Inhibitory effects of helenalin and related compounds on 5-lipoxygenase and leukotriene C(4) synthase in human blood cells

Arachidonic acid in aging: New roles for old players

BACKGROUND

Arachidonic acid (AA), one of the most ubiquitous polyunsaturated fatty acids (PUFAs), provides fluidity to mammalian cell membranes. It is derived from linoleic acid (LA) and can be transformed into various bioactive metabolites, including prostaglandins (PGs), thromboxanes (TXs), lipoxins (LXs), hydroxy-eicosatetraenoic acids (HETEs), leukotrienes (LTs), and epoxyeicosatrienoic acids (EETs), by different pathways. All these processes are involved in AA metabolism. Currently, in the context of an increasingly visible aging world population, several scholars have revealed the essential role of AA metabolism in osteoporosis, chronic obstructive pulmonary disease, and many other aging diseases.

AIM OF REVIEW

Although there are some reviews describing the role of AA in some specific diseases, there seems to be no or little information on the role of AA metabolism in aging tissues or organs. This review scrutinizes and highlights the role of AA metabolism in aging and provides a new idea for strategies for treating aging-related diseases.

KEY SCIENTIFIC CONCEPTS OF REVIEW

As a member of lipid metabolism, AA metabolism regulates the important lipids that interfere with the aging in several ways. We present a comprehensivereviewofthe role ofAA metabolism in aging, with the aim of relieving the extreme suffering of families and the heavy economic burden on society caused by age-related diseases. We also collected and summarized data on anti-aging therapies associated with AA metabolism, with the expectation of identifying a novel and efficient way to protect against aging.

Arnica montana L.: Doesn't Origin Matter?

Arnica montana L. (Asteraceae) has a long and successful tradition in Europe as herbal medicine. Arnica flowers (i.e., the flowerheads of Arnica montana) are monographed in the European Pharmacopoeia (Ph. Eur.), and a European Union herbal monograph exists, in which its use as traditional herbal medicine is recommended. According to this monograph, Arnica flowers (Arnicae flos Ph. Eur.) and preparations thereof may be used topically to treat blunt injuries and traumas, inflammations and rheumatic muscle and joint complaints. The main bioactive constituents are sesquiterpene lactones (STLs) of the helenanolide type. Among these, a variety of esters of helenalin and 11α,13-dihydrohelenalin with low-molecular-weight carboxylic acids, namely, acetic, isobutyric, methacrylic, methylbutyric as well as tiglic acid, represent the main constituents, in addition to small amounts of the unesterified parent STLs. A plethora of reports exist on the pharmacological activities of these STLs, and it appears unquestioned that they represent the main active principles responsible for the herbal drug's efficacy. It has been known for a long time, however, that considerable differences in the STL pattern occur between A. montana flowers from plants growing in middle or Eastern Europe with some originating from the Iberic peninsula. In the former, Helenalin esters usually predominate, whereas the latter contains almost exclusively 11α,13-Dihydrohelenalin derivatives. Differences in pharmacological potency, on the other hand, have been reported for the two subtypes of Arnica-STLs in various instances. At the same time, it has been previously proposed that one should distinguish between two subspecies of A. montana, subsp. montana occurring mainly in Central and Eastern Europe and subsp. atlantica in the southwestern range of the species distribution, i.e., on the Iberian Peninsula. The question hence arises whether or not the geographic origin of Arnica montana flowers is of any relevance for the medicinal use of the herbal drug and the pharmaceutical quality, efficacy and safety of its products and whether the chemical/pharmacological differences should not be recognized in pharmacopoeia monographs. The present review attempts to answer these questions based on a summary of the current state of botanical, phytochemical and pharmacological evidence.

