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

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 (H(2)O(2)) scavenging and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays were used to investigate antioxidant activity. Anti-hemolytic activity was evaluated using H(2)O(2)-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 (IC(50) value = 1.5 mg/mL), H(2)O(2) scavenging assay (IC(50) value = 159.43 μg/mL) and reducing power test (IC(50) 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 H(2)O(2). However, the methanolic extract had no effect on H(2)O(2)-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: [Image: see text] Phytochemical Characterization and Biological Evaluation of Pittosporum tobira seeds