Strategies to enhance the adjuvant effect of Minthostachys verticillata essential oil

CAMPRA NA; MOLIVA M; MONTIRONI I; RAVIOLO J; CAMACHO N; PAREDES A; MALETTO B; PALMA S; REINOSO E; CARIDDI LN

Congreso; Reunión Conjunta SAI, SAIC, SAFIS; 2018

In a previous study we demonstrated that Minthostachys verticillata essential oil (2.5 and 5 mg/ml) has adjuvant effect of humoral immune response. However, the antibody levels were lower than those observed with Al(OH)3. Microencapsulation technique is used in the pharmaceutical industry for increase the biological effectiveness of drugs. The aim of this study was to determine the effect of higher doses of essential oil (EO) as adjuvant of humoral immuneresponse. In addition, microencapsulation of EO was assayed and its cytotoxic effect was evaluated. Balb/c mice (n=4 per group) were immunized by subcutaneous injection (day 0) and revaccinated (day 14 and 28) as follows: Group 1:100 μl saline solution; Group 2:100 μl OVA 0.2 mg/ml; Group 3: OVA+Al(OH)3 0.5 mg/ml; Group 4: OVA+incomplete Freund adjuvant 50%; Group 5-7: OVA+EO (10, 20 and 40 mg/ml). Seven days after last revaccination, serum samples were collected and analyzed for antigen-specific total antibodies (IgG, IgM, IgA) by indirect ELISA. The incorporation of EO into microcapsules of hydroxypropyl methylcellulose and maltodextrin was determined by spray drying. The cytotoxic effect of microencapsulated EO was evaluated on bovine mammary gland epithelialcells (MAC-T). Any mouse died, and no signs in the inoculation zone neither generalized reactions were observed in the immunized groups. Groups 5, 6 and 7 did not showed significant differences in antibody levels respect to group 2. This result suggests that the adjuvant effect of EO is not dose-dependent. The yield of the EO microencapsulation by spray drying was 24%. The microencapsulated EO decreased cell viability in a dose-dependent manner. Theaverage viability percentage of microencapsulated EO 2.5 mg/ml was 78.6 % (p