Ethanol Extracts from Toona sinensis Seeds Alleviate Diabetic Peripheral Neuropathy through Inhibiting Oxidative Stress and Regulating Growth Factor

Transcription

1 Reserch Pper Ethnol Extrcts from Toon sinensis Seeds Allevite Dietic Peripherl Neuropthy through Inhiiting Oxidtive Stress nd Regulting Growth Fctor XIAOHONG WANG, W. Z. LI*, D. KONG 1 AND YU DUAN Deprtment of Phrmcy, 1 Deprtment of Bsic Medicine, Weifng Medicl University, Weifng, Shndong, , People's Repulic of Chin Wng, et l.: Effects of Toon sinensis Seeds on Dietic Neuropthy Toon sinensis (A. Juss.) Roem hs long een used in trditionl Chinese medicine for the tretment of dietic mellitus. The im of this study ws to investigte the effect of ethnol extrcts of T. sinensis seeds on dietic peripherl neuropthy nd the preliminry mechnism. Mle Wistr rts were used for inducing dietic peripherl neuropthy model, the vrition of ody weight; lood glucose, generl sttus, therml perception thresholds nd scitic nerve conduction velocity were used to confirm the dignosis of dietic peripherl neuropthy. After the tretment, the scitic nerve conduction velocity ws ccelerted, the tilflick ltency ws reduced, the hyperglycemi nd oxidtive stress injury in scitic nerve were meliorted, contents of serum nerve growth fctor β were up-regulted nd tumor necrosis fctor α, interleukin-6 were down-regulted significntly (P<.5) compred with the model rts. This reserch demonstrtes tht ethnol extrcts of T. sinensis seeds offers potentil for intervening dietic peripherl neuropthy nd the protective mechnisms my e lleviting hyperglycemi, inhiiting oxidtive stress nd regulting growth fctor nd inflmmtory cytokines. Key words: Toon sinensis, dietic peripherl neuropthy, oxidtive stress, NGF-β, TNF-α Dietic peripherl neuropthy (DPN) is one of the most common chronic complictions in ptients with dietes mellitus (DM) [1]. Nerly 6% of the ptients suffer from peripherl neuropthy [2]. The pthogenesis of DPN includes mny fctors such s metolic, vsculr, utoimmune, oxidtive stress nd neurohormonl growth fctor deficiency [3,4]. Among them, oxidtive stress [5,6] plys n importnt role nd numer of neurohormonl cytokines were involved such s interleukin-1 (IL-1), interleukin-6 (IL-6), tumor necrosis fctor lph (TNF-α), trnsforming growth fctor et 1 (TGF-β1) nd nerve growth fctor et (NGF-β) [7-9]. Thus, the pthophysiology nd therpeutic development of DPN re ctive res of reserch. Toon sinensis (A. Juss.) Roem is widely used s delicious vegetle in Chin. T. sinensis is lso wellknown Chinese her nd ll prts of it, including root, rk, petioles, leves, fruits, nd seeds, hve een used for medicinl purposes. The queous extrcts of T. sinensis leves hve reveled nticncer, ntioxidnt, ntidietic nd ntivirus ntivirl [1-12]. The chemicl composition included polyphenols, sponins, *Address for correspondence E-mil: wnzhongli@hotmil.com 37 Indin Journl of Phrmceuticl Sciences sesquiterpenes, lkloids nd voltile oil [13,14]. In the present reserch, ethnol extrcts from T. sinensis seeds (ETS) were used to oserve the protective effects on peripherl neuropthy in rts with type 2 DM y inhiiting oxidtive stress nd regulting growth fctor in n ttempt to investigte the protective mechnism nd provide evidence for the clinicl tretment of DPN. MATERIALS AND METHODS T. sinensis seeds were purchsed from Jinn Shengke Technology Development Co., Ltd. Chin, nd uthenticted t Deprtment of Phrmcognosy of Weifng Medicl University. The powdered seeds (1 kg) were extrcted with 85% ethnol nd 75% ethnol (2 1 l, ech 3 h), respectively. The comined ethnol extrcts were concentrted to yield crude This is n open ccess rticle distriuted under terms of the Cretive Commons Attriution-NonCommercil-ShreAlike 3. License, which llows other the remix, twek, nd uild up to the non-commercilly, s long s the uthor is credited nd the new cretions re licensed under the identicl terms. Accepted 26 My 216 Revised 21 My 216 Received 16 Sep 215 Indin J Phrm Sci 216;78(3): My - June 216