Anti-Inflammatory Activities of Arnica montana Planta Tota versus Flower Extracts: Analytical, In Vitro and In Vivo Mouse Paw Oedema Model Studies

Arnica montana is well known for its anti-inflammatory properties. While the anti-inflammatory activity of Arnica flowers (Arnicae flos) has been extensively studied, that of the whole plant (Arnicae planta tota) is less characterized. We compared the ability of Arnicae planta tota and Arnicae flos extracts to inhibit the pro-inflammatory NF-κB-eicosanoid pathway, using several in vitro and in vivo assays. We showed that Arnicae planta tota inhibited NF-κB reporter activation, with an IC₅₀ of 15.4 μg/mL (vs. 52.5 μg/mL for Arnicae flos). Arnicae planta tota also inhibited LPS-induced expression of ALOX5 and PTGS2 genes in human differentiated macrophages. ALOX5 and PTGS2 encode the 5-lipoxygenase (5-LO) and cyclooxygenase-2 (COX-2) enzymes that initialize the conversion of arachidonic acid into leukotrienes and prostaglandins, respectively. Arnicae planta tota inhibited 5-LO and COX-2 enzymatic activity in vitro and in human primary peripheral blood cells, with lower IC₅₀ compared to Arnicae flos. Finally, Arnicae planta tota applied topically reduced carrageenan-induced mouse paw oedema more efficiently than Arnicae flos. Altogether, Arnicae planta tota displayed a superior anti-inflammatory activity compared to Arnicae flos, suggesting that Arnicae-planta-tota-containing products might be more effective in alleviating the manifestations of acute inflammation than those based on Arnicae flos alone.

Sesquiterpene Lactones: Promising Natural Compounds to Fight Inflammation

Inflammation is a crucial and complex process that reestablishes the physiological state after a noxious stimulus. In pathological conditions the inflammatory state may persist, leading to chronic inflammation and causing tissue damage. Sesquiterpene lactones (SLs) are composed of a large and diverse group of highly bioactive plant secondary metabolites, characterized by a 15-carbon backbone structure. In recent years, the interest in SLs has risen due to their vast array of biological activities beneficial for human health. The anti-inflammatory potential of these compounds results from their ability to target and inhibit various key pro-inflammatory molecules enrolled in diverse inflammatory pathways, and prevent or reduce the inflammatory damage on tissues. Research on the anti-inflammatory mechanisms of SLs has thrived over the last years, and numerous compounds from diverse plants have been studied, using in silico, in vitro, and in vivo assays. Besides their anti-inflammatory potential, their cytotoxicity, structure–activity relationships, and pharmacokinetics have been investigated. This review aims to gather the most relevant results and insights concerning the anti-inflammatory potential of SL-rich extracts and pure SLs, focusing on their effects in different inflammatory pathways and on different molecular players.

Terpenoids as Potential Geroprotectors

Terpenes and terpenoids are the largest groups of plant secondary metabolites. However, unlike polyphenols, they are rarely associated with geroprotective properties. Here we evaluated the conformity of the biological effects of terpenoids with the criteria of geroprotectors, including primary criteria (lifespan-extending effects in model organisms, improvement of aging biomarkers, low toxicity, minimal adverse effects, improvement of the quality of life) and secondary criteria (evolutionarily conserved mechanisms of action, reproducibility of the effects on different models, prevention of age-associated diseases, increasing of stress-resistance). The number of substances that demonstrate the greatest compliance with both primary and secondary criteria of geroprotectors were found among different classes of terpenoids. Thus, terpenoids are an underestimated source of potential geroprotectors that can effectively influence the mechanisms of aging and age-related diseases.

Applications of Sesquiterpene Lactones: A Review of Some Potential Success Cases

Sesquiterpene lactones, a vast range of terpenoids isolated from Asteraceae species, exhibit a broad spectrum of biological effects and several of them are already commercially available, such as artemisinin. Here the most recent and impactful results of in vivo, preclinical and clinical studies involving a selection of ten sesquiterpene lactones (alantolactone, arglabin, costunolide, cynaropicrin, helenalin, inuviscolide, lactucin, parthenolide, thapsigargin and tomentosin) are presented and discussed, along with some of their derivatives. In the authors’ opinion, these compounds have been neglected compared to others, although they could be of great use in developing important new pharmaceutical products. The selected sesquiterpenes show promising anticancer and anti-inflammatory effects, acting on various targets. Moreover, they exhibit antifungal, anxiolytic, analgesic, and antitrypanosomal activities. Several studies discussed here clearly show the potential that some of them have in combination therapy, as sensitizing agents to facilitate and enhance the action of drugs in clinical use. The derivatives show greater pharmacological value since they have better pharmacokinetics, stability, potency, and/or selectivity. All these natural terpenoids and their derivatives exhibit properties that invite further research by the scientific community.

