Evaluation of chemical compositions and biological activities of Dendrobium species

Dendrobium spp. were investigated for their chemical compositions with HPTLC/CMS, and biological properties, including antioxidant activities (DPPH and ABTS.+ assay), and anti-acetylcholinesterase (AChE). The ethanolic extracts of Dendrobium orchid pseudobulbs (D. chrysotoxum; DC, D. fimbriatum; DF, D. lindleyi; DL, and D. pulchellum; DP) were found to contain caffeic acid, gallic acid, quercetin, rutin hydrate and vanillin. While luteolin was shown in D. fimbriatum and D. lindleyi extracts. D. lindleyi, and D. pulchellum extracts presented the high value of total phenolic and flavonoid contents, resulting in a strong antioxidant property. Moreover, D. chrysotoxum extract expressed AChE inhibitory potential. This research indicated that chemical compounds in Dendrobium would be involved with their biological properties, i.e. antioxidant and anti-AChE. This information can be used to support further in-depth research and product development in health, food, and pharmaceutical.

Synthesis, anti-acetylcholinesterase evaluation, molecular docking and molecular dynamics simulation of novel Psoralen derivatives

INTRODUCTION

Seven new psoralen derivatives were synthesised by carbodiimide coupling to active carboxylic acid to amide formation in mild reaction conditions.

METHODS

The psoralen derivatives were produced through the condensation of seven different types of amine groups consisting of electron withdrawing groups and electron donating groups.

RESULTS

All the synthesised compounds were obtained with moderate to high yields. Structural characterization using ATR-FTIR, 1H NMR, 13C NMR, and HRMS has confirmed their structure. Moreover, in silico evaluation of the psoralen derivatives against the AChE enzyme was performed, and acetylcholinesterase inhibitory activity of psoralen derivatives was also conducted.

CONCLUSION

Results from molecular docking show the potential of compound 12e as AChE inhibitors due to its highest binding energy value. It was further supported by the anti-acetylcholinesterase activity of compound 12e, which has 91.69% inhibition, comparable to galantamine (94.12%). Furthermore, 100 ns run molecular dynamics (MD) simulation was used to refine docking results.

mediated silver nanoparticles: synthesis, characterization, phenolic content, antioxidant, antibacterial and anti-acetylcholinesterase capacities

In this study, we develop here for the first time an easy, eco-friendly method for synthesizing silver nanoparticles (AgNPs) using the lichen Roccella phycopsis. AgNPs formation was first determined by a color change of the lichen filtrate to brown, subsequent to addition of AgNO₃ solution, and confirmed by a maximum absorbance peak at 425 nm in UV-vis spectrum. Scanning electron microscope images showed a spherical shape with a size distribution between 11 and 18 nm, while the elemental composition was elucidated by the energy dispersive X-ray spectroscopy. The chemical compounds responsible for reduction and stabilization of silver nanoparticles were detected by Frourier transform infrared spectroscopy analysis. The synthesized R. phycopsis silver nanoparticles displayed a strong antioxidant activity. Further, the antibacterial activity was more effective against Gram-negative than Gram-positive bacteria. Besides, the R. phycopsis-AgNPs were potent in inhibiting acetylcholinesterase enzyme with IC₅₀ value of 1.65 ± 0.07 mg/mL.

Anti-acetylcholinesterase activity and antioxidant properties of extracts and fractions of Carpolobia lutea

CONTEXT

There is an unmet need to discover new treatments for Alzheimer's disease. This study determined the anti-acetylcholinesterase (AChE) activity, DPPH free radical scavenging and antioxidant properties of Carpolobia lutea G. Don (Polygalaceae).

OBJECTIVE

The objective of this study is to quantify C. lutea anti-AChE, DPPH free radical scavenging, and antioxidant activities and cell cytotoxicity.

MATERIALS AND METHODS

Plant stem, leaves and roots were subjected to sequential solvent extractions, and screened for anti-AChE activity across a concentration range of 0.02-200 μg/mL. Plant DPPH radical scavenging activity, reducing power, and total phenolic and flavonoid contents were determined, and cytotoxicity evaluated using human hepatocytes.

RESULTS

Carpolobia lutea exhibited concentration-dependent anti-AChE activity. The most potent inhibitory activity for the stem was the crude ethanol extract and hexane stem fraction oil (IC₅₀ = 140 μg/mL); for the leaves, the chloroform leaf fraction (IC₅₀ = 60 μg/mL); and for roots, the methanol, ethyl acetate and aqueous root fractions (IC₅₀ = 0.3-3 μg/mL). Dose-dependent free radical scavenging activity and reducing power were observed with increasing stem, leaf or root concentration. Total phenolic contents were the highest in the stem: ∼632 mg gallic acid equivalents/g for a hexane stem fraction oil. Total flavonoid content was the highest in the leaves: ∼297 mg quercetin equivalents/g for a chloroform leaf fraction. At 1 μg/mL, only the crude ethanol extract oil was significantly cytotoxic to hepatocytes.

DISCUSSION AND CONCLUSIONS

Carpolobia lutea possesses anti-AChE activity and beneficial antioxidant capacity indicative of its potential development as a treatment of Alzheimer's and other diseases characterized by a cholinergic deficit.

Phytochemical study of Illicium angustisepalum and its biological activities

Sixteen compounds, including two new natural products (1 and 2), were obtained from the twigs of Illicium angustisepalum. The structures were elucidated based on NMR, MS, IR data and optical rotation values. Compounds 4, 5, 6 and 8 displayed moderate antibacterial activities against clinical isolates; compounds 4, 5, 8, 9 and 15 protected neural cells against oxidative stress; and compounds 10 and 14 exhibited anti-acetylcholinesterase activity.