Electronic Theses and Dissertation

Hiperkolesterolemia merupakan salah satu faktor penyebab penyakit kardiovaskular dan kondisi hiperkolesterolemia dapat meningkatkan risiko penyakit aterosklerosis. Hiperkolesterolemia suatu kondisi meningkatnya kadar kolesterol total (≥ 240 mg/dL) dan kadar LDL (≥ 190 mg/dL) dalam darah. Obat-obatan dari golongan statin atau 3-hydroxy-3-methylglutaryl-coenzym-A (HMG-KoA) reduktase inhibitor umum digunakan dalam pengobatan hiperkolesterolemia. HMG-KoA reduktase merupakan enzim kunci dalam biosintesis kolesterol di hati, dimana HMG-KoA reduktase akan mengkatalisis konversi HMG-KoA menjadi mevalonat yang merupakan tahapan awal dalam biosintesis kolesterol. Penghambatan terhadap HMG-KoA reduktase dapat menurunkan kadar kolesterol total, kolesterol lipoprotein densitas rendah (LDL), dan trigliserida serta meningkatkan kolesterol lipoprotein densitas tinggi (HDL). Penggunaan obat golongan statin seperti simvastatin dan pravastatin dalam jangka panjang memberikan efek samping berupa kerusakan hati dan otot.
Tumbuhan mengandung sejumlah senyawa fitokimia atau metabolit sekunder yang terbukti mampu menurunkan risiko penyakit dan meningkatkan kesehatan. Beberapa hasil penelitian melaporkan bahwa komponen aktif dari ekstrak tumbuhan mempunyai kemampuan menurunkan kadar kolesterol. Beberapa senyawa aktif yang terkandung dalam tumbuhan telah terbukti dapat menghambat aktivitas enzim HMG-KoA reduktase dan menghambat sintesis kolesterol. Tacca leontopetaloides (L.) Kuntze (T.leontopetaloides) atau taka merupakan tumbuhan berumbi yang termasuk ke dalam famili Taccaceae. Bagian umbi dari tumbuhan taka mengandung senyawa aktif seperti glikosida, flavonoid, phenols, alkaloid, tanin, coumarin, polisakarida, glikosida, gum, terpenes, terpenoid, dan taccalin, namun belum ada informasi terkait mekanisme penghambatan aktivitas enzim HMG-KoA reduktase oleh senyawa aktif yang terkandung dalam umbi taka dan potensi umbi taka (T. Leontopetaloides) sebagai antihiperkolesterolemia.
Penelitian ini bertujuan mengidentifikasi senyawa aktif ekstrak umbi taka Kepulauan Banyak Aceh Singkil melalui uji fitokimia dan GC-MS, menganalisis potensi senyawa aktif ekstrak umbi etanol umbi taka sebagai inhibitor HMG-KoA reduktase secara in silico, in vitro dan in vivo menggunakan tikus model hiperkolesterolemia. Uji GC-MS ekstrak umbi taka dilakukan dengan injeksi ekstrak kental umbi taka sebanyak 5 µL ke dalam GC-MS Agilents Technologies 7890GC/5975 MS dengan kolom kapiler HP Ultra 2 dengan panjang 30 m x 0,20 mm dan ketebalan film ID x 0,11 (µm).
Uji in silico atau molecular docking menggunakan ligan uji senyawa aktif hasil dari uji GC-MS dan ligan kontrol Simvastatin, sedangkan struktur molekul protein target HMG-KoA reduktase atau reseptor yang digunakan adalah PDB ID:2R4F. Pengujian secara in vitro dilakukan menggunakan Assay kit HMG-CoA reduktase CS 1090 (Sigma Aldrich) untuk mengetahui potensi penghambatan serbuk simplisia dan ekstrak etanol umbi taka serta simvastatin terhadap aktivitas HMG-KoA reduktase. Uji in vivo dilakukan dengan pemberian pakan tinggi kolesterol untuk membuat tikus hiperkolesterolemia. Tikus hiperkolesterolemia selanjutnya diberikan pakan standar, Simvastatin dan ekstrak etanol umbi taka sesuai kelompok perlakuan selama 4 minggu dan kemudian diukur kadar kolesterol total, HDL, LDL dan trigliserida plasma tikus.
Hasil uji fitokimia menunjukkan bahwa ekstrak umbi taka (T. Leontopetaloides) mengandung sejumlah senyawa metabolit sekunder dari golongan flavonoid, fenolik, tanin, steroid, saponin dan alkaloid, sedangkan uji GC-MS menunjukkan bahwa ekstrak etanol umbi taka mengandung senyawa aktif dari golongan asam lemak yaitu hexadecanoic acid dan 9,12-octadecadienoic acid serta senyawa steroid yaitu stigmasterol, campesterol dan gamma sitosterol. Berdasarkan hasil uji in silico diketahui bahwa nilai energi afinitas ligan kontrol Simvastatin yaitu -8,0 kkal/mol, sedangkan ligan uji yaitu senyawa stigmasterol memiliki nilai energi afinitas (binding affinity) yang mendekati simvastatin yaitu -7,2 kkal/mol. Berdasarkan nilai energi afinitas dan kesamaan beberapa residu asam amino stigmasterol dengan simvastatin menunjukkan bahwa senyawa stigmasterol mempunyai kemampuan sebagai inhibitor HMG-KoA reduktase.
