In vitro antimicrobial activity of Thai stick cannabis Hang Kra Rog Phu Phan (Cannabis sativa L.), sugar leaves extract against pathogenic bacteria

Abstract

Objective: Cannabis sativa L. is aware of a rich source of bioactive substances with various structures that exhibit pharmacological activity in the central nervous system, cardiovascular, cerebrovascular, respiratory, reproductive, and gastrointestinal systems.

Materials and methods: In this study, cannabis sugar leaves were soaked in 99% ethanol, followed by evaporation. The antibacterial effect of the cannabis sugar leaf extract was then evaluated using the disc diffusion method. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were determined using broth dilution.

Results: The results of this study indicated that the cannabis sugar leaf extract inhibited Bacillus cereus, Vibrio cholerae, Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis when compared to tetracycline, but it did not inhibit Pseudomonas aeruginosa. The MIC and MBC of the cannabis sugar leaves extract against B. cereus, V. cholerae, E. coli, S. aureus, and S. epidermidis were 0.977, 1.953, 31.25, 62.5, 125, 250, 250, 500, 250, and 500 mg/ml, respectively. The bioactive compounds in cannabis sugar leaf extract were identified using high-performance liquid chromatography.

Conclusion: The results indicated that the major bioactive compounds were Δ-9- tetrahydrocannabinol (THC) and cannabidiol (CBD). While minor bioactive compounds included gallic acid and tannic acid. These results support the benefits of cannabis sugar leaf extract, which has been used for its pharmacological properties and may be useful as an alternative antimicrobial agent in medicine.

Keywords: Cannabis sativa L.; antimicrobial activity; cannabidiol; gallic acid; tannic acid; Δ-9- tetrahydrocannabinol.

Figure 1.. The morphology of Thai stick cannabis Hang Kra Rog Phu Phan. (A) Cannabis sativa samples identified as the Hang Kra Rog Phu Phan cultivar, cultivated outdoors at a field demonstration, at the Faculty of Natural Resources, Rajamangala University of Technology Isan, Sakonnakhon Campus. (B) Cannabis sativa inflorescence. (C) Cannabis sugar leaves.

Figure 2.. High-performance liquid chromatography (HPLC) results show Δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). The HPLC results showed that the cannabis sugar leaves extract contained 2.24 µg/ml of Δ-9-tetrahydrocannabinol (THC) and 2.05 µg/ml of CBD.

Figure 3.. 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.

Figure 4.. 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.