Inhibition of HMG-CoA reductase activity and cholesterol permeation through Caco-2 cells by caffeoylquinic acids from Vernonia condensata leaves

ABSTRACT The aim of this study was to provide scientific knowledge to support the use of Vernonia condensata Baker, Asteraceae, beverages for their alleged hypocholesterolemic properties by testing their action as HMG-CoA reductase inhibitors and their capacity to lower dietary cholesterol permeation. Chlorogenic acid, and other caffeoylquinic acids derivatives were identified as the main components of these beverages by LC–MS/MS. No changes in the composition were notice after the in vitro gastrointestinal digestion and no toxicity against Caco-2 and HepG2 cell lines was detected. Cholesterol permeation through Caco-2 monolayers was reduced in 37% in the presence of these herbal teas, and the caffeoylquinic acids permeated the monolayers in 30–40% of their initial amount in 6 h. HMG-CoA reductase activity was reduced with these beverages, showing an IC50 of 217 µg ml−1. It was concluded that caffeoylquinic acids, the major components, justified 98% of the enzyme inhibition measured.

Phytochemical Analysis of Plectranthus sp. Extracts and Application in Inhibition of Dental Bacteria, Streptococcus sobrinus and Streptococcus mutans.

Aims: Evaluation of leaves methanol extracts from Plectranthus barbatus and Plectranthus ecklonii (Lamiaceae) against oral pathogens. Place and Duration of the Study: P. barbatus and P. ecklonii, cultivated in Botanic Garden of the University of Lisbon, were collected during winter 2009. Methodology: Methanol extracts were prepared and the compounds separated and identified by HPLC-DAD and mass spectrometry. The anticariogenic activity was determined by measuring the inhibition activity towards the growth of the pathogens Streptococcus mutans and S. sobrinus together with the inhibitory activity against the enzyme glucosyltransferase (GTF) involved in the biosynthesis of glucans. Results: Phytochemical analysis of the extracts revealed the presence of two abietane diterpenoids in P. barbatus and two quinone methides together with rosmarinic acid in P. ecklonii. The two Plectranthus extracts showed bacteriostatic activity with minimum inhibitory concentrations (MIC) of 0.3 mg/mL. The minimum bactericidal concentrations (MBC) obtained for both extracts were 0.6 mg/mL against S. sobrinus and 0.8 mg/mL against S. mutans. After exposing both strains during 2h to P. ecklonii extract, 80% of inhibition against viable cells on a 24h old biofilm was observed. When methanol extracts of P. barbatus and P. ecklonii were used to inhibit the growth of the two bacterial strains in biofilm, IC50 (inhibitory concentration) values were 1.9 mg/mL and 0.57 mg/mL against S. sobrinus biofilm and 0.7 mg/mL and 0.8 mg/mL against S. mutans biofilm, respectively. P. barbatus IC50 values for the biofilm formation were 0.63 mg/mL and 0.13 mg/mL against S. sobrinus and S. mutans, respectively. P. ecklonii IC50 values for the biofilm formation were 0.07 mg/mL and 0.12 mg/mL against S. sobrinus and S. mutans biofilm. GTF from S. sobrinus was inhibited in 30% when 0.3 mg/mL of P. barbatus extract was used. Conclusions: These extracts are important in the control of biofilms and useful in the prevention of oral diseases.