Cytotoxicity and comparative binding mechanism of piperine with human serum albumin and α-1-acid glycoprotein

<div><p>Human serum albumin (HSA) and α-1-acid glycoprotein (AGP) (acute phase protein) are the plasma proteins in blood system which transports many drugs. To understand the pharmacological importance of piperine molecule, here, we studied the anti-inflammatory activity of piperine on mouse macrophages (RAW 264.7) cell lines, which reveals that piperine caused an increase in inhibition growth of inflammated macrophages. Further, the fluorescence maximum quenching of proteins were observed upon binding of piperine to HSA and AGP through a static quenching mechanism. The binding constants obtained from fluorescence emission were found to be <i>K</i>_piperine= 5.7 ± .2 × 10⁵ M⁻¹ and <i>K</i>_piperine = 9.3± .25 × 10⁴ M⁻¹ which correspond to the free energy of −7.8 and −6.71 kcal M⁻¹at 25 °C for HSA and AGP, respectively. Further, circular dichrosim studies revealed that there is a marginal change in the secondary structural content of HSA due to partial destabilization of HSA–piperine complexes. Consequently, inference drawn from the site-specific markers (phenylbutazone, site I marker) studies to identify the binding site of HSA noticed that piperine binds at site I (IIA), which was further authenticated by molecular docking and molecular dynamic (MD) studies. The binding constants and free energy corresponding to experimental and computational analysis suggest that there are hydrophobic and hydrophilic interactions when piperine binds to HSA. Additionally, the MD studies have showed that HSA–piperine complex reaches equilibration state at around 3 ns, which prove that the HSA–piperine complex is stable in nature.</p></div

Molecular binding mechanism of 5-hydroxy-1-methylpiperidin-2-one with human serum albumin

Molecular binding mechanism of 5-hydroxy-1-methylpiperidin-2-one with human serum albumi

Probing the interaction mechanism of menthol with blood plasma proteins and its cytotoxicity activities

Probing the interaction mechanism of menthol with blood plasma proteins and its cytotoxicity activitie

Binding and Molecular Dynamics Studies of 7‑Hydroxycoumarin Derivatives with Human Serum Albumin and Its Pharmacological Importance

Human serum albumin (HSA) is one of the most widely studied proteins and is an important plasma protein responsible for binding and transport of many exogenous and endogenous drugs. Coumarin derivatives play a critical role as anticancer, antidiabetic, anticoagulant, and analgesic agents. Here we have studied the cytotoxic activity of 7-hydroxycoumarin derivatives (7HC-1, 7HC-2, and 7HC-3) on mouse macrophage (RAW 264.7) cell lines. These studies revealed that 7-hydroxycoumarin derivatives caused an increased inhibition in growth of inflamed macrophages in a concentration-dependent manner with an IC₅₀ of 78, 63, and 50 μM. Further studies, using fluorescence, circular dichroism spectroscopy, molecular docking, and molecular dynamics methods, show binding of 7HC (umbelliferone) derivatives with HSA at physiological pH 7.2. The binding constant of 7HC derivatives with HSA obtained from fluorescence emission was found to be <i>K</i>_7HC‑1 = 4.6 ± 0.01 × 10⁴ M^–1, <i>K</i>_7HC‑2 = 1.3 ± 0.01 × 10⁴ M^–1, and <i>K</i>_7HC‑3 = 7.9 ± 0.01 × 10⁴ M^–1 which corresponds to −6.34 kcal/mol, −5.58 kcal/mol, and −6.65 kcal/mol of free energy. In contrast, the binding of these coumarin derivatives (7HC-1, 7HC-2, and 7HC-3) was almost negligible with α-1-glycoprotein (AGP). Circular dichroism (CD) studies revealed a decreased α-helix content with an increase in the β-sheets and random coils in HSA upon interaction with coumarin derivatives, suggesting a partial unfolding of the HSA secondary structure. Site probe studies with phenylbutazone (Site I) and ibuprofen (Site II) indicated that 7HC derivatives specifically bind to sub domains IIIA and IIIB of HSA which is further corroborated by molecular dynamics and docking studies suggesting that binding is specific in nature. The values of free energies and binding constants coincide for both experimental and <i>in silico</i> analysis and suggest that there are hydrophobic interactions when coumarin derivatives bind to HSA. Molecular dynamics studies showed that the HSA–coumarin complex reaches an equilibration state at around 3.5 ns which indicates that the HSA–coumarin complexes were stable. Thus these interactions play a central role in development of coumarin derivative-inspired drugs

New Flavone-Cyanoacetamide Hybrids with a Combination of Cholinergic, Antioxidant, Modulation of β‑Amyloid Aggregation, and Neuroprotection Properties as Innovative Multifunctional Therapeutic Candidates for Alzheimer’s Disease and Unraveling Their Mechanism of Action with Acetylcholinesterase

In line with the modern multi-target-directed ligand paradigm of Alzheimer’s disease (AD), a series of 19 compounds composed of flavone and cyanoacetamide groups have been synthesized and evaluated as multifunctional agents against AD. Biological evaluation demonstrated that compounds <b>7j</b>, <b>7n</b>, <b>7o</b>, <b>7r</b>, and <b>7s</b> exhibited excellent inhibitory potency (AChE, IC₅₀ of 0.271 ± 0.012 to 1.006 ± 0.075 μM) and good selectivity toward acetylcholinesterase, significant antioxidant activity, good modulation effects on self-induced Aβ aggregation, low cytotoxicity, and neuroprotection in human neuroblastoma SK-N-SH cells. Further, an inclusive study on the interaction of <b>7j</b>, <b>7n</b>, <b>7o</b>, <b>7r</b>, and <b>7s</b> with AChE at physiological pH 7.2 using fluorescence, circular dichroism, and molecular docking methods suggested that these derivatives bind strongly to the peripheral anionic site of AChE mostly through hydrophobic interactions. Overall, the multifunctional profiles and strong AChE binding affinity highlight these compounds as promising prototypes for further pursuit of innovative multifunctional drugs for AD