2 extrct (164 g) under reduced pressure. Mle Wistr lino rts weighing etween g were provided y Weifng Medicl Experimentl Animl Center nd red in stndrd niml fcility. The nimls were kept in controlled conditions nd fed with stndrd pellet diet nd wter d liitum. The current study protocol ws pproved y Ethics Committee of Weifng Medicl University for niml studies. Streptozotocin (STZ), 2,2-diphenyl-1-picrylhydrzyl (DPPH) were purchsed from Sigm-Aldrich, St. Louis, MO, USA: Rt NGF-β ( ), TNF-α (R ) nd IL-6(R ) ELISA kit were purchsed from NEO Bioscience technology, Beijing, Chin; totl ntioxidnt cpility (T-AOC, ), mlondildehyde (MDA, ), superoxide dismutse (SOD, ), glutthione peroxidse (GSH-PX, ) ssy kits were purchsed from Jincheng Bioengineering Institute, Nnjing, Chin. All other chemicls nd regents used were of nlyticl grde. Antioxidnt ctivities in vitro: The totl ntioxidnt cpility (T-AOC) kit nd micropltes were used for quntittive ssy. The rection principle is ntioxidnts reduce Fe 3+ to e Fe 2+, while Fe 2+ nd Fehling's sustnces form stle complex compounds. The ETS were dissolved with 8% lcohol; with the concentrtion (mg/ml) s horizontl coordinte nd the sornce s verticl coordinte, reducing power curve ws drwn. Ascoric cid ws used for positive control. DPPH ws dissolved nd diluted with solute lcohol [15] to ttin concentrtion of.2 mmol/l. The ETS were dissolved with 8% lcohol t different concentrtions nd the sme volume of DPPH solution ws dded, nd the mixtures were plced wy from light for 15 min. The sornce ws immeditely detected t 515 nm wvelength with scoric cid s positive control. Fresh liver ws seprted from helthy Wistr rt nd 1% homogente ws mde in ice th. Different concentrtions of ETS were dded into 1.5 ml of homogente, then.1 ml of H 2 O 2 ws dded nd the mixture ws rected in 37 for 3 min. MDA contents were ssessed using thiorituric cid rective sustnces ssy y mesuring the sornce vlue t wvelength of 532 nm. Induction of experimentl DPN nd tretments: Twenty Wistr rts were selected s the control ( 1). The remining rts were fed with high-ft diet (HFD) for 6 w nd were injected intrperitonelly with dose of 35 mg/kg STZ in citrte uffer (ph=4.5). Blood ws drwn from the til vein fter 72 h nd the rts with lood glucose greter thn 16.7 mmol/l were treted s DM rts nd were used for further experiments. 6 w lter, til-flick tests were conducted nd eight control rts nd eight DM rts were selected rndomly for detection of DPN y mens of scitic nerve conduction velocity (SNCV) nd determintion of NGF-β. The normlities of these prmeters were used to confirm the dignosis of DPN. The DPN rts were then divided into four s ccording to their lood glucose grdient, ech 12 s follows: 2 (DPN model); s 3 to 5 (DPN rts treted with ETS.1,.15,.2 g/kg/dy, respectively). The rts in s 1 nd 2 were treted with n equl volume of distilled wter. Ech ws dministered y gvge once dy for 8w. Generl sttus nd food intke were oserved every dy, the vlues of ody weight nd lood glucose were determined regulrly. Til-flick tests: Til-flick tests were conducted efore nd fter dministrtion t the 6 th, 12 th nd 2 th weeks. Tilflick tests were ssessed y til-flick ltency evoked y noxious het stimulus y til-flick instrument (YLS-12A, Yiyn Technology Development Co., Ltd., Shndong, Chin.). In the test, rdint het ws focused on the distl prt of niml s til. The cut-off time