Evaluation of the antibacterial activity of encapsulated d-limonene in β-cyclodextrin-based nanosponge

Following the increasing resistance of bacteria to antibiotics and increasing public awareness of the relationship between food and human health, several studies have been conducted to find potential antimicrobial agents. D-limonene (L) is a liquid and a colorless bioactive compound of the terpene family that has high antioxidant and antimicrobial activity. Due to its low solubility, high volatility, and sensitivity to light, its applications in the food and pharmaceutical industries are limited. In this study, L was incorporated in β-cyclodextrin nanosponges (CD-NS) to overcome these limitations. For the preparation of  L-NS, different molar ratios of β-CD and Diphenyl carbonate (DPC) as cross-linker (1:4, 1:6, and 1:8 of CD: DPC) and different ratios (w/w) of L: NS (1:2, 1:4, and 1:6) were prepared. The results showed the solubility of L increased after encapsulation in the nanosponges. Encapsulated L showed higher antibacterial activity compared to free L and minimum inhibitory concentration (MIC) and minimum bactericidal concentration of  L  decreased 324 and 648 times after encapsulation. Our results propose that CD-NS is a suitable carrier for hydrophobic and sensitive compounds and L-NS can be used as a potential preservative with enhanced antibacterial activity in food applications. It is important to note that the results of this study were obtained in vitro and further studies related to their toxicity (in vivo) are needed for confirmation of their application in the era of nutrition and genomics.