According to a recently published study, cannabis sugar leaves demonstrate promising antimicrobial effects against several bacterial pathogens, including Bacillus cereus, Vibrio cholerae, Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis.
For the study, published by the Journal of Advanced Veterinary and Animal Research, researchers from Rajamangala University of Technology Isan and Kasetsart University prepared ethanol-based extracts from cannabis sugar leaves and tested their antibacterial activity using standard disc diffusion and broth microdilution methods. The analysis revealed that the extract inhibited the growth of five common pathogens but had no effect on Pseudomonas aeruginosa or Vibrio parahaemolyticus.
In disc diffusion assays, the extract produced the largest inhibition zone against Vibrio cholerae (20.10 mm), followed by S. aureus (16.4 mm), S. epidermidis (15.86 mm), E. coli (15.62 mm), and B. cereus (15.53 mm). These effects were compared to tetracycline, which served as the positive control. The negative control (99% ethanol) showed no antibacterial activity.
Antimicrobial activity of cannabis sugar leaves extracts on microorganisms. A 500 mg/ml concentration of fresh cannabis sugar leaves extract (CbEt) was loaded onto discs, which were then placed on nutrient agar plates inoculated with each microorganism: (A) Pseudomonas aeruginosa, (B) Escherichia coli, (C) Bacillus cereus, (D) Staphylococcus aureus, (E) Staphylococcus epidermidis, (F) Vibrio parahaemolyticus, and (G) Vibrio cholerae. The positive control was 30 μg/ml of tetracycline, and the negative control was 99% ethanol.
The broth microdilution results further confirmed the extract’s efficacy. The minimum inhibitory concentrations (MICs) were lowest for B. cereus at 0.977 mg/ml and highest for S. aureus and S. epidermidis at 250 mg/ml. The corresponding minimum bactericidal concentrations (MBCs) ranged from 1.953 mg/ml for B. cereus to 500 mg/ml for S. aureus and S. epidermidis.
High-performance liquid chromatography (HPLC) analysis identified Δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) as the extract’s primary active compounds, with concentrations of 2.24 µg/ml and 2.05 µg/ml, respectively. Gallic acid (0.35 µg/ml) and tannic acid (0.62 µg/ml) were also present as minor components. These compounds are known for their antioxidant and anti-inflammatory properties, with tannic acid in particular recognized for its ability to inhibit bacterial growth through disruption of efflux pumps.
Confirmation of the minimum inhibitory concentration and the minimum bactericidal concentration of Cannabis sugar leaves extract on microorganisms by streak plate method. Different concentrations of cannabis sugar leaves extract were added to inoculated microorganisms, with concentrations ranging from CbEt 1–10; 500, 250, 125, 62.5, 31.25, 15.625, 7.815, 3.906, 1.953, and 0.977 mg/ml, respectively. The samples were then incubated at 37°C for 24 h at 200 rpm on a shaker. Finally, the growth inhibition by cannabis sugar leaf extract was confirmed using a streak plate. (A–B) Escherichia coli, (C–D) Bacillus cereus, (E–E) Staphylococcus aureus, (G–H) Staphylococcus epidermidis, and (I–J) Vibrio cholerae. The positive control was the microorganism itself, while the negative control was the nutrient broth.
The authors highlight that this is the first study to examine the bioactivity of cannabis sugar leaves from the Hang Kra Rog Phu Phan cultivar, a regional Thai strain historically known for its use in traditional Thai stick preparations. While previous studies have investigated cannabis extracts against various microbes, this study adds new evidence of the potential antibacterial value of cannabis sugar leaves, especially from this understudied strain.
Given the rising global threat of antibiotic resistance, the findings suggest that cannabis-derived compounds—particularly when extracted from specific cultivars and plant parts—could offer a valuable source of new antimicrobial agents. The researchers note that further investigation is needed to understand the precise mechanisms of action and to evaluate the safety and efficacy of such extracts in clinical settings.
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