Herbicide and Cytogenotoxic Activity of Inclusion Complexes of Psidium gaudichaudianum Leaf Essential Oil and ß-Caryophyllene on 2-Hydroxypropyl-ß-cyclodextrin.

The present investigation aimed to develop inclusion complexes (ICs) from Psidium gaudichaudianum (GAU) essential oil (EO) and its major compound ß-caryophyllene (ß-CAR), and to evaluate their herbicidal (against Lolium multiflorum and Bidens pilosa) and cytogenotoxic (on Lactuca sativa) activities. The ICs were obtained using 2-hydroxypropyl-ß-cyclodextrin (HPßCD) and they were prepared to avoid or reduce the volatility and degradation of GAU EO and ß-CAR. The ICs obtained showed a complexation efficiency of 91.5 and 83.9% for GAU EO and ß-CAR, respectively. The IC of GAU EO at a concentration of 3000 µg mL-1 displayed a significant effect against weed species B. pilosa and L. multiflorum. However, the ß-CAR IC at a concentration of 3000 µg mL-1 was effective only on L. multiflorum. In addition, the cytogenotoxic activity evaluation revealed that there was a reduction in the mitotic index and an increase in chromosomal abnormalities. The produced ICs were able to protect the EO and ß-CAR from volatility and degradation, with a high thermal stability, and they also enabled the solubilization of the EO and ß-CAR in water without the addition of an organic solvent. Therefore, it is possible to indicate the obtained products as potential candidates for commercial exploration since the ICs allow the complexed EO to exhibit a more stable chemical constitution than pure EO under storage conditions.

Development of inclusion complexes of 2-hydroxypropyl-ß-cyclodextrin with Psidium guajava L. essential oil by freeze-drying and kneading methods for application as Aedes aegypti L. larvicide.

Inclusion complexes (ICs) of 2-hydroxypropyl-ß-cyclodextrin with the essential oil (EO) from Seculo XXI cultivar of Psidium guajava were prepared using kneading (KN) and freeze-drying (FD) methods. The resulting ICs clusters have a nanometric size, with a diameter of approximately 80 and 40 nm for KN and FD, respectively. Complexation efficiency was 80.3% and 50.8% for KN and FD methods, respectively. The larvicidal activity of the EO in DMSO on A. aegypti had LC50 and LC90 values of 51.49 and 64.51 µg mL-1, respectively. For the KN method, the toxicity corresponded to 77.54 and 107.29 µg mL-1 for LC50 and LC90, respectively. FD method demonstrated toxicity at concentrations above 600 µg mL-1. Thus, ICs enable the use of EO in breeding sites for A. aegypti, thus being potential products to be commercially exploited.

Exposure to cellulose acetate films incorporated with garlic essential oil does not lead to homologous resistance in Listeria innocua ATCC 33090.

Essential oils (EOs) have been considered potential green additives for active food packaging. However, sub-lethal concentrations of EOs may lead to bacterial resistance, which is a concern. In this sense, the effects of 1% (GEO1) and 10% (GEO10) of garlic EO in cellulose acetate-based films regarding homologous resistance in Listeria innocua were investigated after incubation at 37 °C/24 h and 7 °C/10 d. The films were also characterized and tested on sliced mozzarella cheese as interfold packaging for 8-days storage at 7 °C. The EO did not alter the mechanical properties of the films nor their thermal degradation profile. However, GEO10 was less permeable to water vapor than GEO1. When tested against L. innocua, the incubation at 7 °C enhanced the films' antimicrobial effect: log reductions of 4.3 and 5.7 were obtained for GEO1 and GEO10, respectively. Moreover, 86.3% of L. innocua cells were injured at sub-lethal level when exposed to GEO10. Despite this, no occurrence of homologous resistance was found. When the active films were tested on cheese against the natural microbiota, they resulted in slices of mozzarella with fewer contaminants, however the reduction was not significant. Nevertheless, we considered this an important finding to the food industry since this work suggested that GEO is a safe active compound from the point of view of homologous resistance to be used against Listeria.

Carvacrol-loaded liposome suspension: optimization, characterization and incorporation into poly(vinyl alcohol) films.

The purpose of this study was to encapsulate carvacrol into liposomes in order to promote its application in active food packaging. Response surface methodology was used to evaluate the effect of the concentration of the liposomal components on its characteristics. The optimum formulation for the preparation of liposomes with the highest encapsulation efficiency (59.0 ± 1.99%) was found to be 3000 µg mL-1 of cholesterol and 4000 µg mL-1 of carvacrol. Carvacrol reduced the polydispersity index and increased the zeta potential and the thermal stability of liposomes. Fourier-transform infrared spectroscopy indicated that the interaction of carvacrol with liposomes occurred probably through hydrogen-bonding. The incorporation into liposomes maintained the antibacterial effect of carvacrol, but when in the film, carvacrol liposomes were not effective against the microorganisms tested. Liposomes may offer a viable option for stabilizing carvacrol, however, more studies are necessary to enable its application in food packaging.