Antidepressant-like effects of salvianolic acid B in the mouse forced swim and tail suspension tests

AimsSalvianolic acid B (SalB), one of the most abundant and bioactive compounds extracted from Salvia miltiorrhiza (Danshen), shows neuroprotective and anti-inflammatory activities in vivo and in vitro. This research was intended to investigate the antidepressant effect of SalB by forced swimming test (FST) and tail suspension test (TST).Main methodsSalB was extracted from S. miltiorrhiza roots and followed by HPLC analysis. Thirty five male C57BL/6 mice were divided into five groups: three SalB groups of different doses, one imipramine group, and one control group. The SalB groups received intraperitoneally (i.p.) 5 mg/kg SalB, 10 mg/kg SalB, and 20 mg/kg SalB respectively. At the same time, the imipramine group received 20 mg/kg imipramine, and the control group saline only. The behavioral tests including FST, TST and locomotor activity test were done after administration of drugs for consecutively three times, at 24, 1, and 0.5 h before the tests.Key findingsSalB, from S. miltiorrhiza with purity of 95%, significantly reduced the immobility time in both the FST and TST tests (doses at 5, 10, 20 mg/kg, i.p.), without changing locomotion in spontaneous motor activity.SignificanceThis data suggests that besides neuroprotective and anti-inflammatory activities, SalB has promising therapeutic potential in treatment of depressive disorders.     

Chronic treatment with estradiol restores depressive-like behaviors in female Wistar rats treated neonatally with clomipramine

Neonatal administration of clomipramine (CMI) induces diverse behavioral and neurochemical alterations in adult male rats that resemble major depression disorder. However, the possible behavioral alterations in adult female rats subjected to neonatal treatment with clomipramine are unknown. Therefore, the aim of this study was to explore the effect of neonatal treatment with CMI on adult female rats in relation to locomotion and behavioral despair during the estrus cycle. Also evaluated was the effect of chronic treatment with E2 on these female CMI rats. We found no effects on spontaneous locomotor activity due to neonatal treatment with CMI, or after 21 days of E2 administration. In the FST, neonatal treatment with CMI increased immobility and decreased active swimming and climbing behaviors. Influence of the ovarian cycle was detected only in relation to climbing behavior, as the rats in the MD phase displayed less climbing activity. Chronic E2 administration decreased immobility but increased only swimming in CMI rats. These results suggest that neonatal treatment with CMI induces despair-like behavior in female rats, but that chronic E2 administration generates antidepressant-like behavior by decreasing immobility and increasing swimming, perhaps through interaction with the serotonergic system.     

Antidepressant-like profile and MAO-A inhibitory activity of 4-propyl-2H-benzo[h]-chromen-2-one

AimsTo evaluate the central nervous pharmacological profile of 4-propyl-2H-benzo[h]-chromen-2-one (FCS-304) in ICR mice and its monoamine oxidase inhibitor activity.Main methodsFCS-304 was evaluated in screening test of central nervous system in ICR mice and against MAO activity.Key findingsFCS-304 (25–200 mg/Kg, p.o.) significantly reduced immobility time during the forced swimming test (FST) and tail suspension test (TST), but did not show effects in the rota-rod tests, maximal electroshock seizures (MES), pentylenetetrazole seizures, light–dark box, barbiturate sleeping time and cold plate tests. Furthermore, FCS-304 inhibited monoamine oxidase A (MAO-A) with IC₅₀: 2.28 ± 0.15 µM, but not MAO-B.SignificanceThese results suggest that FCS-304 could elicit antidepressant effects related to MAO-A inhibitory activity.     

