Comparative evaluation of antibacterial activity of silver nanoparticles synthesized using Rhizophora apiculata and glucose

The focus of the study is to compare the antibacterial efficacy of silver nanoparticles (AgNPs) fabricated by exploiting biological (a mangrove plant, Rhizophora apiculata) and chemical means (Glucose). The synthesized nanoparticles were characterised using UV-visible absorption spectrophotometry (UV-vis), Fourier transform Infra-red Spectroscopy (FTIR) and Transmission electron microscopy (TEM). Biologically synthesized silver nanoparticles (BAgNPs) were observed at 423 nm with particle sizes of 19-42 nm. The chemically synthesized silver nanoparticles (CAgNPs) showed a maximum peak at 422 nm with particle sizes of 13-19 nm. An obvious superiority of the antibacterial potency of BAgNPs compared to the CAgNPs as denoted by the zone of inhibition (ZoI) was noted when the nanoparticles were treated against seven different Microbial Type Culture Collection (MTCC) strains. The current study therefore elucidates that the synthesized AgNPs were efficient against the bacterial strains tested.     

Cytotoxity of two new coumarin derivatives isolated from Launaea mucronata

The chloroform fraction of methanol (MeOH) extract of the aerial parts of Launaea mucronata was in vitro investigated for cytotoxicity against HCT116, HepG2 and MCF-7 cell lines, and resulted with IC₅₀ = 20.0, 18.6 and 14.30 μg/mL, respectively. The chloroform fraction of the MeOH extract was subjected to further fractionation, which led to the isolation of two new coumarin compounds (6-isobutyl coumarin and 6-isobutyl-7-methyl- coumarin). The structures of the new compounds were elucidated by high field 1D and 2D NMR and ESI-MS spectroscopies. Low polar fractions revealed the isolation of other known triterpene compounds which were identified according to its spectral data and comparison with the literature. New coumarin compounds show high cytotoxicity against MCF-7, HCT116 and HepG2 cell lines.     

Two New C-21 Steroidal Glycosides from the Stems of Stephanotis mucronata

Two new C-21 steroidal glycosides, mucronatosides M（1） and N（2）, were isolated from the stems of Stephanotis mucronata, together with one known compound stephanoside M（3）. On the basis of chemical evidence and extensive spectroscopic methods, including one-dimensional and two-dimensional NMR, the structures of the two new compounds were identified as 12-O-tigloyl-20-O-N-methylanthraniloyl sarcoslin 3-O-β-D-glucopyranosyl-（1→4）-6- deoxy-3-O-methyl-β-D-allopyranosyl-（→4）-β-D-cymaropyranosyl-（1→4）-β-D-cymaropyranoside （1）, and 12-O- cinnamoyl-20-O-nicotinoyl（ 2OS）-pregn-6-ene-3 β,5α,8βm12 β,14β,17β,20-heptanol 3-O-β-D-glucopyranosyl-（1→4）-6- deoxy-3-O-methyl-β-D-allopyranosyl-（1→4）-β-D-cymaropyranosyl-（1→4）-β-D-cymaropyranoside （2）.     

黑鳗藤中C_(21)甾体苷的分离和结构测定

从萝藦科植物黑鳗藤[Stephanotis mucronta (Blanco) Merr.]的藤茎中分离 到三个C_(21)甾体去氧糖苷（1） - （3）。通过化学降解和波谱技术，确定它们 的化学结构依次为：12-O-惕各酰基-20-O-乙酰基肉珊瑚苷元3-O-β-黄夹吡喃糖基 -（1→4）-β-磁麻吡喃糖基-（1→4）-β-磁麻吡喃糖苷（1），5，6-双氢-12-O- 乙酰基-20-O-惕各酰基肉珊瑚苷元3-O-β-黄夹吡喃糖基-（1→4）-β-磁麻吡喃糖 基-（1→4）-β-磁麻吡喃糖基（2）；12-O-乙酰基-20-O（N-甲基）邻氨基苯甲酰 基肉珊瑚甘元3-O-β-黄夹吡喃糖基-（1→4）-β-磁麻吡喃糖基-（1→4）-β-磁 麻吡喃糖甘（3）。其中1和2为新化合物，分别命名为mucronatoside A， mucrontoside B。3为已知化合物stephanoside E，系首次从该植物中分离得到。     

