Anti-diabetic effect of Cyclo-His-Pro (CHP)-enriched yeast hydrolysate in streptozotocin-induced diabetic mice

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1 Vol. 12(35), pp , 28 August, 213 DOI: /AJB ISSN Ademi Journls Afrin Journl of Biotehnology Full Length Reserh Pper Anti-dieti effet of Cylo-His-Pro (CHP)-enrihed yest hydrolyste in streptozotoin-indued dieti mie Yooheon Prk 1, Hyun Jung Lee 1, Jng Won Choi 2, Song Hwn Be 3 nd Hyung Joo Suh 1 * 1 Deprtment of Food nd Nutrition, Kore University, Seoul , Repuli of Kore. 2 Deprtment of Bioindustry, College of Life nd Environment, Degu University, Gyeongsn , Repuli of Kore. 3 Deprtment of Food nd Biotehnology, Hnkyong Ntionl University Anseong, Anseong , Repuli of Kore. Aepted 1 August, 212 The present study ws designed to investigte the hypoglyemi effets of the dily orl dose of.5 to.75 g/kg of yest hydrolyste (YH) ontining high Cylo-His-Pro (51. mg CHP/g YH) on norml nd streptozotoin (STZ)-indued dieti rts for 14 dys. In STZ-indued dieti rts, fter dministrtions of the YH for 14 dys, the ody weight gin ws signifintly inresed in dose dependent mnner, nd the plsm gluose levels were deresed pproximtely (6%) s ompred to the STZ indued dieti ontrol group. Gluose level showed signifint differenes etween the dieti ontrol (DC) nd the YH dministered groups in orl gluose tolerne test (OGTT) (P<.5). Results of the OGTT showed signifint derese in the re under urve (AUC) vlue of YH supplemented groups s ompred to the DC group. The present dt suggests tht the CHP-enrihed YH hs potentil nti-dieti effet, whih n help in the ure nd mngement of dietes. Key words: Yest hydrolyste, Cylo-His-Pro (CHP), dietes, streptozotoin. INTRODUCTION Dietes mellitus (DM) is one of the mjor endorine disorder nd glol puli helth prolems, ffeting nerly 1% of the world s popultion. DM onsists of group of syndromes hrterized y hyperglyemi; ltered metolism of lipids, rohydrtes nd proteins; nd the inresed risk of omplitions from vsulr disese (Dvis nd Grnner, 21). Conventionl drugs used in its tretment re ssoited with drwks suh s rigid nd multiple dosing regimen, high-ost, inessiility nd untowrd effets. Sientifi investigtions of lterntives for dietes hve provided vlule lues for the development of therpeuti strtegies. In the lst few dedes, there hs een exponentil growth in the field of lterntives y nturl supplements, owing to their nturl origin nd lesser side effets (Yeh et l., 23), sine nturl soures re usully onsidered to e less toxi with fewer side effets thn syntheti soures (Pri nd Ummheswri, 2). They hve the potentil to imprt therpeuti effet in omplited disorders suh s dietes nd its omplitions (Tiwri nd Ro, 22). With more thn 1 strins of Shromyes erevisie tegorized s generlly reognized s sfe, yest is utilized in iohemil nd medil pplitions (Crver, 1994) s well s mny food industries suh s rewing (Csey nd Ingledew, 1983), winemking (Shinohr et l., 2) nd king (Chell, 1997). Severl studies hve demonstrted tht yest hydrolyste (YH) displys ntioesiti (Jung et l., 29) nd ntidieti tivity (Morley *Corresponding uthor. E-mil: suh196@kore..kr. Tel: Fx:

2 5474 Afr. J. Biotehnol. et l., 1981; Steiner et l., 1989). For these resons, YH is reeiving remrkle ttention s funtionl sustne in the diet food mrket. The ontinuing development of funtionl foods is likely to entil inresed use of different protein soures known to ontin iotive omponents. Cylo-His-Pro (CHP) is nturlly ourring yli dipeptide onsisting of histidyl nd proline nd is metolite of thyrotropin-relesing hormone. As plsm levels of CHP in humns is inresed fter ingestion of gluose, CHP tivity hs een suggested to e relted to glyemi ontrol in ptients with DM. Dietry feeding of CHP with zin supplementtion signifintly improves insulin sensitivity nd gluose lerne in dieti nimls nd humns (Hwng et l., 23; Song et l., 21; Rosenthl et l., 21). Furthermore, severl studies hve demonstrted tht CHP dereses food intke, onsequently, mimiking the tion of leptin, the ppetite ontrol