Antibacterial Activity of Crocus sativus L. Petals Extracts against Foodborne Pathogenic and Spoilage Microorganisms, with a Special Focus on Clostridia

Abstract

In recent years, there has been a growing interest in the use of novel antimicrobial agents able to inhibit or kill food-borne bacteria or to interrupt the onset of food spoilage. Crocus sativus L. petals, typically considered as waste obtained from saffron spice production, could be a source of natural bioactive compounds to be used as food preservatives. The purpose of this work was to investigate the antibacterial properties of two hydroalcoholicsaffron petal extracts obtained by maceration (SPEA) and by ultrasonic bath (SPEB) methods. The main polyphenols identified in both extracts were gallic and chlorogenic acids, representing almost 70% of the phenolic fraction monitored. The antibacterial activity was studied by the agar well-diffusion method, against food-borne pathogenic and spoilage bacteria. Both extracts showed activity mainly against Gram-positive bacteria, in particular those belonging to the Clostridiaceae family (C. perfringens, C. botulinum and C. difficile), with inhibition zone diameters ranging from 13 to 18 mm. The antibacterial properties against Clostridia were further analyzed, determining MIC and MBC and performing a time-kill test. SPEA showed lower MIC/MBC values (250 mg/mL) compared to SPEB (500 mg/mL), suggesting that it could be more active against the assayed strains, probably because of its higher content of gallic acid. SPEA and SPEB, tested at a concentration of 1 × MIC, showed bactericidal activity against C. perfringens, C. botulinum and C. difficile and these results suggest that saffron petals could represent a valuable natural alternative source to conventional preservatives. Further investigations are needed to evaluate possible applications in the food industry.

The Effects of Encapsulation on the In Vitro Anti-Clostridial Activity of Olive Mill Wastewater Polyphenolic Extracts: A Promising Strategy to Limit Microbial Growth in Food Systems

“…The in vitro anti-Clostridial effect of different phenolic compounds has already been reported in the literature. A previous study by Primavilla et al [35] refers to the similar antibacterial activity of Crocus sativus L. extract (1 g/mL) assessed by agar well diffusion, albeit C. botulinum and C. perfringens seemed more sensitive than C. difficile. This diverse outcome is of no surprise as the different chemical composition and formulation of the extracts can lead to different results of microbial growth modulation.…”

“…Concerning the time-kill test, in a previous study testing saffron natural extracts on the same bacterial strains, the LOQ was reached at around 24 h, reflecting different antibacterial actions most certainly due to the different chemical compositions of the extracts [35]. Manuka (Leptospermum scoparium) honey was reported as having in vitro bactericidal activity and a therapeutic role in the prevention of C. difficile infection [43], in addition to potent biofilm inhibition activity in vitro [44].…”

“…As previously described [35], 100 µL of bacteria suspensions (0.5 McFarland in 0.9% sterile saline solution) was spread using a swab on Mueller Hinton agar 5% defibri-nated sheep blood plates (MHAB-Oxoid Limited, Basingstoke, UK). Two-fold serial dilutions were prepared for each extract (EE: from 1 g/mL to 0.125 g/mL; LE: from pure to 0.140 g/mL), and 50 µL of each of them was inoculated in 7 mm holes previously made by scooping out the medium with a sterilized cork borer.…”

Saffron, a Potential Bridge between Nutrition and Disease Therapeutics: Global Health Challenges and Therapeutic Opportunities

“…Many studies have shown that phytochemicals have great antimicrobial potential with several mechanisms of action against both susceptible and resistant microorganisms [148]. Similarly, it is evident from earlier research that C. sativus petals possess strong antibacterial, antifungal, and antioxidant activity [149,150]. A notable antibacterial activity of saffron petals' methanolic extract was reported by Asgarpanaha et al [151] against Escherichia coli, Bacillus cereus, Salmonella typhi, Staphylococcus aureus, and Shigella dysenteriae.…”

Stigmas and Petals of Crocus sativus L. (Taliouine, Morocco): Comparative Evaluation of Their Phenolic Compounds, Antioxidant, and Antibacterial Activities

“…They have been associated with numerous pharmacological effects [ 22 ]. The results of previous studies have suggested that different parts of Crocus sativus L. can be used for their antioxidant activity [ 23 , 24 ] and antibacterial effects against specific bacteria [ 12 , 25 , 26 ].…”