The median raphe nucleus participates in the depressive-like behavior induced by MCH: Differences with the dorsal raphe nucleus

An emerging body of evidence involves the hypothalamic neuropeptide melanin-concentrating hormone (MCH) in the regulation of emotional states. We have reported a pro-depressive effect induced by MCH after its microinjection into the dorsal raphe nucleus (DR) evaluated in the forced swimming test (FST) in rats. Here we extended this study to the median raphe nucleus (MnR). Firstly, the presence of MCH-containing fibers in the rat MnR was analyzed by means of immunohistochemistry. Secondly, the behavioral effect induced by the microinjection of MCH into the MnR was assessed using the FST. Morphological results showed a large density of MCHergic fibers within the MnR. Behavioral results indicated that 100 ng of MCH (but not 50 ng) significantly increased the immobility time and decreased the swimming time, demonstrating a depressive-like effect. In contrast, climbing behavior was not significantly affected. Present findings revealed that the MnR neurons participate in the MCHergic control of affective-related behavioral responses. However, the behavioral patterns induced by MCH in the MnR and DR were different. This could be explained by anatomical and physiological differences between both nuclei.     

Effect of ACTH on the imipramine- and desipramine-induced decrease in duration of immobility time as measured in a rat forced swimming test.

In a rat forced swimming test (FS), we examined the effect of repeated injections of ACTH (adrenocorticotropic hormone) for 14 days on the decreased duration of immobility time produced by imipramine and desipramine. Both imipramine (15 and 30 mg/kg, p.o.) and desipramine (15 and 30 mg/kg, p.o.) significantly decreased the duration of immobility time in the FS. On the other hand, ACTH (100 microg/kg, i.p.) alone did not affect the duration of immobility time in FS. When ACTH (100 microg/kg, i.p.) was injected for 14 days before the 15-min swim session, it counteracted the decreased duration of immobility time induced by both imipramine and desipramine. Thus, ACTH seems to play a key role in decreasing the duration of immobility time of antidepressants in this test.     

Involvement of potassium channels in the antidepressant-like effect of venlafaxine in mice

AimsStudies have shown that the acute administration of venlafaxine elicits an antidepressant-like effect in the mouse forced swim test (FST) by a mechanism dependent on the l-arginine–nitric oxide (NO)–cyclic guanosine monophosphate (cGMP) pathway. Because it has been reported that NO activates different types of potassium (K⁺) channels in the brain, this study investigated the involvement of K⁺ channels in the antidepressant-like effect of venlafaxine in the mouse FST.Main methodsMale adult Swiss mice were pretreated with different K⁺ channel inhibitors or openers 15 min before venlafaxine administration. After 30 min, the open-field test (OFT) and FST were carried out.Key findingsIntracerebroventricular (i.c.v.) pretreatment of mice with subeffective doses of tetraethylammonium (TEA, a non-specific inhibitor of K⁺ channels, 25 pg/site), glibenclamide (an ATP-sensitive K⁺ channel inhibitor, 0.5 pg/site), charybdotoxin (a large- and intermediate-conductance calcium-activated K⁺ channel inhibitor, 25 pg/site) or apamin (a small-conductance calcium-activated K⁺ channel inhibitor, 10 pg/site) was able to potentiate the action of a subeffective dose of venlafaxine (2 mg/kg, i.p.). Moreover, the reduction in the immobility time elicited by an effective dose of venlafaxine (8 mg/kg, i.p.) in the FST was prevented by the pretreatment of mice with the K⁺ channel openers cromakalim (10 µg/site, i.c.v.) and minoxidil (10 µg/site, i.c.v.). The drugs used in this study did not produce any change in locomotor activity.SignificanceThe results demonstrate that the neuromodulatory effects of venlafaxine, via the inhibition of K⁺ channels, are possibly involved in its anti-immobility activity in the mouse FST.     

Synthesis and biological evaluation of a series of benzoxazole/benzothiazole-containing 2,3-dihydrobenzo[b][1,4]dioxine derivatives as potential antidepressants

A series of benzoxazole/benzothiazole-2,3-dihydrobenzo[b][1,4]dioxine derivatives (5a–5d and 8a–8j) was synthesized. Compounds were evaluated for binding affinities at the 5-HT_1A and 5-HT_2A receptors. Antidepressant activities of the compounds were screened using the forced swimming test (FST) and the tail suspension test (TST). The results indicated that the compounds exhibited high affinities for the 5-HT_1A and 5-HT_2A receptors and showed a marked antidepressant-like activity. Compound 8g exhibited high affinities for the 5-HT_1A (K_i = 17 nM) and 5-HT_2A (K_i = 0.71 nM) receptors; it also produced a decrease of the immobility time and exhibited potent antidepressant-like effects in the FST and TST in mice.     

