Dual effect of the herbal matcha green tea (Camellia sinensis L. kuntze) supplement in EA.hy926 endothelial cells and Artemia salina

Screening of antimicrobial activity of Ilex paraguariensis St. Hil. leaf extracts against carbapenemase-producing bacteria

I. paraguariensis St. Hil. is a south American species of agronomic interest with studies supporting its medicinal properties. As the investigation of active ingredients with antimicrobial effect from medicinal plants is a suitable approach to the current antibacterial resistance problem, the aim of the present study was to determine the antibacterial activity of yerba mate ethanolic extracts against carbapenemase-producing gram-negative bacteria (reference strains and clinical isolates). Extracts showed antibacterial activity against Klebsiella pneumoniae ATCC® BAA-2342™ (KPC producing), Providencia rettgeri (NDM producing), Pseudomonas aeruginosa (MBL producing) and P. aeruginosa (VIM producing) at the concentrations tested. The Minimal-Inhibitory-Concentration and Minimal-Bactericidal-Concentration values ranged between 1 and 32 mg.ml-1 for the reference strains, and between 0.125 and 1 mg.ml-1 for the clinical isolates. The MBC/MIC index characterized the extracts as bactericidal. The combinations of commercial antibiotics and extracts showed a synergistic action on the reference strains studied. The lethal concentration 50 obtained using the Artemia salina toxicity assay were higher than 1 mg.ml-1 for all the extracts, indicating a low toxicity. The in vitro activity and low toxicity suggest that ethanolic I. paraguariensis leaf extracts constitute an outstanding source for new antibacterial compounds, and further studies should be carried out to understand their mechanism of action.

Sustainable and effective approach to recover antioxidant compounds from purple tea (Camellia sinensis var. assamica cv. Zijuan) leaves

Camellia sinensis var. assamica cv. Zijuan (purple tea) is known for its content of anthocyanins, flavan-3-ols, and bioactivities. This study aimed to verify the influence of solvent polarity, in a solid-liquid extraction, on the content of phenolic compounds and chlorophylls, instrumental color, and antioxidant activity. Different proportions of water and ethanol (0:100, 25:75, 50:50, 75:25, and 100:0 v/v) were used for extraction. The results showed that the hydroalcoholic extract (75 % ethanol + 25 % water) had the highest contents of total flavonoids, total anthocyanins, chlorophyll A, and total carotenoids, as well as presenting the highest color intensity, proportion of yellow pigments, and antioxidant activity (total reducing capacity and scavenging of the DPPH free radical). Twenty-two compounds were identified, with chlorogenic acid, hesperidin, (-)-epicatechin, (-)-epigallocatechin gallate, and isoquercitrin being the main phenolics. This phenolic-rich extract inhibited lipoperoxidation induced in egg yolk homogenate (IC₅₀ = 455 mg/L), showed no hemolytic behavior when human erythrocytes were subjected to osmotic stress, and exerted in vitro cytotoxic effects against cancer and hybrid cells. The extract obtained with the mixture of non-toxic solvents presented critical bioactivities, as well as a comprehensive identification of phenolic compounds in the cultivar, and has potential to be used in technological applications.

Kaempferol and atherosclerosis: From mechanism to medicine

Natural products possess pleiotropic cardiovascular protective effects owing to their anti-oxidation, anti-inflammation and anti-thrombotic properties. Kaempferol, (3,5,7-trihydroxy-2-(4-hydroxyphenyl)-4H-1-benzopyran-4-one), is a kind of naturally occurring flavonoid existing in many common fruits and vegetables (e.g., onions, broccoli, strawberries and grapes) and particularly in traditional Chinese medicine as exemplified by Ginkgo biloba. Epidemiological, preclinical and clinical studies have revealed an inverse association between the consumption of kaempferol-containing foods and medicines and the risk of developing cardiovascular diseases. Numerous translational studies in experimental animal models and cultured cells have demonstrated a wide range of pharmacological activities of kaempferol. In this article, we reviewed the antioxidant, anti-inflammatory and cardio-protective activities of kaempferol and elucidated the potential molecular basis of the therapeutic capacity of kaempferol by focusing on its anti-atherosclerotic effects. Overall, the review presents the health benefits of kaempferol-containing plants and medicines and reflects on the potential of kaempferol as a possible drug candidate to prevent and treat atherosclerosis, the underlying pathology of most cardiovascular diseases.