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 EB, CARIDDI LN.

Mar del Plata

Congreso; REUNIÓN 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 immune response. 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 epithelial cells (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. The average viability percentage of microencapsulated EO 2.5 mg/ml was 78.6 % (p<0.01 respect to control). This result is encouraging considering that EO at 2.5 mg/ml act as an adjuvant; therefore the microencapsulated EO will be evaluated as a potential adjuvant of the immune response.