Variation in phenolic compounds,alpha-linolenic acid and linoleic acid contents and antioxidant activity of purslane (Portulaca oleraceaL.) during phenological growth stages

摘要

Purslane (Portulaca oleraceaL.) contains a variety of natural products with different biological properties. The objective of this research was to estimate changes in total phenolics, flavonoids, and fatty acids (alpha-linolenic acid and linoleic acid) contents as well as antioxidant activity ofP. oleraceaat different growth stages. Seeds were germinated in soil-filled plastic pots at greenhouse. Leaves and stems were collected at the vegetative and flowering stages. Total phenol and flavonoid contents of the samples were determined by Folin-Ciocalteau and aluminum chloride methods, respectively. The contents of alpha-linolenic and linoleic acids were determined using gas chromatography analysis after transesterification of fatty acids. Furthermore, Ferric reducing antioxidant power and 1,1-diphenyl-2-picrylhydrazyl assays were used to determine the antioxidant activities. The highest contents of total phenols (698.6 mg GAE 100 g(-1)DW), flavonoids (46.9 mg QE 100 g(-1)DW),alpha-linolenic acid (2.7 mg g(-1)DW) and linoleic acid (0.8 mg g(-1)DW) were determined in the leaves at flowering stage. Free radical scavenging capacity was significantly affected (P <= 0.05) by age; and the leaves of purslane had more antioxidant potential compared to stems. A positive correlation was observed between the antioxidant activities and total phenols content. Overall, purslane leaves at flowering stage can be regarded as a valuable source of fatty acids (especially alpha-linolenic acid) and antioxidants in human diet.