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Inhibiting Insulin Resistance and Accumulation of Triglycerides and Cholesterol in the Liver
Published in Christophe Wiart, Medicinal Plants in Asia for Metabolic Syndrome, 2017
Morolic (Figure 3.23) and moronic acid (Figure 3.24) isolated from Rhus chinensis Mill. given to Wistar rats at a single oral dose of 50 mg/kg halved 30 minutes peak glycaemia in oral glucose tolerance tests.307 In sucrose tolerance test morolic acid evoked a 20% reduction of glycaemia at 30 minutes whereby moronic acid reduced glycaemia by more than 50%.307 These oleananes triterpenes given orally at a dose of 50 mg/kg/day 10 day to diabetic rats induced a 60% reduction of glycaemia, lowering of serum cholesterol, and triglycerides.307In vitro, morolic acid and moronic acid at a concentration of 10 µM inhibited the enzymatic activity of 11β-hydroxysteroid dehydrogenase 1 (11β-HSD 1) by 44% and 22%, respectively.307 11-β-hydroxysteroid dehydrogenase 1 catalyzes the conversion of cortisone to cortisol in human, mainly in the liver and adipose tissues and is related to Metabolic Syndrome and obesity-related disorders. Cortisol activates glucocorticoid receptor which is a cause for obesity.308 Glucocorticoids in excess stimulate hepatic glucose production, decrease hepatic glucose utilization and decrease glycogen synthesis contributing to hyperglycemia, decrease insulin action and decrease glucose uptake by skeletal muscles.309 However, 11-β-hydroxysteroid dehydrogenase-2 catalyzes the conversion of 11β-hydroxy ketoglucocorticoids to inactive metabolite in the kidneys and inhibition of this enzyme results in sodium retention and hypertension. Pentacyclic triterpenes inhibit protein-tyrosine phosphatase-1B and it would be interesting to examine the activity of morolic and moronic acid on this enzyme.
Silver nanoparticles obtained from Brazilian pepper extracts with synergistic anti-microbial effect: production, characterization, hydrogel formulation, cell viability, and in vitro efficacy
Published in Pharmaceutical Development and Technology, 2021
Daniele M. de Oliveira, Diego B. Menezes, Lucas R. Andrade, Felipe da C. Lima, Luciana Hollanda, Aleksandra Zielinska, Elena Sanchez-Lopez, Eliana B. Souto, Patrícia Severino
The results depicted in Table 5 corroborate with those found in several publications on the antimicrobial potential of the S. terebinthifolius Raddi extract. Silva et al. demonstrated the antibacterial activity of the essential oil of the Brazilian pepper tree against staphylococcal isolates from dogs with otitis externa, recording a MIC between 78.1 and 1250 μg/mL (Silva et al. 2010). Different types of extracts were prepared by Uliana et al. (Uliana et al. 2016), all showing a strong antimicrobial activity against S. aureus and E. coli. The authors identified 32 constituents in the essential oil (97.90% of the total), being δ-3-carene (68.78%), E-caryophyllene (8.22%), myrcene (6.78%), and α-pinene (4.05%) the main components (Uliana et al. 2016). Gehrke et al. described the in vitro antimicrobial activity of a range of extracts against five Gram positive bacteria (B. subtilis, S. aureus, Staphylococcus epidermidis, Staphylococcus saprophyticus, Streptococcus pyogenes), three Gram-negative bacteria (E. coli, P. aeruginosa, and Shigella sonnei) and four yeasts (Candida albicans, Candida tropicalis, Cryptococcus neoformans, and Saccharomyces cerevisiae) (Gehrke et al. 2013). The authors identified the moronic acid as the most active compound (MIC between 1.5 and 3 μg/mL), which was then tested against a range of other bacteria (i.e. Bacillus cereus, Enterococcus spp., Burkholderia cepacia, Providencia stuartii, Morganella morganii, Enterobacter cloacae, Enterobacter aerogenes, and Proteus mirabilis). A broad spectrum of antibacterial activity was recorded for the leaf aqueous extract with MIC values ranging from 125 to 250 μg/mL against the tested bacteria and fungi. The organic n-hexane extract exhibited excellent antifungal activity against C. albicans, C. tropicalis and C. neoformans with MIC values of 25, 15.5, and 15.5 μg/mL, respectively; however very low anti-bacterial effect. The acetate fraction was shown to be the most active against bacteria.