Synthesis and evaluation of new 3-phenylcoumarin derivatives as potential antidepressant agents

A series of amine substituted 3-phenyl coumarin derivatives were designed and synthesized as potential antidepressant agents. In preliminary screening, all compounds were evaluated in forced swimming test (FST), a model to screen antidepressant activity in rodents. Among the series, compounds 5c and 6a potentially decreased the immobility time by 73.4% and 79.7% at a low dose of 0.5 mg/kg as compared to standard drug fluoxetine (FXT) which reduced the immobility time by 74% at a dose of 20 mg/kg, ip. Additionally, these active compounds also exhibited significant efficacy in tail suspension test (TST) (another model to screen antidepressant compounds). Interestingly, rotarod and locomotor activity tests confirmed that these two compounds do not have any motor impairment effect and neurotoxicity in mice. Our studies demonstrate that the new 3-phenylcoumarin derivatives may serve as a promising antidepressant lead and hence pave the way for further investigation around this chemical space.     

Tricyclic antidepressants and mecamylamine bind to different sites in the human α4β2 nicotinic receptor ion channel

The interaction of tricyclic antidepressants with the human (h) α4β2 nicotinic acetylcholine receptor in different conformational states was compared with that for the noncompetitive antagonist mecamylamine by using functional and structural approaches. The results established that: (a) [³H]imipramine binds to hα4β2 receptors with relatively high affinity (K_d = 0.83 ± 0.08 μM), but imipramine does not differentiate between the desensitized and resting states, (b) although tricyclic antidepressants inhibit (±)-epibatidine-induced Ca²⁺ influx in HEK293-hα4β2 cells with potencies that are in the same concentration range as that for (±)-mecamylamine, tricyclic antidepressants inhibit [³H]imipramine binding to hα4β2 receptors with affinities >100-fold higher than that for (±)-mecamylamine. This can be explained by our docking results where imipramine interacts with the leucine (position 9′) and valine (position 13′) rings by van der Waals contacts, whereas mecamylamine interacts electrostatically with the outer ring (position 20′), (c) van der Waals interactions are in agreement with the thermodynamic results, indicating that imipramine interacts with the desensitized and resting receptors by a combination of enthalpic and entropic components. However, the entropic component is more important in the desensitized state, suggesting local conformational changes. In conclusion, our data indicate that tricyclic antidepressants and mecamylamine efficiently inhibit the ion channel by interacting at different luminal sites. The high proportion of protonated mecamylamine calculated at physiological pH suggests that this drug can be attracted to the channel mouth before binding deeper within the receptor ion channel finally blocking ion flux.     

Gamma-aminobutyric acid production in black soybean milk by Lactobacillus brevis FPA 3709 and the antidepressant effect of the fermented product on a forced swimming rat model

Despite the prevalence and severe effects of depression, the efficacy of currently available antidepressants is often inconsistent, and many exert undesirable side effects. Administration of food containing gamma-aminobutyric acid (GABA) has been proposed as an alternative treatment for depression. Therefore, this study ferments soy-based milk enriched in GABA and tests its anti-depressant activity in Sprague-Dawley (SD) rats. First, Lactobacillus brevis FPA 3709 isolated from fish intestine was selected for its ability to produce GABA during cultivation in MRS broth with monosodium glutamate (MSG). Second, the conditions (substrate composition and treatment, initial pH, and time and temperature of fermentation) for obtaining the highest synthesis of GABA by the selected microorganism were established. Finally, cooked black soybean milk supplemented with 1% MSG, 1% brown sugar, and 0.1% peptone (without adjusting the initial pH level) was fermented (37 °C, 48 h) by L. brevis FPA 3709. SD rats subjected to a forced swimming test (FST) and fed with fermented black soybean milk showed immobility times that were not significantly different from that of rats administered with fluoxetine, a common antidepressant drug, without exhibiting the side effects of lost appetites and reduced body weight typical of fluoxetine use. Fermented black soybean milk enriched with GABA is a good candidate as an alternative treatment of depression.     

