Control of Foodborne Staphylococcus aureus by Shikonin, a Natural Extract

Abstract

Foodborne Staphylococcus aureus (S. aureus) has attracted widespread attention due to its foodborne infection and food poisoning in human. Shikonin exhibits antibacterial activity against a variety of microorganisms, but there are few studies on its antibacterial activity against S. aureus. This study aims to explore the antibacterial activity and mechanism of shikonin against foodborne S. aureus. The results show that the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) of shikonin were equal for all tested strains ranging from 35 μg/mL to 70 μg/mL. Shikonin inhibited the growth of S. aureus by reducing intracellular ATP concentrations, hyperpolarizing cell membrane, destroying the integrity of cell membrane, and changing cell morphology. At the non-inhibitory concentrations (NICs), shikonin significantly inhibited biofilm formation of S. aureus, which was attributed to inhibiting the expression of cidA and sarA genes. Moreover, shikonin also markedly inhibited the transcription and expression of virulence genes (sea and hla) in S. aureus. In addition, shikonin has exhibited antibacterial ability against both planktonic and biofilm forms of S. aureus. Importantly, in vivo results show that shikonin has excellent biocompatibility. Moreover, both the heat stability of shikonin and the antimicrobial activity of shikonin against S. aureus were excellent in food. Our findings suggest that shikonin are promising for use as a natural food additive, and it also has great potential in effectively controlling the contamination of S. aureus in food and reducing the number of illnesses associated with S. aureus.

Antibacterial Activity of Juglone Revealed in a Wound Model of Staphylococcus aureus Infection

“…The results of this study are consistent with the above results, confirming that juglone has antibacterial activity against S. aureus . This antibacterial activity may be related to the naphthoquinone structure of juglone, as our previous study showed that shikonin has good anti- S. aureus activity because it has a naphthoquinone structure [ 17 ]. As another example, plumbagin has better antibacterial activity against methicillin-resistant Staphylococcus aureus [ 18 ].…”

Shikonin: Extraction, properties and applications in active and intelligent packaging

“…In a recent study, the antibacterial activity of shikonin was studied against S. aureus ATCC 29213 strain, and the results were correlated with the intracellular ATP concentration, reflecting the integrity of the bacterial cell membrane. 52 Compared with the untreated group, the intracellular ATP concentration of the shikonin-treated group was significantly decreased, indicating cell membrane damage on shikonin treatment (Figure 4). Besides, the target strain and the source and purity of shikonin may also lead to variation in the results.…”

“…In another similar study involving a different test method, MIC of 125 μg/ml was also observed against S. aureus . In a recent study, the antibacterial activity of shikonin was studied against S. aureus ATCC 29213 strain, and the results were correlated with the intracellular ATP concentration, reflecting the integrity of the bacterial cell membrane 52 . Compared with the untreated group, the intracellular ATP concentration of the shikonin‐treated group was significantly decreased, indicating cell membrane damage on shikonin treatment (Figure 4).…”

“…The effect of shikonin on the intracellular ATP concentration of Staphylococcus aureus strain ATCC29213. Adapted with permission from Wan et al (2021) 52 published by MDPI.…”

“…The recent worldwide confrontation with the Coronavirus disease (COVID‐19) pandemic in late 2019 greatly escalated the interest in antiviral materials. Several natural compounds in plant extracts and natural oils are proven antiviral agents 50–54 . However, before this pandemic, little attention was paid to this activity of natural resources.…”