Thyme essential oil loaded microspheres for fish fungal infection: microstructure, <i>in vitro</i> dynamic release and antifungal activity
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Date
2021
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Abstract
Aims
Evaluate the effect of varying the droplet size of microspheres charged with thyme essential oil (TEO-MS) on their swelling (Sw), release rate (%RR) and in vitro antifungal activity against Saprolegnia sp.
Methods
TEO-MS obtained by ionic gelation were characterised through SEM microscopy and X-ray microtomography. Their Sw and RR% were evaluated at simulated fish-gastrointestinal conditions using gravimetric and spectrophotometric techniques.
Results
For all evaluated droplet sizes (p >= 0.05), TEO was heterogeneously distributed inside of the MS and TEO-MS experimented agglomeration and sphericity loss after the drying process. Under gastric conditions, the acid pH (2.9) limited the Sw (50-100%) of TEO-MS, generating a low RR% (14-18%). Contrary, the slightly alkaline intestinal pH (8.1) favoured the Sw (similar to 3.2 to 3.8 times) and therefore the RR% (42-63%).
Conclusions
TEO-MS (5-100 mg/mL) presented antifungal capacity onto Saprolegnia sp. after the simulated fish digestion, being the small droplet size once the most effective.
Evaluate the effect of varying the droplet size of microspheres charged with thyme essential oil (TEO-MS) on their swelling (Sw), release rate (%RR) and in vitro antifungal activity against Saprolegnia sp.
Methods
TEO-MS obtained by ionic gelation were characterised through SEM microscopy and X-ray microtomography. Their Sw and RR% were evaluated at simulated fish-gastrointestinal conditions using gravimetric and spectrophotometric techniques.
Results
For all evaluated droplet sizes (p >= 0.05), TEO was heterogeneously distributed inside of the MS and TEO-MS experimented agglomeration and sphericity loss after the drying process. Under gastric conditions, the acid pH (2.9) limited the Sw (50-100%) of TEO-MS, generating a low RR% (14-18%). Contrary, the slightly alkaline intestinal pH (8.1) favoured the Sw (similar to 3.2 to 3.8 times) and therefore the RR% (42-63%).
Conclusions
TEO-MS (5-100 mg/mL) presented antifungal capacity onto Saprolegnia sp. after the simulated fish digestion, being the small droplet size once the most effective.
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Keywords
Microspheres, essential oil, microstructure, antifungal capacity