Anti-Inflammatory Properties of Novel 1,2-Benzothiazine Derivatives and Their Interaction with Phospholipid Model Membranes

Abstract

The design of novel anti-inflammatory drugs remains a critical area of research in the development of effective treatments for inflammatory diseases. In this study, a series of 1,2-benzothiazine was evaluated through a multifaceted approach. In particular, we investigated the potential interactions of the potential drugs with lipid bilayers, an important consideration for membrane permeability and overall pharmacokinetics. In addition, we evaluated their ability to inhibit cyclooxygenase 1 and cyclooxygenase 2 activity and selectivity using both a cyclooxygenase inhibition assay and molecular docking simulations. To evaluate their therapeutic potential, we performed in vitro assays to measure cytokine mRNA expression in inflamed cells. The antioxidant activity was evaluated using both in vitro assays, such as 2,2-diphenyl-1-picrylhydrazyl and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid scavenging, to determine the compounds' capacity to neutralize free radicals and reduce oxidative stress. Theoretical calculations, including density functional theory, were used to predict the reactivity profiles of the compounds.

Keywords: 1,2-benzothiazine derivatives; anti-inflammatory activity; antioxidant properties; drug–membrane interaction.

Figure 1

Structure of the model drug—meloxicam.

Figure 2

Structures of a non-ulcerogenic 1,2-benzothiazine (a) and new designed arylpiperazine derivatives of 1,2-benzothiazine (b–d).

Scheme 1

Synthesis of new 1,2-benzothiazine derivatives BS23–BS30.

Figure 3

The exemplary thermograms obtained for DPPC mixed with compounds: (A) BS23 and (B) BS24 as well as for pure lipid (the first curve from the top—black color): DPPC molar ratios from the top to the bottom: 0 (pure lipid), 0.06, 0.08, 0.10, and 0.12; the direction of the endothermic reaction is upwards.

Figure 4

Influence of all studied compounds on the DPPC main transition temperature (A); influence of two studied compounds (BS24 and BS27) and meloxicam on the DPPC main transition temperature (B).

Figure 5

Influence of studied compounds on the DPPC peak half-width.

Figure 6

Relative main transition temperature (T_m/T_m⁰) for DPPC and DMPC in the presence of studied compounds at compound: phospholipid molar ratio 1:10; T_m⁰—the main transition temperature for pure lipid; T_m—the main transition temperature in the presence of studied compounds at compound: phospholipid molar ratio 1:10; full symbols—DPPC, open symbols—DMPC.

Figure 7

Anti-inflammatory effect after incubation of NHDF cells with lipopolysaccharide (LPS) and then the tested compounds. The black column presents the BS23 compound and the white column the BS28 compound. (A) MTT assay; (B) DCF-DA assay. Data presented as a mean and SD; * p < 0.05—significant difference compared to the control (cells with only medium); # p < 0.05 significant difference compared to the positive control (cells treated with only LPS).

Figure 8

Relative expression of TNF-α (left panel) and IL-6 (right panel) in NHDF cells. (A) Control—only NHDF cells, (B) NHDF cells incubated with lipopolysaccharide (LPS), (C) NHDF cells incubated with lipopolysaccharide (LPS) treated with 10 µM of BS23, and (D) NHDF cells incubated with lipopolysaccharide (LPS) treated with 10 µM of BS28. The values represent mean ± SD from three experiments. * p < 0.05—significant difference compared to the control (cells with only medium); # p < 0.05 significant difference compared to the positive control (cells treated with only LPS).

Figure 9

The binding mode of meloxicam (blue and top) and compound BS23 (pink and bottom) in the active center of COX-2.