Pengujian secara in vitro menunjukkan bahwa persentase penghambatan HMG-KoA reduktase ekstrak etanol umbi taka sebesar 88% dan nilai IC50 sebesar 4,92 ppm. Nilai IC50 ekstrak etanol umbi taka tidak jauh berbeda dengan nilai IC50 Simvastatin yaitu sebesar 4,62 ppm. Berdasarkan nilai IC50 dan persentase penghambatan HMG-KoA reduktase ekstrak etanol umbi taka dapat disimpulkan bahwa ekstrak etanol umbi taka mempunya potensi sebagai inhibitor HMG-KoA reduktase. Uji in vivo pada tikus model hiperkolesterol menunjukkan bahwa pemberian ekstrak etanol umbi taka mampu menurunkan kadar kolesterol total, LDL dan trigliserida plasma tikus. Kesimpulan dari penelitian ini adalah ekstrak etanol umbi taka (T.leontopetaloides) dari Kepulauan Banyak Kabupaten Aceh Singkil terbukti mempunyai aktivitas penghambatan terhadap HMG-KoA reduktase dan berpotensi sebagai agen antihiperkolesterolemia.

Hypercholesterolemia is one of the causes of cardiovascular disease and hypercholesterolemia can increase the risk of atherosclerosis. Hypercholesterolemia is a condition of increasing total cholesterol levels (≥ 240 mg/dL) and LDL levels (≥ 190 mg/dL) in the blood. Drugs from the statin or 3-hydroxy-3-methylglutaryl-coenzym-A (HMG-CoA) reductase inhibitors are commonly used in the treatment of hypercholesterolemia. HMG-CoA reductase is a key enzyme in cholesterol biosynthesis in the liver, where HMG-CoA reductase will catalyze the conversion of HMG-CoA to mevalonate, the initial step in cholesterol biosynthesis. Inhibition of HMG-CoA reductase can reduce total cholesterol, low-density lipoprotein cholesterol (LDL), and triglycerides and increase high-density lipoprotein cholesterol (HDL). Long-term use of statin drugs such as simvastatin and pravastatin can cause side effects, such as the liver and muscles damage. Plants contain several phytochemical compounds or secondary metabolites that are proven to be able to reduce disease risk and improve health. Several studies have reported that the active components of plant extracts can lower cholesterol levels. Several active compounds contained in plants have been shown to inhibit HMG-CoA reductase enzyme activity and inhibition of cholesterol synthesis. Tacca leontopetaloides (L.) Kuntze (T.leontopetaloides) or Tacca is a plant belonging to the family Taccaceae. The tuber part of the Tacca plant contains active compounds such as glycosides, flavonoids, phenols, alkaloids, tannins, coumarins, polysaccharides, glycosides, gums, terpenes, terpenoids, and taccalin, but there is no information regarding the mechanism of inhibition of HMG-CoA reductase activity by active compounds that contained in Tacca tubers and the potential of Tacca tubers (T. leontopetaloides) as an antihypercholesterolemia. This study aims to identify the active compounds of the Banyak Island of Tacca tuber extract through phytochemical tests and GC-MS, to analyze the potential of the active compounds of the ethanolic tuber extract of Tacca tubers as HMG-CoA reductase inhibitors in silico, in vitro, and in vivo using a rat model of hypercholesterolemia. The GC-MS test of Tacca tuber extract was carried out by injecting 5 µL of thick Tacca tuber extract into the GC-MS Agilent Technologies 7890GC/5975 MS with an HP Ultra 2 capillary a column with a length of 30 m x 0.20 mm and a film thickness ID x 0.11 (µm). The in silico or molecular docking using the ligand test of the active compound resulting from the GC-MS test and Simvastatin as the control ligand, while the molecular structure of the HMG-CoA reductase target protein or the receptor used is PDB ID:2R4F. Testing in vitro was conducted using an assay kit HMG-CoA reductase CS 1090 (Sigma Aldrich) to determine the inhibitory potential of Simplicia powder and ethanol extract of tacca tuber and simvastatin on HMG-CoA reductase activity. The in vivo test was carried out by giving high-cholesterol feed to make the hypercholesterol rat. The hypercholesterolemia rats were then fed standard feed, simvastatin, and ethanol extract of Tacca tubers according to the treatment group for 4 weeks, and then the total cholesterol, HDL, LDL, and plasma triglyceride levels were measured. Phytochemical test results showed that Tacca tuber extract (T. leontopetaloides) contained several secondary metabolites from the flavonoid, phenolic, tannin, steroid, saponin, and alkaloid groups, while the GC-MS test showed that the ethanol extract of tacca tuber contained active compounds from the fatty acid group, namely hexadecanoic acid and 9,12-octadecadienoic acid as well as steroid compounds stigmasterol, campesterol, and gamma sitosterol. Based on in silico test results that the binding affinity of the Simvastatin control ligand is -8.0 kcal/mol, while the tested ligand, namely the stigmasterol compound, has a binding affinity that is close to simvastatin, namely -7.2 kcal/mol. Based on the binding affinity and the similarity of several amino acid residues of stigmasterol and simvastatin, it shows that the compound stigmasterol can act as an HMG-CoA reductase inhibitor. The in vitro test showed that the percentage of HMG-CoA reductase inhibition of the ethanol extract of Tacca tuber was 88% and the IC50 of 4.92 ppm. The IC50 of ethanol extract of Tacca tuber is not much different from the IC50 of Simvastatin is equal to 4.62 ppm. Based on IC50 and the percentage of HMG-CoA reductase inhibition of the ethanol extract of Tacca tuber. It can be concluded that the ethanol extract of Tacca tuber has the potential as an HMG-CoA reductase inhibitor. In the in vivo test in a rat model of hypercholesterolemia, it was shown that the administration of ethanol extract of Tacca tuber was able to reduce the total cholesterol, LDL, and plasma triglyceride levels of rats. The conclusion of this study is the ethanol extract of Tacca tuber (T.leontopetaloides) from the Banyak Islands of Aceh Singkil District has been shown to have inhibitory activity against HMG-CoA reductase and has the potential as an antihypercholesterolemia agent.