Phytochemical screening, total phenolic content and antioxidant activities of Marrubium vulgare L. collected in three development stages

The change of phenolic compounds and antioxidant activities of plants extracts are widely attributed to numerous conditions and parameters viz. geographical conditions, type of extraction, and type of extract. Thus, this study was the first one conducted to evaluate the phenolic composition, the content of total polyphenols, flavonoids, and proanthocyanidins, and the antioxidant activities of methanolic extract of M. vulgare aerial part collected in three development stages (before flowering, during flowering, and after flowering periods). Phytochemical screening was carried out using standard methods of precipitation and coloration reactions. The total polyphenol, flavonoid, and proanthocyanidins contents were determined using the Folin-Ciocalteu method, aluminum chloride colorimetric method, and vanillin method, respectively. The antioxidant activity was assessed by two methods: DPPH and ABTS scavenging activity. Preliminarily phytochemical screening revealed the presence of saponins, essential oil, cardiac glucosides, sterols and triterpenes, and the absence of alkaloids. In addition, tannins were absence in March and present in May and July. The total phenol content of M. vulgare extracts showed a highest flavonoid and proanthocyanidin contents during flowering period (1.644 mg QE.g-1 extract, and 0.195 mg CE.g-1 extract, respectively) while polyphenol content was highest before flowering period (0.043 mg GAE.g-1 extract). Afterward, M. vulgare methanolic extract exhibited a potent antioxidant activity during flowering period with an IC50 value of 2.23 mg.ml-1. From the current study, this plant contains natural antioxidant substances which can be used as antioxidant agents to treat several diseases.