Dapsone as a potential treatment option for Henoch-Schönlein Purpura (HSP).

Henoch-Schönlein Purpura (HSP, IgA vasculitis) is an immunoglobulin A (IgA) mediated disorder characterized by systemic vasculitis with variable presentation, frequently affecting the skin, mucous membrane, joints, kidneys, and rarely lungs and the central nervous system. Interestingly, enhanced production of interleukin-8 (IL-8) levels are found during active disease and increased levels have been reported in supernatants from human umbilical venous endothelial cells after stimulation with sera from patients affected by HSP. While corticosteroid therapy is currently the recommended treatment for HSP, dapsone, an anti-leprosy agent, has also recently been suggested to have therapeutic efficacy due to its ability to suppress IL-8. Moreover, in addition to IL-8 suppression, dapsone has been reported to exert various anti-inflammatory effects by inhibiting the generation of toxic free radicals, myeloperoxidase mediated halogenation that converts H2O2 to HOCl, leukocyte chemotaxis, production of tumor necrosis factor, and other anti-inflammatory molecules. This review aims to provide a solid hypothesis for the pathogenesis of vasculitis in HSP. Moreover, we highlight potential mechanistic actions of dapsone in hopes that dapsone may be considered as an alternative viable treatment for patients affected by HSP.

Phytochemical screening and evaluation of in vitro antioxidant and antimicrobial activities of the indigenous medicinal plant Albizia odoratissima.

CONTEXT: Albizia odoratissima (L. f.) Benth has been used in Indian folk medicine to treat numerous inflammatory pathologies, such as leprosy, ulcers, burns and asthma. OBJECTIVE: To evaluate the antioxidant and antimicrobial properties of A. odoratissima. MATERIALS AND METHODS: Dried leaves of A. odoratissima were extracted in organic solvents (hexane, chloroform, ethyl acetate, and methanol). The total phenolic content (TPC) and total flavonoid content (TFC) were determined using the Folin-Ciocalteu and aluminum chloride colorimetric methods, respectively. The antioxidant activity was examined using 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydrogen peroxide (H2O2), 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS), and ferric reducing antioxidant power (FRAP) assays. The antibacterial activity was examined using minimum inhibitory concentration (MIC) and the minimum bacterial concentration (MBC), determined by broth microdilution method against Gram-negative bacteria (Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, and Proteus vulgaris) and Gram-positive bacterium (Staphylococcus aureus). RESULTS: The TPC ranged from 4.40 ± 1.06 to 1166.66 ± 31.85 mg GAE/g of dry weight (DW), and the TFC ranged from 48.35 ± 3.62 to 109.74 ± 1.84 mg QE/g of DW. The IC50 values of the ethyl acetate extract for DPPH, ABTS, and H2O2 were 10.96 ± 0.40, 4.35 ± 0.07, and 163.82 ± 1.52 µg/mL, respectively. Both methanol and ethyl acetate extracts demonstrated effective antibacterial activity with MICs and MBCs values ranging 136-546 µg/mL and 273-1093 µg/mL, respectively, against the tested pathogenic species. CONCLUSIONS: The leaves of A. odoratissima showed potent free radical scavenging property and antimicrobial activity.

H2O2 and (.)NO scavenging by Mycobacterium leprae truncated hemoglobin O.

Kinetics of ferric Mycobacterium leprae truncated hemoglobin O (trHbOFe(III)) oxidation by H2O2 and of trHbOFe(IV)O reduction by (.)NO and NO2- are reported. The value of the second-order rate constant for H2O2-mediated oxidation of trHbOFe(III) is 2.4 x 10(3) M(-1) s(-1). The value of the second-order rate constant for (.)NO-mediated reduction of trHbOFe(IV)O is 7.8 x 10(6) M(-1) s(-1). The value of the first-order rate constant for trHbOFe(III)ONO decay to the resting form trHbOFe(III) is 2.1 x 10(1) s(-1). The value of the second-order rate constant for NO2--mediated reduction of trHbOFe(IV)=O is 3.1 x 10(3) M(-1) s(-1). As a whole, trHbOFe(IV)O, generated upon reaction with H2O2, catalyzes (.)NO reduction to NO2-. In turn, (.)NO and NO2- act as antioxidants of trHbOFe(IV)O, which could be responsible for the oxidative damage of the mycobacterium. Therefore, Mycobacterium leprae trHbO could be involved in both H2O2 and (.)NO scavenging, protecting from nitrosative and oxidative stress, and sustaining mycobacterial respiration.