A Potential New Source of Therapeutic Agents for the Treatment of Mucocutaneous Leishmaniasis: The Essential Oil of Rhaphiodon echinus

Abstract

Weeds are an important source of natural products; with promising biological activity. This study investigated the anti-kinetoplastida potential (in vitro) to evaluate the cytotoxicity (in vitro) and antioxidant capacity of the essential oil of Rhaphiodon echinus (EORe), which is an infesting plant species. The essential oil was analyzed by GC/MS. The antioxidant capacity was evaluated by reduction of the DPPH radical and Fe³⁺ ion. The clone Trypanosoma cruzi CL-B5 was used to search for anti-epimastigote activity. Antileishmanial activity was determined using promastigotes of Leishmania braziliensis (MHOM/CW/88/UA301). NCTC 929 fibroblasts were used for the cytotoxicity test. The results showed that the main constituent of the essential oil was γ-elemene. No relevant effect was observed concerning the ability to reduce the DPPH radical; only at the concentration of 480 μg/mL did the essential oil demonstrate a high reduction of Fe³⁺ power. The oil was active against L. brasiliensis promastigotes; but not against the epimastigote form of T. cruzi. Cytotoxicity for mammalian cells was low at the active concentration capable of killing more than 70% of promastigote forms. The results revealed that the essential oil of R. echinus showed activity against L. brasiliensis; positioning itself as a promising agent for antileishmanial therapies.

Keywords: GC–MS; Rhaphiodon echinus; leishmanicidal; trypanocidal.

Figure 1

Co-occurrence analysis of components obtained in the essential oil of Rhaphiodon echinus. Note: the size of the circle or node is equivalent to the occurrence number of the descriptor.

Figure 2

(A) Reduction of DPPH radicals by the essential oil of Rhaphiodon echinus leaves. Data are expressed as mean ± SEM of n = four independent experiments. (B) Reduction of Fe³⁺ to Fe²⁺ (110 µM) by the essential oil from Rhaphiodon echinus leaf (1–480 µg/mL). The oil was incubated for 10, 20, 30, 50, 100, and 200 min.

Figure 2

(A) Reduction of DPPH radicals by the essential oil of Rhaphiodon echinus leaves. Data are expressed as mean ± SEM of n = four independent experiments. (B) Reduction of Fe³⁺ to Fe²⁺ (110 µM) by the essential oil from Rhaphiodon echinus leaf (1–480 µg/mL). The oil was incubated for 10, 20, 30, 50, 100, and 200 min.

Figure 3

Cytotoxicity of the essential oil of Rhaphiodon echinus. As for the absence of error bars, the software used does not efficiently present such graphic elements since they have a negligible value [16].

Figure 4

Survival of Leishmania brasiliensis promastigotes and Trypanosoma cruzi epimastigotes treated with essential oil of Rhaphiodon echinus, and their respective LC₅₀ values.