No abstract

Artemisia herba-alba Asso. (Wormwood) is a wild aromatic herb that is popular for its healing and medicinal effects and has been used in conventional as well as modern medicine. This research aimed at the extraction, identification, and quantification of phenolic compounds in the aerial parts of wormwood using Soxhlet extraction, as well as characterizing their antimicrobial and anitoxidant effects. The phenolic compounds were identified in different extracts by column chromatography, thin layer chromatography (TLC), and high performance liquid chromatography. Five different fractions, two from ethyl acetate extraction and three from ethanolic extraction were obtained and evaluated further. The antimicrobial activity of each fractions was evaluated against two Gram-positive (Bacillus cereus and Staphylococcus aureus) and two Gram-negative microorganisms (Escherichia coli and Proteus vulgaris) using the disc-diffusion assay and direct TLC bioautography assay. Fraction I inhibited B. cereus and P. vulgaris, Fraction II inhibited B. cereus and E. coli, Fraction III inhibited all, except for P. vulgaris, while Fractions IV and V did not exhibit strong antimicrobial effects. Their antioxidant capabilities were also measured by calculating their ability to scavenge the free radical using DPPH method and the ferric reducing antioxidant power (FRAP) assay. Ethanolic fractions III and V demonstrated excellent antioxidant properties with IC50 values less than 15.0 μg/mL, while other fractions also had IC50 values less than 80.0 μg/mL. These antioxidant effects were highly associated with the number of phenolic hydroxyl group on the phenolics they contained. These extracts demonstrated antimicrobial effects, suggesting the different phenolic compounds in these extracts had specific inhibitory effects on the growth of each bacteria. The results of this study suggested that the A. herba-alba can be a source of phenolic compounds with natural antimicrobial and antioxidant properties which can be used for potential pharmaceutical applications.

No abstract

Kaempferol (KA) is a natural flavonol that can be found in plants and plant-derived foods with a plethora of different pharmacological properties. In the current study, we developed an efficient extraction method for the isolation of KA from ultrasonicated basil leaves (Ocimum basilicum). We successfully employed a Box–Behnken design (BBD) in order to investigate the effect of different extraction variables including methanol concentration (40–80%), extraction temperature (40–60 °C), and extraction time (5–15 min). The quantification of KA yield was carried out by employing a validated densitometric high performance thin layer chromatography in connection with ultraviolet detection (HPTLC-VIS). The obtained data showed that the quadratic polynomial model (R2 = 0.98) was the most appropriate. The optimized ultrasonic extraction yielded 94.7 ng/spot of KA when using methanol (79.99%) at 60 °C for 5 min. When using toluene-ethyl acetate-formic acid (70:30:1 v/v/v) as a solvent, KA was detected in basil leaves at an Retention factor (Rf) value of 0.26 at 330 nm. Notably, the analytical method was successfully validated with a linear regression of R2 = 0.99, which reflected a good linear relationship. The developed HPTLC-VIS method in this study was precise, accurate, and robust due to the lower obtained results from both the percent relative standard deviation (%RSD) and SEM of the O. basilicum. The antioxidant activity of KA (half maximal inhibitory concentration (IC50) = 0.68 μg/mL) was higher than that of the reference ascorbic acid (IC50 = 0.79 μg/mL) and butylated hydroxytoluene (BHT) (IC50 = 0.88 μg/mL). The development of economical and efficient techniques is very important for the extraction and quantification of important pharmaceutical compounds such as KA.

dione [ Figure 1], a white powdered, water soluble plant alkaloid, is found in many plant species such as coffee and green tea. Caffeine at submillimolar concentrations exerts a wide variety of physiological effects on different organisms [11] and has long been known to have numerous actions, [12] including inhibition of phosphodiesterases, thereby increasing intracellular cAMP, direct effects on intracellular calcium concentrations, indirect effects on intracellular calcium concentrations via membrane hyperpolarizationThe present study was conducted to isolate the most important bioactive compound from Coffea arabica (coffee) beans and Camellia sinensis (green tea) leaves. Caffeine (3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione) was isolated from both plants using a liquid-liquid extraction method, detected on thin layer chromatography (TLC) plates in comparison with standard caffeine, which served as a positive control. Moreover, Fourier transform infrared (FTIR) spectrometer and High performance liquid chromatography (HPLC) analyses were used to confirm the purity and characterization of the extracted caffeine. The isolated material(s) from both plants were investigated for their single and combined antibacterial activities against six selected pathogenic bacteria. The Grampositive bacteria were; Staphylococcus aureus, Bacillus cereus and Gram-negative bacteria included; Escherichia coli, Proteus mirabilis, Klebsiella pneumonia and Pseudomonas aeruginosa. Both compounds at a concentration of 2 mg/ml showed similar antibacterial activities against all tested bacteria, except for P. mirabilis, and the highest inhibitory effect was observed against P. aeruginosa using a modified agar diffusion method. The minimal inhibitory concentration (MIC) of caffeine was determined using a broth microdilution method in 96 multi-well microtitre plates. MIC values ranged from 62.5 to 250.0 µg/ml for the caffeine isolated from coffee and 62.5 to 500.0 µg/ml for green tea caffeine. Combination results showed additive effects against most pathogenic bacteria especially for P. aeruginosa, using both antibacterial assays.