Phenolic composition and antioxidant activities of two Phlomis species: A correlation study

Abstract

Two traditional Chinese medicines (Phlomis umbrosa Turcz. and Phlomis megalantha Diels), as well as five pure phenolic compounds (protocatechic, chlorogenic, benzoic, rosmarinic acid, and rutin) have been studied for antioxidant activities in acetone and methanol extracts from leaves. An HPLC method was developed to quantify the amounts of 14 phenolic compounds in the leaf extracts. The antioxidant capacities of the studied species are high. Almost all samples were capable of directly scavenging DPPH and superoxide free radicals, inhibiting linoleic acid oxidation, acting as reducing agents, and reducing plasmid DNA damage induced by hydroxyl radicals. Among different extracts, the acetone extract of P. megalantha exhibited the highest antioxidant activity. The major phenolic compounds identified were protocatechic, chlorogenic, caffeic, rosmarinic acid, and (−)-epicatechin. Antioxidant activities of pure compounds and correlation analysis indicated that protocatechic and rosmarinic acids were the major contributors to the observed antioxidant activities of the investigated Phlomis extracts. To cite this article: Y.

Pedalium murex Linn (Pedaliaceae) fruits: a comparative antioxidant activity of its different fractions

“…Recently, interest has increased considerably in finding naturally occurring antioxidants for use in foods or medicinal materials to replace synthetic antioxidants [6] . It has been demonstrated that plants, containing high amounts of secondary metabolites like phenolic have been identified as a free radical or active oxygen scavengers and can prevent damages caused by oxidative stress [19][20][21] . Increasing experimental evidence has suggested that these compounds can affect a wide range of cell biological functions by virtue of their radical scavenging properties [6] .…”

“…High phenolic compounds from plant source lead to a positive activity as antioxidant. But this can be governed not only through the correlation coefficient but also through the scavenging activity in various antioxidant assays [20] . The antioxidant activity of the phenolic compounds was attributed to its redox properties, which allow them to act as reducing agents, hydrogen donators, singlet oxygen quenchers, and metal chelating property [23] .…”

Chemical composition of essential oil and antioxidant activity of leaves and stems of Phlomis lurestanica

“…Also, the amount of flavonoid for these three species was reported to be 4.97, 4.11, and 1.99 (mg QE/g extract), respectively. Zhang and Wang [24] showed that the phenol contents of P. umbrosa and P. megalantha were 39.43 and 55.20 (mg GAE/g extract), respectively; also, the flavonoid contents were reported to be 7.12 and 35.91 (mg EE/g extract), respectively.…”

“…This shows that the leaves have a stronger hydrogen donating capacity than the stems. Zhang and Wang [24] reported the IC 50 of P. umbrosa and P.megalantha to be 20.2 and 15.7 µg/ml, respectively; also, the IC 50 in P. caucasica, P. lanceolata, and P. aucheri was reported to be 0.1 mg/mL. [15] β-carotene/linoleic acid assay The methanolic extracts of the leaves and stems showed high antioxidant activity in β-carotene/ linoleic acid assay.…”

“…The antioxidant activity in P. umbrosa 88.6% and P. megalantha 87.8% have been previously reported. [24] In P. bourgaei, the antioxidant activity was measured in three concentrations (0.4, 1.0, and 2.0), such that the activities were 69.28, 80.19, and 82.62%, respectively. [20] Sarikurkcu et al [25] reported the antioxidant activity of P. armeniaca to be 75.63%.…”