antioxidant, bactericidal, and anticholinesterase properties of Cannabis root extracts from both soil and hydroponic cultivation.

Extracts showed strong antioxidant activity across multiple assays, protected mitochondrial membrane in THP-1 cells, and exhibited anti-inflammatory and bactericidal/fungicidal efficacy. Notably, soil-cultivated roots displayed superior anti-inflammatory effects.

These findings demonstrate the remarkable antioxidant, anti-inflammatory, and anti-microbial activities of Cannabis roots, supporting their traditional uses and challenging their perception as mere waste. This study highlights the therapeutic potential of Cannabis roots extracts and suggests avenues for further research and application.”

https://pubmed.ncbi.nlm.nih.gov/39351095/

“In conclusion, this study sheds light on the chemical profile and significant therapeutic potential of Cannabis root extracts, confirming the validity of their traditional uses and challenging their conventional status as waste products of Cannabis cultivation.

The results presented in this work add evidence to the broad spectrum of biological systems in which Cannabis-sourced derivatives have a potential effect, not only because of cannabinoids, but also because of the possible action of phenolic and nitrogen-containing compounds. Through comprehensive investigation, we have demonstrated their remarkable antioxidant, anticholinesterase, and anti-inflammatory activities, along with their ability to protect mitochondrial membranes.

These findings underscore the importance of reevaluating the utilization of Cannabis roots in various therapeutic contexts, potentially offering new avenues for drug discovery and development. By recognizing the value of these often-overlooked plant components, we may uncover novel treatments for a range of medical conditions, thereby contributing to the advancement of natural product pharmacology and healthcare innovation. Further research in this area is warranted to elucidate the underlying mechanisms and explore the full therapeutic potential of Cannabis root extracts.”

https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2024.1465136/full

Cannabis sativa L. essential oil: chemical characterisation and antimicrobial activity against methicillin-resistant Staphylococcus pseudintermedius

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“Cannabis sativa L. essential oil has attracted the interest of the scientific community thanks to its numerous biological activities. Several studies have evaluated EOs as alternative therapeutic approaches to limit the use of antibiotics; the present study aimed to evaluate the in vitro inhibitory and bactericidal activity of the essential oils obtained from the leaves and inflorescences of two hemp genotypes against twenty-one multidrug-resistant, methicillin-resistant Staphylococcus pseudintermedius strains isolated from canine clinical samples.

Both EOs were mainly represented by sesquiterpene hydrocarbons, with a prevalence of β-caryophyllene and α-humulene. However, different relative amounts of phytocannabinoids were also detected. Microbiological results evidenced better outcomes for the EO characterised by the highest content of phytocannabinoids, which in turn showed no differences among the tested strains. Nevertheless, both the EOs showed better inhibitory and bactericidal activities than their main constituent, β-caryophyllene, tested individually, highlighting the presence of synergistic effects among the EO compounds.”

https://pubmed.ncbi.nlm.nih.gov/39229937/

https://www.tandfonline.com/doi/full/10.1080/14786419.2024.2398733

Long-term stability and bactericidal properties of galenic formulations of Cannabis sativa oils

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“The long-term stability in real and accelerated time for galenic oils based on full-spectrum cannabis has been studied, using sesame oil as a dilutant. Sesame oil is one of the most used vehicles in the cannabis pharmaceutical industry due to the costs and increased oral bioavailability of cannabinoids. The real-time assays conducted at 25 °C over twelve months demonstrated high stability and showed no significant changes in the composition of cannabinoids, total polyphenols, flavonoids, or antioxidant capacity. In these studies, it was observed that there was no development of microorganisms compromising the stability of the oils over a year. The three oil varieties exhibited a high bactericidal capacity against E. coli, S. aureus, and P. larvae.”

https://pubmed.ncbi.nlm.nih.gov/39025316/

Combinations of Cannabinoids with Silver Salts or Silver Nanoparticles for Synergistic Antibiotic Effects against Methicillin-Resistant Staphylococcus aureus

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“Silver has been shown to improve the antibiotic effects of other drugs against both Gram- positive and -negative bacteria. In this study, we investigated the antibiotic potential of cannabidiol (CBD), cannabichromene (CBC) and cannabigerol (CBG) and their acidic counterparts (CBDA, CBCA, CBGA) against Gram-positive bacteria and further explored the additive or synergistic effects of silver nitrate or silver nanoparticles using 96-well plate growth assays and viability (CFUs- colony-forming units).

All six cannabinoids had strong antibiotic effects against MRSA with minimal inhibitory concentrations (MICs) of 2 mg/L for CBG, CBD and CBCA; 4 mg/L for CBGA; and 8 mg/L for CBC and CBDA. Using 96-well checkerboard assays, CBC, CBG and CBGA showed full or partial synergy with silver nitrate; CBC, CBDA and CBGA were fully synergistic with silver nanoparticles against MRSA.

