In vitro antimicrobial activity of Cannabis sativa extracts against Methicillin-resistant Staphylococcus aureus (MRSA)

Source / Quelle: https://www.sciencedirect.com/science/article/pii/S0254629926004242

Abstract

Cannabis sativa is a medicinal plant with promising antimicrobial properties, and humans have been utilising it for thousands of years as a source of food (seeds) and medicine. Antimicrobial resistance remains a significant challenge worldwide, making it difficult to manage microbial infections caused by multidrug-resistant strains. This study assessed the antimicrobial activity of two Cannabis sativa strains from Limpopo Province, South Africa, against multidrug-resistant microorganisms.

Methanol and distilled water extracts of the two Cannabis sativa strains were prepared using maceration extraction, and the antimicrobial activity was assessed using standardised assays. Phytochemical constituents of the extracts were analysed using standard qualitative screening methods. Methanol extracts consistently showed the highest yields (>10%), while distilled water had lower yields. The Cannabis sativa extracts exhibited antimicrobial activity against Methicillin-resistant Staphylococcus aureus (MRSA) only, and no inhibition of growth was observed on Enterococcus faecium, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Candida albicans. Minimum Inhibitory Concentrations (MICs) of the extracts ranged from 3.13 mg/ml to 12.5 mg/ml, while the Minimum Bactericidal Concentrations (MBCs) values indicated bactericidal activity from 6.25 mg/ml. Preliminary phytochemical screening revealed the presence of various bioactive compounds. These findings demonstrate that Cannabis sativa crude extracts possess localised, low-potency inhibitory effects against MRSA, serving as a baseline for future compound isolation. Consequently, further studies involving compound isolation, quantitative phytochemical analysis, and mechanistic investigations are required to fully evaluate their antimicrobial potential.

Keywords

Antimicrobial activity; Cannabis sativa; Multidrug-resistant strains

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1. Introduction

The development of new antimicrobial agents is a priority since antimicrobial resistance has become a serious worldwide health problem, and it is estimated that by 2050, antimicrobial resistance will cause 10 million deaths per year (Walsh et al., 2023). This challenge has sparked interest in medicinal plants, which offer a vast and largely unexplored source of potential drug discovery (Chaachouay and Zidane, 2024).

Cannabis sativa L. is a lighter green plant that belongs to the Cannabaceae family (Pant et al., 2024). It is also known as hemp, marijuana (Schilling et al., 2020). In South Africa, the plant is also known as Dagga, Matekwane, Intsangu, and Insangu, depending on the South African language (Du Toit, 1996; Kepe, 2003). The first usage of Cannabis sativa was documented in Chinese traditional medicine, and since then, it has had a significant existence in society. Different countries in this decade have also used Cannabis sativa for recreational purposes (Peng and Shahidi, 2021; Zuardi, 2006). It has been utilised by humans for many years for medical use, fibre production and the seeds have been used as a food source. Due to its health benefits, it has been widely adopted for medical applications and has recently prompted extensive research into its genetic characteristics and pharmacological properties (Kumar et al., 2021; Peng and Shahidi, 2021).

Cannabis sativa contains over 500 bioactive compounds, of which 120 are cannabinoids. These include cannabinoids, terpenes, flavonoids, phenolics, alkaloids, and others (Radwan et al., 2021). The common cannabinoids are cannabidiol (CBD), delta-9-tetrahydrocannabinol (D9-THC), also known as THC, cannabigerol (CBG), cannabinol (CBN), and others. The derivatives of these compounds are cannabidiolic acid (CBDA), Tetrahydrocannabinolic acid (THCA), cannabigerolic acid (CBGA), and others (Radwan et al., 2021). Cannabinoids have recently become widely used due to their effective antimicrobial activity (Karas et al., 2020). Cannabis sativa chemotypes differ by THC: CBD ratios. Chemotype I has more THC content than CBD and is known as a drug type. Chemotype II has relatively equal amounts and is an intermediate type. Chemotype III (fibre/hemp-type) has more CBD than THC. It includes Futura 75 and CBD Carmagnola strains, which were selected for their non-psychoactive profiles and high CBD yields, enabling a focused evaluation of CBD-mediated antimicrobial effects against multidrug-resistant microorganisms. Chemotype IV is CBG-dominant, and Chemotype V lacks the presence of cannabinoids (Haczkiewicz et al., 2025; Pacifico et al., 2006; Singh et al., 2021).

