SINTESIS 2apostrof,4apostrof-DIHIDROKSI-3,4-DIMETOKSIKHALKON DAN UJI AKTIVITASNYA SEBAGAI TABIR SURYA SECARA IN VITRO

SEKAR TAWANG PUTRIANINGRUM, Prof. Drs. Sabirin Matsjeh, Ph.D. ; Dr. Winarto Haryadi, M.Si.

2015 | Skripsi | S1 KIMIA

Sintesis 2apostrof,4apostrof-dihidroksi-3,4-dimetoksikhalkon melalui kodensasi Claisen-Schmidt dan uji aktivitasnya sebagai tabir surya secara in vitro telah dilakukan. Sintesis 2,4-dihidroksiasetofenon dilakukan melalui asilasi Friedel-Crafts dari resorsinol. Asam asetat glasial digunakan sebagai agen pengasilasi dan ZnCl2 sebagai katalis. Pemurnian dilakukan dengan rekristalisasi. Produk 2,4-dihidroksiasetofenon direaksikan dengan 3,4-dimetoksibenzaldehida dan KOH 40% untuk mensintesis khalkon. Campuran diaduk selama 48 jam pada temperatur ruang dan diasamkan dengan HCl 10% hingga terbentuk padatan. Rekristalisasi dilakukan untuk memurnikan padatan. Produk 2apostrof,4apostrof-dihidroksi-3,4-dimetoksikhalkon diuji aktivitasnya sebagai tabir surya secara in vitro menggunakan spektrofotometer UV-Vis. Khalkon dilarutkan dalam etanol dan dibuat variasi konsentrasi dari 2-40 mikrogram/mL. Larutan diukur absorbansi maksimumnya pada rentang panjang gelombang 200-400 nm untuk mengetahui tipe serapan UV. Panjang gelombang maksimum digunakan untuk mengukur absorbansi seluruh larutan khalkon berbagai konsentrasi untuk menghitung harga faktor perlindungan matahari (Sun Protecting Factor atau SPF). Produk sintesis asetofenon dan khalkon dianalisis strukturnya menggunakan spektrometer IR, GC-MS, dan H-NMR. Hasil sintesis 2,4-dihidroksiasetofenon berwujud padatan oranye kekuningan dengan titik lebur 141-144 C dan rendemen 38,05%. Hasil sintesis 2apostrof,4apostrof-dihidroksi-3,4-dimetoksikhalkon berwujud padatan kuning kecoklatan dengan titik lebur 195-199 C dan rendemen 19,94%. Absorbansi maksimum senyawa khalkon dicapai pada panjang gelombang 276 nm (UV-C) dan 370 nm (UV-A) sehingga dapat digunakan sebagai tabir surya anti UV-C dan anti UV-A. Pengukuran absorbansi larutan berbagai konsentrasi dilakukan pada panjang gelombang 370 nm (UV-A) karena sinar UV-C diserap lapisan ozon di atmosfer. Proteksi minimal (SPF 2-12) dicapai mulai konsentrasi 12 mikrogram/mL. Proteksi sedang (SPF 12-30) dicapai pada konsentrasi 40 mikrogram/mL.

Synthesis of 2apostrophe,4apostrophe-dihydroxy-3,4-dimethoxychalcone and in vitro test of its sunscreen activity has been carried out. The research was started by synthesizing 2,4-dihydroxyacetophenone through Friedel-Crafts acylation from resorcinol. Glacial acetic acid was used as acylating agent and ZnCl2 as catalyst. Recrystalization was done using HCl:aquades (1:11) to purify the product. Product of acetophenone was then reacted with 3,4-dimethoxybenzaldehyde in the presence of KOH 40% through Claisen-Schmidt condensation to collect 2apostrophe,4apostrophe-dihydroxy-3,4-dimethoxychalcone. The synthesis was done by constant stirring for 48 hours at room temperature. The mixture was acidified using HCl 10% until the solid was formed. Then the solid obtained was recrystalized using methanol. Product of 2apostrophe,4apostrophe-dihydroxy-3,4-dimethoxychalcone was then diluted using ethanol to a range of concentration from 2 microgram/mL to 40 microgram/mL. The maximum absorbance of the solution was first measured using spectrophotometer UV-Vis at wavelength 200-400 nm. The wavelength was used to measure the absorbance of all solutions. The absorbances were then used to count the SPF (Sun Protecting Factor) values. Structures of both products were analysed using spectrometer IR, GC-MS, and H-NMR. Spectrophotometer UV-Vis was used to analyse the structure of chalcone product as well. Yellowish-orange solid was obtained from the first synthesis.The yield was 38,05% and its melting point was 141-144 C. It was confirmed as 2,4-dihydroxyacetophenone. Brownish-yellow solid was collected from the second synthesis. The yield was 19,94% and its melting point was 195-199 C. It was confirmed as 2apostrophe,4apostrophe-dihydroxy-3,4-dimetoxychalcone. Maximum absorbance of this chalcone was reached at 276 nm (UV-C) and 370 nm (UV-A) so that it could be used as sunscreen anti UV-C and anti UV-A. Yet the absorbance measurement of all solutions was done at 370 nm because UV-C radiation was absorbed by ozone layer at atmosphere. Minimum protection (SPF 2-12) was reached from 12 microgram/mL. Moderate protection (SPF 12-30) was reached at 40 microgram/mL.

Kata Kunci : 2,4-dihidroksiasetofenon, khalkon, tabir surya, Sun Protecting Factor