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This study, for the first time, has investigated the relationships between alterations of mangiferin contents in mango leaves at different maturity stages and their antibacterial properties. Leaves were classified into six different maturity stages based on their color: (1) young dark reddish brown, (2) young yellow, (3) young light green, (4) mature green, (5) old dark green, and (6) old yellow leaves. Ethanol extracts were then examined against Gram-positive and Gram-negative bacteria, applying broth dilution and agar well diffusion methods. In addition, we also measured the mangiferin contents in leaves at different stages for the purpose of evaluating how the changes in this phytochemistry value affects their activities against bacteria. The results showed that extracts from leaves at young ages had better antibacterial properties than those from old leaves, as evidenced by the lower minimum inhibitory concentrations and larger inhibitory zones. In addition, we also found that the contents of mangiferin were significantly decreased followed the maturation process. These results suggest that mango leaves at young stages, especially dark reddish brown and young yellow leaves, are preferable for application in bacterial infections and other therapies related to mangiferin's constituents. [ABSTRACT FROM AUTHOR]

Processing with heat treatment has been reported to alter several therapeutic effects of turmeric. In Vietnamese traditional medicine, turmeric has been long used for bacterial infections, and roasting techniques are sometimes applied with this material. However, there have been no studies investigating the effects of these thermal processes on the plant's antibacterial properties. Our study was therefore performed to examine the changes that roasting produced on this material. Slices of dried turmeric were further subjected to light-roasting (80 °C in 20 min) or dark-roasting (160 °C in 20 min) processes. Broth dilution and agar-well diffusion methods were applied to examine and compare the effects of ethanol extracts obtained from non-roasted, light-roasted and dark-roasted samples, on a set of 6 gram-positive and gram-negative bacteria. In both investigations, dark-roasted turmeric was significantly less antibacterial than non-roasted and light-roasted materials, as evident by the higher values of minimum inhibitory concentrations and the smaller diameters of induced inhibitory zones. In addition, dark-roasting was also found to clearly reduce curcumin contents, total polyphenol values and antioxidant activities of the extracts. These results suggest that non-roasting or light-roasting might be more suitable for the processing of turmeric materials that are aimed to be applied for bacterial infections. [ABSTRACT FROM AUTHOR]

Essential oils from Cinnamomum cassia bark and Eucalyptus globulus leaves have been traditionally applied for bacterial infections, through both of aromatherapy and oral application. (E)-cinnamaldehyde and 1,8 cineole have been identified as their major secondary metabolites, and are also generally considered as the main active ingredients responsible for their medicinal applications. However, ethnobotanical doctors still prefer to use whole essentials oils over purified compounds in bacterial infections. We therefore hypothesized that multi-compound extracts might exert better effects than isolated ingredients. In order to verify the hypothesis about advantages of whole materials, we examined antibacterial properties of the 2 plant essential oils in the comparison with their isolated major compounds, such as (E)-cinnamaldehyde and 1,8 cineole. Effects of liquid- and vapor-phase were examined on a set of 6 gram-positive and -negative bacteria, applying broth dilution, agar well diffusion and disc volatilization methods. In all 3 investigations, we observed that whole cinnamon and eucalyptus oils, with the lower concentrations of (E)-cinnamaldehyde (89.1%) and 1,8 cineole (61.2%), were able to induce better effects than the purified active compounds (≥ 99%). These results partly explain the advantages of using whole essential oils over isolated ingredients, and therefore support the application of traditional dosage forms for bacterial infections in ethnomedicine. [ABSTRACT FROM AUTHOR]