Immunomodulating action of the 3-phenylcoumarin derivative 6,7-dihydroxy-3-[3',4'-methylenedioxyphenyl]-coumarin in neutrophils from patients with rheumatoid arthritis and in rats with acute joint inflammation.

OBJECTIVE: To examine whether free (3-PD-5free) and/or liposomal (3-PD-5lipo) 6,7-dihydroxy-3-[3',4'-methylenedioxyphenyl]-coumarin (3-PD-5) (1) modulate the effector functions of neutrophils from patients with rheumatoid arthritis under remission (i-RA) and with active disease (a-RA), in vitro; and (2) exert anti-inflammatory effect in a rat model of zymosan-induced acute joint inflammation. METHODS AND RESULTS: Incorporation of 3-PD-5 into unilamellar liposomes of soya phosphatidylcholine and cholesterol was efficient (57.5 ± 7.9%) and yielded vesicles with low diameter (133.7 ± 18.4 nm), polydispersity index (0.39 ± 0.06), and zeta potential (- 1.22 ± 0.34 mV). 3-PD-5free (1 µM) and 3-PD-5lipo (3 µM) equally suppressed elastase release and reactive oxygen species generation in neutrophils from healthy subjects and i-RA and a-RA patients, stimulated with immune complexes. 3-PD-5free (20 µM) suppressed the release of neutrophil extracellular traps and chemotaxis in vitro, without clear signs of cytotoxicity. 3-PD-5lipo (1.5 mg/kg, i.p.) diminished joint edema and synovial infiltration of total leukocytes and neutrophils, without changing the synovial levels of TNF-α, IL-1ß, and IL-6. CONCLUSION: Altogether, the results reported herein indicate that 3-PD-5 is a promising modulator of the early stages of acute joint inflammation that can help to diminish not only excessive neutrophil infiltration in the synovia but also neutrophil activation and its outcomes in RA patients.

In vitro evaluation of the antioxidant activity of liposomal flavonols by the HRP-H2O2-luminol system.

Considering that antioxidant flavonols have been reported to be beneficial to human health, but that their low water solubility and bioavailability limit their administration through systemic route, the development of suitable flavonol-carriers is of great importance for clinical therapeutics. The aim of this study was to prepare liposomes containing flavonols or not and evaluate their antioxidant activity. Vesicles were obtained by ethanol injection method and characterized in terms of entrapment efficiency, size and zeta potential. Inhibitory activity of liposomal flavonols on reactive oxygen species generation was assessed in vitro using luminol-H(2)O(2)-horseradish peroxidase technique. Antioxidant activity of liposomal flavonols is dependent on concentration and chemical structure of active compound. Quercetin and myricetin are the most active flavonols (IC(50) = 0.6-0.9 µmol/L), followed by kaempferol (IC(50) = 3.0-4.5 µmol/L) and galangin (IC(50) = 4.0-7.0 µmol/L). Our results suggest that antioxidant-loaded liposomes may be promising tools for therapy of diseases where oxidative stress is involved.

Incorporation of Baccharis dracunculifolia DC (Asteraceae) leaf extract into phosphatidylcholine-cholesterol liposomes improves its anti-inflammatory effect in vivo.

The aerial parts of Baccharis dracunculifolia (BdE) is used in the Brazilian folk medicine to treat inflammatory conditions. Here we examined the ability of free and liposomal BdE to modulate reactive oxygen species generation in human neutrophils in vitro and zymosan-induced acute joint inflammation in Wistar rats. We prepared biocompatible liposomes of soya phosphatidylcholine and cholesterol with low diameter, homogeneous size distribution, and neutral surface charge. Free BdE decreased joint swelling, total leucocyte and neutrophil infiltration, and the synovial levels of tumour necrosis factor-α and interleukins 6 and 1ß. Incorporation of BdE into liposomes preserved its capacity to inhibit the neutrophil superoxide anion and total reactive oxygen species generation, and improved its anti-inflammatory effect in vivo by decreasing the effective BdE dose by nearly sixfold. The same liposome type lowered the effective dose of caffeic acid by nearly sixteenfold. Therefore, incorporation of BdE into phosphatidylcholine-cholesterol liposomes improves its anti-inflammatory effect.