Kopi robusta (Coffea canephora) merupakan salah satu komoditas unggulan yang berada di Provinsi Lampung. Selain sebagai olahan minuman, biji kopi robusta juga dapat dimanfaatkan sebagai bahan tambahan alami dalam sediaan produk kosmetik. Masker gel peel-off merupakan salah satu jenis produk kosmetik yang dapat berfungsi sebagai anti-aging pada wajah. Pada penelitian ini, formulasi masker gel peel-off berhasil dipreparasi dengan memanfaatkan ekstrak biji kopi robusta. Metode formulasi masker gel peel-off dilakukan melalui proses in-situ. Hasil uji fitokimia menunjukkan senyawa metabolit sekunder yang terkandung dalam ekstrak biji kopi robusta yaitu alkaloid, flavonoid, saponin, dan tannin. Analisis spektrofotometer UV-vis menunjukkan kadar senyawa flavonoid sebesar 5,86 mg/g. Hasil uji pH masker gel peel-off menggunakan ekstrak kopi robusta sebesar 5,3. Masker gel peel-off tidak menyebabkan reaksi iritasi pada kulit. Sifat fisik dari masker gel peel-off terlihat berwarna coklat dengan bentuk semisolid. Hasil uji aktivitas antioksidan masker gel peel-off menunjukkan nilai IC50 sebesar 7,104 ppm. Dari data yang ada dapat disimpulkan bahwa senyawa flavonoid dalam ekstrak biji kopi robusta sangat berpengaruh terhadap aktivitas antioksidan dalam formulasi sediaan masker gel peel-off.
BIOSYNTHESIS AND CHARACTERIZATION OF GOLD NANOPARTICLES AND THEIR INTERACTION STUDY WITH METFORMIN. Synthesis of gold nanoparticles successfully carried using Imperata cylindrica L leaf extract. In this study, the approach used through green synthesis method is a reaction betwen of the HAuCl4 solution (concentration variation as 3; 5; 7 x 10-4 M) with Imperata cylindrica L leaf extract. Results of UV-Vis showed of gold nanoparticles has a maximum wavelength at 530 nm with absorbance value of 1.4. Results of FTIR shows a shift the absorption peak at wavenumber of 3392 cm-1 to 3404 cm-1. PSA and PZC showed the distribution of gold nanoparticles was 48.84 nm with a charge of 20.5 mV. Gold nanoparticles has a spherical shape and an average particle size of 20 nm which can be seen from the results of the characterization using TEM. XRD showed crystalize size average of gold nanoparticles as 20.47 nm. The interaction between of gold nanoparticles with metformin can be seen in the absorbance decrease of 0.38 at a wavelength of 531 nm and the results of PSA shows an average particle size of AuNPs@metformin is 122 nm. From the characterization data can be concluded the gold nanoparticles were successfully synthesized using natural bioreductors by utilizing secondary metabolites from Imperata cylindrica L leaf extract.
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