for the til-flick rection ws set to 16 s to void dmge to the til [16]. Prior to ny tretment, the rts were llowed to cclimtize to the test procedure nd pprtus for t lest 2 min. The test ws repeted three times for ech rt nd men of three mesures ws reported. The intervl of three mesurements ws 5 min. SNCV detection nd iomrker nlysis: The experiment nimls were nesthetized with 1% chlorl hydrte (.4 ml/1 g) fter overnight fsting. With the sujects prone, right scitic nerves were dissected with glss needle. The stimulting nd recording electrodes were plced directly under the scitic nerve nd the distnce etween the stimultion electrode nd recording electrode ws recorded. Then the nerve conductions were mde nd recorded using the Functionl Experiment System (BL-42s, Timeng, Sichun, Chin). SNCV ws clculted using the following equtions: SNCV: s/t (m/s)=distnce etween stimulting nd recording electrode/ ltency [17]. After SNCV ws detected, lood smples My - June 216 Indin Journl of Phrmceuticl Sciences 38

3 from hert were collected nd the serum iomrkers including NGF-β, TNF-α nd IL-6 were determined y commercil ELISA kits using BioTek microplte reder (Gene Co., Ltd. USA.). The left scitic nerve ws immeditely mde into 1% homogente (tissue grm/sline volume in milliliter=1:9) used for nlysis of MDA, SOD, nd GSP-PX using the commercil kits. Sttisticl nlysis: The experimentl results were sujected to nlysis of vrince using SPSS 16. nd expressed s men±sd. RESULTS AND DISCUSSION Antioxidnt ctivities in vitro re shown in fig. 1. The sornce t 51 nm showed the ntioxidnt cpility of ETS in spite of the inferiority compred with scoric cid. The IC 5 vlues of ETS nd positive OD concentrtion(mg/ml) Fig. 1: Totl ntioxidnt ctivities of the ETS. ETS; scoric cid. All vlues re expressed in men±sd; n=3. control drug on DPPH rdicl nd lipid peroxidtion were detected nd the results re listed in Tle 1. They indicte tht the extrcts could well scvenge DPPH rdicls nd inhiited lipid peroxidtion. During the experiment period, 4 rts died from intutions prolems during drug dministrtion including 2 in 2, 1 in 3 nd 1 in 5. The nimls were immeditely necropsied fter deth, nd no normlity ws oserved in gross exmintion. Rts in DPN showed depressive spirit, less ctivity, increse of feeding, drinking, urinting nd other signs of DM. Tretment s improved these generl fetures. The lood glucose nd ody weight of the experimentl rts re shown in Tle 2. The ody weight of norml rts mrkedly incresed from 2±2 g t the seline to 358±32 g t the end of the experiment (P<.5). By contrst, the vlues of DPN rts were decresed fter period of increse cused y the HFD. Treted s prevented the ody weight loss to vrying degrees. The lood glucose levels of DPN rts were significntly higher thn tht of norml rts in 1 (P<.5); however, the lood glucose levels of rts in s 3 to 5 were significntly decresed t the end. The results of effects on oxidtive stress in scitic nerve of DPN rts re listed in Tle 3. Compred with tht of rts in norml control, the MDA contents in scitic nerve of rts in DPN were significntly incresed while the SOD nd GSH PX ctivities were significntly decresed (P<.5). The s treted ETS pprently prevented these normities (P<.5). DPN, one of the most common chronic complictions TABLE 1: IC 5 OF POLYPHENOLS ON REACTIVE OXYGEN RADICALS (n=5) ETS (mg/ml) Ascoric cid (μg/ml) DPPH.33± ±.75 Lipid peroxidtion 8.19 ± ±4.19 All vlues re expressed in men±sd. TABLE 2: EFFECTS ON BODY WEIGHT AND BLOOD GLUCOSE Group n Body weight (g) Blood glucose (mm) w 6 w 12 w 2 w w 6 w 12 w 2 w ±2 251±23 284±23 358±32 3.3±.3 3.4±.4 3.2±.3 3.8± ±2 438±36 58±49 434±41 3.3±.3 2.9± ± ± ±2 441±38 471±4 481±39 3.3± ± ± ± ±2 439±32 462±36 499±37 3.3± ± ± ± ±2 424±33 453±37 484±4 3.3±.3 2.7± ± ±1.2 All vlues re expressed in men±sd. P<.5 compred with the norml control ; P<.5 compred with the DPN. My - June 216 Indin Journl of Phrmceuticl Sciences 39

