Disertasi

Sintesis Konjugat Vitamin E-Asam Valerat dan Vita Vitamin E-Asam Kaprilat Serta Potensinya dalam Menghambat Pertumbuhan Sel HepG2 = Synthesis of Vitamin E-Valeric Acid and Vitamin ECaprylic Acid Conjugate and Their Potential in Inhibiting HepG2 Cell Growth.

Latar Belakang: Senyawa turunan vitamin E yaitu α-tokoferol asetat dan α- tokoferol suksinat telah terbukti memiliki aktivitas antikanker, namun penelitian tentang turunan vitamin E lain belum pernah dilakukan. Sintesis turunan vitamin E melalui pengikatan vitamin E dengan asam lemak (yaitu asam valerat dan asam kaprilat) menghasilkan konjugat vitamin E-asam lemak (konjugat vitamin E-asam valerat dan konjugat vitamin E-asam kaprilat) yang belum pernah dilaporkan. Pada penelitian ini akan dianalisis, apakah perpanjangan rantai karbon asam lemak yang terikat pada α-tokoferol akan menghasilkan aktivitas biologis yang lebih kuat dibandingkan α-tokoferol itu sendiri. Metode: Tahap penelitian adalah 1) sintesis konjugat vitamin E-asam lemak menggunakan metode Steglich, pemisahan, pemurnian, penentuan struktur dan karakteristik konjugat; 2) kemampuan toksisitas konjugat pada larva Artemia salina Leach menggunakan Brine Shrimp Lethality Test (BSLT); 3) kemampuan antioksidasi konjugat in vitro dengan 2,2-difenil-1-pikrilhidrazil (DPPH); 4) uji digesti konjugat oleh pankreatin; 5) kemampuan antioksidasi konjugat in vitro terhadap sel darah merah domba (SDMD); 6) kemampuan sitotoksisitas konjugat terhadap sel mononuklear darah tepi (SMDT); 7) kemampuan konjugat untuk menurunkan viabilitas sel HepG2. Hasil: Dua konjugat yaitu α-tokoferol valerat (α-TVal) dan α-tokoferol kaprilat (α- TCap) telah berhasil disintesis. α-TCap (LC50=1.936 µg/mL) bersifat tidak berbahaya terhadap larva Artemia salina Leach. Sementara kemampuan α-TVal (IC50=325±4,465 µg/mL) menetralkan radikal DPPH lebih baik dibandingkan α- TCap (IC50=1.984±36,249 µg/mL). α-TCap lebih sulit terhidrolisis oleh enzim pankreatin menjadi vitamin E kembali. Konjugat α-TVal (konsentrasi 10 mg/mL) mampu menurunkan MDA dan meningkatkan GSH pada SDMD yang teroksidasi H2O2. Konjugat ini pula mampu melindungi membran SDMD yang berupa lipid dari serangan radikal bebas H2O2. Pemberian α-TCap dapat menurunkan viabilitas SMDT dalam jumlah kecil. α-TCap (IC50=4.194 µg/mL) mampu menurunkan viabilitas sel HepG2. Kesimpulan: Konjugat α-TVal memiliki kemampuan antioksidan lebih baik dibandingkan α-TCap. Konjugat α-TCap memiliki kemampuan toksisitas dan menurunkan viabilitas sel HepG2 lebih baik dibandingkan α-TVal. Semakin pendek rantai karbon konjugat, kemampuan antioksidan semakin tinggi. Semakin panjang rantai karbon konjugat, kemampuan toksisitas dan menurunkan viabilitas sel HepG2 semakin tinggi.
Kata Kunci: α-tokoferol valerat, α-tokoferol kaprilat, HepG2, α-tokoferol


Introduction: Derivatives of vitamin E, namely α-tocopherol acetate and α- tocopherol succinate, have been shown to possess anticancer activity. However, research on other vitamin E derivatives has not been conducted. The synthesis of vitamin E derivatives by binding vitamin E with fatty acids (namely valeric acid and caprylic acid) results in vitamin E-fatty acid conjugates (vitamin E-valerate conjugate and vitamin E-caprylate conjugate) that have not been previously reported. This study will investigate whether extending the carbon chain of fatty acids attached to α-tocopherol enhances its biological activity compared to α- tocopherol itself. Methods: The research steps are: 1) synthesis of vitamin E-fatty acid conjugates using the Steglich method, including separation, purification, structural determination, and characterization of the conjugates; 2) evaluation of the conjugates' toxicity on Artemia salina Leach larvae using the Brine Shrimp Lethality Test (BSLT); 3) evaluation of the conjugates' in vitro antioxidant capacity using the 2,2-diphenyl-1 -picrylhydrazyl (DPPH) assay; 4) digestion test of the conjugates by pancreatin; 5) in vitro antioxidant capacity of the conjugates on sheep red blood cells (SRBCs); 6) evaluation of the conjugates' cytotoxicity on peripheral blood mononuclear cells (PBMC); 7) evaluation of the conjugates' ability to decrease the HepG2 cells viability. Results: Two conjugates, α-tocopherol valerate (α-TVal) and α-tocopherol caprylate (α-TCap), have been successfully synthesized. An α-TCap (LC50=1.936 µg/mL) is non-toxic to Artemia salina Leach larvae. In contrast, α-TVal (IC50=325±4.465 µg/mL) demonstrates better DPPH radical scavenging ability compared to α-TCap (IC50=1.984±36.249 µg/mL). An α-TCap is more resistant to hydrolysis by pancreatin enzyme. The α-TVal conjugate (at a concentration of 10 mg/mL) can reduce MDA and increase GSH levels in H2O2-oxidized SRBCs. This conjugate also protects the lipid membrane of SRBCs from H2O2-induced free radical damage. Administration of α-TCap can slightly reduce PBMC viability. An α-TCap (IC50=4.194 µg/mL) effectively reduces the viability of HepG2 cells. Conclusion: The α-TVal conjugate exhibits superior antioxidant properties compared to α-TCap. Conversely, the α-TCap conjugate demonstrates greater toxicity and more effectively decreases the viability of HepG2 cells than α-TVal. A shorter carbon chain in the conjugate correlates with increased antioxidant activity, whereas a longer carbon chain correlates with increased toxicity and a greater reduction in HepG2 cell viability.
Key words: α-tocopherol valerate, α-tocopherol caprylate, HepG2, α-tocopherol