Anti-allergic effects of sesquiterpene lactones from Saussurea costus (Falc.) Lipsch. determined using in vivo and in vitro experiments

ETHNOPHARMACOLOGICAL RELEVANCE

Saussurea costus (Falc.) Lipsch. root has been used in Asian traditional medicine for the treatment of asthma, rheumatism, and other conditions. S. costus extracts were shown to alleviate house dust mite-induced atopic-like dermatitis in Nc/Nga mice; besides, sesquiterpene lactones were isolated from S. costus extracts.

AIMS OF THE STUDY

We aimed to investigate the effects of sesquiterpene lactones (alantolactone, costunolide, and dehydrocostuslactone) in allergic asthma using female Balb/c mice and rat RBL-2H3 mast cells.

MATERIALS AND METHODS

Antigen-induced degranulation was assessed by measuring β-hexosaminidase activity in vitro. In addition, a murine ovalbumin-induced allergic asthma model was used to test the in vivo efficacy of sesquiterpene lactones.

RESULTS

Sesquiterpene lactones inhibited antigen-induced degranulation, wherein dehydrocostuslactone > costunolide > alantolactone in potency. Administration of sesquiterpene lactones decreased the number of immune cells, particularly eosinophils, and reduced the expression and secretion of Th2 cytokines (IL-4 and IL-13) in the bronchoalveolar lavage fluid and lung tissues of mice with ovalbumin-induced allergic asthma. Histological studies showed that sesquiterpene lactones reduced inflammation and mucin production in the lungs. Similar to the in vitro study, dehydrocostuslactone showed the highest potency, followed by costunolide and alantolactone.

CONCLUSION

These findings provide evidence that sesquiterpene lactones might be potential anti-allergic therapeutics.

Common structural and pharmacophoric features of mPGES-1 and LTC4S

Prostaglandins and leukotrienes are produced in the COX and 5-LOX pathways of the inflammatory process. The current drugs target the upstream enzymes of either of the two pathways, leading to side effects. We have attempted to target the downstream enzymes simultaneously. Two compounds 2 and 3 (10 μM), identified by virtual screening, inhibited mPGES-1 activity by 53.4 ± 4.0 and 53.9 ± 8.1%, respectively. Structural and pharmacophore studies revealed a set of common residues between LTC4S and mPGES-1 as well as four-point pharmacophore mapping onto the inhibitors of both these enzymes as well as 2 and 3. These structural and pharmacophoric features may be exploited for ligand- and structure-based screening of inhibitors and designing of dual inhibitors.

Modulation of Cox-1, 5-, 12- and 15-Lox by popular herbal remedies used in southern Italy against psoriasis and other skin diseases

Acanthus mollis (Acanthaceae), Achillea ligustica, Artemisia arborescens and Inula viscosa (Asteraceae) are used in Southern Italy against psoriasis and other skin diseases that occur with an imbalanced production of eicosanoids. We here assessed their in vitro effects upon 5-, 12-, 15-LOX and COX-1 enzymes as well as NFκB activation in intact cells as their possible therapeutic targets. All methanol crude extracts inhibited both 5-LOX and COX-1 activities under 200 µg/mL, without significant effects on the 12-LOX pathway or any relevant in vitro free radical scavenging activity. NFκB activation was prevented by all extracts but A. mollis. Interestingly, A. ligustica, A. arborescens and A. mollis increased the biosynthesis of 15(S)-HETE, an anti-inflammatory eicosanoid. A. ligustica (IC50 =49.5 µg/mL) was superior to Silybum marianum (IC50 =147.8 µg/mL), which we used as antipsoriatic herbal medicine of reference. Its n-hexane, dichloromethane and ethyl acetate fractions had also inhibitory effects on the LTB4 biosynthesis (IC50 s=9.6, 20.3 and 68 µg/mL, respectively) evidencing that the apolar extracts of A. ligustica are promising active herbal ingredients for future phytotherapeutical products targeting psoriasis.

Topical herbal therapies for treating osteoarthritis

BACKGROUND

Before extraction and synthetic chemistry were invented, musculoskeletal complaints were treated with preparations from medicinal plants. They were either administered orally or topically. In contrast to the oral medicinal plant products, topicals act in part as counterirritants or are toxic when given orally.