hormone (Morley et l., 1981; Steiner et l., 1989). Hene, CHP plys n importnt role in regulting insulin nd leptin sensitivity, while no evidene of toxiity or side effets ssoited with its orl dministrtion hs een reported (Song et l., 25, 29). We developed CHP ontining high ontent of YH for possile pplitions of this yli dipeptide in metoli disorder therpy. In the previous study (Jung et l., 211), we inresed the CHP ontent in the YH tht ws otined from enzymti hydrolysis nd riefly ssessed the ntidieti effet y the orl gluose tolerne test (OGTT) in type 1 dieti niml model. The purpose of this study ws to ssess the nti-dieti effet of YH with high CHP ontent in norml nd streptozotoin (STZ)-indued rts. MATERIALS AND METHODS Animls nd diets The niml protool ws pproved y the Kore University Animl Cre Committee. Mle Sprgue-Dwley (SD) rts, otined t 6 weeks of ge (2 ± 1 g), from Centrl L. Animl In. (Seoul, Kore) were housed individully in plsti ges with grted stinless steel floor. The olony ws mintined t 24 ± 1 C with 6% reltive humidity nd 12 h light/12 h drk yle. The rts hd d liitum ess to wter nd the rodent how (Smyng Co., Seoul, Kore). Composition (g/1 kg of diet) of the how ws: moisture, 8; protein, 23; ft, 35; fier, 5; rohydrte, 6; nd wter. Preprtion of the dieti rts STZ (Sigm-Aldrih, St. Louis, MO, USA) ws used to indue dietes. The nimls were given intrperitonel injetions of freshly prepred STZ (4 mg/kg in.1 M itrte uffer, ph 4.5) for 5 dys, nd the norml ontrol () group ws injeted with.1 M itrte uffer only. Five dys fter STZ tretment, lood ws olle-ted from the tip of the til vein, nd fsting gluose level ws mesured (Tkmur et l., 1999). The STZ injetion destroyed suffiient numer of islet et ells to e model of type 1 dietes with the gluose level of over 3 mg/dl. After the STZ-indution period, the rts were seprted into four groups (six rts/group) sed on their lood gluose level nd ody weight. Tretment ws strted 8 dys fter the STZ injetion. YH preprtion An 8% yest suspension ws hydrolyzed for 48 h using Flvourzyme (endoprotese nd exopeptidse from Aspergillus oryze). The hydrolysis temperture ws 5 C for the rude enzymes, nd the enzyme : yest sustrte rtio ws 1:1 for the enzymes. The hydrolysis of yest with enzymes ws performed in.1 M phosphte uffer. ph ws djusted to the optiml vlues for the Flvourzyme speifi proteses (ph 7.) efore hydrolysis ws initited. Hydrolysis ws intivted y heting t 9 C for 5 min. The YH otined from enzymti hydrolysis ws first pssed through.2 μm memrne filter (Stoon ssette, Srtorius, Goettingen, Germny). A portion of the solution ws removed immeditely, nd the filtrte ws then pumped through 1 kd moleulr weight ut-off memrne (Stoon ssette, Srtorius). The YH otined from ultrfiltrtion ws dsored with tive ron. The YH otined from ultrfiltrtion, nd the resulting sustne were dried nd used s the YH (51. mg/g CHP). YH dministrtion YH ws suspended in distilled wter nd dministered orlly through n intrgstri tue t doses of.5 or.75 g/kg ody weight. The volume of dministrted extrt ws 1 ml for eh niml. The rts were divided into four groups (eight rts/group): : 1 ml wter for norml ontrol; DC: 1 ml wter for dieti rts; YH-1:.5 g/kg ody weight YH; or YH-2:.75g/kg ody weight YH for dieti rts, nd eh group of rts ws treted dily for 14 dys using n intrgstri tue. At the end of the experimentl period, the rts were nesthetized with ethyl ether, nd lood ws olleted from the dominl rtery into heprinized sterile tue. Plsm ws otined y entrifugtion t 1,8 g for 3 min nd stored t -8 C until further nlysis. The liver, spleen nd kidneys were exised nd weighed fter srifiing the nimls. Fsting lood gluose level Blood gluose levels were monitored every week fter 12 h fst in venous lood tken from the til vein using gluose nlyzer. Fsting lood gluose ws mesured fter 14 dys of YH tretment during whih the nimls were fed norml diet. Rts were fsted for 12 h, nd lood ws olleted from the tip of the til vein. Blood gluose level ws mesured using lood gluose nlyzer (Supergluord II, Arkry In., Kyoto, Jpn) sed on the gluose oxidse method (Brhm nd Trinder, 1972). Results re expressed s gluose mg/dl lood. Orl gluose tolerne test On the dy of niml srifie, fter n overnight fst, min lood ws tken from the tip of the til vein from ll the rts. Rts tht hd een dministered YH (.75 g/kg ody weight), reeived orl lod of 3% gluose solution (2 g gluose/kg ody weight). Blood smples were olleted from the til vein t 3, 6, 9 nd 12 min fter the orl gluose lod nd treted s desried previously for the plsm gluose nlysis (Hn et l., 27). Blood gluose level ws expressed s inrements from seline. Inrementl res under the response urves (AUC) were lulted using the trpezoidl rule, with fsting levels onsidered s seline. Sttistil nlysis All sttistil nlyses were performed using the Sttistil Pkge

3 Prk et l Tle 1. Effet of yest hydrolyste on ody weight in norml nd STZ-indued dieti rts. Group 1 Initil ody weight (g) Finl ody weight (g) Body weight gin (g/14 dys) Norml ontrol ± ± ± 2.94 Dieti ontrol ± ± ± 1.31 d Dieti YH ± ± ±.29 Dieti YH ± ± ± Dieti YH-1; STZ-indued dieti rts given.5 g/kg of yest hydrolyste; Dieti YH-2, STZ-indued dieti rts given.75 g/kg of yest hydrolyste. 2 Men ± SEM; vlues with different supersripts letters within the sme olumn re signifintly different t P<.5 y Dunn s multiple rnge test. Plm gluose (mg/dl) DC YH-1 (.5 g/kg) YH-2 (.75 g/kg) Time (dy) Figure 1. Effet of yest hydrolyste on plsm gluose in norml nd STZindued dieti rts. Vlues with different supersripts letters within the olumn re signifintly different t P<.5 y Dunn s multiple rnge test;, 1 ml wter for norml ontrol; DC, 1 ml wter for dieti rts; YH-1,.5 g/kg ody weight YH; YH-2,.75 g/kg ody weight YH for dieti rts. for Soil Sienes (SPSS) version 12. (SPSS In., USA). The differenes mong groups were evluted y one-wy nlysis of vrine (ANOVA) nd Dunn's multiple rnge tests. All dt were reported s the men nd stndrd error. A level of P<.5 ws used s the riterion for sttistil signifine. RESULTS Body weight gin in STZ-indued mie during the 14 dy period YH or vehile ws dministered orlly to STZ-indued mie for 14 dys, nd ody weight ws mesured. As shown in Tle 1, no signifint differenes in initil ody weight were oserved mong the STZ-dieti groups. The group ontinued to gin weight until the end of the study. STZ produed signifint ody weight losses s ompred to tht in the group. After 14 dys of testing, finl ody weights nd men ody weight gins were signifintly lower (P<.5) in ll STZ-dieti groups s ompred to those of the group. Men weight gins in the YH dministered groups were signifintly higher (P<.5) thn those in the DC group, nd signifint improvements (P<.5) in ody weight were oserved in the YH-2 group. Fsting lood gluose levels in STZ-indued mie during the 14 dy period The effet of repeted orl dministrtion of YH or vehile on fsting lood gluose levels in the STZ-dieti groups during 14 dys of tretment re presented in Figure 1. Intrperitonel dministrtion of STZ to rts

4 5476 Afr. J. Biotehnol. Tle 2. Effet of yest hydrolyste on orgn weights in norml nd STZ-indued dieti rts. Group 1 Liver (g/1 g of ody weight) Spleen (g/1 g of ody weight) Kidney (g/1 g of ody weight) Norml ontrol 4.42 ± ±.2 NS.48 ±.4 NS Dieti ontrol 4.92 ±.1.6 ±.3.6 ±.6 Dieti YH ±.1.58 ±.3.54 ±.4 Dieti YH ±.1.59 ±.5.51 ±.5 1 Dieti YH-1, STZ-indued dieti rts given.5 g/kg of yest hydrolyste; Dieti YH-2, STZ-indued dieti rts given.75 g/kg of yest hydrolyste. 