Rini Pramesti

Application of imaging Raman spectroscopy to study the distribution of Kappa carrageenan in the seaweed Kappaphycus alvarezii

Raman imaging spectroscopy has been applied to analyze carrageenan production in the red alga, Kappaphycus alvarezii. The Raman spectra of the sample suggested that the thallus of K. alvarezii mainly consists of cellulose and carrageenan. A partial least square regression prediction model for carrageenan semi-quantitative analysis was built with a simple two-material system and applied to visualize the three-dimensional carrageenan distribution in the algal body. The images clearly depicted the carrageenan distribution in carrageenan-rich and carrageenan-poor samples. Images stained for carrageenan with methylene blue showed results similar to those from analysis with Raman imaging spectroscopy. Our results suggest that Raman imaging spectroscopy, which is nondestructive and label free, is an accurate and useful method for detecting carrageenan distribution in algae.

Cytotoxicity and Phytochemical Profiling of Sargassum Sp. Extract As Anti-Mdr Bacteria

Sargassum sp. contains bioactive compounds having the potential as an antibacterial agent. Sargassum sp. was collected from five different locations, i.e., Teluk Awur, Panjang Island, Bandengan, Ujung Piring, and Bondo. There were several different species of Sargassum sp. identified from each sampling locations. The collected seaweeds were washed, naturally dried, and ground to the powder-sized dry material. Dry seaweed was extracted gradually using n-hexane, ethyl acetate, and methanol (1:3 w/v). The antibacterial analysis was conducted based on Agar Diffusion method using Zobell as media. Resistance analysis was performed to evaluate the resistance of pathogen against commercial antibiotics, namely, chloramphenicol, ampicillin, erythromycin, amoxycillin, and tetracycline. Each Sargassum sp. extract was tested against three candidates of MDR bacteria, i.e., Staphylococcus aureus, Escherichia coli, and S. epidermidis. Results showed that S. aureus was resistant towards four out of five commercial antibiotics. E. coli and S. epidermidis were not susceptible to two and three out of five commercial antibiotics, respectively. N-hexane, ethyl acetate and methanol yielded 0.1-0.3%, 0.3-0.7 % and 0.8-4.7% of dry extract. Ethyl acetate extract of Sargassum from Teluk Awur performed the best antibacterial activity and contained an alkaloid, flavonoid, and phenolic compounds. Toxicity analysis showed that this ethyl acetate extract had LC50 at 463 ppm and categorized as chronic toxicity.