OBJECTIVES

To update the previous Cochrane review of herbal therapy for osteoarthritis from 2000 by evaluating the evidence on effectiveness for topical medicinal plant products.

SEARCH METHODS

Databases for mainstream and complementary medicine were searched using terms to include all forms of arthritis combined with medicinal plant products. We searched electronic databases (Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, AMED, CINAHL, ISI Web of Science, World Health Organization Clinical Trials Registry Platform) to February 2013, unrestricted by language. We also searched the reference lists from retrieved trials.

SELECTION CRITERIA

Randomised controlled trials of herbal interventions used topically, compared with inert (placebo) or active controls, in people with osteoarthritis were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, assessed the risk of bias of included studies and extracted data.

MAIN RESULTS

Seven studies (six different medicinal plant interventions; 785 participants) were included. Single studies (five studies) and non-comparable studies (two studies) precluded pooling of results.Moderate evidence from a single study of 174 people with hand osteoarthritis indicated that treatment with Arnica extract gel probably results in similar benefits as treatment with ibuprofen (non-steroidal anti-inflammatory drug) with a similar number of adverse events. Mean pain in the ibuprofen group was 44.2 points on a 100 point scale; treatment with Arnica gel reduced the pain by 4 points after three weeks: mean difference (MD) -3.8 points (95% confidence intervals (CI) -10.1 to 2.5), absolute reduction 4% (10% reduction to 3% increase). Hand function was 7.5 points on a 30 point scale in the ibuprofen-treated group; treatment with Arnica gel reduced function by 0.4 points (MD -0.4, 95% CI -1.75 to 0.95), absolute improvement 1% (6% improvement to 3% decline)). Total adverse events were higher in the Arnica gel group (13% compared to 8% in the ibuprofen group): relative risk (RR) 1.65 (95% CI 0.72 to 3.76).Moderate quality evidence from a single trial of 99 people with knee osteoarthritis indicated that compared with placebo, Capsicum extract gel probably does not improve pain or knee function, and is commonly associated with treatment-related adverse events including skin irritation and a burning sensation. At four weeks follow-up, mean pain in the placebo group was 46 points on a 100 point scale; treatment with Capsicum extract reduced pain by 1 point (MD -1, 95% CI -6.8 to 4.8), absolute reduction of 1% (7% reduction to 5% increase). Mean knee function in the placebo group was 34.8 points on a 96 point scale at four weeks; treatment with Capsicum extract improved function by a mean of 2.6 points (MD -2.6, 95% CI -9.5 to 4.2), an absolute improvement of 3% (10% improvement to 4% decline). Adverse event rates were greater in the Capsicum extract group (80% compared with 20% in the placebo group, rate ratio 4.12, 95% CI 3.30 to 5.17). The number needed to treat to result in adverse events was 2 (95% CI 1 to 2).Moderate evidence from a single trial of 220 people with knee osteoarthritis suggested that comfrey extract gel probably improves pain without increasing adverse events. At three weeks, the mean pain in the placebo group was 83.5 points on a 100 point scale. Treatment with comfrey reduced pain by a mean of 41.5 points (MD -41.5, 95% CI -48 to -34), an absolute reduction of 42% (34% to 48% reduction). Function was not reported. Adverse events were similar: 6% (7/110) reported adverse events in the comfrey group compared with 14% (15/110) in the placebo group (RR 0.47, 95% CI 0.20 to 1.10).Although evidence from a single trial indicated that adhesive patches containing Chinese herbal mixtures FNZG and SJG may improve pain and function, the clinical applicability of these findings are uncertain because participants were only treated and followed up for seven days. We are also uncertain if other topical herbal products (Marhame-Mafasel compress, stinging nettle leaf) improve osteoarthritis symptoms due to the very low quality evidence from single trials.No serious side effects were reported.

AUTHORS' CONCLUSIONS

Although the mechanism of action of the topical medicinal plant products provides a rationale basis for their use in the treatment of osteoarthritis, the quality and quantity of current research studies of effectiveness are insufficient. Arnica gel probably improves symptoms as effectively as a gel containing non-steroidal anti-inflammatory drug, but with no better (and possibly worse) adverse event profile. Comfrey extract gel probably improves pain, and Capsicum extract gel probably will not improve pain or function at the doses examined in this review. Further high quality, fully powered studies are required to confirm the trends of effectiveness identifed in studies so far.

