Judul: Identifikasi Komponen Antibakteri pada Ekstrak Buah Takokak (Solanum torvum Swartz) dengan Kromatografi Lapis Tipis
Abstrak: Turkey berry (Solanum torvum Swartz) is one of medicinal plants and indigenous vegetables which grows abundantly in Indonesia. It has been known to have antibacterial activity againts some pathogen bacterias, including Bacillus cereus. The aim of this study is to determine turkey berry’s metabolites that have antibacterial activity by TLC method. The dried turkey berry was extracted by eight different combinations of methanol and water. These extracts were then divided into two parts: for antibacterial activity analysis and for TLC analysis. Extract with good antibacterial activity and showed more spots in TLC was further identified by two-dimentional TLC. The Rf score of this extract was also compared with reference compounds. F1 extract which was extracted by methanol:water (1:0) showed the highest diameter of inhibition. It also had more TLC spots than other extracts. F1 extract was then chosen to be identified by two-dimentional TLC. It showed 14 sub-spots which have maximum absorption at 200-400 nm. Some sub-spots of F1 extract also showed similar Rf score with reference compounds. Based on its TLC profile, F1 extract may contain saponin, gallic acid, quercetin, myricetin, kaempferol, and apigenin. However, since TLC has limited resolution, it is possible that F1 contains other flavonoids and phenolic acids that may also responsible for its antibacterial activity.
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Judul: Metabolomic application for identification bioactive components: antibacterial components from takokak fruit extracts (Solanum torvum Swart).
Abstrak: Solanum torvum Swartz, commonly known as Takokak, has been traditionally used in Indonesia to cure several diseases. Fruits of Solanum torvum Swartz are used to cure anti-edemic, as analgesic, to improve blood circulation, to alleviate pain, as antitusive, as anti-inflammatory, to relieve stomach pain, toothache, cataracts, menstruation disorders, hemorrhoids, sore breasts, influenza, swelling, ulcers, soreness, sore waist, high uric acid, bone loss, heart palpitations, and for detoxification (Andarwulan et al. 2012). The antibacterial activity of Takokak fruit has been reported as well (Chah et al. 2000, Bari et al. 2010, Sivapriya et al. 2011). However, up to now no reports yet on compounds responsible for takokak’s antibacterial activity. Metabolomics has been found to be more efficient for identification tool of active principles in a complex mixture such as plant extract than the conventional way, which is known as bioassay guided isolation. To achieve this, a specific extraction method that is able to extract the widest possible range of metabolites, and a suitable analytical tool to detect them are required (Yuliana et al. 2011). From 4507,5 g fresh Takokak fruits 376 g dried powder was obtained. Extraction and fractionation with diverse polarity of solvents gave 5,62 g of methanol extract (M), 3,09 g of n-hexane fraction (H), 1,37 g of chloroform fraction (K), 2,59 g of ethyl acetate fraction (E), and 11,78 g of water fraction (A). The result of antibacterial activity indicated that among all the tested extracts and fractions, M extract and K fraction exhibited medium antibacterial activity against Staphylococcus aureus while others did not. Inhibition zone diameters of M extract were between 4-4,5 mm and K fraction were between 6,5–6,8 mm. The results of TLC showed 6 spots of M extract, 1 spot of H fraction, 10 spots of K fraction, 3 spots of E fraction, and 1 spot of A fraction. The TLC spots appearance (blue fluorescence in UV 366 and 254 nm) suggested that steroid components are probably the active components of Takokak fuit. Furthermore analysis to provide chemical compoisition of the extract and fractions was conducted by with HPLC. The chromatograms of each sample were converted into excel file and then were correlated to its antibacterial activity. There are several possible plots as OPLS outputs to be used to interpret the results. In this study we used score plot, Y-related coefficient plot, and X varian plot. The score plot showed good separation between active and non-active takokak extracts and fractions therefore the study was promising to conduct further. Next, the OPLS Y-related coefficient plot was evaluated. In this study, we are interested to find peak of 17,76 – 18,08 min retention time with a high positive correlation value, which means that the higher peak intensity or the higher peak area value implicates to the higher antibacterial activity as well. In further analysis, we used X varian plot to identify the extract or the fraction where the peak of 17,76 – 18,08 min retention time was dominant. It was discovered that the peak was dominant in fractions K measured at UV λ = 310 nm. Therefore, we chose
Keyword: metabolomics, Takokak, antibacterial activity, OPLS, torvoside

Judul: Implementation of Long Short-Term Memory for Gold Prices Forecasting
Abstrak: Emas merupakan salah satu bentuk investasi dan disebut sebagai aset safe haven karena kestabilannya dalam kondisi pasar yang tidak stabil. Peramalan harga emas menjadi penting bagi investor sebagai alat bantu pengambilan keputusan. Penelitian ini bertujuan untuk melihat pengaruh validasi silang dalam memperoleh hyperparameter LSTM (optimizer, learning rate, dan epoch) terbaik yang akan digunakan dalam peramalan. LSTM sebagai bagian metode deep learning dapat digunakan dalam peramalan selain menggunakan metode klasik. Algoritma ini merupakan pengembangan dari recurrent neural network yang banyak digunakan dalam peramalan deret waktu. LSTM dianggap unggul dan mampu meminimalkan kesalahan, serta mampu melakukan peramalan untuk periode jangka panjang dibanding metode lain. Walk forward validation dengan skenario pergeseran jendela (tahunan, semester, dan kuartal) sebagai bentuk validasi silang digunakan untuk melihat keakuratan metode. Data yang digunakan berasal dari World Gold Council dengan periode data harian untuk tanggal 1 Januari 2003 sampai dengan 20 Januari 2023. Optimizer yang digunakan adalah adam dan RMSProp dengan nilai learning rate 0,01; 0,001; dan 0,0001, serta nilai epoch 100, 500, dan 1000. Model terbaik adalah model dengan nilai MAPE terkecil sebesar 12,41% pada proses validasi menggunakan optimizer RMSProp, nilai learning rate 0,01, dan epoch 100. Hasil peramalan menunjukkan kecenderungan harga emas untuk meningkat dalam delapan tahun mendatang., Gold is a form of investment and is referred to as a safe haven asset because of its stability in unstable market conditions. Gold price forecasting is important for investors as decisions making tool. This study aims to study the effect of cross-validation in obtaining the best LSTM hyperparameters (optimizer, learning rate, and epoch) to be used in forecasting. LSTM as part of deep learning methods can be used in forecasting beside the classical method. Algorithm in the LSTM is developed based on a recurrent neural network that is widely used in time series forecasting. It was found that the LSTM is superior compared to other methods for its ability to minimize errors and to forecast for long-term periods. Walk forward validation with window shift scenarios (annual, semester, and quarter) as a form of cross validation is used to see the accuracy of the method. The data used came from the World Gold Council with daily data periods for January 1, 2003, to January 20, 2023. The optimizer used is adam and RMSProp each with learning rate values of 0.01; 0.001; and 0.0001, and with epoch values of 100, 500, and 1000. The best model was the model with the smallest MAPE value of 12.41% in the validation process using an optimizer RMSProp, a learning rate of 0.01, and epoch value of 100. Forecasting results show a tendency for gold prices to increase in the next eight years.
Keyword: deep learning, forecasting, gold, hyperparameter, LSTM