The work will be presented today (June 23) in San Francisco at ASM Microbe, the annual meeting of the American Society for Microbiology; the research has not yet been published in a peer-reviewed journal.
Many more studies will be needed to see if CBD could be used as an antibiotic in people. Research will need to determine the dose needed to kill bacteria in the body, whether this dose is safe and how the antibiotic might be delivered, Adalja said.
“Just because [CBD] has antibiotic activity in an in vitro assay doesn’t mean it does in the human body,” said Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security in Baltimore, who wasn’t involved with the study. “Lots of different compounds … have [antibiotic] activity in a petri dish.”
Still, Adalja said the research is promising. “[It’s] more evidence that there [are] a lot of untapped avenues of research with CBD,” he said.
In addition, studies suggest that CBD may have anti-inflammatory effects, but whether it also has antibiotic effects has been unclear.
Cannabidiol , or CBD, has been touted for a wide variety of health benefits, most notably as a treatment for people with certain forms of epilepsy. Now, new research is showing that CBD is surprisingly effective at killing bacteria in a petri dish, including those responsible for many serious infections, such as staph and its drug-resistant sibling, MRSA. In fact, CBD even appears to be just as effective as widely used antibiotics at killing bacteria, such as Staphylococcus aureus and Streptococcus pneumoniae.
It’s worth noting that the study was conducted in collaboration with Botanix Pharmaceuticals, a biopharmaceutical company that produces CBD-based products.
“Given cannabidiol’s documented anti-inflammatory effects, existing safety data in humans, and potential for varied delivery routes, it is a promising new antibiotic worth further investigation,” said Dr Mark Blaskovich at the University of Queensland’s Institute for Molecular Bioscience’s Centre for Superbug Solutions, according to a press release.
Lone and Lone investigated and compared the protein yield and antimicrobial and antioxidant effects of C. sativa following both aqueous and acetone extraction . From 500 g samples, protein extraction from aqueous methodologies yielded 4.8 g of crude extract and 3.2 g from acetone. When compared with the aqueous extract, the acetone extract displayed fractionally superior bactericidal properties. A concentration-dependent response was observed against all strains, with V. cholera being marginally the most responsive bacteria, closely followed by P. aeruginosa. The fungal response was slightly more pronounced in C. albicans compared to C. neoforms. Additionally, this study found that C. sativa has antioxidant properties, thus widening its potential for clinical use.
A post-antibiotic world is fast becoming a reality, given the rapid emergence of pathogens that are resistant to current drugs. Therefore, there is an urgent need to discover new classes of potent antimicrobial agents with novel modes of action. Cannabis sativa is an herbaceous plant that has been used for millennia for medicinal and recreational purposes. Its bioactivity is largely due to a class of compounds known as cannabinoids. Recently, these natural products and their analogs have been screened for their antimicrobial properties, in the quest to discover new anti-infective agents. This paper seeks to review the research to date on cannabinoids in this context, including an analysis of structure–activity relationships. It is hoped that it will stimulate further interest in this important issue.
Novak and co-workers evaluated the essential oils of five different cultivars of C. sativa against a large panel of Gram-positive and Gram-negative pathogens. The most abundant compounds in each oil sample were α-pinene, myrcene, trans-β-ocimene, α-terpinolene, trans-caryophyllene and α-humulene. The antimicrobial activity was in general poor, with only modest activity against Acinetobacter calcoaceticus and Brevibacterium linens. No ∆ 9 -THC and very low levels of CBD and CBN were detected in all the essential oils, which suggests a role of these compounds in the antimicrobial activity of C. sativa . A later study evaluated the oil of the seeds from the whole plant, extracted by petroleum ether and methanol. It was found (via the cup–plate agar diffusion method) that each extract exhibited an antimicrobial effect against Gram-positive pathogens. This is consistent with the study by Van Klingeren et al. , although the cannabinoid content of the plant specimen was not characterized. No significant antifungal activity was observed. Intriguingly, minor activity against Gram-negative bacteria was also reported, albeit a modest effect (note that the petroleum ether extract was inactive against Pseudomonas aeruginosa) . Hot water and ethanol leaf extracts have also been shown to possess an inhibitory effect against Gram-negative pathogens .
2. Antibacterial Effects of C. sativa Extracts
Sarmadyan et al. investigated the antimicrobial properties of “Hashish” against common hospital-associated bacterial strains . Disk diffusion experiments found that cannabis extract exerted the greatest antimicrobial effects on S. aureus 25923, with an inhibition zone of 14 mm, followed by MRSA, E. coli and K. pneumoniae with values of 12, 10 and 7 mm, respectively. No activity was observed in P. aeruginosa or A. baumannii. This trend regarding spectrum of activity is consistent with the findings of Vu et al., whereby extracts from Vietnamese derived C. sativa plants were found to possess modest antimicrobial activity against Gram-positive bacteria, with Gram-negative bacteria being less susceptible . Similarly, Lelario and co-workers also observed that the major components of C. sativa extracts displayed moderate activity only against Gram-positive pathogens .
The first reports detailing the antibacterial activity of cannabinoids date back to the 1950s [41,42]. These experiments were conducted before the phytochemistry of cannabis was well characterized, which means that the bactericidal effect of C. sativa could not be directly attributed to a specific constituent. This was achieved in 1976, where it was found that ∆ 9 -THC and CBD are bacteriostatic as well as bactericidal against a panel of Gram-positive pathogens (see below) . There has also been great interest in the antibacterial properties of the essential oils and various extracts from C. sativa, such as those derived from petroleum ether, methanol and hot water. Various methods for isolating C. sativa extracts have also been applied. Traditional techniques include cold-pressing and solvent extraction, however higher yielding technologies which generate superior products are now emerging . Pressurized liquid extraction circumvents the need for filtration, whereas ultrasonic-assisted extraction (UAE) methods use less solvent and have short processing times, with higher yields and equivalent quality. “Green” methods include microwave-assisted extraction and supercritical fluid extraction, however up-scaling is challenging for the latter process .
The discovery of antibiotics is undoubtedly one of the most important scientific achievements in modern medicine and has saved millions of lives since their discovery. However, their misuse has resulted in the emergence of antibacterial resistance (AMR), which is a significant threat to global human health. It is estimated that global deaths could reach 10 million per year by 2050 with a cumulative cost to global economic output of US$100 trillion . The World Health Organization has highlighted that AMR is one of the three greatest threats to healthcare systems globally . For example, immuno-compromised patients such as organ transplant recipients and those who are undergoing chemotherapy treatment are particularly vulnerable and depend on the efficacy of antibiotics to fight off infection [3,4]. The spread of multidrug-resistant (MDR) bacteria therefore threaten these significant advancements in medical care. Despite this, only four new classes of antibiotics have reached the clinic in the past four decades . The development of new classes of anti-infective agents with novel modes of action is therefore essential to address the growing threat of AMR.
An interesting application for C. sativa-derived compounds is to use them for water filtration and purification purposes. Nadir et al. immobilized a mixture of cannabinoids and terpenes onto a polyethersulfone hybrid membrane. Bacterial decline was observed for both Gram-positive and Gram-negative pathogens. For example, an 88% decrease bacterial load for S. aureus was measured for the hybrid membrane compared to 30% for the standard membrane. Similar results were reported for several other species, including for Pseudomonas aeruginosa and Escherichia coli. This study represents a cost-effective solution for water filtration and antibacterial purification . All these examples highlight the great potential of C. sativa and its antimicrobial properties for applications in food, agriculture and drug discovery.