Phenolic Content and Antioxidant Capacity of Tobacco Seed-Derived Products

Tobacco seeds (Nicotiana tabacum L.) represent a promising nicotine-free source of bioactive compounds, particularly polyphenols and natural antioxidants. This study evaluated the total phenolic content (TPC) and antioxidant activity of tobacco seeds, defatted seed cake, and seed oil obtained from oriental tobacco varieties cultivated under organic and conventional conditions over two consecutive years (2020–2021). Extracts from tobacco seed-derived products were prepared using different solvents (water, 60% methanol, 80% methanol, 80% ethanol, and 95% ethanol). TPC was determined by the Folin–Ciocalteu method, while antioxidant capacity was assessed by DPPH, ABTS, and FRAP assays. In addition, the Relative Antioxidant Capacity Index (RACI) and the Phenolic Antioxidant Coefficient (PAC) were applied to compare the antioxidant performance of the different samples and to estimate the contribution of phenolic compounds to the overall antioxidant activity under the two cultivation conditions. The results showed that extraction efficiency strongly depended on solvent polarity, with 60% methanol providing the highest recovery of phenolic compounds from seeds and seed cake, while 80% ethanol was more effective for oil. Seed cake extracts exhibited higher TPC (1.15 ± 0.04 mg GAE g−1–3.98 ± 0.10 mg GAE g−1) and antioxidant activity than seed extracts (0.070 ± 0.04 mg GAE g−1–2.02 ± 0.02 mg GAE g−1) and oil (0.29 ± 0.01 mg GAE g−1–1.70 ± 0.17 mg GAE g−1), indicating enrichment of phenolic compounds after oil removal. Among the tested extraction conditions, 95% ethanol and 60% methanol extracts showed the strongest antioxidant potential, with maximum FRAP (23.10 mM TE g−1), DPPH (3.35 mM TE g−1), and ABTS (14.70 mM TE g−1) values depending also on variety and harvest year. Organically produced samples showed higher TPC and RACI values than conventionally produced materials, while PAC analysis revealed the strongest association between phenolic compounds and antioxidant capacity in the FRAP assay. These findings provide a comparative evaluation of the antioxidant potential of tobacco seed-derived fractions and the effectiveness of the extraction methods used for their recovery.