Exploring the Epicarp Potential from Acrocomia aculeata Fruits: Chemical Analysis, Antioxidant and Antimicrobial Activities

Abstract

The interest in new sources of bioactive compounds has been driven by the search for natural antioxidants capable of attenuating the toxicity of reactive oxygen species, as well as the emergence of pathogens resistant to antimicrobials. In this sense, we explored the potential of the macaúba epicarp. Compounds such as piceatannol, 3,4,5,3',5'-penta-hydroxy-trans-stilbene (PHS), and in lower amounts, resveratrol were identified in extracts through techniques such as medium-pressure liquid chromatography, HPLC-MS, and imaging mass spectrometry (IMS), which confirmed the exclusive localization of PHS and piceatannol in the outer epicarp. Extraction with aqueous acetone (Me₂CO:H₂O) and its EtOAC fraction showed the highest yields of stilbenes and, moreover, it efficiently increased the tolerance of Saccharomyces cerevisiae to oxidative stress. Additionally, the Me₂CO:H₂O extract presented antibacterial and anti-cryptococcal activity, with piceatannol and resveratrol increasing survival rates of Galleria mellonella subjected to fungal infection. In silico ADMET (absorption, distribution, metabolism, excretion and toxicity) analysis indicates low toxicity for piceatannol, PHS, and resveratrol, in addition to pharmacokinetic parameters that allow their use. These findings indicate the use of macaúba epicarp as a source of bioactive compounds valuable for the food, cosmetic, and pharmaceutical industries.

Keywords: Galleria mellonella; Saccharomyces cerevisiae; agricultural by-products; antimicrobial activity; antioxidant activity; macaúba epicarp; mass spectrometry imaging; stilbenes.

Figure 1

Analysis of the phenolic profile of the crude extracts and fractions of macaúba epicarp: (a) effects of different solvents on the extraction of stilbenes; (b) analysis of the EtOAc and aqueous fractions obtained from the extract Me₂CO:H₂O. The data were reported as the peak areas of the compounds in 20 μg of the dry extract.

Figure 2

Spatial distribution analysis of stilbenes in macaúba fruit by imaging mass spectrometry in the epicarp (E) and mesocarp (M). (a) Piceatannol (m/z 243.0661) and (b) PHS (m/z 259.0610) were detected exclusively in the external layer of the epicarp across all six fruits analyzed. The color scale indicates ion intensity. Histological images are available on the Supplementary Materials.

Figure 3

Evaluation of the protective effect against reactive oxygen species. (a) Evaluation of cell susceptibility. (b) Effect of Me₂CO:H₂O extract and EtOAc fraction on survival rates of cells stressed with 1 mM H₂O₂. Results are expressed as the survival percentage and represent the mean ± standard deviation of at least three independent experiments. * Represents significantly different results compared to the positive control (1.0 mM H₂O₂) at p < 0.05.

Figure 4

Evaluation of the antifungal potential of stilbenes in Galleria mellonella larvae infected with C. neoformans H99. Larvae infected with 1 × 10⁶ cells/larva were incubated in the dark, at room temperature, in sterilized Petri dishes for 1 h. They were then treated with 100 mg/kg of resveratrol or piceatannol.