Pharmacological and histological effects of Centaurea bruguierana ssp. belangerana on indomethacin-induced peptic ulcer in rats

The species Centaurea bruguierana (DC.) Hand.-Mazz. ssp. belangerana (DC.) Bornm. (CBB) (Asteraceae), known as "Baad-Avard" in Borazjan, Bushehr Province, southern Iran, is used in folk medicine as a hypoglycemic herb in diabetes and as a remedy for peptic ulcer disorders. Total 80% EtOH extract and petroleum ether, CHCl(3), EtOAc, n-BuOH, and remaining fractions obtained by solvent-solvent fractionation of dried aerial flowering parts of the plant were investigated for anti-ulcer activity against indomethacin-induced ulcerogenesis in rats. Anti-ulcer activity was evaluated by measuring the ulcer index (UI) and ulcer inhibition. The UI was significantly reduced in all treated animals. A dramatic decrease in the UI was observed following the administration of total extract (100 mg/kg, p < 0.001) and CHCl(3) fraction (42 mg/kg, ***p < 0.001) in comparison with the control group. The percentage ulcer inhibition with total extract at a dose of 100 mg/kg (97.66%) and CHCl(3) fraction at a dose of 42 mg/kg (96.96%) was found to be higher (p < 0.001) than the reference group (cimetidine 100 mg/kg) (87.08%). The pharmacological and histological results of the present study proved that the aerial flowering parts of CBB possess preventive activity against peptic ulcer, supporting the traditional assertion in southern Iranian folk medicine.

Sesquiterpene lactones from Lychnophora pohlii: neutrophil chemiluminescence inhibition and free radical scavenger activity

Excessive production of reactive oxygen species (ROS) by polymorphonuclear leucocytes (PMNLs) is thought to contribute to the pathology of many inflammatory diseases. Sesquiterpene lactones (STLs) seem to be important contributors to the anti-inflammatory activity of many species of Lychnophora (Asteraceae), which have been widely used in Brazilian folk medicine because of this pharmacological property. In this study, the inhibitory effects of three STLs isolated from Lychnophora pohlii (lychnopholide, centratherin and goyazensolide) on rabbit PMNL oxidative burst were evaluated by the luminol-enhanced chemiluminescence (CL-lum) assay. All STLs tested showed concentration-dependent inhibitory activity on CL-lum but were not cytotoxic to PMNLs (evaluated by lactate dehydrogenase release) under the assessed conditions. Moreover, goyazensolide, the most active STL, had no free radical scavenger property, as assessed by 1,1-diphenyl-2-picrylhydrazyl radical assay, and had no inhibitory effect on the luminol-horseradish peroxidase-hydrogen peroxide chemiluminescence. Taken together, the results of this investigation suggest that the concomitant presence of methacrylate ester and hydroxyl groups contributes to a high inhibitory effect on PMNL oxidative metabolism. This effect was not mediated by free radical scavenger or cytotoxic effects, but probably by inhibition of enzymes involved in the signal transduction pathways of the ROS generation process.

Evidence of effectiveness of herbal medicinal products in the treatment of arthritis. Part I: Osteoarthritis

Herbal medicinal products (HMPs) are used in a variety of oral and topical forms for the treatment of osteoarthritis. The aim of this study was to update a previous systematic review published in 2000. We searched electronic databases (MEDLINE, EMBASE, CISCOM, AMED, CINAHL, Cochrane registers) to June 2007, unrestricted by date or language, and included randomized controlled trials that compared HMPs with inert (placebo) or active controls in patients with osteoarthritis. Five reviewers contributed to data extraction. Disagreements were discussed and resolved by consensus with reference to Cochrane guidelines and advice from the Cochrane Collaboration.Thirty-five studies (30 studies identified for this review update, and 5 studies included in the original review) evaluating the effectiveness of 22 HMPs were included. However, due to differing HMPs, interventions, comparators, and outcome measures, meta-analysis was restricted to data from studies of three HMPs: topical capsaicin, avocado-soybean unsaponifiables, and the Chinese herbal mixture SKI306X showed benefit in the alleviation of osteoarthritic pain.Several studies investigating products from devil's claw, and a powder from rose hip and seed, reported favorable effects on osteoarthritic pain, whereas two studies of a willow bark extract returned disparate results. Three studies of Phytodolor N(R) were of limited use because doses and measures were inconsistent among trials. The remaining single studies for each HMP provided moderate evidence of effectiveness. No serious side effects were reported with any herbal intervention.Despite some evidence, the effectiveness of none of the HMPs is proven beyond doubt. The obvious potential benefits of HMPs in the treatment of osteoarthritis are reduced reliance on synthetic medications with the associated risks of harmful adverse events, but further clinical trials are necessary before HMPs can be adopted in osteoarthritis treatment guidelines.

