Chemical analysis, antibacterial, and antioxidant activities of flavonoid‐rich extracts from four Moroccan propolis

Phytotoxic phenols from the needles of Cedrus deodara

During the course of screening for anti-seed germination phytochemicals, the methanol fraction of the Cedrus deodara fresh needles showed potent activity. Bioactivity-guided fractionation led to the isolation of thirty-eight phenolic compounds. Four ones were identified as previously undescribed including (7S,8S)-3-methoxy-9'-acetoxy-3',7-epoxy-8,4'-oxyneoligna-4,9-diol (7), (7S,8R)-dihydro-3'-hydroxy-8-acetoxymethyl-7-(4-hydroxy-3-methoxy-phenyl)-1'-benzofuranpropanol (10), (8S)-4,9,9'-trihydroxy-3,3'-dimethoxy-8,4'-oxyneolignan (11) and (7S,8S)-4,7,9'-trihydroxy-3,3'-dimethoxy-9-acetoxy-8,4'-oxyneolignan (16), respectively. The potential phytotoxic effects of these compounds on the seed germination and root elongation of Arabidopsis thaliana were evaluated by the filter paper assay developed in our laboratory. Bioassay results indicated that caffeic acid (36) displayed most significant inhibitory activities against the seed germination and root elongation of A. thaliana, stronger than those of the commercial herbicides acetochlor and glyphosate at the same concentration of 200 μg/mL. Ditetrahydrofuran lignan (1), dihydrochalcone (25), and eight simple phenols (28, 29, 31, 33-35, 37 and 38) completely inhibited the seed germination of A. thaliana at the concentration of 400 μg/mL, which were as active as acetochlor. Dihydroflavone (21) and the simple phenols 32-34 displayed stronger inhibitory effects on the root elongation of A. thaliana than that of glyphosate. The inhibitory effects of these active compounds on the seed germination and root elongation of Amaranthus tricolor and Lactuca sativa were evaluated as well. The phytotoxic activity of 11, 16, 22, 25, 31, 34, 37 and 38 were detected for the first time. In addition, the structure-activity relationships of the same class of these phytochemicals were discussed.

Determination of Chemical Compounds and Investigation of Biological Properties of Matricaria chamomilla Essential Oils, Honey, and Their Mixture

This exploratory investigation aimed to determine the chemical composition and evaluate some biological properties, such as antioxidant, anti-inflammatory, antidiabetic, and antimicrobial activities, of Matricaria chamomilla L. essential oils (EOs). EOs of M. chamomilla were obtained by hydrodistillation and phytochemical screening was performed by gas chromatography-mass spectrophotometry (GC-MS). The antimicrobial activities were tested against different pathogenic strains of microorganisms by using disc diffusion assay, the minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) methods. The antidiabetic activity was performed in vitro using the enzyme inhibition test. The antioxidant activity of EOs was tested using the free radical scavenging ability (DPPH method), ferrous ion chelating (FIC) ability, and β-carotene bleaching assay. The anti-inflammatory effects were tested in vivo using the carrageenan-induced paw edema method and in vitro using the inhibition of the lipoxygenase test. The analysis of the phytochemical composition by GC-MS revealed that camphor (16.42%) was the major compound of EOs, followed by 3-carene (9.95%), β-myrcene (8.01%), and chamazulene (6.54%). MCEO, honey, and their mixture exhibited antioxidant activity against the DPPH assay (IC50 ranging from 533.89 ± 15.05 µg/mL to 1945.38 ± 12.71 µg/mL). The mixture exhibited the best radical scavenging activity, with an IC50 of 533.89 ± 15.05 µg/mL. As antidiabetic effect, EO presented the best values against α-glucosidase (265.57 ± 0.03 μg/mL) and α-amylase (121.44 ± 0.05 μg/mL). The EOs and honey mixture at a dose of 100 mg/kg exhibited a high anti-inflammatory effect, with 63.75% edema inhibition after 3 h. The impact of EOs on the studied species showed an excellent antimicrobial (Staphylococcus aureus ATCC 29213 (22.97 ± 0.16 mm)), antifungal (Aspergillus niger (18.13 ± 0.18 mm)) and anti-yeast (Candida albicans (21.07 ± 0.24 mm) effect against all the tested strains. The results obtained indicate that the EOs of M. chamomilla could be a potential drug target against diabetes, inflammation and microbial infections; however, further investigations to assess their bioactive molecules individually and in combination are greatly required.