Are the reactive oxygen-derived species (ROS) interactive properties of the many therapeutic drugs from various categories pertinent to their beneficial effects?

Anti-inflammatory effects of locally applied enzyme-loaded ultradeformable vesicles on an acute cutaneous model

Superoxide dismutase (SOD) and catalase (CAT) are active scavengers of reactive oxygen species and were incorporated into ultradeformable vesicles with the aim of increasing enzyme bioavailability (skin delivery). These special very adaptable vesicles have been formulated and optimized for enzyme transport in order to penetrate into or across the intact skin barrier. Anti-inflammatory activity of SOD-loaded, CAT-loaded and of SOD- and CAT-loaded ultradeformable vesicles applied epicutaneously was measured using different protein doses on the skin, on an arachidonic acid-induced mouse ear oedema. The biological anti-oedema activity is a measurement of drug-targeting potentiation in the organ. Delivery by means of deformable vesicles was compared to conventional vesicles or the absence of an enzyme carrier mediated transport. This was done at various times following prophylactic application of the test formulations. Positive reference groups were treated epicutaneously with several low molecular weight non-steroidal anti-inflammatory drugs (NSAIDs). The latter included indomethacin (3 mg kg(-1)), etofenamate (30 mg kg(-1)) and piroxicam (1 mg kg(-1)) and reduced the oedema by 94 +/- 4%, 81 +/- 4% and 42 +/- 5%, respectively, if measured 30 min after ear treatment with a NSAID. Of the enzyme-loaded carriers tested, only the enzyme-loaded ultradeformable vesicles reduced the swelling of ears significantly: SOD (90 microg kg(-1)), CAT (250 microg kg(-1)) and SOD (90 microg kg(-1)) plus CAT (250 microg kg(-1)) reduced the oedema by 70 +/- 12%, 65 +/- 10% and 61 +/- 19%, respectively, at t = 30 min. Aqueous enzyme solutions and empty carriers had no such effect. The combination of two enzymes resulted in no increased therapeutic effect, but the results are inconclusive since only two dose combinations were tested. The results presented in this study suggest that antioxidant enzymes delivered by means of ultradeformable lipid vesicles can serve as a novel region-specific treatment of inflammation.

Inhibitory effects of resveratrol analogs on unopsonized zymosan-induced oxygen radical production

Resveratrol, a natural hydroxystilbene, has been reported to have anti-inflammatory and anticarcinogenic activities. Inhibitory effects of resveratrol and its analogs on reactive oxygen species (ROS) production in unopsonized zymosan-stimulated murine macrophage Raw264.7 cells, human monocytes, and neutrophils were analyzed to investigate if the anti-inflammatory and anticarcinogenic activities of resveratrol are related to the inhibition of ROS production. Resveratrol was a potent inhibitor of ROS production in both unopsonized zymosan-stimulated Raw264.7 cells and human monocytes and neutrophils. Resveratrol exhibited 50% inhibition values (IC50) of 17 microM in activated Raw264.7 cells, 18 microM in human monocytes, and 23 microM in human neutrophils. 3,5-Dihydroxy-4'-methoxystilbene or 3,4'-dimethoxy-5-hydroxystilbene exhibited IC50 values of 63 or 73 microM in Raw264.7 cells, 51 or >100 microM in human monocytes, and 10 or 37 microM in human neutrophils, respectively. Trimethylresveratrol, piceid, and 3,5-dihydroxy-4'-methoxystilbene-3-O-beta-D-glucoside were weak inhibitors of ROS production. Thus, resveratrol was identified as a potent inhibitor of ROS production, which might be one biochemical mechanism related to its anti-inflammatory and anticarcinogenic activities. The number and position of hydroxy substituents in resveratrol analogs seem to play an important role in the inhibitory potency of ROS production.

Antioxidants for hypertension

Increasing evidence implicates reactive oxygen species in the pathogenesis of hypertension and its cardiovascular complications. By altering the balance in the endothelium between vasoconstrictors such as thromboxane and isoprostanes and vasodilators such as nitric oxide, reactive oxygen species contribute to endothelium-dependent contractions and increased vascular resistance. Antioxidants can restore endothelial function and decrease blood pressure in several models of hypertension and in some, but not all, studies of humans with essential hypertension. The potential of antioxidant therapy for hypertension is considerable.

Why tryptophan hydroxylase is difficult to purify: a reactive oxygen-derived species-mediated phenomenon that may be implicated in human pathology

1. Attempts and apparently successful procedures to obtain reasonable quantities of electrophoretically homogenous mammalian brain-derived tryptophan hydroxylase, (TPH), have been described, starting in the early 1970s. This work has been carried out with the primary objective to obtain specific antisera to this enzyme to map out serotonergic pathways in the nervous system. 2. By using a multitude of techniques, antisera have indeed been fabricated and employed. However, it is doubtful if pure, native TPH has ever been produced. Indeed, there is strong evidence that more than one isoform of TPH exists in the rat brain. Thus, these antisera are probably directed against TPH-derived polypeptides and not the holoenzyme(s). 3. The difficulty in the purification of TPH lies not only in its subjectivity to proteolysis, but more importantly in its probable capacity to produce superoxide leading to hydrogen perioxide formation. This, in turn, may undergo Fenton chemistry with iron at the active site of the protein to produce hydroxyl radicals that directly attack and destroy the enzyme molecule. Evidence for such a mechanism is presented together with possible protocols that might be used to produce pure stable holo TPH(s). 4. It is hypothesized that similar oxidative events may take place in vivo under certain conditions leading to pathological results. Strategies to block these events are suggested.