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Öğe Aşırı beslenmeye bağlı oluşan insülin direncinin biyokimyasal gelişimi ve AMP-ile aktive edilmiş protein kinaz (AMPK)’ın fonksiyonu(2020) Yaman, Mustafa; Kişmiroğlu, Cemalettin; Uğur, Halime; Belli, İsmail; Özgür, BahtiyarAşırı beslenme ve obezitenin, insülin direnci, diyabet, hipertansiyon, kardiyovasküler hastalıklar ve kanser gibi birçok kronik hastalığa neden olduğu bilinmektedir. İnsülin direnci, glikozun kas ve diğer dokulara taşınmasında hücrelerin insülininin etkisine yanıt verme yeteneğinin azalması olarak tanımlanır. Obezitenin gelişmesiyle birlikte yağ dokusundan salınan esterlenmemiş yağ asitleri, gliserol ve proinflamatuar sitokinler insülin direncine neden olur. Özellikle MCP-1 ve TNF-? gibi sitokin ve kemokinler adipositlerde trigliseridlerin hidrolizine neden olur. Ortaya çıkan serbest yağ asitleri dolaşım yoluyla kas, karaciğer ve beta hücrelerine taşınır ve DAG, TAG ve seramid olarak depolanır. Bu yağ asitleri türevlerinin birikimi hem IRS’yi bloke ederek insülin direncine, hemde hücre içi enerji sensörü olan AMPK’nin aktivasyonunun azalmasına neden olur. AMPK’nin aktivasyonunun azalması sonucu glukoz taşıyıcı proteininin translokasyonu azalır ve insülin direnci gelişir. Bunun yanında, AMPK’nin aktivasyonunun azalması dokularda lipit birikimine, hücresel işlev bozukluklarına ve birçok kronik hastalığın gelişmesine neden olur. Egzersizin yanında metformin, AICAR ve TZDs gibi bazı farmasötik ilaçların hem lipit birikimini azalttığı hem de AMPK’nin aktivasyonunu artırarak insülin direncini engellediği bildirilmiştir.Öğe Determination and evaluation of in vitro bioaccessibility of added vitamin C in commercially available fruit-, vegetable-, and cereal-based baby foods(Elsevier Science Ltd, 2020) Uğur, Halime; Çatak, Jale; Mizrak, Ömer Faruk; Cebi, Nur; Yaman, MustafaKnowing the bioaccessibility of vitamin C in foodstuffs produced for infants and young children is necessary to determine their daily vitamin C intake. The purpose of the present study was to investigate the bioaccessibility of vitamin C in fruit-, vegetable-, and cereal-based baby foodstuffs by an in vitro digestion model at varying gastric pHs. The concentrations of measured vitamin C were higher than the declared amounts on their label. The bioaccessibility of vitamin C ranged from 10.4 to 43.4%, and from 0.4 to 19.2% in fruit-and vegetable-based baby foodstuffs (declared vitamin C fortified) at gastric pH 1.5 and 4, respectively. For cereal-based baby foodstuffs, the bioaccessibility ranged from 1.3 to 53.8%, and from 0.3 to 26.3% at gastric pH 1.5 and 4, respectively. As revealed in this research, the bioaccessibility of vitamin C in baby foodstuffs is very low in both gastric pH conditions.Öğe Determination of aflatoxins and ochratoxin a levels in nuts and dried fruits in Turkey with evaluation of the estimated daily intake(VUP Food Research Institute, 2023) Uğur, Halime; Omurtag, Gülden Zehra; Omurtag Korkmaz, Burcu İrem; Yaman, MustafaA total of 140 samples, including nuts and dried fruits sold in the province of Istanbul, Turkey, were examined for the presence of aflatoxins and ochratoxin A (OTA) by high-performance liquid chromatography (HPLC), which were quantitatively determined and estimated daily intakes (EDI) were calculated. It was found that aflatoxins load was higher in nuts and OTA load was higher in dried fruits. The highest level of aflatoxins was found in a packaged roasted hazelnut sample (8.043 mu g center dot kg-1). The maximum OTA level was detected in an unpackaged raisin sample (0.505 mu g center dot kg-1). The highest EDI values of aflatoxins were seen in hazelnut samples and were determined as 0.025 ng center dot kg-1 body weight (BW) per day. EDI of OTA was similar between the groups (0.000-0.001 ng center dot kg-1 BW per day). As a result, the contents detected for both toxins in the products examined were below the legal limits, except for one hazelnut sample (aflatoxin B1: 7.645 mu g center dot kg-1). The EDI values were below the limit values set by the European Food Safety Authority. However, since it is possible for these values to rise to risky levels, the risk of contamination should be minimized by taking the necessary precautions.