4 TABLE 3: EFFECTS ON OXIDATIVE STRESS INDICATORS IN SCIATIC NERVE OF DPN RATS Group n SOD (U/mg prot) 95.14± ± ± ± ±8.5 MDA (nmol/mg prot) 2.82± ± ± ± ±.42 GSH PX (U) ± ± ± ± ±9.55 All vlues re expressed in men±sd. P<.5 compred with the norml control ; P<.5 compred with the DPN. of DM, is heterogeneous of disorders with vrious pthologies nd hyperglycemi must e the inititor. To dietic, ffected y the hyperglycemi in vivo, crohydrte oxidtion increses nd series of pthwys re ctivted, which led to the unlnced oxidtion nd nti-oxidiztion of orgnisms nd the excessive ctive oxygen rdicls, cusing the dmge of tissues nd cells, finlly resulting in mny DM complictions. Oxygen free rdicl dmge is the min contriutor to DPN nd is regrded s the direct or indirect common pthwy in which DPN progresses [18]. Biomrkers for oxidtive dmge such s MDA were demonstrted to increse in dietes. Oxidtive stress lso diminishes endogenous ntioxidnt enzyme defenses such s SOD nd GSH-PX ctivities [19], which re very importnt to the regultion of oxidtive sttus in dietes. The reserch shows tht the ETS possesses certin ntioxidnt ctivity in vitro nd in vivo. The chnges efore nd fter dministrtion suggest tht one of the mechnisms of the protective effect my e nti-oxidtive stress. Til-flick is one of the stndrd tests for mesuring the rte of nociception. In this study, significnt increse in the til-flick ltency ws oserved fter 6 w of STZ induction (P<.5). These deficits were significntly reversed fter treting with ETS for 8 w (P<.5, fig. 2). The results of effects on SNCV in DPN rts re shown in fig 3. Influenced y DM, the SNCV of DPN rts in 2 ws much slowed compred with the norml sujects in Group 1 (P<.5). However, s 3, 4 nd 5 were notly improved thn 2 (P<.5). In clinicl exmintion, the lower lims usully revel norml senstions of virtion, pressure, pin, nd temperture perception [2], nd DPN is mnifested y deficit in nerve conduction velocity s well s therml perception thresholds [21]. In the present study, we successfully induced DPN models y feeding them HFD for 12 w ccompnied y n injection of low dose STZ. 6 w fter modeling, erly functionl normlities in the peripherl nerves were oserved, including therml hyperlgesi nd reduction in SNCV til-flick ltency (s) nd y the end of the experiment, these normlities ecme more noticele nd ccompnied with disordered growth fctor nd oxidtive stress injury. The llevition of these prmeters y ETS showed the protective effect on DPN. Fig. 4 shows the effect of ETS on contents of serum NGF-β efore nd fter tretment. The concentrtions Fig.2: Effect on til-flick ltency. 6 w; 12 w; 2 w. All vlues re expressed in men±sd. P<.5 compred with the norml control ; P<.5 compred with the DPN. S/T (m/s) Fig. 3: Scitic nerve conduction velocity in experiment rts. Before tretment; After tretment. All vlues re expressed in men±sd. P<.5 compred with the norml control ; P<.5 compred with the DPN. My - June 216 Indin Journl of Phrmceuticl Sciences 31

