Identification of chalcones as potent and selective PDE5A1 inhibitors

Isolation, bioassay and 3D-QSAR analysis of 8-isopentenyl flavonoids from Epimedium sagittatum maxim. as PDE5A inhibitors

BACKGROUND

As known, inhibition of phosphodiesterase 5 (PDE5) has the therapeutic effect on male erectile dysfunction (ED), and the processed folium of Epimedium sagittatum Maxim. (PFES) characterized by 8-isopentenyl flavonoids is a famous herb for treating ED. However, the main flavonoids inhibitory activities, structure-activity relationship (SAR) and signaling pathway have been not systematically studied so that its pharmacodynamic mechanism is unclear.

METHODS

We aimed to initially reveal the PFES efficacy mechanism for treating ED. For the first time, 6 main 8-isopentenyl flavonoids (1-6) from PFES were isolated and identified. Then based on HPLC detection, we proposed a novel method to screen inhibitors among them. We further analyze the three-dimensional quantitative structure-activity relationship (3D-QSAR) for those inhibitors.

RESULTS

The results were verified by cellular effects of the screened flavonoids. Among 6 compounds, Icariin: (1), 2-O''rhamnosylicaridide II (2) and Baohuoside I (3) were identified with significant activities (IC₅₀ = 8.275, 3.233, 5.473 μM). Then 3D-QSAR studies showed that the replacement of C8 with bulky steric groups as isopentenyl, C3 with positive charge groups and C4' with a hydrogen bond acceptor substituent could increase inhibitory effects. In contrast, the substitution of C7 with bulky steric groups or hydrophilic groups tended to decrease the efficacies. And compounds 1, 2, 3 could increase cGMP level and decrease cytoplasmic Ca²⁺ of rat corpus cavernosum smooth muscle cells (CCSMCs)by activating PKG.

CONCLUSION

8-isopentenyl flavonoids could be the main pharmacodynamic substances of PFES in the treatment for ED, and some had significant PDE5A1 inhibitory activities so as to activate cGMP/PKG/Ca²⁺ signaling pathway in CCSMCs, that was related to the substituents at the key sites such as C8, C3, C4' and C7 in the characteristic compounds.

Vasorelaxant Effect of Novel Nitric Oxide-Hydrogen Sulfide Donor Chalcone in Isolated Rat Aorta: Involvement of cGMP Mediated sGC and Potassium Channel Activation

BACKGROUND AND OBJECTIVE

Recently, nitric oxide (NO) and hydrogen sulfide (H2S) donating moieties were extensively studied for their role in the vasculature as they are responsible for many cellular and pathophysiological functioning. The objective of the present study is to evaluate novel NO and H2S donating chalcone moieties on isolated rat aorta for vasorelaxation, and to investigate the probable mechanism of action.

METHODS

To extend our knowledge of vasorelaxation by NO and H2S donor drugs, here we investigated the vasorelaxing activity of novel NO and H2S donating chalcone moieties on isolated rat aorta. The mechanism of vasorelaxation by these molecules was investigated by performing in vitro cGMP mediated sGC activation assay and using Tetraethylammonium chloride (TEA) as a potassium channel blocker and Methylene blue as NO blocker.

RESULTS

Both NO and H2S donating chalcone moieties were found to be potent vasorelaxant. The compound G4 and G5 produce the highest vasorelaxation with 3.716 and 3.789 M of pEC50, respectively. After the addition of TEA, G4 and G5 showed 2.772 and 2.796 M of pEC50, respectively. The compounds Ca1, Ca2, and D7 produced significant activation and release of cGMP mediated sGC which was 1.677, 1.769 and 1.768 M of pEC50, respectively.

CONCLUSION

The vasorelaxation by NO-donating chalcones was blocked by Methylene blue but it did not show any effect on H2S donating chalcones. The vasorelaxing potency of NO-donating molecules was observed to be less affected by the addition of TEA but H2S donors showed a decrease in both efficacy and potency. The cGMP release was more in the case of NO-donating molecules. The tested compounds were found potent for relaxing vasculature of rat aorta.

The synthesis of a novel pentoxifylline derivative with superior human sperm motility enhancement properties

mPTF1 demonstrated lower genotoxicity, higher affinity for PDEs, & reasonable pharmacokinetic, druglikeness & ADMET properties compared to Pentoxifylline.

Investigation of anti-inflammatory, nitric oxide donating, vasorelaxation and ulcerogenic activities of 1, 3-diphenylprop-2-en-1-one derivatives in animal models

The main aim of this work is to find out novel chemical moieties with potent anti-inflammatory and vasorelaxant activities with reduced gastric toxicities. For fulfilling the above aim, here we investigated novel chalcones (1, 3-diphenylprop-2-en-1-one derivatives) with nitric oxide (NO) and hydrogen sulphide (H₂ S) donating potency for anti-inflammatory activity by carrageenan-induced rat paw oedema. These molecules then further evaluated for in-vitro NO-releasing potency and vasorelaxation effect on isolated adult goat aortic tissue. The promising molecules were further screened for ulcerogenic activity in the rat model. The tested compounds produced % inhibition in paw oedema ranging from 29.16% to 79.69% and standard drug Diclofenac sodium produced 85.30% reduction in paw oedema after 5 hours. Out of this dataset, compounds AI1, AI7, Ca1, B2, B10, D2, and E8 showed 73.01%, 79.69%, 75.02%, 75.46%, 74.35%, 73.9% and 74.35% reduction in paw oedema respectively, which is approximately 80%-90% to that of standard Diclofenac sodium. The compound Ca1 was found to release 0.870 ± 0.025 mol/mol of NO and standard Glyceryl trinitrate (GTN) was found to release 0.983 ± 0.063 mol/mol of NO. The compound Ca1 produced 950.2 μmol/L of EC₅₀ whereas standard GTN produced 975.8 μmol/L of EC₅₀ for aortic smooth relaxation. The compounds Ca1 produced 0.1117 of ulcer index which is far less than that of standard Diclofenac sodium (1.148). The potent lead molecules were further evaluated to understand the mechanism of vasorelaxation by using specific antagonists or blockers of NO and H₂ S.

Synthesis, docking studies and in vitro evaluation of novel chalcones as potent inhibitors of phosphodiesterase 5 from human platelets and 5A from bovine recombinant

Chalcones with a nitric oxide (NO) donating scaffold and a variety of substituents were synthesized. A docking study was performed and molecules were evaluated for in vitro phosphodiesterase 5 and 5A inhibitory potency.