Chemical constituents and theira-glucosidase inhibitory activity of the stem of Salacia chinensis L.

Salacia chinensis L., known as “Chop mao” in Vietnam, is a climbing shrub that belongs to the Celastraceae family. The stem of S. chinensis L. is used as a traditional medicine for the treatment of diabetes, rheumatoid arthritis, back pain, … The dried powdered stem of S. chinensis L. was collected in Phu Yen province and was extracted with methanol to yield methanol extract. The methanol extract was suspended in H2O and partitioned successively with n-hexane, CHCl3, EtOAc to obtain n-hexane, CHCl3, EtOAc, and H2O fractions, respectively. The CHCl3 fraction was subjected to a series of chromatographic separation to afford four purified compounds including 3-oxolup-20(29)-en-30-al (1), betulin-3-caffeate (2), 2-(4-hydroxy-3,5-dimethoxylphenyl)ethanol (3), and acetosyringone (4). Their structures were elucidated on the basis of the spectroscopic analysis and comparison with literature data. The isolated compounds were tested for their α-glucosidase inhibitory activity. The result indicated that all compounds (1-4) possessed significant α-glucosidase at the testing concentration of 100 µM with the percent inhibition values of 9.5 ± 1.3, 70.89 ± 0.25, 44.2 ± 1.6, and 6.7 ± 1.7 %, respectively. In addition, betulin-3-caffeate (2) and 2-(4-hydroxy-3,5-dimethoxylphenyl)ethanol (3) show more potent α-glucosidase inhibitory activity, with IC50 values of 69.7 and 152.0 µM, respectively, than that of positive control acarbose (IC50 = 214.5 µM).

Antimicrobial screening and hemolytic activity of products obtained from Piper montealegreanum Yuncker and effect in vitro on growth of Staphylococcus aureus

This study aimed to determine spectrum of antimicrobial activity of crude ethanolic extract (CEE), chloroform (CHCl3) and ethyl acetate (EtOAc) fractions, to determine influence of CHCl3 fraction on Staphylococcus aureus growth and hemolytic activity. Antimicrobial screening of CEE, CHCl3 and EtOAc fractions was carried out using broth microdilution technique against standard strains: Staphyloccocus aureus ATCC25923, Escherichia coli ATCC25922, Pseudomonas aeruginosa ATCC27853 and Candida albicans ATCC76645 to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Time kill curves were performed to determine influence of CHCl3 fraction on MIC and ½ MIC concentrations on S. aureus growth. Hemolytic activity of CHCl3 was performed in human erythrocytes to report the cytotoxic effect. CHCl3 fraction showed activity against S. aureus with MIC=1024 µg mL-1 and MBC=2048 µg mL-1. This fraction did not show activity against other tested strains, as well as the CEE and EtOAc fraction. Time kill curve of S. aureus treated with CHCl3 fraction showed that at MIC this fraction has bacteriostatic activity, which was not observed with the ½ MIC. Hemolytic activity demonstrated that when CHCl3 fraction in MIC does not present membrane damage of erythrocytes, since it did not cause hemolysis. Studies should be conducted to evaluate the activity of CHCl3 fraction against S. aureus with different antimicrobial resistance profiles, in addition to evaluating the potential for resistance reversion by in vitro combination studies. The study demonstrated that the species P. montealegreanum can be an important source of compounds of importance for combating microorganisms of clinical importance.

Future in the Past: Azorella glabra Wedd. as a Source of New Natural Compounds with Antiproliferative and Cytotoxic Activity on Multiple Myeloma Cells

Multiple myeloma (MM) is the second most common hematologic malignancy and, although the development of novel agents has improved survival of patients, to date, it remains incurable. Thus, newer and more effective therapeutic strategies against this malignancy are necessary. Plant extracts play an important role in anti-tumor drug discovery. For this reason, in the investigation of novel natural anti-MM agents, we evaluated the phytochemical profiles, in vitro antioxidant activity, and effects on MM cells of Azorella glabra (AG) Wedd. Total polyphenols (TPC), flavonoids (TFC), and terpenoids (TTeC) contents were different among samples and the richest fractions in polyphenols demonstrated a higher antioxidant activity in in vitro assays. Some fractions showed a dose and time dependent anti-proliferative activity on MM cells. The chloroform fraction (CHCl3) showed major effects in terms of reduction of cell viability, induction of apoptosis, and cell cycle arrest on MM cells. The apoptosis induction was also confirmed by the activation of caspase-3. Importantly, the CHCl3 fraction exhibited a negligible effect on the viability of healthy cells. These results encourage further investigations on AG extracts to identify specific bioactive compounds and to define their potential applications in MM.