Evaluation of nutritional values, phenolic profile, aroma compounds and biological properties of Pittosporum tobira seeds

Abstract

Background: Plant essential oils and phenolic compounds are widely used for their medicinal properties. Thus, the aim of this study is to evaluate the nutritional values, the chemical composition, antioxidant activity and anti-hemolytic effects of Pittosporum tobira seeds. Methods: The aroma compounds were isolated using two methods (Headspace-solid phase microextraction (HS-SPME) and hydrodistillation (HD)) and analyzed by gas chromatography coupled with mass spectrometry (GC-MS). Bioactive phenolic compounds were identified by mean of high-performance liquid chromatography (HPLC-DAD). Reducing power, hydrogen peroxide (H2O2) scavenging and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays were used to investigate antioxidant activity. Anti-hemolytic activity was evaluated using H2O2-induced hemolysis of red blood cells (RBC). Results: Oxygenated sesquiterpenes, sesquiterpene hydrocarbons and oxygenated monoterpenes were the most volatile fractions identified by HD and HS-SPME coupled to GC-MS but their quality and amount were quite different according to the extraction methodology. The main phenolic compounds identified by HPLC were caffeic acid, followed by cinnamic acid and gallic acid. P. tobira seeds essential oils showed significant antioxidant activity in DPPH (IC50 value = 1.5 mg/mL), H2O2 scavenging assay (IC50 value = 159.43 μg/mL) and reducing power test (IC50 value = 0.982 mg/mL) compared to methanolic extract. Moreover, the results revealed that the essential oil was able to protect RBC from hemolysis induced by H2O2. However, the methanolic extract had no effect on H2O2-induced hemolysis of RBC as compared to the essential oil and the standard vitamin C. Conclusions: P. tobira may be used as a new natural source of antioxidant with therapeutic application in diseases caused by reactive oxygen species. Graphical Abstract: [Figure not available: see fulltext.]Phytochemical Characterization and Biological Evaluation of Pittosporum tobira seeds.