Anti-inflammatory properties of Salograviolide A purified from Lebanese plant Centaurea ainetensis

BACKGROUND

Anti-inflammatory activities of medicinal plants have largely been attributed to their content of sesquiterpene lactones (SLs). SLs are predominantly found in the sunflower family Asteraceae and have been isolated from many plants of this family, particularly Centaurea. The anti-inflammatory activities of extract of Centaurea ainetensis, a Lebanese endemic plant, and the isolated active molecule were assessed for their potential ant-inflammatory activities.

METHODS

Plant extract from Centaurea ainetensis, and the isolated active ingredient Salograviolide A (SA), a sesquiterpene lactones guaianolide, were used for the study. Western blotting and electrophoretic mobility shift assays were used to test the effects of the plant extract and SA on interleukin-1 (IL-1) induced increase in cyclooxygenase-2 (COX-2) levels and in nuclear factor-kappaB (NF-kappaB) translocation in an intestinal epithelial cell (IEC) of inflammation. Their effects on inflammation score and cytokine levels were also studied in an iodoacetoamide-induced rat model of inflammation.

RESULTS

Plant extract and SA were shown to reverse the effects observed by IL-1 on COX-2 levels and NF-kappaB translocation in IEC. SA decreased the level of inflammatory cytokines and the level of inflammation in the animal model.

CONCLUSION

These findings suggest that SA may be useful in the development of natural therapies for inflammatory diseases.

Medicinal herbs for the treatment of rheumatic disorders--a survey of European herbals from the 16th and 17th century

ETHNOPHARMACOLOGICAL RELEVANCE

From the 16th up into the 18th century botanical and medicinal knowledge in Europe was documented and spread in magnificently illustrated herbals. For the most part modern science has neglected this source of knowledge and old remedies have not been systematically evaluated pharmacologically.

AIM OF THE STUDY

Rheumatic disorders and chronic inflammatory and degenerative diseases of the musculoskeletal system were chosen in an attempt to discuss remedies described in the old herbals in the viewpoint of modern science.

MATERIALS AND METHODS

Five of the most important European herbals of the 16th and 17th century were searched for terms related to rheumatic diseases, and plants and recipes described for their treatment. An extensive search of the scientific data banks Medline and SciFinder scholar was done to find recent results concerning the phytochemistry and possible antiphlogistic activities of the plants.

RESULTS

Sixty-three plants were identified in the herbals for this indication. More than half of them have shown in vitro or in vivo antiphlogistic activities.

CONCLUSIONS

European herbals may be a valuable source of information for the selection of plants for focussed screening programmes. Information contained in these herbals should be explored in a systematic manner.

Sesquiterpene lactone helenalin suppresses Leydig and adrenocortical cell steroidogenesis by inhibiting expression of the steroidogenic acute regulatory protein

Helenalin is a potent anti-inflammatory and anti-neoplastic agent isolated from several plant species of the Asteracea family. Here, we have investigated the effects of helenalin on steroidogenesis activated by adrenocorticotropic hormone (ACTH) and human chorionic gonadotropin (hCG) in primary cultures of rat adrenocortical and Leydig cells. Our findings demonstrate that helenalin inhibits both ACTH- and hCG-activated steroidogenesis in these cells. This effect was already evident after 2-3 h treatment with helenalin. In contrast, steroidogenesis from 22R-OHC, a cell-permeable form of cholesterol, was not inhibited by helenalin, suggesting that the expression of the steroidogenic acute regulartory (StAR) protein might be inhibited by this compound. Indeed, helenalin attenuated StAR protein expression activated by ACTH and hCG in adrenocortical and Leydig cells as assessed by PAGE/Western analyses. This inhibitory action of helenalin on steroidogenic cell functions indicates novel mechanisms of action of this compound which may be of potential therapeutic interest. However, it also poses safety concerns relating to possible negative side-effects on anabolism and systemic stress.