In vivo gene delivery of XIAP protects against myocardial apoptosis and infarction following ischemia/reperfusion in conscious rabbits

AimsWe tested the hypothesis that an in vivo gene delivery of the pro-survival protein XIAP (X-chromosome linked inhibitor of apoptosis protein) protects against myocardial apoptosis and infarction following ischemia/reperfusion.Main methodsNineteen rabbits were chronically instrumented with a hydraulic occluder placed around the circumflex coronary artery. Adenovirus harboring XIAP (Ad.XIAP; 1 × 10¹⁰ pfu/ml) or β-galactosidase (5 × 10⁹ pfu/ml), as a control, was constructed and transfected into the heart using a catheter placed into the left ventricle accompanied by cross-clamping. 1–2 weeks after gene delivery, myocardial ischemia was induced by a 30-min occlusion followed by reperfusion for four days. Protein expression was determined by Western blot and apoptosis (% of myocytes) was quantified by TUNEL staining.Key findingsMyocardial infarct size, expressed as a fraction of the area at risk, was reduced in Ad.XIAP (n = 5) compared to control (n = 7) rabbits (21 ± 3% vs. 30 ± 2%, p < 0.05). Apoptosis was reduced in Ad.XIAP rabbits compared to control rabbits (2.96 ± 0.68% vs. 8.98 ± 1.84%, p < 0.01). This was associated with an approximate 60% decrease in the cleaved caspase-3 level in Ad.XIAP rabbits compared to control rabbits.SignificanceThe current findings demonstrate that overexpression of XIAP via in vivo delivery in an adenovirus can reduce both myocardial apoptosis and infarction following ischemia/reperfusion, at least in part, due to the ability of XIAP to inhibit caspase-3. These findings confirm previous work suggesting a link between myocardial apoptosis and infarction i.e., anti-apoptotic therapy was effective in reducing myocardial infarct size.     

Subchronic stress-induced depressive behavior in ovariectomized mice

AimsMood disorders including depression are more common in women than men, particularly in times of lower estradiol levels. In this study, we investigated the effect of estrogen on emotional behavior in mice in a stress environment.Main methodsFemale mice were divided into four groups: two groups were ovariectomized (OVX) and two were sham-operated. One group each of OVX and sham mice was kept in a normal environment and the other groups were assigned to a daily stress (1 h/day) for 7 days from 5 days after operation. On the 14th day after operation, subjects were measured to assess behavioral specificity, locomotor activity, elevated plus-maze (EPM) behavior, passive avoidance (PA) behavior and forced swimming behavior.Key findingsThe OVX plus stress (OVX + S) group showed a significant prolongation of immobility compared with the other groups. In all the groups there were no changes in locomotor activity, EPM behavior or PA behavior. We further examined the effect of estrogen against depressive behavior in the OVX + S group. The vehicle or 17β-estradiol (E2) was administered s.c. to OVX + S mice for 4 days beginning on post-operative day 11. Subchronic E2 treatment decreased the stress response and improved depressive behavior relative to the vehicle group.SignificanceThese data have important implications regarding the prevention of depression in postmenopausal women undergoing estrogen therapy.     