Recent studies showed that extracts derived from the Cannabis sativa plant, leaves, essential oils, and isolated compounds such as phenolics, terpenes and cannabinoids, exhibit a great antimicrobial activity against multidrug-resistant bacteria such as MRSA, Enterococcus faecium, Bacillus subtilis, Klebsiella pneumoniae, and others (Chakraborty et al., 2018; Mahmud et al., 2021; Schofs et al., 2021). Previous studies have demonstrated the antimicrobial activity of Cannabis sativa against multidrug-resistant strains, and these studies have largely focused on reference strains or isolated strains from other countries, such as Europe and America (Mahmud et al., 2021; Schofs et al., 2021). A critical knowledge gap therefore exists on the antimicrobial activity of Cannabis sativa extracts against multidrug-resistant clinical isolates from South African healthcare settings, particularly Limpopo Province. Antimicrobial resistance patterns may vary geographically due to differences in antimicrobial use and the diversity of circulating microbial strains (Salam et al., 2023). Consequently, the evaluation of local clinical multidrug-resistant isolates remains important for determining the potential relevance of extracts within specific regional contexts.

A South African study by Mokoto (2021) contributed to the international research on the antimicrobial activity of cannabis. This research is particularly significant due to the regulatory restrictions that have historically limited such studies in South Africa. The findings indicated that Cannabis sativa/indica extracts were effective against drug-resistant pathogens, including Candida and Mycobacterium species. The exhibited antimicrobial activity of Cannabis sativa extracts aligns with the World Health Organisation's goals and global health programs, suggesting promising options to combat antimicrobial resistance (Ribeiro et al., 2024).

The antimicrobial activity of Cannabis sativa extracts is influenced by several factors, including the target microorganism, plant component, and extraction solvent (Essien, 2011; Schofs et al., 2021). The antimicrobial activities of Cannabis sativa extracts are attributed to their bioactive compounds, which are primarily recovered using various solvents such as methanol and distilled water (Liu et al., 2022; Motiejauskaitė et al., 2023). Studies have documented that synergistic interactions among the bioactive compounds in Cannabis sativa extracts are a crucial factor influencing its antimicrobial activity. Although individual cannabinoids, terpenes, and flavonoids have their antimicrobial effect, their synergistic interaction in extracts exhibits a stronger effect than that of any single compound on its own (Iseppi et al., 2019; Karas et al., 2020; Koltai et al., 2019). Concentration of bioactive compounds, which determines the antimicrobial activity of Cannabis sativa extracts, is influenced by various external factors such as geographic origin, plant age, time of collection, and the nature of the soil, as well as internal factors like genetic information, cultivars, accessions, and maturity (Nafis et al., 2019; Zheljazkov et al., 2020). These factors may influence the phytochemical composition of Cannabis sativa strains from Limpopo Province, potentially affecting their antimicrobial efficacy.

Historically, cannabis in South Africa has primarily been used in traditional medicine for treating a range of illnesses, such as diabetes, epilepsy, pain, diarrhoea, and bronchial conditions, including asthma and coughing (Mhlongo and Van Wyk, 2019; Mudau et al., 2020; Ndlangamandla et al., 2024). Despite the medicinal benefits of Cannabis sativa, further research is required to fully understand the chemical composition and genetic variation of strains found in South Africa (Ndlangamandla et al., 2024). Furthermore, its antimicrobial activity has not been sufficiently explored, warranting further investigation.

This study aimed to comparatively assess the antimicrobial activity of methanol and distilled water extracts of Cannabis sativa strains against clinically relevant multidrug-resistant isolates, MRSA, Enterococcus faecium, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Candida albicans from Limpopo Province. Additionally, the study investigated the bioactive compounds of these extracts. This study directly addresses region-specific antimicrobial activity data for local multidrug-resistant pathogens and contributing comparative evidence on the antimicrobial activity of Cannabis sativa extracts sourced from Limpopo Province against clinically resistant strains.

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