Evaluation of phenolic profiles, antioxidant activities, and cytotoxic and apoptotic potentials of Phlomis angustissima and Phlomis fruticosa, medicinal plants from Turkey

Abstract

The genus Phlomis belongs to the family Lamiaceae and has over 100 species distributed across Europe, Asia, North Africa, and Turkey. Some Phlomis species are consumed as herbal teas for various diseases in traditional medicine. This study investigates the phenolic profiles, antioxidant activities, and cytotoxic properties of the methanol, ethyl acetate, and water extracts of leaves and flowers of P. angustissima, which is endemic to Turkey, and of P. fruticosa. Basic phenolics were identified by RP-HPLC-DAD. Antioxidant parameters and total- phenolics, -flavonoids, and -tannins were analysed spectrophotometrically. MTT cell proliferation was detected with a microplate reader. Apoptosis was analysed by flow cytometry. Among the identified phenolics, hesperidin, kaempferol, catechin, epicatechin, epigallocatechin, eupatorin, and chlorogenic, vanillic, syringic, p-coumaric, ferulic, and benzoic acids are reported in this study for the first time. The values of radical scavenging capacities (DPPH·, HO·, and NO·) and antioxidant activities (metal chelating and reducing power) were found to be significant. Both Phlomis species are rich in total-phenolics, -flavonoids, and -tannins. The best IC50 values of the P. angustissima and P. fruticosa extracts against five different cancer cell lines were, respectively determined as 23±1.42 and 26±1.68 ppm against ACC-201 cells, 40±2.32 and 28±2.1 ppm against OE-33 cells, and 80±3.21 ppm against HeLa cells (P. fruticosa), and the death types of the cancer cells were apoptotic. The results obtained for P. angustissima and P. fruticosa show that they are promising in terms of future applicability in food and medical fields as natural biopotential resources.