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 (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

Phytochemical Characterization and Biological Evaluation of Pittosporum tobira seeds

Protective effects of kaempferol against reactive oxygen species-induced hemolysis and its antiproliferative activity on human cancer cells

The protective effects of kaempferol against reactive oxygen species (ROS)-induced hemolysis and its antiproliferative activity on human cancer cells were evaluated in this study. Kaempferol exhibited strong cellular antioxidant ability (CAA) with a CAA value of 59.80 ± 0.379 μM of quercetin (QE)/100 μM (EC50 = 7.74 ± 0.049 μM). Pretreatment with kaempferol significantly attenuated the ROS-induced hemolysis of human erythrocyte (87.4% hemolysis suppressed at 100 μg/mL) and reduced the accumulation of toxic lipid peroxidation product malondialdehyde (MDA). The anti-hemolytic activity of kaempferol was mainly through scavenging excessive ROS and preserving the intrinsic antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; and glutathione peroxidase, GPx) activities in normal levels. Additionally, kaempferol showed significant antiproliferative activity on a panel of human cancer cell lines including human breast carcinoma (MCF-7) cells, human stomach carcinoma (SGC-7901) cells, human cervical carcinoma (Hela) cells and human lung carcinoma (A549) cells. Kaemperol induced apoptosis of MCF-7 cells accompanied with nuclear condensation and mitochondria dysfunction.