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

Abstract

Purslane (Portulaca oleracea L.) 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 (α-linolenic acid and linoleic acid) contents as well as antioxidant activity of P. oleracea at 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 α-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 (698.6mg GAE 100g-1 DW), flavonoids (46.9mg QE 100g-1 DW), α-linolenic acid (2.7mgg-1 DW) and linoleic acid (0.8mgg-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 α-linolenic acid) and antioxidants in human diet.