ABSTRAKPenanganan kondisi disfungsi endotel sebelum terjadi kerusakan lebih lanjut sangatlah penting, karena berakibat terjadinya resistensi insulin dan hiperglikemia. Diharapkan dengan pemberian Catechins Green tea GMB-4 dapat memperbaiki kerusakan endotel melalui penghambatan oksidasi NADPH dan peningkatan produksi NO sehingga dapat mencegah terjadinya komplikasi lanjut pada pasien dengan diabetes Millitus. Desain penelitian ini true eksperimen dengan pendekatan post test only control group design. Subyek penelitian ini adalah kultur sel endotel yang berasal dari Human Umbilical Vein Endothelial Cell (HUVEC) yang dipapar glukosa 30 mM dan diberi perlakuan dengan Catechins Green tea GMB-4 dengan 3 dosis yaitu 0,03 mg/ml;0,3 mg/ml dan 3 ng/ml. Setelah pemberian selama 12 jam selanjutnya dilakukan analisa kadar NADPH dan Nitric Oxide (NO) dengan metode Colorimeter menggunakan NADPH Assay kit ab65349 dan Nitric Oxide Assay kit KGE001.Hasil penelitian menunjukan ada penurunan kadar NADPH pada kultur HUVEC setelah perlakuan Catechins Green tea GMB-4 pada dosis 0,3 mg/ml, dan terjadi peningkatan kadar Nitric oxide pada perlakuan dosis 0,03 mg/ml dan dosis 0,3 mg/ml. Hasil uji statistic one way Anova didapatkan nilai signifikan 0,000 untuk kadar NO dan NADPH. Sehingga dapat di simpulkan pemberian Catechins Green tea GMB-4 pada dosis 0,3 mg/ml dapat menurunkan oksidasi NADPH dan meningkatkan produksi NO secara signifikan. Pemberian Catechins Green tea GMB-4 dapat mengaktivasi eNOS dan berperan dalam penghambatan oksidasi NADPH melalui pospotidylinositol-3 kinase, cAMP dependent protein kinase dan jalur Akt. Catechins juga mengkatalisis produksi NO dari L-arginin dan menghambat ROS dengan jalan mengikat ion metal pada reaksi redok, menghambat transkripsi faktor, menghambat enzim prooksidan dan meningkatkan enzim antioksidan.Kata kunci: antioksidan, Catechins Green tea GMB-4, NO, NADPHÃÂ ABSTRACTHandling conditions of endothelial dysfunction before further damage is very important, because it results in insulin resistance and hyperglycemia. Expected by administration of Green Tea Catechins GMB-4 can improve endothelial damage through inhibition of NADPH oxidation and NO production increased so as to prevent the occurrence of further complications in patients with diabetes millitus. True experimental design of this study to approach post-test only control group design. The subjects of this study were cultured endothelial cells derived from Human Umbilical Vein Endothelial Cell (HUVEC) were exposed to 30 mM glucose and treated with Green Tea Catechins GMB-4 with 3 doses are 0.03 mg / ml, 0.3 mg / ml and 3 ng / ml. Analized NADPH levels and Nitric Oxide (NO) with Colorimeter method using NADPH Assay kit ab65349 and Nitric Oxide Assay kit KGE001. The results showed decrease in NADPH levels in cultured HUVEC after treatment of Green Tea Catechins GMB-4 at a dose of 0.3 mg / ml, and an increase in levels of nitric oxide in the treatment dose of 0.03 mg / ml and 0.3 mg / ml . Results of one way ANOVA statistical test obtained significant value of 0.000 for the levels of NO and NADPH.. So it can be concluded giving Green tea Catechins GMB-4 at a dose of 0.3 mg / ml can reduce the oxidation of NADPH and increased NO production significantly. Provision of Green tea Catechins GMB-4 can activate eNOS and play a role in the inhibition of NADPH oxidation through pospotidylinositol-3 kinase, cAMP dependent protein kinase and Akt pathways. Catechins also catalyze the production of NO from L-arginine and inhibited ROS by binding the metal ions on the reaction redok, inhibits transcription factor, inhibits prooxidant enzymes and increases antioxidant enzymes.Keywords: antioksidant, Catechins Green tea GMB-4, NO, NADPH