Essential Oils from Four Brazilian Piper Species: GC-MS and HPTLC Profiling, Cytotoxicity Screening, and Behavioral Deterrence Against Imported Fire Ants.

Background

Brazilian Piper species are chemically diverse sources of volatile metabolites, yet direct comparative datasets integrating complementary analytical and biological endpoints remain limited.

Methods

This study compared hydrodistilled essential oils (EOs) from Piper amalago, P. diospyrifolium, P. grazielae, and P. solmsianum using GC-MS, HPTLC fingerprinting, qualitative HPTLC-DPPH visualization, in vitro cytotoxicity screening, and behavioral assays with imported fire ants.

Results

GC-MS revealed distinct chemical profiles among the four analyzed EOs. P. solmsianum was dominated by monoterpenes, mainly β-pinene (28.21%) and myrcene (24.73%); P. diospyrifolium was characterized by trans-β-caryophyllene (22.06%); and P. grazielae by germacrene D (14.06%), trans-β-caryophyllene (12.53%), and bicyclogermacrene (9.50%). P. amalago showed a mixed terpene profile containing bicyclogermacrene (11.00%), spathulenol (9.21%), and β-phellandrene (8.12%). HPTLC generated visually discriminative fingerprints that complemented the GC-MS profiles and identified chromatographic zones for subsequent compound-level characterization. Qualitative HPTLC-DPPH visualization revealed DPPH-reactive zones, most prominently in P. grazielae. The EOs produced moderate, cell-line-dependent cytotoxic responses, with P. grazielae showing the lowest IC50 values against BT-549 (45 µg/mL) and SK-OV-3 (43 µg/mL) cells and modest apparent selectivity indices (1.56-1.72). P. amalago reduced sand removal by hybrid imported fire ants at 31.25 µg/g, whereas P. solmsianum reduced sand removal by hybrid and red imported fire ants at 62.5 and 31.25 µg/g, respectively; neither oil caused mortality at 125 µg/g.

Conclusions

The four EOs showed distinct chemical and biological profiles under the standardized conditions employed. P. grazielae showed the lowest IC50 values in the cytotoxicity screening and the most prominent DPPH-reactive chromatographic response, whereas P. amalago and P. solmsianum produced measurable nonlethal deterrence of fire ant digging behavior.