Five New Furostanol Glycosides from the Fruits of Tribulus terrestris with NO Production Inhibitory Activity.

Eight furostanol glycosides including five undescribed compounds, named tribufurostanosides A-E (1-5), and three known ones (6-8) were isolated from the fruits of Tribulus terrestris L. Their chemical structures were determined by the IR, HR-ESI-MS, 1D-, and 2D-NMR spectra. Furostanols 1-8 significantly inhibited nitric oxide production in LPS activated RAW 264.7 cells with IC50 values ranging from 14.2 to 64.7 µM, compared to that of the positive control compound, dexamethazone (IC50 13.6 µM).

Chemical Composition, Anti-bacterial Activity and Molecular Docking Studies of Essential Oil Isolated from Sa Sam Nam (Launaea sarmentosa).

Launaea sarmentosa, also known as Sa Sam Nam, is a widely used remedy in Vietnamese traditional medicine and cuisine. However, the chemical composition and bioactivity of its essential oil have not been elucidated yet. In this study, we identified 40 compounds (98.6% of total peak area) in the essential oil via GC-MS analysis at the first time. Among them, five main compounds including Thymohydroquinone dimethyl ether (52.4%), (E)-α-Atlantone (9.0%), Neryl isovalerate (6.6%), Davanol D2 (isomer 2) (3.9%), and trans-Sesquisabinene hydrate (3.9%) have accounted for 75.8% of total peak area. The anti-bacterial activity of the essential oil against 4 microorganisms including Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa has also investigated via agar well diffusion assay. The results showed that the essential oil exhibited a strong antibacterial activity against Bacillus subtilis with the inhibition zones ranging from 8.2 to 18.7 mm. To elucidate the anti-bacterial effect mechanism of the essential oil, docking study of five main compounds of the essential oil (Thymohydroquinone dimethyl ether, (E)-α-Atlantone, Neryl isovalerate, Davanol D2 (isomer 2), and trans-Sesquisabinene hydrate) against some key proteins for bacterial growth such as DNA gyrase B, penicillin binding protein 2A, tyrosyl-tRNA synthetase, and dihydrofolate reductase were performed. The results showed that the main constituents of essential oil were highly bound with penicillin binding protein 2A with the free energies ranging -27.7 to -44.8 kcal/mol, which suggests the relationship between the antibacterial effect of essential oil and the affinity of main compounds with penicillin binding protein. In addition, the free energies of main compounds of the essential oil with human cyclooxygenase 1, cyclooxygenase 2, and phospholipase A2, the crucial proteins related with inflammatory response were less than diclofenac, a non-steroidal antiinflammatory drug. These findings propose the essential oil as a novel and promising anti-bacterial and anti-inflammatory medicine or cosmetic products.

Tributelosides A-D: Four Undescribed Spirostan Glycosides Isolated from the Branches and Leaves of Tribulus terrestris with Their NO Production Inhibitory Activity in LPS Activated RAW 264.7 Cells.

Four undescribed spirostan glycosides, (25S)-5α-spirostan- 12-one-2α,3ß-diol-3-O-ß-D-glucopyranosyl-(1→4)-ß-D-galactopyranoside (1), (25S)-5α-spirostan-12-one-2α,3ß-diol-3-O-ß-D-galatopyranosyl-(1→2)-ß-D-glucopyranosyl- (1→4)-ß-D-galactopyranoside (2), (25S)-5α-spirostan-12-one-2α,3ß-diol-3-O-ß-D-glucopyranosyl-(1→2)-[ß-D-glucopyranosyl-(1→3)]-ß-D-glucopyranosyl-(1→4)-ß-D-galactopyranoside (3), and hecogenin 3-O-ß-D-glucopyranosyl-(1→3)-[ß-D-xylopyranosyl-(1→2)]-ß-D-glucopyranosyl-(1→4)-[α-L-rhamnopyranosyl-(1→2)]-ß-D-galactopyranoside (4), together with eleven known compounds (5-15) were isolated from the branches and leaves of Tribulus terrestris. Their chemical structures were established through spectroscopic methods, including HR-ESI-MS, 1D-, and 2D-NMR spectra. Preliminary biological evaluation on NO production inhibitory activity in LPS activated RAW 264.7 cells showed that compounds 1-3, 5, and 6 had significant inhibitory effects with IC50 values ranging from 2.4 to 18.3 µM, compared to that of the positive control compound, dexamethazone (IC50 13.6 µM).