2 Men ± SEM; vlues with different supersripts letters within the sme olumn re signifintly different t P<.5 y Dunn s multiple rnge test; NS, not signifint. used signifint dietogeni response with signifint inreses (P<.5) in fsting lood gluose levels s ompred to those in the group. Plsm gluose level inresed ontinuously in the DC group during the experimentl period, rehing finl level of pproximtely 5 mg/dl. YH dministered t two different doses of.5 nd.75 g/kg ody weight to the STZtreted dieti groups resulted in signifint redution (P<.5) of fsting lood gluose levels, whih ws ssoited with tretment durtion. After 14 dys of tretment, the fsting lood gluose levels in the STZ-indued dieti mie treted with YH t.75 g/kg (193.8 ± 1.12 mg/dl) were signifintly lower (P<.5) s om-pred to those of the DC group (474. ± mg/dl). Orgn weights in the STZ-indued mie We investigted the influene of YH on the liver, spleen nd kidney weight (Tle 2). The DC group (4.92 ±.1 g/1 g ody weight) hd signifintly greter (P<.5) liver weights thn the group (4.42 ±.1 g/1 g ody weight). The liver weight ws signifintly hnged y YH dministrtion in dose dependent mnner. Spleen weight ws not signifintly different (P<.5) regrdless of dietes indution. However, the DC group (.6 ±.3 g/1 g ody weight) exhiited greter spleen weight thn the (.57 ±.2 g/1 g ody weight) nd YH dministered groups (.58 ±.3 nd.59 ±.5 g/1 g ody weight, respetively). Dietes indued y STZ injetion resulted in inresed kidney weight; the YH dministered groups hd deresed kidney weight when ompred with the DC group. Orl gluose tolerne test The OGTT nd the lulted AUC were used to determine the gluose response to YH dministrtion. As result, the DC, YH-1, YH-2 nd groups showed signifint inreses (P<.5) in lood gluose levels t 3 min fter pproximtely 522. ± 6.21, 443. ± 3.59, ± 6.29 nd 29.3 ± 3.1 mg/dl gluose gvges, respetively. However, the DC group (248.8 ± 7.68 mg/dl) did not reover seline gluose level even fter 12 min. The OGTT results show tht lood gluose deresed signifintly (P<.5) in the YH dministered groups when ompred with tht in the DC group (Figure 2A). Furthermore, the AUC ws signifintly smller in the YH dministered groups thn in the DC group (Figure 2B). The AUC of the STZ-indued dieti mie treted with YH-2 ws signifintly smller (P<.5) thn tht in the YH-1 group. DISCUSSION DM is hroni metoli disorder ffeting mjor proportion of the popultion worldwide. Conventionl therpies for DM hve mny disdvntges suh s side effets nd high rte of seondry filure. In ontrst, nturl soures re expeted to hve similr effiy without side effets s those of onventionl drugs. CHP exists in severl ommon nutritionl supplements, nd it is known to hve ntioesity effets (Jung et l., 29) s well s ntidieti tivity (Morley et l., 1981; Steiner et l., 1989). This study ws undertken to evlute the hypoglyemi tivity of YH with high ontent of CHP in norml nd STZ-indued dieti rts. STZ is used to indue DM y seletively ffeting pnreti β-ells. Thus, STZ ffets endogenous insulin relese nd inreses lood gluose levels (So et l., 211). Finl ody weights nd men ody weight gins were signifintly lower (P<.5) in ll STZ-dieti groups fter 14 dys of testing, s ompred to those of the group (Tle 1). The indution of DM with STZ is ssoited with hrteristi loss of ody weight due to inresed musle loss (Chtterjee nd Shinde, 1994). However, hypoglyemi tretment with mediinl hers my help STZ-indued dieti rts to reover from hyperglyemi (Hwng et l., 25; Prsd et l., 29). Tretment with YH signifintly improved ody weight, inditing tht it prevented musle loss due to hyperglyemi onditions. The liver weights were signifintly greter (P<.5) in the DC group s ompred to those of the group, nd the YH dministered groups showed signifint hnges in liver weight in dose-dependent mnner s ompred to those of of the DC group. The lipid metoli pthwy is tivted y etyl-coa in STZ-indued dieti rts, rther thn norml gluose metolism, due to redued

5 Prk et l (A) DC YH-1 (.5 g/kg) YH-2 (.75 g/kg) 6 5 (B) Plsm gluose (mg/dl) AUC -12 min Time (min) DC YH-1 (.5 g/kg) YH-2 (.75 g/kg) 6 5 (B) 4 AUC -12 min in) 9 12 DC YH-1 YH-2 Figure 2. Effet of yest hydrolyste on orl gluose tolerne test (A) OGTT nd integrted re under the urves (AUCs) over period of to 12 min (B) in norml nd STZ-indued dieti rts). Vlues with different supersripts letters within the olumn re signifintly different t P<.5 y Dunn s multiple rnge test., 1 ml wter for norml ontrol; DC, 1 ml wter for dieti rts; YH-1,.5 g/kg ody weight YH; YH-2,.75 g/kg ody weight YH for dieti rts.

