Strategies for Avoiding Benzopyrone Hepatotoxicity in Lymphedema Management-The Role of Pharmacogenetics, Metabolic Enzyme Gene Identification, and Patient Selection.

INTRODUCTION: Benzopyrones are plant-derived chemicals which have an evidenced degree of clinical efficacy in lymphedema management indicated in past trials. Unfortunately, in some of these cases idiosyncratic hepatotoxicity have been documented in a minority of patients. This review aims to tackle the problem of benzopyrone (particularly coumarin) toxicity by considering their metabolic pathways and identifying relevant alleles needed to take a targeted pharmacogenetic approach in its future use. METHODS AND RESULTS: The nontoxic 7-hydroxylation and the toxic heterocyclic "ring-splitting" epoxidation pathways are the two main detoxification pathways in the hepatometabolism of coumarin, the former catalyzed by CYP2A6 and the latter by possibly CYP1A and CYP2E. Acetaldehyde dehydrogenase (ALDH) clears toxic aldehyde intermediates. CYP2A6 polymorphism screening methods, including genotyping, by real-time polymerase chain reaction and chromatography-mass spectroscopy functional metabolite assays; efficiency of these techniques are continually improving. ALDH polymorphisms have also been implicated, with clinically viable screening tests, rapid genotyping, and sensitive questionnaires already available for ALDH2*1/ALDH2*2. Dysfunctional polymorphisms of the above genes and others are significantly more prevalent in Eastern Asian populations, uncommon in Caucasian populations. The role of other enzymes/genes in the pathway is yet to be clarified. CONCLUSION: Although screening techniques are becoming increasingly clinically feasible, uncertainty remains on the link between the genotype, metabolic phenotype, and the exact gene products involved. These must be elucidated further before a targeted pharmacogenomic approach is fully viable. In the meantime, treatment should be avoided in those with vulnerable familial and ethnic descents if used.

Shilajit attenuates behavioral symptoms of chronic fatigue syndrome by modulating the hypothalamic-pituitary-adrenal axis and mitochondrial bioenergetics in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Shilajit has been used as a rejuvenator for ages in Indian ancient traditional medicine and has been validated for a number of pharmacological activities. AIM OF THE STUDY: The effect of processed shilajit which was standardized to dibenzo-α-pyrones (DBPs;0.43% w/w), DBP-chromoproteins (DCPs; 20.45% w/w) and fulvic acids (56.75% w/w) was evaluated in a rat model of chronic fatigue syndrome (CFS). The mitochondrial bioenergetics and the activity of hypothalamus-pituitary-adrenal (HPA) axis were evaluated for the plausible mechanism of action of shilajit. MATERIALS AND METHODS: CFS was induced by forcing the rats to swim for 15mins for 21 consecutive days. The rats were treated with shilajit (25, 50 and 100mg/kg) for 21 days before exposure to stress procedure. The behavioral consequence of CFS was measured in terms of immobility and the climbing period. The post-CFS anxiety level was assessed by elevated plus maze (EPM) test. Plasma corticosterone and adrenal gland weight were estimated as indices of HPA axis activity. Analysis of mitochondrial complex chain enzymes (Complex I, II, IV and V) and mitochondrial membrane potential (MMP) in prefrontal cortex (PFC) were performed to evaluate the mitochondrial bioenergetics and integrity respectively. RESULTS: Shilajit reversed the CFS-induced increase in immobility period and decrease in climbing behavior as well as attenuated anxiety in the EPM test. Shilajit reversed CFS-induced decrease in plasma corticosterone level and loss of adrenal gland weight indicating modulation of HPA axis. Shilajit prevented CFS-induced mitochondrial dysfunction by stabilizing the complex enzyme activities and the loss of MMP. Shilajit reversed CFS-induced mitochondrial oxidative stress in terms of NO concentration and, LPO, SOD and catalase activities. CONCLUSION: The results indicate that shilajit mitigates the effects of CFS in this model possibly through the modulation of HPA axis and preservation of mitochondrial function and integrity. The reversal of CFS-induced behavioral symptoms and mitochondrial bioenergetics by shilajit indicates mitochondria as a potential target for treatment of CFS.

Pharmacological treatment for chronic oedema.