Evaluation of vitamin E in the treatment of erectile dysfunction in aged rats

AimsThe present study aims to elucidate the role of oxidative stress in erectile dysfunction associated with aging and to investigate the effect of treatment with vitamin E in this respect.Main methodsRats were divided into four groups: young (3-month-old), aged rats (18-month-old), aged rats given 80 IU of vitamin E/rat/day for 21-days, aged rats given 5 mg/kg of sildenafil/day for 21-days. Intracavernosal pressure/mean arterial pressure (ICP/MAP), nitric oxide production, TBARS, GSH levels and SOD activity in corpus cavernosum were measured.Key findingsSignificant decrease in ICP/MAP was observed in aged rats at both low and high frequency of stimulation. Significant increase in ICP/MAP was observed in aged rats treated with vitamin E over the range of 0.8 to 5 Hz but young control values were not restored. Percentage potentiation of ICP/MAP than aged group at 0.8 Hz was 326 ± 41.3% and 897 ± 72.2% for vitamin E and sildenafil respectively. Decreased levels of NO₂/NO₃ and SOD activity in the penile tissue observed with aging were elevated back to control by either vitamin E or sildenafil. Penile concentration of TBARS was 20.86 ± 0.83 for aged rats vs. 11.39 ± 0.79 nmol/g tissue for young controls. Both vitamin E and sildenafil reduced penile TBARS in aged rats.SignificanceThis study proves that antioxidant therapy with vitamin E ameliorates the age-associated erectile dysfunction. Sildenafil may exert some antioxidant properties which add to the advantages of its long-term use. The effect of combinations of low-dose sildenafil and vitamin E on age-associated erectile dysfunction merits to be studied.     

Effect of cervical spine position on upper limb myoelectric activity during pre-manipulative stretch for Mills manipulation: a new model, relations to peripheral nerve biomechanics and specificity of Mills manipulation

Objectives(A) Describe a new method of investigation of the possible muscular effects of the commonly practiced Mills manipulation for lateral elbow pain (epicondylalgia), (B) ascertain if myoelectric activity is influenced during the pre-manipulative stretch for Mills manipulation, (C) establish whether muscle responses are influenced by ipsilateral lateral flexion of the cervical spine which reduces mechanical tension in the peripheral nerves of the upper limb.SampleEight asymptomatic subjects were tested bilaterally (N = 16).MethodsMyoelectric measurements – EMG signals were recorded with a 16 channel pocket EMG patient unit and processed off-line. Measurement of joint positions-three CCD adjustable cameras sensitive to 10 mm reflective passive markers applied at specific locations on the subjects’ bodies were used to reconstruct and verify accuracy of body movements and were correlated with EMG recordings.ResultsCompared with the standard (anatomical) position of the cervical spine in which Mills manipulation is typically performed, cervical spine ipsilateral lateral flexion produced significantly reduced activity in muscles that restrain the manipulation movement (elbow extension), namely biceps brachii (P = 0.018) and brachioradialis (P = 0.000). The affected muscles may therefore produce protective effects during the manipulation.ConclusionsChanges in myoelectric activity were in a pattern that suggests that muscle and neural mechanisms may be an integral part of the Mills manipulation. Cervical spine ipsilateral lateral flexion may be used to reduce mechanical stresses in the peripheral nerves and extraneous muscle activity, making Mills’ manipulation potentially safer and more specific.     

Regulation of contractility and metabolic signaling by the β2-adrenergic receptor in rat ventricular muscle

AimsCardiac function is modulated by the sympathetic nervous system through β-adrenergic receptor (β-AR) activity and this represents the main regulatory mechanism for cardiac performance. To date, however, the metabolic and molecular responses to β₂-agonists are not well characterized. Therefore, we studied the inotropic effect and signaling response to selective β₂-AR activation by tulobuterol.Main methodsStrips of rat right ventricle were electrically stimulated (1 Hz) in standard Tyrode solution (95% O₂, 5% CO₂) in the presence of the β₁-antagonist CGP-20712A (1 μM). A cumulative dose–response curve for tulobuterol (0.1–10 μM), in the presence or absence of the phosphodiesterase (PDE) inhibitor IBMX (30 μM), or 10 min incubation (1 μM) with the β₂-agonist tulobuterol was performed.Key findingsβ₂-AR stimulation induced a positive inotropic effect (maximal effect = 33 ± 3.3%) and a decrease in the time required for half relaxation (from 45 ± 0.6 to 31 ± 1.8 ms, ? 30%, p < 0.001) after the inhibition of PDEs. After 10 min of β₂-AR stimulation, p-AMPKα^T172 (54%), p-PKB^T308 (38%), p-AS160^T642 (46%) and p-CREB^S133 (63%) increased, without any change in p-PKA^T197.SignificanceThese results suggest that the regulation of ventricular contractility is not the primary function of the β₂-AR. Rather, β₂-AR could function to activate PKB and AMPK signaling, thereby modulating muscle mass and energetic metabolism of rat ventricular muscle.     

