Antioxidant potential and carbohydrate digestive enzyme inhibitory effects of five Inula species and their major compounds

The present study was designed to examine in-vitro antidiabetic activities of different extracts of flowers, leaves and roots of Inula helenium ssp. turcoracemosa, L montbretiana, I. peacockiana, I thapsoides ssp. thapsoides and I. viscosa extracts. I. viscosa and I. montbretiana flower, I. thapsoides and I. viscosa leaf and I. helenium root methanol extracts exhibited remarkable alpha-glucosidase inhibitory activity. Additionally, alpha-amylase inhibitory activities of the extracts were moderate at only 3000 mu g/mL. Based on the results of in-vitro antidiabetic activity tests; antioxidant activities, total phenol and flavonoid contents of the most promising extracts were evaluated. To identify compounds responsible for the antidiabetic activity, major compounds of Inula species were analyzed for their in-vitro enzyme inhibitory activity. Quercetin, luteolin and rutin exhibited a significant inhibition on alpha-glucosidase at 10 mM concentrations. Consequently, Inula species could potentially be used by diabetic patients for their antidiabetic and antioxidant activities. (C) 2017 SAAB. Published by Elsevier B.V. All rights reserved

Antimicrobial Activity of Flavonoids against Extended-Spectrum β-Lactamase (ESβL)-Producing Klebsiella pneumoniae

Purpose: In the present study, six flavonoids (5,7-dimethoxyflavanone-4'-O-β-D-glucopyranoside, 5,7dimethoxyflavanone-4'-O-[2''-O-(5'''-O-trans-cinnamoyl)-β-D-apiofuranosyl]-β-D-glucopyranoside, naringenin-7-O-β-D-glucopyranoside, 5,7,3'-trihydroxy-flavanone-4'-O-β-D-glucopyranoside, rutin, and nicotiflorin) isolated from Galium fissurense , Viscum album ssp. album and Cirsium hypoleucum were screened against extended-spectrum β-lactamase producing multidrug-resistant (trimetoprimesulphametoxazole, sulbactam-ampicillin, clavulonate-amoxicilin, ceftriaxon, cefepime, imipenem, ceftazidime, tobramicin, gentamicin, ofloxacin, ciprofloxacin) bacteria Klebsiella pneumoniae (ESβLs). Methods: We performed susceptibility testing according to the Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS) and used an inhibition endpoint for determination of the minimum inhibition concentrations (MICs). Results: All the flavonoids showed in vitro antimicrobial activity against all the isolated strains of K. pneumoniae similar to the control antibacterial (ofloxacin) at the concentrations of 32 -64 µg ml-l; another control, ampicillin, had no activity. Since, ESβL-producing strains are known to be resistant to all β-lactam antibiotics, our results fall notably within the concentration range for antimicrobial activity. Conclusion: To the best of our knowledge, this is the first report of the study of the activity of these flavonoids against (ESβL)-producing K. pneumoniae and may throw light to the low-toxicity of flavonoids, and their potentials for developing therapies for infections caused by ESβL-producing bacteria in the future. Further work is under investigation to identify their precise antibacterial mechanism