5 of NGF-β were significntly decresed (P<.5) efore tretment compred with norml controls, which cn help to mnifest the neurologic dmge. The NGF-β contents were pprently incresed in s treted with ETS (P<.5). The results in fig. 5 showed tht serum levels of pro-inflmmtory cytokines TNF-α nd IL-6 were significntly (P<.5) incresed in DPN rts compred with the norml controls. Treted with ETS significntly decresed the contents of IL-6 (P<.5) nd the effects on TNF-α showed significntly decresed only in the treted with high dose ETS. A series of studies hve shown tht, NGF-β nd proinflmmtory cytokines IL-6 nd TNF-α re ll importnt iomrkers of neuropthy, they might hve vitl implictions cliniclly. The role of TNF-α is NGF-β (ng/ml) Fig. 4: Contents of NGF-β in dietic peripherl neuropthy rts. Before tretment; After tretment. All vlues re expressed in men±sd. P<.5 compred with the norml control ; P<.5 compred with the DPN. TNF-α (pg/ml) IL-6 (pg/ml). Fig. 5: Contents of IL-6 nd TNF-α in dietic peripherl neuropthy rts. TNF-α; IL-6. All vlues re expressed in men±sd. P<.5 compred with the norml control ; P<.5 compred with the DPN. still controversil nd Mgrinelli s clinicl reserch showed it ws not found to e ssocited with DPN. Dt from niml models documented tht TNF-α ws down regulted in the dorsl root gnglion in erly stges of experimentl dietes, while the opposite occurred in lter stge [22,23]. In our reserch men vlue of serum TNF-α level ws found significntly incresed in DPN rts nd decresed in high dose ETS compred with DPN model rts. It might thus e hypothesized tht the model rts were in lter stge of DPN fter the whole experiment. The proinflmmtory cytokines IL-6 hs een linked to vrious dietic complictions [24]. In our reserch men vlue of serum IL-6 level ws found incresed in DPN rts nd decresed in three ETS s significntly. NGF performs vitl neuroprotective role with the ility to potentite xonl growth. A low serum NGF-β level is correlted with neurl dmge in type 2 DM. Evidence showed tht ptients with more severe symptoms hd lower NGF levels [25]. Our findings suggested tht ETS could significntly decrese TNF-α nd increse NGF-β level, which might e importnt protective mechnisms ginst DPN. In summry, llevition of DPN in rts y erly intervention with ETS is result of the suppression of multiple pthogenic mechnisms, including lleviting hyperglycemi, inhiiting oxidtive stress nd regulting growth fctor, etceter. Nevertheless, we still do not know the underlying moleculr mechnisms tht ETS used to regulte these chnges. In our further studies, we will seprte the ctive components for investigting the further moleculr mechnisms nd contriute to djuvnt tretment for DPN. Acknowledgments: The uthors thnk Prof. Fengin Wng of Weifng Medicl University for mesuring the scitic nerve conduction velocity nd to Dr. Chongmei Xu of the Deprtment of Phrmcognosy of Weifng Medicl University for plnt uthentiction. Finncil support nd sponsorship: This work ws supported y the Ntionl Nturl Science Foundtion of Chin ( ), the Scientific nd Technologicl Innovtion Foundtion of Weifng Medicl University (K13224) nd the Trditionl Chinese Medicine Science nd Technology development projects of Shndong province ( ). Conflicts of interest: There re no conflicts of interest. My - June 216 Indin Journl of Phrmceuticl Sciences 311

6 REFERENCES 1. Boulton AJ, Vinik AI, Arezzo JC, Arezzo JC, Bril V, Feldmn EL, et l. Dietic neuropthies: sttement y the Americn Dietes Assocition. Dietes Cre 25;28: Wng Y, Chen Z, Ye R, He Y, Li Y, Qiu X. Protective effect of Jiweiugn decoction ginst dietic peripherl neuropthy. Neurl Regen Res 213;8: El Boghddy NA, Bdr GA. Evlution of oxidtive stress mrkers nd vsculr risk fctors in ptients with dietic peripherl neuropthy. Cell Biochem Funct 212;3: Kim ES, Lee SW, Mo EY, Moon SD, Hn JH. Inverse ssocition etween serum totl iliruin levels nd dietic peripherl neuropthy in ptients with type 2 dietes. Endocrine 215;5: Wu YB, Shi LL, Wu YJ, Xu WH, Wng L, Ren MS. Protective effect of gliclzide on dietic peripherl neuropthy through Drp-1 medited-oxidtive stress nd poptosis. Neurosci Lett 212;523: Ftni AJ, Al-Rejie SS, Auohshish HM, Al-Assf A, Prmr MY, Ol MS, et l. Neuroprotective effects of Gymnem sylvestre on streptozotocin-induced dietic neuropthy in rts. Exp Ther Med 215;9:167-8,. 