Seasonal variation of antioxidant activity and properties in Ulva lactuca Linnaeus, 1753: A compression study in pre and post monsoon to the northern coasts of the Oman Sea

Ulva lactuca (Ul) is a green macroalgae that contains commercially valuable molecules components. The purpose of this study was to evaluate and compare seasonal variations of antioxidant activity (AOA) of U. l. sample harvested from locations of Tang, Chabahar and Gowatr in the northern coast of the Oman Sea (IRAN). Sampling was carried out during April to May (spring) and October to November (autumn) 2020, representing pre- and post-monsoon, respectively. No significant difference (P > 0.05) were observed between samples harvested in pre- and post-monsoon from all three locations, except for the ferric reducing antioxidant power (FRAP) content. The FRAP on post-monsoon shows a significant difference between all studied locations (P < 0.05). In this season, the FRAP content was measured 69 ± 0.05; 0.60 ± 0.06 and 0.50 ± 0.06 mg GAE g − 1 for Tang, Chabahar and Gowatr, respectively (P  0.95) was calculated for parameters showing a significant contribution by β-carotene (βC) with FRAP content (R = -0.004) in pre-monsoon, as well as total phenolic content (TPC) with anthocyanin content (ACN) (R = -0.013); Half-maximal inhibitory concentration (IC 50 ) with total flavonoid content (TFC) (R = -0.010) and radical scavenging activity assay (DPPH) with IC 50 content (R = 0.022) in post-monsoon. AOA analysis along with PCA (principal component analysis) in pre-monsoon confirm relationships and FRAP, TPC, ACN and βC determined sample distribution along PC1 (main components 1), while DPPH, IC 50 and TFC along the PC2. However, in post monsoons all parameters determined sample distribution along PC1.