Piper crocatum is one of medicinal herbal plants with a large number of benefits. Usually herbal plants have activity as antibacterial agent. Therefore, the objectives of this research were to obtain information on antibacterial activities of the leaf extracts of Piper crocatum againts four types of bacteria, in that Staphylococcus, Bacillus substilis, Escherichia coli, and Pseudomonas aeruginosa and then to analyze the phytochemistry of the leaf extracts of Piper crocatum. The leaves of Piper crocatum were extracted by maceration and reflux using ethanol 30%. The assays of the antibacterial activities and phytochemistry on the extracts were carried out using the method of Maria Bintang. Results showed that the yield of the extraction using ethanol by maceration method was 20.8%. Meanwhile, using the reflux method, the yield was obtained about 26.25%. The phytochemistry analysis showed that the leaf extracts of Piper crocatum contained alkaloid, steroid and tanin. According to this study, it was found that the leaf extract of Piper crocatum can be used to inhibit the growth of B. subtilis and P. aeuruginosa, but can not inhibit the growth of E.coli and S. aureus.

Melanocytes are an important component of skin pigmentation through their ability to produce melanin assisted by the enzyme tyrosinase which is a core enzyme in melanogenesis. The high phenolic and flavonoid compounds in the leaves, seeds and skin of avocados have potential as ligands (inhibitors) of tyrosinase related protein-1. This study aims to determine the active compounds from the leaves, seeds, and skin of avocados that play a role in inhibiting the activity of the tyrosinase enzyme in humans so that it can inhibit the formation of melanin. The research was conducted by molecular anchoring method using YASARA Structure software. The results showed that of the 68 active compounds of avocado leaves, seeds, and skins, there were 11 active compounds that had binding affinity for tyrosinase related protein-1, namely quarcetin, epicatechin, apigenin, 3-Hydroxytyrosol, scopoletin, abscisic acid, citric acid, coumaric acid. , quinic acid, vanillin, and caffeic acid. The active compound abscisic acid is the ligand with the best inhibitory potential with a bond free energy (∆G) of -2,645 kcal/mol which interacts with 17 amino acid residues. The research results can be used as a reference in in vitro and in vivo studies of the human tyrosinase enzyme.

High cost production is one of the constraints of the commercial xylitol production due to high energy needed and pure raw materials. Therefore, it is necessary to improve the xylitol production eficiently with lower production cost by using microorganisms. The research objectives were to determine the optimum xylitol production from xylose by metabolism of C. guilliermondii and effect of glucose as a co-substrate in fermentation medium. The ratio of glucose : xylose (g/L) was 1:25, 1:12, 1:5 and 1:2.5 respectively. The xylitol concentration was measured by spectrophotometer method (D-sorbytol/D-xylitol kit). The result showed that the exponential phase of Candida guilliermondii was 12 h to 36 of incubation and optimum of incubation time to produce the highest xylitol was 72 h. The best ratio- of glucose : xylose to produce xylitol was 9 g/L glucose : 45 g/L xylose (1 : 5). The xylitol concentration produced from medium with the addition of glucose was 2.85 g/L. This concentration increased five times compared to that in the medium without addition of glucose that only reached 2.85 g/L. According to this study, the addition of glucose as a co-substrate could increase the xylitol production.

Graptophyllum pictum (L.) Griff is one of the medicinal plants in Indonesia that has been proved to have antioxidant, antidiabetic, and analgesic properties. However, there is no report about the relationship of its genetic diversity with accession and ethnic aspects. Thus, we carried out polymorphism studies and clusterization of 34 samples G. pictum that were collected from 10 ethnics in Western Indonesia. The research purpose was to determine the polymorphism and kinship relations between ethnic groups and accessions of G. pictum in Western Indonesia. DNA was isolated using the GeneJET Plant Genomic DNA purification mini kit. Sequence Related Amplified Polymorphism (SRAP) was used as a molecular marker in PCR amplification. We analyzed the data using NTSYS and PopGene 1.3 softwares. We found 8 combinations of selected primers with polymorphic percentage average of 72.23% and 45 loci. The ethnicity that has the highest polymorphic percentage is Kutai (East Kalimantan) of 55.56%. The diversity between population and accession is moderate with Dissimilarity Index (DI) not more than 0.69. Ribun ethnic in West Kalimantan is the oldest ancestry ethnic that has locus marker at 24th and 41st position. In conclusion, we found that G. pictum in Western Indonesia is divided into 4 clusters.

Ethanol is considered as the most promising alternative fuel, since it can be produced from a variety of agriculturally-based renewable materials, such as sugarcane bagasse. Lignocellulose as a major component of sugarcane bagasse is considered as an attractive renewable resource for ethanol production due to its great availability and relatively low cost. The major problem of lignocellulose is caused by its need for treatment to be hydrolyzed to simple sugar before being used for bioethanol production. However, pretreatment using acid as hydrolyzing agent creates some inhibitor compounds that reduce ethanol production because these compounds are potential fermentation inhibitors and affect the growth rate of the yeast. Reduction of these by-products requires a conditioning (detoxification and culture starter adaptation). Thus, the aim of this study was to evaluate bioethanol production by fermentation with and without detoxified sugarcane bagasse acid hydrolysate using adapted and non-adapted culture of C. tropicalis. According to this study, the highest ethanol amount was obtained about 0.43 % (v/v) with an ethanol yield of 2.51 % and theoretical yield of 4.92 % by fermentation of sugarcane bagasse hydrolysate with detoxification using the adapted strain of C. tropicalis at 72 hours fermentation time. Furthermore, the addition of 3 % glucose as co-substrate on detoxified-hydrolysate media only achieved the highest ethanol concentration 0.21 % after 24 hours fermentation with the ethanol yield 0.69 % and theoretical ethanol yield 1.35 %, thus it can be concluded that the addition of glucose could not increase the ethanol production.