SINTESIS SENYAWA ISOFLAVON DARI MINYAK DAUN CENGKEH DAN UJI AKTIVITAS ANTIKANKER SECARA IN VITRO

ANDI HAIRIL ALIMUDDIN, Prof Drs. Sabirin Matsjeh, Ph.D

2012 | Disertasi | S3 Ilmu Kimia

isolasi minyak daun cengkeh. Eugenol terlebih dahulu dikonversi menjadi 3,4-dimetoksibenzil karboksilat dan 3,4-dimetoksibenzil sianida sebelum dikondensasikan dengan senyawa fenol untuk menghasilkan senyawa isoflavon. Senyawa isoflavon yang disintesis telah diuji aktivitas antikanker menggunakan sel kanker T47D. Sintesis 3,4-dimetoksibenzil karboksilat melalui dua cara yaitu oksidasi metileugenol menggunakan KMnO4 (rendemen 21%) dan hidrolisis 3,4- dimetoksibenzil sianida menggunakan H2SO4 65% (rendemen 85%). Sintesis 3,4-dimetoksibenzil sianida dari eugenol melalui beberapa tahapan reaksi yaitu metilasi eugenol menggunakan dimetil sulfat menghasilkan metileugenol (89,78%) yang kemudian diisomerisasi menggunakan t-BuOK dalam DMSO menghasilkan metilisoeugenol (85,7%). Oksidasi produk isomerisasi dengan KMnO4 ,menghasilkan 3,4-dimetoksibenzaldehida (85,45%). Aldehida direduksi oleh NaBH4 (98,21%) diikuti substitusi dengan SOCl2 menghasilkan 3,4- dimetoksibenzil klorida. Nitrilisasi menggunakan NaCN menghasilkan 3,4- dimetoksibenzil sianida (89,5%). Reaksi asilasi Friedel-Crafts antara 3,4- dimetoksibenzil karboksilat dengan resorsinol menggunakan katalis BF3-Et2O menghasilkan 3,4-dimetoksibenzil 2',4'-dihidroksifenil keton (76%). Sintesis 3,4- dimetoksibenzil-2',4',6'-trihidroksifenil keton (56%) melalui reaksi Houben- Hoesch antara 3,4-dimetoksibenzil sianida dengan floroglusinol. Sintesis 7- hidroksi-3',4'-dimetoksiisoflavon dan 5,7-dihidroksi-3',4'-dimetoksiisoflavon masing-masing dari 2,4-dihidroksifenil-3',4'-dimetoksibenzil keton dan 3,4- dimetoksibenzil-2',4',6'-trihidroksifenil keton menggunakan reagen BF3- Et2O/DMF/benzena sulfonil klorida masing-masing diperoleh dengan rendemen 84 dan 83%. Derivatisasi 7-hidroksi-3',4'-dimetoksiisoflavon menggunakan benzil klorida, benzoil klorida, asetil klorida, etil-2-kloro-asetat dan DMS menghasilkan 7-O-benzil-3',4'-dimetoksiisoflavon (80,9%), 7-O-benzil-3',4'-dimetoksiisoflavon (83,7%), 7-O-etoksikarbonilmetil-3',4'-dimetoksiisoflavon (74,5%), 7-O-asetil- 3',4'-dimetoksiisoflavon (78,2%) dan 7,3',4'-trimetoksiisoflavon (78,9%). Derivatisasi 5,7-dihidroksi-3',4'-dimetoksi-isoflavon menghasilkan 7-Oetoksikarbonilmetil- 5-hidroksi-3',4'-dimetoksi-isoflavon (72,4%), 7-Okarboksilmetil- 5-hidroksi-3',4'-dimetoksiisoflavon (93,4%), 5,7-O-dibenzoil-3',4'- dimetoksiisoflavon (82,5%) dan 7-O-asetil-5-hidroksi-3',4'-dimetoksiisoflavon (75,4%). Hasil uji sitotoksik senyawa isoflavon hasil sintesis dilakukan terhadap sel kanker T47D mempunyai nilai IC50 di atas 100 μg/mL. Senyawa isoflavon hasil sintesis ternyata tidak menunjukkan aktivitas sitotoksik terhadap sel line kanker T47D.

Synthesis of isoflavone derivatives from eugenol, isolated from clove leaves oil, had been conducted. Firstly, eugenol was converted into 3,4-dimethoxybenzyl carboxylate and 3,4-dimethoxybenzyl cyanide. The two compounds were then condensed with phenolic compounds to produce isoflavone. The synthesized isoflavones were used in in vitro anticancer assay against T47D cancer cell line. Synthesis of 3,4-dimethoxybenzyl carboxylate was conducted in two ways: oxidation of methyleugenol using KMnO4 (21% yield) and hydrolysis of benzyl cyanide using H2SO4 65% (85% yield). 3,4-Dimethoxybenzyl cyanide was obtained from eugenol via several steps. Methylation of eugenol using DMS gave methyleugenol (89,78%), which was then isomerized using t-BuOK in DMSO to give methyl isoeugenol (85,7%). The isomerization product was oxidized with KMnO4 to produce 3,4-dimethoxybenzaldehyde (85,45%). The aldehyde was reduced by NaBH4 (98,21%), followed by substitution using SOCl2 to yield 3,4- dimethoxybenzyl chloride. Nitrilization of the previous product using NaCN produced 3,4-dimethoxybenzylcyanide (89.5%). Then, Friedel-Crafts acylation between 3,4-dimethoxybenzylcarboxylate and resorcinol in the presence of BF3- Et2O yielded 3,4-dimethoxbenzyl-2',4'-dihydroxyphenyl ketone in 76% yield. In addition, the benzyl cyanide derivative was reacted with phloroglucinol to afford 3,4-dimethoxybenzyl-2',4',6'-trihydroxyphenyl ketone in 56% yield, based on Houben-Hoesch reaction. Isoflavones of 7-hydroxy-3',4'-dimethoxyisoflavone and 5,7-dihydroxy-3',4'-dimethoxisoflavone were obtained from the benzyl- and phenyl ketones in 84% and 83% yields, respectively, using the reagent of BF3- Et2O/DMF/benzene suphonyl chloride. Derivatization of 7-hydroxy-3',4'- dimethoxyisoflavones using reagents of benzyl chloride, benzoyl chloride, acetyl chloride, ethyl-2-chloroacetate and DMS produced 7-O-benzyl- (80.9% yield), 7- O-benzoyl- (83.7% yield), 7-O-acetyl- (78.2% yield), 7-O-ethoxycarbonylmethyl- (74.5% yield) and 7,3’,4’-trimethoxyisoflavone (78,9%). Furthermore, derivatization of 5,7-hydroxy 3’,4’-dimethoxyisoflavones produced 7-Oethoxycarbonylmethyl- (72.4% yield), 7-O-carboxylmethyl- (93,4%), 5,7-Odibenzoyl- (82.5% yield) and 7-O-acetyl- (75.4% yield). The citotoxic test of the synthesized isoflavones to cancer cell of T47D showed that all isoflavones had IC50 higher than100 μg/mL. The isoflavones, in fact, did not display anticancer activity to T47D cancer cell line.

Kata Kunci : eugenol, isoflavon, asilasi Friedel-Crafts, reaksi Houben-Hoesch