Synergistic effect between silver nanoparticles produced by green synthesis and lemongrass essential oil (Cymbopogon citratus (DC)) against Candida albicans.

Everardo A. MENEZES(a),Francisco. A. CUNHA(a, b), Mariane. C. N. LIMA(a), Maria C.S.O. CUNHA (a), Mary Anne A. B. BANDEIRA(c),Pierre B. A. FECHINE(b)*
(b)- Laboratório de Microbiologia de Leveduras – Departamento de Análises Clínicas, Universidade Federal do Ceará – UFC.  (a) - Grupo de Química de Materiais Avançados (GQMAT)- Departamento de Química Analítica e Físico-Química, Universidade Federal do Ceará – UFC, Campus do Pici, CP 12100, CEP 60451-970 Fortaleza – CE, Brazil. (c)- Departamento de Farmácia, Universidade Federal do Ceará, Fortaleza-CE, Brazil 
Author to whom correspondence should be addressed. E-mail: menezes@ufc.br 

Nanotechnology is a field of science that is expanding and bringing together diverse fields, such as biology, engineering, physics, chemistry and materials science. Particles with sizes ranging from 1 to 100 nm are also studied as part of this field, in which scientific advances in the control of the physical and chemical properties thereof could revolutionize the treatment of various diseases. Essential oils (EOs) and silver nanoparticles (AgNPs) are from different class of substances. However, both has been studied due to its bactericidal, fungicidal and virucidal properties. The purpose of work was evaluate the synergistic activity of lemongrass (Cymbopogon citratus) essential oil associated with silver nanoparticles (AgNPs) against C. albicans. The essential oil was extracted from the leaves (Cymbopogon citratus), while the AgNPs were synthesized, purified and characterized by using non-toxic compounds (green synthesis). For this study, 20 strains of C. albicans were seeded, purified and identified. Synergism between the lemongrass oil and the AgNPs was evaluated by the disk diffusion protocol on Mueller-Hinton agar, supplemented with 2% glucose and 0.05% methylene blue. The AgNPs had a diameter of 73.64 ± 43.54 nm for those produced from glucose and 126.1 nm ± 66.08 nm (mean ± SD) for the route using ribose. The main constituents of the essential oil were geranial, neral and β-myrcene. The AgNPs prepared from glucose and ribose brought about an increase in the fungal growth inhibition area of 100% and 53%, respectively, compared to the oil used alone. This synergistic effect can be attributed to different mechanisms of action of the EO and AgNPs. EO acts by destabilizing cell membranes and AgNPs inactivate enzymes, DNA and other cellular components and prevent C. albicans from replicating, leading to death of the yeast. The synergistic effect of AgNPs against bacteria was evaluated, and the results prove the synergistic action with known antimicrobials. This new combination (lemongrass essential oil + AgNPs) has potential to be used in the treatment of its and other fungal infections, and can be used as an alternative product from renewable source.

Synergistic effect between silver nanoparticles produced by green synthesis and lemongrass essential oil (Cymbopogon citratus (DC)) against Candida albicans