Cytotoxic and Antileishmanial Potential of Pilocarpus microphyllus Essential Oil: In Vitro and In Silico Study

Abstract

The essential oil of Pilocarpus microphyllus (jaborandi) (EOJ), a species traditionally recognized for its alkaloid-based pharmacological properties, remains poorly investigated despite its richness in bioactive terpenes. In this study, the chemical profile of EOJ obtained from fresh and dried leaves was determined by gas chromatography-mass spectrometry, revealing 24 constituents, predominantly γ-cadinene (23.6%) and trans-caryophyllene (22.9%). Antifungal activity was observed against Cryptococcus neoformans (minimum inhibitory concentration: 149-2395 µg/mL), while antileishmanial potential was confirmed against Leishmania amazonensis promastigotes (half-maximal inhibitory concentration [IC₅₀]: 22.8-25.2 µg/mL). EOJ also exhibited cytotoxic effects on HCT-116 and PC-3 cell lines (IC₅₀: 27.8-29.2 µg/mL). In silico studies revealed strong binding affinities with therapeutic targets: γ-cadinene to Nectin-4 (ΔG = -7.3 kcal/mol) and trans-caryophyllene to lanosterol 14α-demethylase (ΔG = -5.7 kcal/mol). Absorption, distribution, metabolism, excretion, and toxicity predictions indicated favorable oral absorption and low genotoxicity. Altogether, EOJ demonstrates multitarget bioactivity, and its major constituents represent promising leads for antifungal, antileishmanial, and anticancer drug development.

Keywords: Pilocarpus microphyllus; cytotoxicity; molecular docking; trans‐caryophyllene; γ‐cadinene.

FIGURE 1

Chromatograms show the chemical structures of the constituents of the essential oil extracted from the P. microphyllus (commonly known as jaborandi) leaves.

FIGURE 2

3D molecular docking of the protein‐ligand complex with 6UEZ—Lanosterol 14α‐demethylase (Chain A color: green; Chain B color: gray) and ligand trans‐caryophyllene (Color: blue), illustrating the active binding site (A) with the respective interactions (B) with amino acids.

FIGURE 3

Growth inhibition (%) of Leishmania amazonensis promastigotes after exposure to essential oils obtained from fresh leaves (A, FL‐EOJ) and dry leaves (B, DL‐EOJ) of P. microphyllus (6.25–800 µg/mL). Amphotericin B was used as a positive control, and vehicle (1% DMSO) as a negative control. Data are expressed as mean ± SD from three independent experiments (n = 3), each performed in triplicate wells; error bars represent SD. Statistical differences versus the negative control (vehicle, 1% DMSO) were evaluated by one‐way analysis of variance (ANOVA) followed by Dunnett's multiple‐comparisons test. p < 0.05 vs negative control.

FIGURE 4

3D molecular docking of the ligand‐protein complex with 1LML—leishmanolysin from L. major (chain A color: coral) and trans‐caryophyllene (color: blue), illustrating the active binding site (A) with the respective interactions (B).

FIGURE 5

3D molecular docking of the ligand‐protein complex with 4MAN (chain A color: pink; Chain B: purple) and γ‐cadinene (color: red), illustrating the active binding site (A) with the respective interactions (B).

FIGURE 6

3D molecular docking of the ligand‐protein complex with 1E3G (chain A color: khaki) and trans‐caryophyllene (color: blue), illustrating the active binding site (A) with the respective interactions (B).