Chemical composition of <i>Ruellia paniculata</i> essential oil and antioxidant and biological activities of its methanolic extract and hydrolate

This study analysed the volatile compounds of <i>Ruellia paniculata</i> (Acanthaceae) from the North/Northwest Fluminense biome, Brazil. Essential oils were extracted from fresh and dried leaves by hydrodistillation and analysed using gas chromatography-mass spectrometry (GC-MS). The volatile profile of fresh leaves was dominated by low molecular weight compounds, with (Z)-hex-3-en-1-ol as the major constituent. Dried leaves, in contrast, had a higher concentration of sesquiterpenes, particularly tau-cadinol. GC-MS analysis revealed significant differences in the chemical composition of the oils from fresh and dried leaves. The essential oils showed antioxidant activity, assessed by the DPPH method, and cytotoxic effects against <i>Artemia salina</i> larvae. These findings suggest that <i>R. paniculata</i> essential oils have promising potential for further biological evaluations, including their antifungal and antibacteriyal properties. This study contributes to the understanding of the chemical and biological properties of a less-studied plant species from the Acanthaceae family.