7. Mgrinelli F, Brini C, Romno M, Ruggero S, Toffnin E, Triolo G, et l. The ssocition etween serum cytokines nd dmge to lrge nd smll nerve fiers in dietic peripherl neuropthy. J Dietes Res 215; Hussin G, Rizvi SA, Singhl S, Zuir M, Ahmd J. Serum levels of TNF-α in peripherl neuropthy ptients nd its correltion with nerve conduction velocity in type 2 dietes mellitus. Dietes Met Syndr 213;7: Zheng LR, Zhng YY, Hn J, Sun ZW, Zhou SX, Zho WT et l. Nerve growth fctor rescues dietic mice hert fter ischemi/reperfusion injury vi up-regultion of the TRPV1 receptor. J Dietes Complictions 215;29: Wng CC, Tsi YJ, Hsieh YC, Lin RJ, Lin CL. The queous extrct from Toon sinensis leves inhiits microgli-medited neuroinflmmtion. Kohsiung J Med Sci 214;3: Liu H, Tsi Y, Chng S. Toon sinensis lef extrct inhiits lipid ccumultion through up-regultion of genes involved in lipolysis nd ftty cid oxidtion in dipocytes. J Agric. Food Chem 214;62: Yu WJ, Chng CC, Kuo TF, Tsi TC, Chng SJ. Toon sinensis Roem lef extrcts improve ntioxidnt ctivity in the liver of rts under oxidtive stress. Food Chem Toxicol 212;5: Kkumu A, Ninomiy M, Efdi M, Adf M, Hyshi M, Tnk K, et l. Phytochemicl nlysis nd ntileukemic ctivity of polyphenolic constituents of Toon sinensis. Bioorg Med Chem Lett 214;24: Yng HL, Chen SC, Lin KY, Wng MT, Chen YC, Hung HC, et l. Antioxidnt ctivities of queous lef extrcts of Toon sinensis on free rdicl-induced endothelil cell dmge. J Ethnophrmcol 211;37: Fu R, Zhng YT, Guo YR, Hung QL, Peng T, Xu Y, et l. Antioxidnt nd nti-inflmmtory ctivities of the phenolic extrcts of Spium seiferum (L.) Rox leves. J Ethnophrmcol 213;147: Temhurne SV, Skrkr DM. Effect of Fluoxetine on n Experimentl Model of Dietes- induced Neuropthic Pin Perception in the Rt. Indin J Phrm Sci 211;73: Cui XP, Li BY, Go HQ, Wei N, Wng WL, Lu M. Effects of grpe seed pronthocynidin extrcts on peripherl nerves in streptozocin-induced dietic rts. J Nutr Sci Vitminol (Tokyo) 28;54: Stvniichuk R, Drel VR, Shevlye H, Mksimchyk Y, Kuchmerovsk TM, Ndler JL, et l. Biclein llevites dietic peripherl neuropthy through inhiition of oxidtivenitrostive stress nd p38 MAPK ctivtion. Exp Neurol 211;23: Koneri RB, Smddr S, Simi SM, Ro ST. Neuroprotective effect of triterpenoid sponin isolted from Momordic cymlri Fenzl in dietic peripherl neuropthy. Indin J Phrmcol 214;46: Ding Y, Di X, Jing Y, Zhng Z, Li Y. Functionl nd morphologicl effects of grpe seed pronthocynidins on peripherl neuropthy in rts with type 2 dietes mellitus. Phytother Res 214;28: Kmiz S, vn Neck JW, Cosgun SG, vn Velzen MH, Jnssen JA, Avzverdi N, et l. An erly dignostic tool for dietic peripherl neuropthy in rts. PLoS One 215;1(5):e Cvusoglu T, Krdeniz T, Cgilty E, Krdeniz M, Yigitturk G, Acikgoz E, et l. The protective effect of losrtn on dietic neuropthy in dietic rt model. Exp Clin Endocrinol Dietes. 215; 123: Sleh A, Smith DR, Blkrishnn S, Dunn L, Mrtens C, Tweed CW et l. Tumor necrosis fctor-α elevtes neurite outgrowth through n NF-κB-dependent pthwy in cultured dult sensory neurons: Diminished expression in dietes my contriute to sensory neuropthy. Brin Res 211;1423: Dhmodhrn U, Viswnthn V, Krishnmoorthy E, Rjrm R, Arvindhn V. Genetic ssocition of IL-6, TNF-α nd SDF-1 polymorphisms with serum cytokine levels in dietic foot ulcer. Gene Jul 215;565: Kim HC, Cho YJ, Ahn CW, Prk KS, Kim JC, Nm JS, et l. Nerve growth fctor nd expression of its receptors in ptients with dietic neuropthy. Diet Med 29;26: My - June 216 Indin Journl of Phrmceuticl Sciences 312