Öğe Investigation of formation of well-known AGEs precursors in cookies using an in vitro simulated gastrointestinal digestive system(Elsevier Ltd, 2022) Yaman, Mustafa; Demirci, Mehmet; Ede Çintesun, Elif; Kurt, Edanur; Mızrak, Ömer FarukThe present study investigated the influence of in vitro stimulated digestion system on the content of glyoxal and methylglyoxal in commercial cookies. Glyoxal and methylglyoxal levels in different cookie samples were analyzed before and after in vitro digestion with High Performance Liquid Chromatography. Initial glyoxal and methylglyoxal values ranged between 42.9 and 126.6 µg/100 g, and between 22.9 and 507.3 µg/100 g, respectively. After in vitro digestion, formation of glyoxal and methylglyoxal values were increased up to 645% and 698%, respectively. The results revealed that in vitro stimulated digestion conditions strongly increased the amount of glyoxal and methylglyoxal in cookies. The amount of fructose was found to be more effective on the formation of both GO and MGO than those of glucose and sucrose. Further studies are needed to extensively investigate glyoxal and methylglyoxal formation under in vitro conditions in such foods.Öğe Investigation of the alpha-dicarbonyl compounds in some snack foods by HPLC using precolumn derivatization with 4-Nitro-1,2-Phenylenediamine(Biointerface Research in Applied Chemistry, 2022) Ede Çintesun, Elif; Tanyıldız, Sena Nur; Yıldırım, Hatice; Mızrak, Ömer Faruk; Yaman, MustafaSnack foods are widely consumed in today's modern diet. Food processing techniques and food composition may increase advanced glycation products (AGEs) in snack foods. The present study aimed to determine the most potent precursors of AGEs in snack foods. For this purpose commonly consumed some snacks foods ere obtained from markets in Istanbul. Turkey. The amount of alpha dicarbonyl compounds (alpha-DCs.) glyoxal (GO). and methylglyoxal (MGO) ere determined by high-performance liquid chromatography. The measured amount of GO and MGO ranged between 4-684 mu g/100 g and 28-1573 mu g/100 g in snack foods. respectively. In our study. high levels of MGO were detected in wafer hazelnut chips with cheese and peanuts. Due to their high-fat content, the formation of GO and MGO may occur through lipid peroxidation. In addition. the fragmented state of hazelnuts and peanuts in samples may increase lipid peroxidation. Free sugar content in Turkish delight and cake with fruit might contribute to the alpha-DCs formation by caramclization reaction due to high temperature. In conclusion. snack products that are frequently consumed have many unfavorable features for health. It is important to limit snack food consumption in terms of reducing AGEs exposure.Öğe Investigation of the deoxynivalenol and ochratoxin a levels by high-performance liquid chromatography of cereals sold in the markets in Türkiye(Sociedade Brasileira de Ciencia e Tecnologia de Alimentos, SBCTA, 2023) Şahin, Semih; Eyüpoğlu, Ozan Emre; Yaman, Mustafa; Çal Doğan, Tuğbagül; Omurtag Korkmaz, Burcu İrem; Omurtag, Gülden ZehraThe current research was conducted to determine the deoxynivalenol (DON) and ochratoxin A (OTA) levels of 24 pieces of wheat flour, 24 pieces of rice, 24 pieces of corn flour, and 24 pieces of whole wheat flour obtained from the markets in Istanbul by HPLC. DON was detected in 4 of the 96 grain cereal samples at levels between 0.94 and 1.16 µg/kg (LOQ, 0.92 µg/kg). Besides, from the analyzed