13th Conference on Medicinal and Aromatic Plants of Southeast European Countries (CMAPSEEC 2026)

Background: Aromatic plants have been allies of humanity since ancient times. The secret of their effectiveness lies in the chemical composition which consists of molecules that protect our cells from oxidative stress and several pathologies. Aromatic plants used for essential oil (EO) production generate steam distillation residues (SDR) rich in bioactive compounds with high antioxidant power. The aim of this study was to assess the phenolic composition of SDR extracts obtained from different aromatic plants and their antioxidant power.

Materials and Methods: Lemon balm and lavender SDR and fresh aromatic plants (FAP) were used to produce antioxidant extracts. Different hydroalcoholic solvent mixtures were used for extraction. The phenolic composition and antioxidant activity of SDR extracts were determined and compared with those of the corresponding fresh aromatic plants.

Results: Aqueous extracts showed the highest phenolic content, ranging from 14.15 mg gallic acid equivalents (GAE)/g dry matter (DM) in lemon balm FAP to 19.61 mg GAE/g DM in lavender SDR. Lavender SDR extracts were richer in polyphenols than the corresponding FAP extracts, whereas the opposite trend was observed for lemon balm. Rosmarinic acid was the most abundant hydroxycinnamic acid detected, with 646.58 µg/g DM in lavender, and 608.65 µg/g DM in lemon balm. Lavender SDR extracts showed higher antioxidant power than the corresponding FAP extracts, whereas fresh lemon balm extracts showed higher antioxidant power than SDR extracts. Lavender 50% ethanol SDR extract exhibited the highest radical scavenging activity (67.16%) and ferric reducing power (16.60 mg ascorbic acid equivalents/g DM).

Conclusions: The objectives of this study were to determine if the steam distillation process, used for EO production, makes plants more available for subsequent extraction of bioactive compounds, and to assess the potential for using spent residues as a source of natural antioxidants. Our results demonstrate that SDR can be exploited to produce antioxidant blends for food and cosmetic sectors.

Acknowledgements: this study was suppported by the grant from GAL IRPINIA CONSORZIO (PSR CAMPANIA 2014-2020 Misura 19 – Azione 2. Project “IrpiniaEssenziale”.