Добірка наукової літератури з теми "ISOPETASINA"

The coronavirus disease 2019 (COVID-19), caused by a novel coronavirus (SARS-CoV-2), has spread worldwide, affecting over 250 million people and resulting in over five million deaths. Antivirals that are effective are still limited. The antiviral activities of the Petasites hybdridus CO2 extract Ze 339 were previously reported. Thus, to assess the anti-SARS-CoV-2 activity of Ze 339 as well as isopetasin and neopetasin as major active compounds, a CPE and plaque reduction assay in Vero E6 cells was used for viral output. Antiviral effects were tested using the original virus (Wuhan) and the Delta variant of SARS-CoV-2. The antiviral drug remdesivir was used as control. Pre-treatment with Ze 339 in SARS-CoV-2-infected Vero E6 cells with either virus variant significantly inhibited virus replication with IC50 values of 0.10 and 0.40 μg/mL, respectively. The IC50 values obtained for isopetasin ranged between 0.37 and 0.88 μM for both virus variants, and that of remdesivir ranged between 1.53 and 2.37 μM. In conclusion, Ze 339 as well as the petasins potently inhibited SARS-CoV-2 replication in vitro of the Wuhan and Delta variants. Since time is of essence in finding effective treatments, clinical studies will have to demonstrate if Ze339 can become a therapeutic option to treat SARS-CoV-2 infections.

Abstract Petasites hybridus extract is used in the treatment of seasonal allergic rhinitis. The aim of this study was to evaluate the active constituent petasin and its isomers isopetasin and neopetasin (petasins) in the P. hybridus extract Ze 339 for liberation, dissolution, absorption, and metabolism. The determination of pH-dependent thermodynamic solubility was performed via the shake-flask method. Petasins exhibited a low solubility that was pH independent. In vivo, the concentration of solute drugs is decreased continuously by intestinal absorption. Therefore, low solubility is not assumed to be critical for in vivo performance. Additionally, dissolution of an herbal medicinal product containing P. hybridus extract Ze 339 was assessed. Furthermore, high permeability through Caco-2 monolayers was evident. Using an in situ rat model, absorption capacity for petasins was found in all tested intestinal segments, namely, duodenum, jejunum, and ileum. Besides, high metabolism was evident both in Caco-2 monolayers and in the rat intestine. To compare intestinal and hepatic metabolism of petasins, in vitro enzyme assays using liver and intestinal cytosol and microsomes (S9 fraction) of rats and humans were performed. A significantly higher metabolic rate was found in the liver S9 fraction of both species compared with the intestinal S9 fraction.

The TRPA1 represents a key target in pain modulation. It is manly expressed in primary sensory neurons, where It can be activated by a wide series of exogenous chemicals, and also detects and can be sensitized by a series of endogenous molecules, including oxidative/nitrative/carbonylic stress (ROS/RNS/RCS) byproducts deriving from inflammatory processes. TRPA1 and ROS are emerging as a major pathway in different pain conditions, including migraine headache, which affects almost 15% of the adult worldwide population, with an enormous social and economic cost. In the first study presented here, we examined the effect of the butterbur component [Petasites hybridus (L.)] isopetasin on TRPA1. Butterbur is currently indicated as level A recommendation for migraine prophylaxis by the American Headache Society guidelines, and its major constituents, petasin and isopetasin, are considered responsible for its antimigraine effects. Our results showed that isopetasin is able to gate mouse, rat and human (native and recombinant) TRPA1 channel. In addition, isopetasin acts as a partial agonist on the channel. A chronic treatment in mice with isopetasin showed that this molecule can target TRPA1 and induce desensitization of the channel and defunctionalization of trigeminal nerve terminals, attenuating their ability to release the calcitonin gene-related peptide (CGRP), the main mediator of migraine pain. Successful treatment and prevention with isopetasin, may provide a solid basis for future investigations of TRPA1-tropic approaches for migraine. In the second part, we investigated the possibility that some constituents of saffron [Crocus sativus (L.)] could as well target TRPA1. Saffron has been used for centuries not only for food flavoring and coloring, but also to treat headache in Indian traditional medicine. Furthermore, saffron constituents safranal, crocin and picrocrocin, have been reported to possess analgesic properties in various animal models of pain. We showed that safranal can activate human and rodent TRPA1, acting as a partial agonist. Desensitization experimental protocols in vitro showed that safranal is able to desensitize TRPA1, in a homologous manner. Chronic treatment with safranal in mice confirmed this hypothesis. This mechanism could account for the antinociceptive properties of safranal. Another part of this three years study aimed at investigating glyceryl trinitrate (nitroglycerin, GTN)-induced migraine-like attacks. GTN has long been used as a clinical provocation test for migraine. In most migraineurs, GTN administration evokes headaches that fulfill the criteria of a typical migraine attack. Moreover, GTN administration in rodents and humans induces a delayed and prolonged hyperalgesia, and is able to release the active vasodilator nitric oxide (NO), which is a known TRPA1 agonist. Our study provided evidence that the delayed and prolonged GTN-evoked allodynia in mice is entirely dependent from TRPA1 activation. GTN directly activates TRPA1 in vitro and in vivo (only if given locally). However, systemic treatment with GTN indicated that NO, liberated from GTN by ALDH-2, activates TRPA1 to induce allodynia. By gating TRPA1 in trigeminal nociceptors, NO leads to activation of NOX1/NOX2, which generate ROS and the ensuing aldehyde endproducts. These molecules ultimately activate TRPA1 again, generating an autocrine pathway. TRPA1 antagonists currently in clinical development, or established antimigraine drugs identified as selective channel inhibitors, may be used to verify if a mechanism similar to the present one mediates the effects induced by GTN in migraineurs. Finally, we investigated the possibility that ibuprofen-acyl glucuronide (IAG), a metabolite of ibuprofen, could antagonize TRPA1. Ibuprofen is a classical NSAID, widely used to relieve inflammation and several types of pain, including headache. Its therapeutic effects are attributed to a non-selective, reversible inhibition of COX1 and COX2. 10-15% of ibuprofen is metabolized, through glucuronidation, to IAG, which may covalently bind various macromolecules. Our major finding is that IAG, but not ibuprofen, antagonizes the proalgesic TRPA1 channel. IAG was able, unlike ibuprofen, to selectively inhibit the human and rodent TRPA1 channel. IAG attenuated nociception evoked only by reactive TRPA1 agonists. A systemic administration of ibuprofen also produced a partial attenuation of TRPA1-mediated nociception, probably due to the formation of IAG through liver metabolism. Local IAG produced a more potent anti-inflammatory effect than ibuprofen, attributable to a combination of COX-inhibition and TRPA1-antagonism, since PGE2 levels were ablated by both compounds in the same way. Hence, the analgesic and anti-inflammatory activity of ibuprofen can be attributed to TRPA1 inhibition, in addition to COX inhibition, via IAG generation. The findings of this three years study indicate that TRPA1 expressed in neuronal and non-neuronal cells is a key mediator in inflammatory and neuropathic pain modulation. Our results suggest novel therapeutic approaches to treat pain, in particular migraine, involving TRPA1 antagonists and TRPA1-desensitizing agents.