samples, DON was detected in 3 pieces of ashura wheat, 2 pieces of rice, and 5 pieces of corn flour between LOD and LOQ. The highest DON level was found in the corn flour sample (1.16 µg/kg), which was sold unpacked. OTA was detected in 11 of the samples (0.87-6.97 µg/kg) consisting of 3 corn flours (1.51-2.23 µg/kg) and 8 whole wheat flours (0.87-6.97 µg/kg). The highest OTA level was found in the packaged whole wheat flour sample (6.97 µg/kg) bought from the market. Since DON and OTA exposure can be observed frequently in cereals and may increase to possible risky levels, further work should be done to determine the precautions necessary to minimize the risks of contamination.Öğe Measurement of advanced glycation end products could be used as an indicator of unhealthy nutrition for colorectal cancer risk(Routledge Journals, Taylor & Francis Ltd, 2022) Şahingöz Erdal, Gülçin; Yaman, Mustafa; Yıldırım Servi, Esra; Uğur, Halime; Kasapoğlu, Pınar; Çikot, Murat; Işıksaçan, NilgünThe main culprit behind most cancers is the accumulation of reactive oxygen species. Glyoxal (GO) and methylglyoxal (MGO) are reactive intermediates created by food processing and they are precursors of advanced glycation end products (AGE) that cause glycative stress. We aimed to evaluate the relationship between AGE levels of healthy volunteers and treatment-naive patients diagnosed with colorectal cancer. The study consisted of patients diagnosed with colorectal cancer and healthy volunteers who underwent routine colonoscopy. The study was conducted with a total of 42 cases, 47.6% (n = 20) female. The ages of the participants in the study ranged from 41 to 82 years, and the mean was 60.57 +/- 10.78 years. The GO and MGO values of the patient group were found to be significantly higher than those of the control group (p = 0.007, p = 0.001, respectively). The risk of colorectal cancer was 22 and 57 times higher in individuals with GO and MGO values above 1.25 mu g/mL and 0.0095 mu g/mL, respectively. The blood AGE level is closely related to diet, and it can be decreased through the appropriate improvement of diet. Thus, the measurement of AGE can be used to predict whether a person's nutrition is healthy or unhealthy and prevent increased risk of colorectal cancer.Öğe Vitamin C ve hastalıklar üzerine etkisi(2020) Uğur, Halime; Eker, Sümeyye; Çatak, Jale; Yaman, MustafaVitamin C, vücuttaki çeşitli biyokimyasal ve fizyolojik süreçler için gerekli olan esansiyel bir mikrobesin ögesidir. Birçok meyve ve sebzede bulunan vitamin C, insan vücudunda sentezlenemediğinden dışarıdan diyetle alınması gerekmektedir. İndirgenmiş form olan L-askorbik asit ve yükseltgenmiş form olan L-dehidroaskorbik asit (DHA)’in, her ikisi de vitamin C aktivitesini korumaktadır. Askorbik asit, sodyum bağımlı vitamin C taşıyıcıları (SVCT'ler) aracılığıyla hücreye taşınırken, DHA glikoz taşıyıcı ailesi (GLUT'lar) yoluyla taşınır. Vitamin C’nin oral alımından sonra plazmadaki konsantrasyonu, hücreye ve hücre içi organellere girmek için gerekli olan taşıyıcılar tarafından sıkı bir şekilde kontrol edilmektedir. Vitamin C, triptofanın nörotransmitter olan serotonine dönüşümü, folik asit aktivasyonu ve kolesterolün safra asitlerine dönüşümü gibi bir dizi metabolik fonksiyonda önemli bir rol oynamaktadır. Biyosentetik ve gen düzenleyici enzim ailesinin bir kofaktörü olmasının yanı sıra güçlü antioksidan aktivitesi sayesinde vücudun serbest radikal hasarını azaltarak çoğu hastalığa karşı da koruyucu etki göstermektedir. Son yıllarda yapılan araştırmalar, birçok kronik hastalık üzerine vitamin C’nin olası yeni terapötik etkilerine odaklanmıştır. Bu derlemede yeterli miktarda vitamin C alımının normal vücut fonksiyonlarının sürdürülmesine, bazı hastalıklarda tedaviye yardımcı olmasına ve eksikliğinin çeşitli hastalık risklerini artırmasına yönelik etki mekanizmalarına değinilmiştir.