Anti-inflammatory profile of dehydrocostic acid, a novel sesquiterpene acid with a pharmacophoric conjugated diene

Sesquiterpene acids are natural products that, in contrast with the thoroughly studied sesquiterpene lactones, have received little pharmacological attention. A good source of this class of compounds is Inula viscosa (Asteraceae), a plant with documented anti-inflammatory effects. The present paper gives the results of our investigations on the biochemical mechanisms involved in the anti-inflammatory activity of one such compound, dehydrocostic acid. The most salient findings were that in vitro dehydrocostic acid inhibits leukotriene B(4) production (IC(50)=22 microM), elastase activity (IC(50)=43 microM) and bee venom phospholipase A(2) activity (IC(50)=17 microM). Furthermore, this sesquiterpenoid was effective on some models of acute edema induced by PLA(2) and 12-O-tetradecanoylphorbol 13-acetate (TPA) Comparison of these data with that known for ilicic acid firmly suggests that the presence of a semiplanar ring A is essential for an improved inhibitory activity on inflammatory mediators.

Quantitative structure-activity relationship of sesquiterpene lactones as inhibitors of the transcription factor NF-kappaB

Sesquiterpene lactones (SLs) are the active compounds of a variety of traditionally used medicinal plants from the Asteraceae family. They are known to possess a considerable antiinflammatory activity in different inflammation models. They inhibit the transcription factor NF-kappaB probably by alkylating cysteine38 in the DNA binding domain of the p65 subunit. Here we investigate a set of 103 different sesquiterpene lactones representing 6 structural groups (44 germacranolides, 16 heliangolides, 22 guaianolides, 9 pseudoguaianolides, 2 hypocretenolides, 10 eudesmanolides) for their NF-kappaB inhibiting properties and the resulting IC(100)-values were submitted to a QSAR study. Properties important for the inhibition potency are discussed for the whole data set and for subsets of the different structural classes.

Lipoxygenase inhibitors from natural plant sources. Part 1: Medicinal plants with inhibitory activity on arachidonate 5-lipoxygenase and 5-lipoxygenase[sol ]cyclooxygenase

Arachidonate 5-lipoxygenase is the key enzyme in leukotriene biosynthesis and catalyses the initial steps in the conversion of arachidonic acid to biologically active leukotrienes. Leukotrienes are considered as potent mediators of inflammatory and allergic reactions and regarding their pro-inflammatory properties the inhibition of 5-lipoxygenase pathway is considered to be interesting in the treatment of a variety of inflammatory diseases. Besides 5-lipoxygenase inhibitors, drugs able to block the 5-lipoxygenase as well as the cyclooxygenase metabolic pathway are also of therapeutic value. A potential source for new 5-lipoxygenase inhibitors is undoubtedly provided by the abundance of medicinal plants used in traditional medicine. The present review article reports the results from a comprehensive literature search of plants that have been tested for 5-lipoxygenase inhibitory activity over the past 15 years. The obtained information is summarized in a tabular format and promising plant species and chemical classes of compounds are presented. Relevant in vitro tests are also described in this article.

Characteristics, clinical effect profile and tolerability of a nasal spray preparation of Artemisia abrotanum L. for allergic rhinitis