碩士
臺北醫學大學
藥理學研究所
95
PDE4 is present in inflammatory cells and bronchial smooth muscles. The increased cAMP level by PDE4 inhibitors leads to have bronchodilator and anti-inflammatory effects. Petasites formosanus Kitamura, a perennial herb, is used as a folk medicine for treating hypertension, tumor and asthma in Taiwan. In the present study, we investigated mechanisms of antiasthmatic action of S-petasin and S-isopetasin, the main constituents of the plant. First, S-petasin has proven to concentration-dependently inhibit PDE3/4 activities with a respective IC50 value of 27.55 and 16.56 μM, which did not significantly differ from each other. According to the Lineweaver-Burk analysis, S-petasin (3~30 μM) competitively inhibited PDE3/4 activities, and had a Ki value of 27.6 and 23.3 μM, respectively, which also did not differ from each other. However, S-isopetasin had no effect on PDE1~PDE5 (IC50 > 100 μM). The airway hyperresponsiveness (AHR) was measured in unrestrained, sensitized and OVA-secondarily challenged BALB/c mice by barometric plethysmography using a whole-body plethysmograph after exposure of methacholine (MCh, 6.25~50 mg/ml). In the present results, S-petasin (10~30 μmol/kg, s.c. or 30~100 μmol/kg, p.o.) dose-dependently and significantly attenuated the enhanced pause (Penh) value induced by MCh (50 mg/ml) and significantly suppressed the increase of total inflammatory cells, eosinophils, neutrophils, and lymphocytes, and also significantly attenuated the release of IL-2, IL-4, IL-5, IFN-γ and TNF-α in bronchoalveolar lavage fluid (BALF) of the mice with some exceptions at lower dose. It also significantly reduced total and OVA-specific IgE in serum and in BALF. In the opposite, it dose-dependently and significantly increased IgG2a in serum suggesting that the anti-inflammation was potentiated. S-petasin displaced [3H]-rolipram from high affinity rolipram binding sites (HARBS) of particulates of whole brains isolated from sensitized guinea pigs, with an EC50 value beyond 300 μM. Therefore, the PDE4H/PDE4L ratio (> 300 μM/16.56 μM) of S-petasin was beyond 18. S-petasin did not shorten the duration of anathesia induced by xylazine/ketamine, suggesting that its adverse effect, such as nausea, vomiting and gastric hypersecretion, may be little. S-petasin (30~300 μM) and S-isopetasin (30~300 μM) significantly relaxed the baseline tension, but did not suppress cumulative OVA (10~100 μg/ml)-induced contractions in isolated sensitized guinea pig trachealis. S-isopetasin (30~300 μM) competitively antagonized cumulative ACh-induced contractions in guinea pig trachealis, because the slope of Schild plot did not significantly differ from unity. The pA2 value of S-isopetasin was calculated to be 4.70 ± 0.66 (n=18). According to the analysis of Scatchard plot, the muscarinic receptor binding sites in cultured human tracheal smooth muscle cells (HTSMCs) revealed a single population (Hill coefficient 1.00). The equilibrium dissociation constant (Kd) and the maximal receptor density (Bmax) for [3H]-NMS binding were 766 pM and 0.189 pmol/mg of protein, respectively. The –logIC50 value of S-isopetasin, methoctramine and 4-DAMP for displacing 0.4 nM [3H]-NMS specific binding was 5.05, 6.25, and 8.56, respectively, suggesting that the [3H]-NMS binding is predominantly on M3 cholinoceptors of cultured HTSMCs. The potency of S-petasin for displacing [3H]-NMS binding in cultured HTSMCs appeared greater (about 2.2-fold) than that against cumulative ACh-induced contractions in guinea pig trachealis, suggesting that S-isopetasin may be more effective in human airway smooth muscles than in guinea pig trachealis. Threfore, S-isopetasin may have benefits as a bronchodilator for treating asthma. In conclusion, S-petasin selectively and competitively inhibited PDE3/4 activities, and potentiated its anti-inflammatory and bronchodilator effects. S-isopetasin antagonized the activation of M3 cholinoceptors of cultured HTSMCs and had bronchodilator effect. The above results suggest that S-petasin and S-isopetasin may have the potential for treating asthma.