HPLC profiling of selected phenolic acids and flavonoids in Salvia eigii, Salvia hierosolymitana and Salvia viridis growing wild in Jordan and their in vitro antioxidant activity

Background: Salvia eigii., Salvia hierosolymitana and Salvia viridis are native to the Mediterranean region, and are used in traditional medicine for the treatment of many ailments. In the current investigation, the methanolic extracts obtained from the air dried aerial parts of S. eigii, S. hierosolymitana and S. viridis from Jordan were screened for their total phenolics content (TPC), total flavonoids content (TFC) and their in vitro antioxidant activity. Additionally, the presence of four bioactive phenolic acids including gallic acid, caffeic acid, rosmarinic acid and salvianolic acid B and other seven flavonoids including luteolin-7-O-glucoside, apigenin, apigenin-7-O-glucoside, rutin, nariginin, hesperidin and quercetin was determined using Liquid chromatography-Electron Spray Ionization-Tandom Mass Spectrometry (LC-ESI-MS/MS).

Methods: Antioxidant activity of the obtained three extracts were examined via the DPPH^•, ABTS^{• +} radical scavenging methods in addition to Ferrous Ion Chelating (FIC) effect. TFC and TPC of the extracts were measured using the aluminum chloride colorimetric method and the Folin-Ciocalteau method, respectively. The presence and concentration of the selected 11 compounds was further determined through LC-ESI-MS/MS.

Results: The results indicated that three Salvia species had high total flavonoids content expressed in mg quercetin/g dry extract (S. heirosolymitana: 770.85 ± 5.26; S. eigii: 520.60 ± 6.24, S. viridis: 311.36 ± 4.41). S. heirosolymitana had the highest DPPH^• activity (0.184 ± 1.22 × 10^-2 mg/ml) and FIC effect (0.354 ± 0.018 mg/ml). S. heirosolymitana had slightly higher ABTS^{• +} scavenging activity than S. eigii (0.176 ± 1.16 × 10^-2 mg/ml; 0.183 ± 0.031 mg/ml, respectively). All 11 compounds were detected in the extracts of the three Salvia species. Luteolin-7-O-glucoside was detected in high concentration levels in the three species (1756.73, 21651.36, and 26125.14 mg/kg dry plant; S. eigii, S. hierosolyimitana and S. viridis, respectively), yet rosmarinic acid had the highest contribution to both S. hierosolymitana (27124.93 mg/kg) and S. eigii (15783.33 mg/kg). Notably, S. hierosolymitana and S. viridis contained salvianolic acid B (896.11; 890.9 mg/kg).

Conclusions: The three Salvia species exhibited good antioxidant activity, especially S. heirosolymitana due to its high TPC, TFC, and the presence of high concentration levels of romarinic acid and other phenolic acids and flavonoids. This is the first phytochemical and antioxidant evaluation of S. eigii, S. hierosolymitana and S. viridis from Jordan. Prior to this investigation, no phytochemical investigation on S. eigii was reported.

Keywords: Antioxidant activity; LC-ESI-MS/MS; Salvia eigii; Salvia hierosolymitana; Salvia viridis; Total flavonoid content; Total phenolic content.