Chronic oedema is mainly treated by physical methods (compression, lymphatic drainage, massage and exercise), with drugs not having a major role to play. However, antibiotics are essential in the management of cellulitis, a common and important complication of chronic oedema. Diuretics and cortico-steroids may be appropriate in some types of oedema such as that associated with advanced cancer. Analgesics may be helpful in managing pain, particularly in the short term e.g. pain from cellulitis, although long-term use may also be appropriate, e.g. in cancer pain. Benzopyrones are not routinely used in the management of lymphoedema in the UK.

The importance of carcinogen dose in chemoprevention studies: quantitative interrelationships between, dibenzo[a,l]pyrene dose, chlorophyllin dose, target organ DNA adduct biomarkers and final tumor outcome.

Chlorophyllin (CHL) is a potent antimutagen in vitro, an effective anti-carcinogen in several animal models, and significantly reduced urinary biomarkers of aflatoxin B(1) (AFB(1)) exposure in a human population. Here we report an expanded analysis of CHL chemoprevention using the potent environmental hydrocarbon dibenzo[a,l]pyrene (DBP). A dose-dose matrix design employed over 12 000 rainbow trout to evaluate the interrelationships among dietary carcinogen dose, anti-carcinogen dose, carcinogen-DNA adduct levels at exposure and eventual tumor outcome in two target organs. Included was an evaluation of the pharmaceutical CHL preparation (Derifil), used previously in a study of individuals chronically exposed to AFB(1). CHL was pre-, co- and post-fed at doses of 0-6000 p.p.m. and co-fed with DBP at doses of 0-371.5 p.p.m. for 4 weeks. This protocol generated a total of 21 dose-dose treatment groups, each evaluated with three or more replicates of 100 animals. The DBP-only treatment produced dose-responsive increases in liver and stomach DBP-DNA adducts, whereas increasing CHL co-treatment doses produced successive inhibition in liver (49-83%) and stomach (47-75%) adduct levels at each DBP dose examined. The remaining 8711 trout were necropsied, 10 months later. DBP treatment alone produced a logit incidence versus log [DBP] dose-response curve in stomach that was linear; CHL co-treatment provided dose-dependent tumor inhibition which ranged from 30 to 68% and was predictable from the adduct response. The Derifil CHL preparation was also found to effectively reduce DNA adduction and final tumor incidence in stomach (as well as liver), with a potency compatible with its total chlorin content. Liver tumor incidence in the DBP-only groups appeared to plateau near 60%. At DBP doses of

[Comparison of fenoterol (Berotec) with the antiallergic benzopyrene compound PR-D 92 and a placebo in regard to the cutaneous immediate reaction in allergic patients (author's transl)]. / Wirkungsvergleich von Fenoterol (Berotec) mit einem Antiallergikum aus der Reihe der Benzopyrane (PR-D 92) unter Placebo-Kontrolle bei der Kutanen Sofortreaktion des Menschen.

After discussion of today's knowledge of the mechanism of allergic reactions with particular regard to the adenylyl cyclase system a report is given on an experimental study in which Fenoterol (Berotec), PR-D 92 (Bisbenzopyran) as well as placebo were repeatedly applied to defined areas of the forearm of 30 patients with known pollen allergies. The expansion of the allergy-induced erythemae and weals was exactly measured. A comparison of the sizes showed approximately 50% inhibition of the reaction following application of Berotec, the difference being highly significant compared with PR-D 92 and placebo. There was no statistical difference between the last two.

Drug-induced proteolysis: a correlation with oedema-reducing ability.

A very strong correlation has been shown to exist between acid and neutral protease activity levels in the skin, the acid protease activity level of the oedema fluid, and the oedema-reducing ability of the benzo-pyrones and related drugs. Macrophages, which are believed to be the main cells affected by the drugs, are very common in thermally injured tissues. Their lysosomal enzymes work at an acid pH. Since the main acid protease is cathepsin D, the overall acid protease levels are representative of changes in cathepsin D levels. Elevated levels are concomitant with more complete and rapid digestion of accumulated protein. The resulting fragments then can rapidly leave the injured tissues, freeing the oedema fluid. This form of proteolysis is very much different from that which is used by pharmacologists as a measure of inflammation. Normal proteolysis in inflammation represents an estimate of tissue derangement, but the proteolysis induced by drugs such as the benzo-pyrones represents a means of lessening some of the more injurious effects of this derangement. The results presented here strongly confirm this.