Phytochemical Profile and Antioxidant Activity of Aerial and Underground Parts of Salvia bulleyana Diels. Plants

Abstract

Plants have been used for medical purposes since ancient times. However, a detailed analysis of their biological properties and their associated active compounds is needed to justify their therapeutic use in modern medicine. The aim of the study was to identify and quantify the phenolics present in hydromethanolic extracts of the roots and shoots of the Chinese Salvia species, Salvia bulleyana. The qualitative and quantitative analyses were carried out by ultrahigh-performance liquid chromatography with electrospray ionization mass spectrometry detection (UHPLC-PDA-ESI-MS), and high-performance liquid chromatography with photodiode array (HPLC-PDA) detection. The extracts of S. bulleyana were also screened for their antioxidant activity using ferric ion (Fe³⁺) reducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), diammonium 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) cation (ABTS), superoxide radical anion (O₂^•-), and inhibition of lipid peroxidation assays. The S. bulleyana extracts were found to contain 38 substances, of which 36 were phenols, with a total level of 14.4 mg/g DW (dry weight) in shoots, and 23.1 mg/g DW in roots. Twenty-eight phenols were polyphenolic acids or their derivatives, the most abundant in shoots being rosmarinic acid, and in roots, salvianolic acid K followed by rosmarinic acid. The other major phenolic acids were caffeic acid, caffeoyl-threonic acids, isomers of lithospermic acid, salvianolic acid F, salvianolic acid B, and yunnaneic acid E. In addition to polyphenolic acids, nine flavonoids were detected in the shoot extract. While both extracts showed significant antioxidant activity, the shoot extract, containing both polyphenolic acids and flavonoids, demonstrated a slightly greater antioxidant potential in some of the anti-radical tests than the roots. However, the root extract proved to be slightly more effective in the lipid peroxidation inhibition test. Thus, S. bulleyana was demonstrated as a promising source of antioxidants, and worthy of further more detailed studies.

Keywords: antiradical activity; hydromethanolic extract; lithospermic acid; phenolic profiling; rosmarinic acid; salvianolic acid K; shoots.

Figure 1

Salvia bulleyana plants.

Figure 2

UV chromatograms obtained from the UPLC–MS/MS system recorded at 325 nm of the hydromethanolic extracts from aerial parts (A) and roots (B) of S. bulleyana. Peak numbers correspond to compound numbers in Table 1.

Figure 3

Antioxidant properties of the aerial parts and roots of S. bulleyana hydromethanolic extracts in TPC (A), FRAP (B), DPPH (C), ABTS (D), NBT (E) and TBARS (F) assays. Values are presented as means ± standard error (SE). Values marked with different letters for the same assay have statistically significant difference (p < 0.05). * The values are the percentage of inhibition for the given extract concentration.