Sustainable valorization of seeds from eight aquatic plant species as a source of oil and lipophilic bioactive compounds

Potential biomass valorization of aquatic plant seeds of eight species was studied. Merremia emarginata (Convolvulaceae), Nelumbo nucifera (Nelumbonaceae), Schoenoplectus articulatus (Cyperaceae), Cleome viscosa (Cleomaceae), Ipomoea purpurea (Convolvulaceae), Rorippa palustris (Brassicaceae), Ludwigia parviflora (Onagraceae), and Hygrophila auriculata (Acanthaceae) were investigated for their oil yield and their lipophilic bioactive compound composition. The ultrasound-assisted extraction of oil followed by GC and HPLC analyses was applied for the determination of bioactive compounds. The oil yield ranged from 1.7 to 29.1%, in N. nucifera and H. auriculata, respectively. The studied species differed significantly with respect to the composition of fatty acids and bioactive compounds (statistically assessed). Unsaturated fatty acids (UFA) were the predominant group of fatty acids (74–88%) in the investigated samples. Four species were mainly comprised of γ-tocopherol (88–99%) (M. emarginata, C. viscosa, I. purpurea, L. parviflora), while the other four studied samples were dominated by γ-tocotrienol (72%) in N. nucifera, β-tocotrienol (72%) in S. articulates, α- and γ-tocopherol (49% and 41%, respectively) in R. palustris, and α-tocopherol (91%) in H. auriculata. β-Sitosterol was the main sterol (46–69%) in the majority of studied species, with the exception of H. auriculata, in which Δ5-stigmasterol (50%) dominated. Considerable levels of campesterol in each species (13–25%) were also recorded. Squalene was detected only in I. purpurea, R. palustris, and L. parviflora. The studied species were characterized by considerable quantities of carotenoids, tocochromanols, phytosterols, and squalene (0.6–6.9, 51–634, 292–2480, and 0–22 mg/100 g oil, respectively). Seeds of several studied aquatic species can be considered as an alternative source of oil and/or valuable lipophilic ingredients for industrial applications.