Background:The genus Phlomis is a member of Lamiaceae (Labiatae) family. About 10 species of this genus, among more than 100 species, are endemic to Iran. Phlomis rigida Labill. can be used as antimicrobial, anti-inflammatory, wound healing and antioxidant in drug investigations, based on literature. Objective: The aim of this study is to evaluate the composition, antioxidant, antibacterial and cytotoxic activity of essential oils and extract from leaves and flowers of P. rigida from Iran. The present study is the first research on P. rigida from Iran. Methods: Essential oils of leaves and flowers of P. rigida were studied by GC-MS and GC-FID to evaluate the chemical compositions. DPPH free radical scavenging method was used to evaluate the antioxidant effect of leaves and flowers extracts. Antimicrobial properties of the essential oils and extracts were investigated against various microorganisms in brain heart infusion agar to evaluate the minimum inhibitory concentration. A brine shrimp test (BST) was done to study the cytotoxicity of methanol extracts and essential oils from leaves and flowers in different concentrations. The growth inhibitory effects of the methanol extract from leaves and flowers were assessed against four cancer cell lines including MCF-7, MDBK, HT-29 and A-549. Results: Essential oils analysis showed 34 compounds and the main compounds were (Z)-β-ocimene (25.6 %), isobornyl acetate (16.6 %), trans-verbenol (12.6 %) and α-pinene (7.6 %). As a result of analysis of methanol extracts from leaves, luteolin, luteolin-7-O-glucoside and rosmarinic acid were isolated and identification for the first time from P. rigida growing in Iran. Investigation of antibacterial properties of the essential oil of flowers also showed 16 mm diameters of inhibition zone against Proteus vulgaris. Conclusion: The results of this study showed that the antibacterial effect of P. rigida essential oil could be due to the presence of its monoterpenes.

Background: Scutellaria platystegia Juz. is an herbaceous perennial, distributed in the northwest of Iran and southern Caucasian countries? Objectives: This study aimed to examine the antioxidant and antibacterial activities of the aerial part of S. platystegia and to determine the phytochemical constituents of its extract and essential oil. Methods: The ferric reducing ability of plasma (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) methods were used to examine the antioxidant effects of fractions obtained from the hydroalcoholic extract of the aerial part of S. platystegia. The antibacterial activity screening was also performed using the disk diffusion and microdilution methods. The phytochemical constituents of the most active fractions were investigated using column chromatography. Nuclear magnetic resonance (NMR) imaging and UV-Vis spectral analysis were used to determine the chemical structure of the isolated compounds. The GC-MS technique was also employed to identify the essential oil composition of the plant. Results: In the antioxidant activity assay, the n-butanol fraction was the most potent fraction, with a half maximal inhibitory concentration (IC50) of 16.14 ± 0.8 µg/mL on the DPPH assay and 736.4 ± 4.6 mmol FeSO4.7H2O equivalent per gram of sample on the FRAP assay. The n-butanol fraction exhibited very strong antibacterial activities against Staphylococcus aureus, Staphylococcus epidermidis, and Shigella dysenteriae (inhibition zone diameter: 20 - 25 mm, MIC: 125 - 250 µg/mL). The phytochemical analysis of the most active fractions resulted in the isolation of the following components from the chloroform fraction: 5,7,2'-trihydroxy-8,6'-dimethoxyflavone; 5-hydroxy-6,7,8,2',6'-pentamethoxyflavone; 5,2',6'-trihydroxy-7,8-dimethoxyflavone; 5,2',6'-trihydroxy-6,7,8-trimethoxyflavone; and 5,4'-dihydroxy-7-methoxyflavone. Besides, the following components were extracted from the n-butanol fraction: luteolin-7-O-β-D-glucopyranoside; verbascoside; apigenin; kaempferol; caffeic acid; rosmarinic acid; apigenin-7-O-β-D-glucopyranoside; apigenin-7-O-β-D-(-6''-(E)-caffeoyl)-glucopyranoside; and luteolin. Fourteen compounds were also identified in the plant essential oil; terpinen-4-ol (44.41%), α-terpineol (10.75%), caryophyllene oxide (9.61%), and thymol (8.73%) were the main compounds. Conclusions: This study introduced S. platystegia as a plant rich in bioactive phenolic compounds, with considerable antioxidant and antimicrobial activities. Therefore, it can be suggested as a potential candidate to be evaluated in future biological studies.