Daphne mucronata-mediated phytosynthesis of silver nanoparticles and their novel biological applications,compatibility and toxicity studies

This contribution reports the biosynthesis of silver nanoparticles (AgNPs) using aqueous leaf extracts of D. mucronata and their diverse applications. Synthesized AgNPs were characterized using diverse techniques, i.e. UV, XRD, EDS, SEM, TEM, FTIR and TGA/DTA. These techniques confirmed the authenticity of the synthesized nanoparticles. The bimodulated AgNPs revealed the highest radical scavenging potential, i.e. 86.4% relative to plant extract at 600?μg/ml. Escherichia coli was found to be the most susceptible strain to AgNPs. Growth of vancomycin-resistant Staphylococcus aureus was also inhibited. Hemolytic activity revealed negligible hemolysis, indicating the biocompatible nature of biomodulated AgNPs. Furthermore, no mutagenic properties were shown by the biogenic AgNPs. Synthesized nanoparticles possessed promising insecticidal potential and had no phytotoxic activity. No haemagglutination was observed for biogenic AgNPs.     

Polyketides from the mangrove-derived endophytic fungus Acremonium strictum

Five new polyketide derivatives, 6′-hydroxypestalotiopsone C (1), acropyrone (2), bicytosporone D (3), waol acid (4), and pestalotiopene C (5), together with seven known metabolites (6–12), were obtained from extracts of the endophytic fungus Acremonium strictum, isolated from the mangrove tree Rhizophora apiculata. The structures of the isolated compounds were elucidated on the basis of comprehensive NMR and MS analysis. Compounds 6, 7, and 9 showed moderate cytotoxic activity against human cisplatin-sensitive (IC₅₀ values 27.1, 76.2, and 8.3 μM, respectively) and resistant A2780 cell lines (IC₅₀ values 12.6, 30.1, and 19.0 μM, respectively), whereas only 9 exhibited antibacterial activity against Staphylococcus aureus (MIC value 14.3 μM).     

Oxypregnane-oligoglycosides from the Stems of Stephanotis mucronata （Asclepiadaceae）

Four new oxypregnane-oligoglycosides, mucronatosides A (1), B (2), C (3), and D (4),together with one known stephanoside E (5) were isolated from the stems of Stephanotis mucronata (Blanco) Merr.. Their chemical structures were determined on the basis of chemical and extensive spectroscopic methods including one-dimensional and two-dimensional NMR.     

13α-Hydroxymethylenedeacetyllaurenobiolide, a New Germacranolide from Tanacetopsis mucronata

The new sesquiterpene lactone 13-hydroxymethylenedeacetyllaurenobiolide was isolated from the aerial part of Tanacetopsis mucronata S. Koval. (Asteraceae). Its structure was established using spectral data and X-ray structure analysis. The germacranolide macrocycle has the chair-chair conformation with the configuration ₁D¹⁴, ¹⁵D₅.     

Pestalotiopisorin B,a new isocoumarin derivative from the mangrove endophytic fungus Pestalotiopsis sp. HHL101

Abstract

A new isocoumarin derivative pestalotiopisorin B (1), along with six known compounds, (R)-(-)- mellein methyl ether (2), pestalotiopyrone G (3), (R)-mevalonolactone (4), pestalotiollides A–B (5–6) and pestalotiopsol A(7) were isolated from Pestalotiopsis sp., an endophytic fungus obtained from Chinese mangrove plant Rhizophora stylosa. Their structures were elucidated unambiguously by the comprehensive analysis of extensive spectroscopic data. Compound 1 exhibited modest antibacterial activity against Escherichia coli and Pseudomonas aeruginosa with 12.5?μg/ml, 50?μg/ml, respectively. Compound 4 showed moderate calcineurin inhibitory activity towards p-nitrophenyl phosphate (IC₅₀ =134.29?±?5.377?μM).     

Isomeric ent‐Labdane‐Type Diterpenoids from the Stems of Rhizophora mucronata

Two new constitutional isomers of ent‐labdane‐type diterpenoids, 1 and 2 , with an unusual seven‐membered lactone moiety (i.e., 1 ), together with two known compounds, 3 and 4 , were isolated from the acetone extract of Rhizophora mucronata. Their structures were elucidated as rhizomucronol A and B ( 1 and 2 , resp.) by spectroscopic analyses and chemical evidence. The absolute configuration of 2 was established by applying the Mosher ester procedure.