Using CFU assays, combinations of CBC, CBGA and CBG with either silver nitrate or silver nanoparticles, all at half or quarter MICs, demonstrated strong, time-dependent inhibition of bacterial growth (silver nitrate) and bactericidal effects (silver nanoparticles). These data will lead to further investigation into possible biomedical applications of specific cannabinoids in combination with silver salts or nanoparticles against drug-resistant Gram-positive bacteria.”

https://pubmed.ncbi.nlm.nih.gov/38927140/

“In conclusion, these studies confirm the antibiotic activity of CBG, CBC and CBD and the acidic forms of these agents against drug-resistant Gram-positive bacteria. The addition of silver, either as salts or nanoparticles, to select cannabinoids allows for much improved and, in some cases, synergistic antibiotic activity. Collectively, these findings strongly support further investigation of cannabinoid-enhanced silver preparations to assess their antimicrobial spectrum of activity and potential application in wound dressings or catheter coatings for an extended and more powerful antibiotic profile.”

https://www.mdpi.com/2079-6382/13/6/473

Spent Material Extractives from Hemp Hydrodistillation as an Underexplored Source of Antimicrobial Cannabinoids

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“Hemp (Cannabis sativa L.) has been used for millennia as a rich source of food and fibers, whereas hemp flowers have only recently gained an increased market interest due to the presence of cannabinoids and volatile terpenes. Currently, the hemp flower processing industry predominantly focuses on either cannabinoid or terpene extraction.

In an attempt to maximize the valorization of hemp flowers, the current study aimed to evaluate the phytochemical composition and antimicrobial properties of several extracts obtained from post-distillation by-products (e.g., spent material, residual distillation water) in comparison to the essential oil and total extract obtained from unprocessed hemp flowers.

A terpene analysis of the essential oil revealed 14 monoterpenes and 35 sesquiterpenes. The cannabinoid profiling of extracts showed seven acidic precursors and 14 neutral derivatives, with cannabidiol (CBD) reaching the highest concentration (up to 16 wt.%) in the spent material extract. The antimicrobial assessment of hemp EO, cannabinoid-containing extracts, and single compounds (i.e., CBD, cannabigerol, cannabinol, and cannabichromene) against a panel of 20 microbial strains demonstrated significant inhibitory activities against Gram-positive bacteria, Helicobacter pylori, and Trichophyton species.

In conclusion, this work suggests promising opportunities to use cannabinoid-rich materials from hemp flower processing in functional foods, cosmetics, and pharmaceuticals with antimicrobial properties.”

https://pubmed.ncbi.nlm.nih.gov/38927152/

“Considering that the hemp flower essential oil industry generates significant amounts of unused biomass rich in cannabinoids, the strategy implemented in the current work could afford high-added-value by-products within the hemp production chain, contributing to the principles of the circular economy and sustainability. Altogether, this work can open promising avenues for utilizing cannabinoid-rich materials obtained during hemp flower processing in functional foods or cosmeceutical and pharmaceutical products with antimicrobial properties.”

https://www.mdpi.com/2079-6382/13/6/485

Cannabis sativa (Hemp) seed-derived peptides WVYY and PSLPA modulate the Nrf2 signaling pathway in human keratinocytes

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“Cannabis sativa (Hemp) seeds are used widely for cosmetic and therapeutic applications, and contain peptides with substantial therapeutic potential.

Two key peptides, WVYY and PSLPA, extracted from hemp seed proteins were the focal points of this study. These peptides have emerged as pivotal contributors to the various biological effects of hemp seed extracts. Consistently, in the present study, the biological effects of WVYY and PSLPA were explored.

We confirmed that both WVYY and PSLPA exert antioxidant and antibacterial effects and promote wound healing.

We hypothesized the involvement of the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway in these observed effects, given that Nrf2 is reported to be a central player in the regulation of these observed effects. Molecular-level investigations unequivocally confirmed the role of the Nrf2 signaling pathway in the observed effects of WVYY and PSLPA, specifically their antioxidant effects.

Our study highlights the therapeutic potential of hemp seed-derived peptides WVYY and PSLPA, particularly with respect to their antioxidant effects, and provides a nuanced understanding of their effects. Further, our findings can facilitate the investigation of targeted therapeutic applications and also underscore the broader significance of hemp extracts in biological contexts.”

https://pubmed.ncbi.nlm.nih.gov/38781174/

“Although a more in-depth investigation into the precise roles of each peptide is necessary, we believe that a thorough examination of the highly specific roles of various peptides could lead to a broad range of medical and biological applications. In conclusion, we confirmed that the peptides WVYY and PSLPA derived from hemp seed extracts exhibit multiple effects, including antioxidant mechanisms. We propose that the overall “effect” of hemp extract originates from these contributions.”

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0298487

Exploring the versatile roles of the endocannabinoid system and phytocannabinoids in modulating bacterial infections

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“The endocannabinoid system (ECS), initially identified for its role in maintaining homeostasis, particularly in regulating brain function, has evolved into a complex orchestrator influencing various physiological processes beyond its original association with the nervous system. Notably, an expanding body of evidence emphasizes the ECS’s crucial involvement in regulating immune responses.

While the specific role of the ECS in bacterial infections remains under ongoing investigation, compelling indications suggest its active participation in host-pathogen interactions. Incorporating the ECS into the framework of bacterial pathogen infections introduces a layer of complexity to our understanding of its functions.

While some studies propose the potential of cannabinoids to modulate bacterial function and immune responses, the outcomes inherently hinge on the specific infection and cannabinoid under consideration. Moreover, the bidirectional relationship between the ECS and the gut microbiota underscores the intricate interplay among diverse physiological processes.

The ECS extends its influence far beyond its initial discovery, emerging as a promising therapeutic target across a spectrum of medical conditions, encompassing bacterial infections, dysbiosis, and sepsis.

This review comprehensively explores the complex roles of the ECS in the modulation of bacteria, the host’s response to bacterial infections, and the dynamics of the microbiome. Special emphasis is placed on the roles of cannabinoid receptor types 1 and 2, whose signaling intricately influences immune cell function in microbe-host interactions.”

https://pubmed.ncbi.nlm.nih.gov/38775488/

https://journals.asm.org/doi/10.1128/iai.00020-24