Cryopreservation of umbilical cord mesenchymal cells in xenofree conditions

Background aimsMesenchymal stromal cells (MSC) are being used to treat and prevent a variety of clinical conditions. To be readily available, MSC must be cryopreserved until infusion. However, the optimal cryopreservation methods, cryoprotector solutions and MSC sensitivity to dimethyl sulfoxide (DMSO) exposure are unknown. This study investigated these issues.MethodsMSC samples were obtained from human umbilical cord (n = 15), expanded with Minimal Essential Medium-alpha (α-MEM) 10% human serum (HS), resuspended in 25 mL solution (HS, 10% DMSO, 20% hydroxyethyl starch) and cryopreserved using the BioArchive^® system. After a mean of 18 ± 7 days, cell suspensions were thawed and diluted until a DMSO concentration of 2.5% was reached. Samples were tested for cell quantification and viability, immunophenotype and functional assays.ResultsPost-thaw cell recovery: 114 ± 2.90% (mean ± SEM). Recovery of viable cells: 93.46 ± 4.41%, 90.17 ± 4.55% and 81.03 ± 4.30% at 30 min, 120 min and 24 h post-thaw, respectively. Cell viability: 89.26 ± 1.56%, 72.71 ± 2.12%, 70.20 ± 2.39% and 63.02 ± 2.33% (P < 0.0001) pre-cryopreservation and 30 min, 120 min and 24 h post-thaw, respectively. All post-thaw samples had cells that adhered to culture bottles. Post-thaw cell expansion was 4.18 ± 0.17 ×, with a doubling time of 38 ± 1.69 h, and their capacity to inhibit peripheral blood mononuclear cells (PBMC) proliferation was similar to that observed before cryopreservation. Differentiation capacity, cell-surface marker profile and cytogenetics were not changed by the cryopreservation procedure.ConclusionsA method for cryopreservation of MSC in bags, in xenofree conditions, is described that facilitates their clinical use. The MSC functional and cytogenetic status and morphologic characteristics were not changed by cryopreservation. It was also demonstrated that MSC are relatively resistant to exposure to DMSO, but we recommend cell infusion as soon as possible.     

Low serum zinc levels in patients undergoing coronary angiography correlate with immune activation and inflammation

IntroductionLow serum zinc concentrations are associated with adverse outcomes. To explain this phenomenon we aimed to investigate whether low zinc levels are related to immune activation, renal function and coronary artery disease (CAD).MethodsSerum concentrations of zinc and the immune activation markers neopterin and C-reactive protein (CRP) were measured in 2048 patients derived from the LUdwigshafen RIsk and Cardiovascular Health (LURIC) study, a cohort study among patients referred for coronary angiography.ResultsZinc concentrations did not differ between patients with CAD (mean ± SD: 13.3 ± 2.4 μmol/L) and controls (13.3 ± 2.2 μmol/L; Welch's t test: p = n.s.) but CAD patients had higher neopterin (8.6 ± 7.4 nmol/L) and CRP (9.7 ± 19.6 mg/L) concentrations compared to controls (neopterin: 7.5 ± 4.8 nmol/L, p = 0.0005; CRP: 5.5 ± 10.0 mg/L, p < 0.0001). There was an inverse correlation between serum zinc concentrations and neopterin (Spearman's rank correlation: r_s = ?0.222) and CRP (r_s = ?0.166; both p < 0.0001) concentrations.ConclusionsOur results indicate increased inflammatory processes in patients with low zinc levels. Further studies should clarify whether inflammation related processes such as renal wasting contribute to zinc deficiency and underlie the adverse health consequences of low serum zinc levels.     

