Potential Effects of Essential Oil from Plinia cauliflora (Mart.) Kausel on Leishmania: In Vivo, In Vitro, and In Silico Approaches

Abstract

In the search for new chemotherapeutic alternatives for cutaneous leishmaniasis (CL), essential oils are promising due to their diverse biological potential. In this study, we aimed to investigate the chemical composition and leishmanicidal and anti-inflammatory potential of the essential oil isolated from the leaves of Plinia cauliflora (PCEO). The chemical composition of PCEO showed β-cis-Caryophyllene (24.4%), epi-γ-Eudesmol (8%), 2-Naphthalenemethanol[decahydro-alpha] (8%), and trans-Calamenene (6.6%) as its major constituents. Our results showed that the PCEO has moderate cytotoxicity (CC₅₀) of 137.4 and 143.7 μg/mL on mice peritoneal exudate cells (mPEC) and Vero cells, respectively. The PCEO was able to significantly decrease mPEC infection by Leishmania amazonensis and Leishmania braziliensis. The value of the inhibitory concentration (IC₅₀) on amastigote forms was about 7.3 µg/mL (L. amazonensis) and 7.2 µg/mL (L. braziliensis). We showed that PCEO induced drastic ultrastructural changes in both species of Leishmania and had a high selectivity index (SI) > 18. The in silico ADMET analysis pointed out that PCEO can be used for the development of oral and/or topical formulation in the treatment of CL. In addition, we also demonstrated the in vivo anti-inflammatory effect, with a 95% reduction in paw edema and a decrease by at least 21.4% in migration immune cells in animals treated with 50 mg/kg of PCEO. Taken together, our results demonstrate that PCEO is a promising topical therapeutic agent against CL.

Keywords: Plinia cauliflora; chemotherapy; cutaneous leishmaniasis; essential oils; phlogistic signs.

Figure 1

Plinia caulifora Kausel sample collection area.

Figure 2

Effect of PCEO on the cell viability of mPEC Vero cells. The cell viability was assayed by measuring the intracellular ATP level using Cell-Title-Glo luminescent cell viability assay. Each cell type was analyzed in three independent experiments in triplicate, and data are shown as mean ± SD. * Significant difference compared to the control group (p < 0.05).

Figure 3

Effect of PCEO on promastigote forms of Leishmania amazonensis (A) and Leishmania braziliensis (B). The cell viability was assayed by measuring the intracellular ATP level using Cell-Title-Glo luminescent cell viability assay. Each cell type was analyzed in three independent experiments in triplicate, and data are shown as mean ± SD. * Significant difference compared to the control group (p < 0.05).

Figure 4

Effects of PCEO on Leishmania amazonensis and (A) Leishmania braziliensis intracellular amastigotes (B). Each bar represents the mean ± standard deviation of three independent experiments in triplicate. PMD: 30 µM pentamidine; * significant difference of each group compared to the control group (p ≤ 0.05).

Figure 5

The effects of PCEO on the ultrastructure of Leishmania braziliensis (left column) and Leishmania amazonensis (right column), as observed by SEM. (A,B) Control cells; (C,D) low magnification of the promastigote culture treated with PCEO IC₅₀, showing shortening and wrinkling of the cell body. (E,F) Promastigotes treated with twice IC₅₀ PCEO presenting drastic morphological alterations, with shrinkage of the cell membrane. Some of the cells had short or absent flagella (white arrow).

Figure 6

Mass spectrometry and chemical structures of major four constituintes of PCEO: β–cis–caryophyllene (A), epi–γ–eudesmol (B), 2-naphthalenemethanol [deanhydro.alpha] (C), and trans-calamenene (D).

Figure 7

Effect of PCEO on inflammatory cells migration. PCEO: Plinia cauliflora essential oil from leaves. Data expressed as mean ± standard deviation. ANOVA and Dunnett test, p < 0.05, * vs. control; ! vs. Indomethacin.