Four Unidentified Compounds Isolated from the Stem Barks of Aphanamixis polystachya and Their NO Production Inhibition in LPS Activated RAW 264.7 Cells.

Phytochemical study on the methanol extract of the stem barks of Aphanamixis polystachya led to the isolation of four previously undescribed (1-4) and ten known compounds (5-14). Their chemical structures were elucidated to be 11-methoxysawaranospiroride C (1), 6α,9S,10,13-tetrahydroxymegastigmane-3-one (2), 11-hydroxyaphanamixin B (3), (2Z,6E,13E)-2,6,13-triene-11,15-dihydroxyphytanic acid (4), cinnacasside D (5), cinnacasside E (6), vilsonol F (7), (3S,5R,6S,7E,9R)-3,5,6,9-tetrahydroxy-7-en-megastigmane (8), (3S,5R,6R,7E,9R)-3,6,9,10-tetrahydroxy-7-en-megastigmane (9), citroside A (10), threo-1-(3,4,5-trimethoxyphenyl)-1,2,3-propanetriol (11), 3,4,5-trimethoxyphenyl-1-O-ß-D-glucopyranoside (12), p-coumaric acid (13), ferulic acid (14) by HR-ESI-MS, ECD, 1D-, and 2D-NMR spectra. Compounds 1, 3, 4, and 9 showed NO production inhibitory activity in LPS activated RAW 264.7 cells with IC50 values of 42.0, 67.9, 20.5, and 78.6 µM, respectively, while the remaining compounds were inactive with IC50 values over 100 µM.

Precise cuts for tailoring chromene-phenyl COX inhibitors with Ligand Designer.

Cyclooxygenases 1 and 2 (COX-1/2) are enzymes renowned for inducing inflammatory responses through the production of prostaglandins. Thus, the development of COX inhibitors has been a promising approach for identifying compounds with anti-inflammatory potential. In this study, we designed 27 new compounds (1-27) based on the structure of a previously known COX inhibitor, using the Ligand Designer tool. Our aim was to improve the affinity of the compounds with COX enzymes by inducing interactions with residue Arg120 while retaining the good π-π stacking interactions of the chromene-phenyl scaffold. Through screening based on ligand-binding free energy defined by molecular docking simulations and MM/GBSA technique, compounds 9 and 10 were identified as having the highest ability to inhibit COX proteins. The binding affinities of the two compounds with COX-1/2 were superior to those of the original NAI10 compound and the reference drug indomethacin. Our virtual screening suggests that compounds 9 and 10 have a strong ability to inhibit COX-1/2 and thus could be promising candidates for further anti-inflammatory drug studies. In essence, our study underscores the pivotal role of the N-aryl iminocoumarin scaffold in shaping the future landscape of novel anti-inflammatory drug development.

Circulation of human respiratory syncytial virus and new ON1 genotype in northern Viet Nam, 2017–2020

@#Objective: Human respiratory syncytial virus (RSV) is a primary cause of paediatric severe acute respiratory infection (SARI) worldwide, especially in developing countries. We investigated the genetic characteristics of RSV in northern Viet Nam to determine the prevalence and distribution of subtypes as well as the diversity and transmission patterns of genotypes. Methods: In two facilities, from January 2017 to December 2020, 1563 clinical specimens were collected from paediatric patients hospitalized with SARI and tested for RSV. Selected positive samples underwent sequencing analysis targeting the second hypervariable region of the G gene using next-generation sequencing. Results: The RSV positivity rate was 28.02% (438/1563 samples), and prevalence was highest in children aged <1 year (43.84%; 192/438). Subtype RSV-A accounted for 53.42% (234/438) of cases, RSV-B for 45.89% (201/438), and there was coinfection in 0.68% (3/438). Both subtypes cocirculated and peaked during August–September in each year of the study. Phylogenetic analysis showed that RSV-A samples belonged to the ON1 genotype, which has three subgenotypes: ON1.1, ON1.2 and ON1.3. However, we did not find the 72-nucleotide duplication in the second hypervariable region of the G gene, a characteristic of genotype ON1, in any RSV-A samples. RSV-B samples belonged to genotype BA9. Discussion: Our results provide additional molecular characterization of RSV infections in Viet Nam. Specially, our study is the first to report the absence of the 72-nucleotide duplication in the G gene of RSV-A genotype ON1 in Viet Nam, which may help in understanding the genetic evolution of RSV and be useful for vaccine development in the future.