Association between interleukin 15 receptor, alpha (IL15RA) polymorphism and Korean patients with ossification of the posterior longitudinal ligament

ObjectivesRecently, a number of evidences have been reported concerning the genetic factor involved in the development of ossification of the posterior longitudinal ligament (OPLL). The purpose of this study was to investigate single nucleotide polymorphisms (SNPs) of the interleukin 15 receptor, alpha (IL15RA) gene as a risk factor in Korean patients with OPLL.DesignTo investigate the genetic association, two coding SNPs (rs2296139, Thr73Thr; rs2228059, Asn182Thr) in IL15RA were genotyped in 166 OPLL patients and 230 control subjects. SNPStats, SNPAnalyzer, and Helixtree programs were used for association analysis.ResultsIn the present study, we found the association between a missense SNP (rs2228059) and the risk of OPLL in codominant (p = 0.0028, OR = 1.58, 95% CI = 1.17–2.14), dominant (p = 0.0071, OR = 1.82, 95% CI = 1.17–2.82), and recessive models (p = 0.036, OR = 1.79, 95% CI = 1.04–3.09). The frequency of rs2228059 allele was significantly associated with the susceptibility of OPLL (p = 0.0043, OR = 1.52, 95% CI = 1.14–2.02). After Bonferroni correction, the missense SNP (rs2228059, Asn182Thr) still had significant correlations (p = 0.0056 in codominant model; p = 0.0142 in dominant model; p = 0.0086 in allele analysis). Haplotype variation in IL15RA was associated with OPLL (global haplotype test, p = 0.025).ConclusionsThese results suggest that IL15RA polymorphism may be associated with the susceptibility of OPLL in Korean population.     

Resveratrol in combination with other dietary polyphenols concomitantly enhances antiproliferation and UGT1A1 induction in Caco-2 cells

AimsThe only FDA approved medication for colorectal cancer (CRC) prevention is celecoxib. Its adverse effects underline the need for safer drugs. Polyphenols like resveratrol are in clinical trials for this purpose. This study aimed at examining effects of resveratrol alone and in combination with curcumin or chrysin on UGT induction in Caco-2 cells. Phytochemical combinations were selected using drug combination analyses of various anti-proliferation ratios of resveratrol + curcumin and resveratrol + chrysin.Main methodsCell proliferation and UGT1A1 induction assays were carried out with individual polyphenols and combinations. Cell viability was determined with AlamarBlue assays. UGT1A1 mRNA was quantified via real time RT-PCR. UGT activity was determined with 4-methylumbelliferone (4MU) glucuronidation.Key findingsCell proliferation IC₅₀ estimates (± SE) for resveratrol, curcumin and chrysin were 20.8 ± 1.2, 20.1 ± 1.1 and 16.3 ± 1.3 μM respectively. Combination of anti-proliferative effects showed additivity for resveratrol + chrysin and resveratrol + curcumin. Resveratrol at its IC₅₀ mediated a four-fold induction of UGT1A1 mRNA in a concentration independent manner. Chrysin at its IC₅₀ induced UGT1A1 expression seven-fold while Curcumin at its IC₉₀ mediated a two-fold induction. The 20 μM:40 μM resveratrol + curcumin and 20 μM :32 μM resveratrol + chrysin combinations mediated the greatest increases in mRNA expression (12 and 22 folds respectively). Significant increase in 4-MU glucuronidation was observed with combinations exhibiting maximal mRNA induction.SignificancePhytochemical combinations can offer greater chemoprevention than single agents. These chemicals might offer safer options than present synthetic therapeutics for CRC prevention.