6 5478 Afr. J. Biotehnol. insulin levels (Goldstein nd Brown, 1977). Bsed on this hypothesis, inresed synthesis nd umultion of hepti triglyerides n e well explined y the liver hypertrophy in STZ-indued dieti rts. DM indued y STZ resulted in inresed kidney weight. The DC group exhiited greter kidney weight gins thn the group. However, the YH dministrted groups showed deresed kidney weights s ompred to the DC group, inditing tht renl enlrgement ommonly ours in DM ptients. The inrese in kidney volume nd size my e due to the inresed glomerulr filtrtion rte in erly stge DM. MNeill (1999) reported tht suh dieti nimls develop glomerulr hypertrophy, renl hyper filtrtion nd enlrgement, inresed urinry lumin exretion, nd glomerulr extrellulr mtrix umu- ltion within weeks of DM onset. The results of this study support the possiility tht CHP in YH might e effetive in preventing renl filure in dieti nimls. The intrperitonel dministrtion of STZ to SD rts used signifint dietogeni response with signifint inreses in the levels of fsting lood gluose s ompred to those of the group. After 14 dys of tretment, the fsting lood gluose levels of the STZindued dieti mie treted with YH t.75 g/kg were signifintly lower (P<.5) thn those of the DC group. As result, in vivo tretment with YH resulted in signifint redution in lood gluose level due to n inresed rte of gluose elimintion. The OGTT results revel tht lood gluose level ws signifintly deresed in the YH dministered groups s ompred to tht of the DC group. Furthermore, the AUC ws signifintly lower in dosedependent mnner (P<.5) in the YH dministered groups s ompred to the DC group. Hyperglyemi ws indued y intrperitonel STZ. Mintining lood gluose t levels lose to norml nd preventing dieti omplitions re mjor gols in the tretment of DM (Control nd Group, 1994). YH my enhne gluose utiliztion, euse it signifintly dereses lood gluose levels in gluose-loded rts, lthough the ext mehnisms re unler. Similr results were reported y Song et l. (21), in whih prostte extrt ontining zin nd CHP signifintly deresed lood gluose nd improved gluose tolerne nd insulin sensitivity in STZ-indued dieti rts. These results indite tht CHP hs strong ility to stimulte intestinl zin sorption, ellulr zin uptke nd promoted gluose utiliztion (Rosenthl et l., 21; Song et l., 21, 23). Zin defiieny ritilly ffets DM, euse zin tivtes insulin reeptor β-suunits, therey exerting n influene on gluose metolism (Song et l., 21). Although, the ext mehnism of the ntidieti effet of CHP hs not een lerly estlished, it is likely tht CHP is involved in regulting insulin nd leptin sensitivity y stimulting zin metolism euse of the following rguments: orl intke of CHP plus zin signifintly improves gluose tolerne in dieti nd overweight nimls in the stte of deresed or unhnged insulin levels (Hwng et l., 23; Song et l., 21); high CHP onentrtions inhiit insulin nd glugon seretion from islet ells in vitro (Wiler et l., 1984); nd CHP stimultes zin trnsport mehnisms ross the smll intestine nd musle ell memrne to inrese zin use (Rosenthl et l., 21). Aordingly, it is ssumed tht the YH-ontining CHP might ffet zin metolism. In onlusion, YH ontining CHP ws useful s therpeuti gent to improve gluose tolerne in dieti rts. Further investigtions re needed to eluidte the moleulr mehnisms y whih the ntidieti effets of CHP re medited. ACKNOWLEDGEMENT This study ws supported y the Tehnology Development Progrm for Food, Ministry for Food, Agriulture, Forestry nd Fisheries, Repuli of Kore (Projet No.: ). REFEREES Brhm D, Trinder P (1972). An improved olour regent for the determintion of lood gluose y the oxidse system. Anlyst 97(151): Chtterjee MN, Shinde K (1994). Text Book of Medil Biohemistry. Metolism of Crohydrte. Jypee Brothers Medil Pulishers Privte Ltd., New Delhi, Indi. p Chell M (1997). New developments in redmking. Food Mnu. 72:21 22 Control D, Group CTR (1994). Effet of intensive dietes tretment on the development nd progression of long-term omplitions in dolesents with insulin-dependent dietes mellitus: Dietes Control nd Complitions Tril. J. Peditr. 125(2): Crver JD (1994). Dietry nuleotides: ellulr immune, intestinl nd hepti system effets. Journl of Nutrition 124:144S-148S. Csey GP, Ingledew WM (1983). High grvity rewing: influene of pithing rte nd wort grvity on erly yest viility. J. Am. So. Brew. 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