A nasal spray formulation containing an extract of Artemisia abrotanum L. was developed for therapeutic use in patients with allergic rhinitis and other upper airway disorders. The nasal spray preparation used contains a mixture of essential oils (4 mg/ml) and flavonols (2.5 microg/ml), of which some components have been shown to possess antiinflammatory, expectorant, spasmolytic as well as antiseptic and antimicrobial activities. The most important constituents in the essential oil fraction of the preparation are 1,8-cineole, linalool and davanone, while the flavonol fraction contains centauredin, casticin and quercetin dimethyl-ethers. No trace of thujon was observed in the essential oil of the Artemisia abrotanum L. genotype "Tycho" used for the manufacture of the nasal spray preparation. In 12 patients with diagnoses of allergic rhinitis, allergic conjunctivitis and/or bronchial obstructive disease, the nasal spray was given immediately after the appearance of characteristic allergic nasal symptoms. In 10 of the 12 patients, allergic rhinitis with nasal congestion, sneezing and rhinorrhea was dominant. After administration of the nasal spray, all patients experienced a rapid and significant symptom relief of nasal symptoms, comparable to the effect of antihistamine and chromoglicate preparations which several of the patients had used previously. The effect was present within 5 minutes after the administration and lasted for several hours. In 7 of the 10 rhinitis patients with concomitant symptoms of allergic conjunctivitis, a significant subjective relief of eye symptoms was also experienced. In 3 of the 6 patients who had a history of characteristic symptoms of endogenous, exogenous or exercise induced bronchial obstructive disease, there was a bronchial symptom relief by the nasal spray preparation which was experienced as rapid and clinically significant. It is concluded from the present proof of concept study, that a nasal spray formulation containing an extract characterised by a mixture of essential oils and flavonols from the Artemisia abrotanum L. genotype "Tycho", appears to be clinically useful and suitable for the prophylactic and therapeutic management of patients with allergic rhinitis and adjuvant symptoms.

Signal transduction mediated by the Ras/Raf/MEK/ERK pathway from cytokine receptors to transcription factors: potential targeting for therapeutic intervention

The Ras/Raf/Mitogen-activated protein kinase/ERK kinase (MEK)/extracellular-signal-regulated kinase (ERK) cascade couples signals from cell surface receptors to transcription factors, which regulate gene expression. Depending upon the stimulus and cell type, this pathway can transmit signals, which result in the prevention or induction of apoptosis or cell cycle progression. Thus, it is an appropriate pathway to target for therapeutic intervention. This pathway becomes more complex daily, as there are multiple members of the kinase and transcription factor families, which can be activated or inactivated by protein phosphorylation. The diversity of signals transduced by this pathway is increased, as different family members heterodimerize to transmit different signals. Furthermore, additional signal transduction pathways interact with the Raf/MEK/ERK pathway to regulate positively or negatively its activity, or to alter the phosphorylation status of downstream targets. Abnormal activation of this pathway occurs in leukemia because of mutations at Ras as well as genes in other pathways (eg PI3K, PTEN, Akt), which serve to regulate its activity. Dysregulation of this pathway can result in autocrine transformation of hematopoietic cells since cytokine genes such as interleukin-3 and granulocyte/macrophage colony-stimulating factor contain the transacting binding sites for the transcription factors regulated by this pathway. Inhibitors of Ras, Raf, MEK and some downstream targets have been developed and many are currently in clinical trials. This review will summarize our current understanding of the Ras/Raf/MEK/ERK signal transduction pathway and the downstream transcription factors. The prospects of targeting this pathway for therapeutic intervention in leukemia and other cancers will be evaluated.

The effect of sesquiterpene lactones on the release of human neutrophil elastase

Sesquiterpene lactones (SLs) are natural products responsible for the anti-inflammatory activity of a variety of medicinal plants, mainly from the Asteraceae family. Here, we investigated whether they also influence the process of exocytosis of pro-inflammatory enzymes, such as the human neutrophil elastase (HNE). Altogether, eight structurally different SLs from the eudesmanolide, guaianolide, pseudoguaianolide, and germacranolide type were studied. Neutrophils were isolated from fresh human blood. After pre-incubation with different concentrations of the respective SL and cytochalasin B, the exocytosis of elastase was initiated either by platelet activating factor or N-formyl-methionyl-leucyl-phenylalanine. Inhibition of HNE release was measured by p-nitroaniline formation. The SLs exhibited an inhibitory effect on elastase release from neutrophils challenged either by platelet activating factor or N-formyl-methionyl-leucyl-phenylalanine. Concentration-response curves were recorded and the IC(50) values ranged from 2 to 30 microM. Studies on isolated HNE showed that a selective direct inhibition on HNE can be excluded. Interestingly, the inhibitory activity did not correlate with the number of alpha,beta-unsaturated carbonyl functions. The structure-activity relationship and the molecular mechanism are discussed.