Characterization and antinociceptive activity (in vivo) of kempferol-3,4′-di-O-α-L-rhamnopyranoside isolated from Dryopteris cycadina

Elucidation of glycosylation sites of kaempferol di-O-glycosides from methanolic extract of the leaves of Prunus domestica subsp. syriaca

RATIONALE

Flavonol glycosides containing the glycosylation patterns 3,4'-di-O and 4',7-di-O are rare in nature and they have not yet been studied in detail by electrospray ionization mass spectrometry (ESI-MS(+/-), in contrast to the flavonol glycosides containing the glycosylation pattern 3,7-di-O.

METHOD

The leaves from Prunus domestica L. subsp. syriaca were extracted with pure methanol or, in order to perform hydrolysis and extraction simultaneously, with a 5% methanolic solution of hydrochloric acid. The high-performance liquid chromatography (HPLC)/ESI-MS(+/-) analyses were performed using a Waters model 2690 HPLC pump and a Waters/Micromass ZQ2000 mass spectrometer.

RESULTS

Three kinds of kaempferol di-O-glycosides have been identified, namely kaempferol-3-O-hexoside-7-O-rhamnosides, kaempferol-3-O-pentoside-4'-O-rhamnosides and kaempferol 4',7-di-O-rhamnoside. The identification was performed on the basis of the abundances of the respective Y-type product ions.

CONCLUSIONS

The abundances of [Yⁿ ₀ - H]^-· , Yⁿ ₀ ^- and Yⁿ ₀ ⁺ product ions were of crucial importance for the determination of glycosylation patterns. The obtained results can be useful for HPLC/ESI-MS identification of rare flavonol-di-O-glycosides.

DFT calculations and POM analyses of cytotoxicity of some flavonoids from aerial parts of Cupressus sempervirens: Docking and identification of pharmacophore sites

Two known polyphenols named apigenin 7-O-β-d-glucopyranoside (S1) and querctine-3-O-glucoside (S2), along with another two new compounds apigenin 4'-geranyl-8-glucopyranosyl-7-O-α-glucopyranoside (S3) and apigenin 4'-pernyl-8-glucopyranosyl -7-O-α-glucopyranoside (S4), were isolated from the leaves of Cupressus sempervirens. Structure elucidation of the isolated polyphenols was established on the basis of detailed spectroscopic analysis like 1D and 2D NMR analyses including ¹H NMR, ¹³C NMR, COSY, DEPT, HMQC, UV, and Electron Spray Ionization Mass Spectroscopy (ESI-MS). Density Functional Theory (DFT) of computational, Petra/Osiris/Molinspiration (POM), and docking analyses methods were applied in the structural validation of new isolated compounds. The isolated compounds S1-S4 showed significant cytotoxicity against human hepatocellular liver carcinoma HepG2 cells, MCF-7, HC116 and A549.

In Vitro α-glucosidase Inhibition and Computational Studies of Kaempferol Derivatives from Dryopteris cycanida

BACKGROUND

Dryopteris cycadina has diverse traditional uses in the treatment of various human disorders which are supported by pharmacological studies. Similarly, the phytochemical studies of this plant led to the isolation of numerous compounds.

METHODOLOGY

The present study deals with α-glucosidase inhibition of various kaempferol derivates including kaempferol-3, 4/-di-O-α- L-rhamnopyranoside 1, kaempferol-3, 5-di-O-α-L-rhamnoside 2 and kaempferol-3,7-di-O-α- L-rhamnopyranoside 3.

RESULTS

The results showed marked concentration-dependent inhibition of the enzyme when assayed at different concentrations and the IC50 values of compounds 1-3 were 137±9.01, 110±7.33, and 136±1.10 mM, respectively far better than standard compound, acarbose 290±0.54 mM. The computational studies revealed strong docking scores of these compounds and augmented the in vitro assay.

CONCLUSION

In conclusion, the isolated kaempferol derivatives 1-3 from D. cycadina exhibited potent α- glucosidase inhibition.

Potent in Vitro α-Glucosidase Inhibition of Secondary Metabolites Derived from Dryopteris cycadina

α-glucosidase is responsible for the hydrolysis of complex carbohydrates into simple absorbable glucose and causes postprandial hyperglycemia. α-glucosidase inhibition is thus the ideal target to prevent postprandial hyperglycemia. The present study was therefore designed to analyze the effects of various compounds isolated from Dryopteris cycadina against α-glucosidase including β-Sitosterol 1, β-Sitosterol3-O-β-d-glucopyranoside 2, 3, 5, 7-trihydroxy-2-(p-tolyl) chorman-4-one 3, Quercetin-3-0-β-d-glucopyranoside (3^/→0-3^///)- β-d- Quercetin -3-0- β –d-galactopyranoside 4 and 5, 7, 4^/-Trihydroxyflavon-3-glucopyranoid 5. The in vitro spectrophotometric method was used for the analysis of test compounds against possible inhibition. Similarly, molecular docking studies were performed using the MOE software. These compounds showed concentration-dependent inhibition on α-glucosidase, and compounds 1 (IC₅₀: 143 ± 0.47 µM), 3 (IC₅₀:133 ± 6.90 µM) and 5 (IC₅₀: 146 ± 1.93 µM) were more potent than the standard drug, acarbose (IC₅₀: 290 ± 0.54 µM). Computational studies of these compounds strongly supported the in vitro studies and showed strong binding receptor sensitivity. In short, the secondary metabolites isolated from D. cycadina demonstrated potent α-glucosidase inhibition that were supported by molecular docking with a high docking score.