Objective: This study is aimed to develop marine resources, which is focused on the determination of phytochemical composition and exploration of seaweeds Ulva lactuca and Eucheuma cottonii, as a potential antibreast cancer and anticolorectal cancer agents.Methods: Seaweeds U. lactuca collected from Parangtritis beach, Yogyakarta, Central Java, Indonesia, whereas E. cottonii collected from Salemo Island, South Sulawesi, Indonesia. Seaweeds U. lactuca and E. cottonii were macerated in organic solvents, n-hexane, chloroform, ethyl acetate, and ethanol, respectively. After maceration for 3 days, the mixture was filtered; the filtrate was concentrated by rotary evaporator. The concentrated extract of n-hexane, ethyl acetate, ethanol, and chloroform was then analyzed by thin layer chromatography. Phytochemical test of the concentrated extract was conducted to identify the metabolites containing in the seaweeds. Furthermore, the cytotoxic activity of the n-hexane, ethyl acetate, ethanol, and chloroform extract of U. lactuca and E. cotonii were evaluated as a growth inhibitor of breast MCF-7 and colorectal HCT-116 cancer cells by MTT cell proliferation assay.Results: Phytochemical test for the concentrated extracts of U. Lactuca showed the positive result for metabolites of steroids, glycosides, flavonoids, and tannins, whereas the concentrated extracts of E. cottonii showed the positive result for metabolites of steroids, glycosides, and flavonoid. Both concentrated extracts of U. lactuca and E. cotonii exhibited anticancer activity against breast MCF-7 and colorectal HCT-116 cells with IC 50 ranging from 21 µg/mL to 99 µg/mL. Conclusion:Our results clearly demonstrate seaweeds U. Lactuca and E. cotonii as promising candidates for the new antibreast and anticolorectal cancer agents.

In order to minimize re-discovery of already known anti-infective compounds, we focused our screening approach on understudied, almost untapped marine environments including marine invertebrates and their associated bacteria. Therefore, two sea cucumber species, Holothuria leucospilota and Stichopus vastus, were collected from Lampung (Indonesia), and 127 bacterial strains were identified by partial 16S rRNA-gene sequencing analysis and compared with the NCBI database. In addition, the overall bacterial diversity from tissue samples of the sea cucumbers H. leucospilota and S. vastus was analyzed using the cultivation-independent Illumina MiSEQ analysis. Selected bacterial isolates were grown to high densities and the extracted biomass was tested against a selection of bacteria and fungi as well as the hepatitis C virus (HCV). Identification of putative bioactive bacterial-derived compounds were performed by analyzing the accurate mass of the precursor/parent ions (MS1) as well as product/daughter ions (MS2) using high resolution mass spectrometry (HRMS) analysis of all active fractions. With this attempt we were able to identify 23 putatively known and two previously unidentified precursor ions. Moreover, through 16S rRNA-gene sequencing we were able to identify putatively novel bacterial species from the phyla Actinobacteria, Proteobacteria and also Firmicutes. Our findings suggest that sea cucumbers like H. leucospilota and S. vastus are promising sources for the isolation of novel bacterial species that produce compounds with potentially high biotechnological potential.

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The manuscript investigated the isolation, characterization and anti-infective potential of valinomycin (3), streptodepsipeptide P11A (2), streptodepsipeptide P11B (1), and one novel valinomycin analogue, streptodepsipeptide SV21 (4), which were all produced by the Gram-positive strain Streptomycescavourensis SV 21. Although the exact molecular weight and major molecular fragments were recently reported for compound 4, its structure elucidation was not based on compound isolation and spectroscopic techniques. We successfully isolated and elucidated the structure based on the MS2 fragmentation pathways as well as 1H and 13C NMR spectra and found that the previously reported structure of compound 4 differs from our analysis. Our findings showed the importance of isolation and structure elucidation of bacterial compounds in the era of fast omics technologies. The here performed anti-infective assays showed moderate to potent activity against fungi, multi drug resistant (MDR) bacteria and infectivity of the Hepatitis C Virus (HCV). While compounds 2, 3 and 4 revealed potent antiviral activity, the observed minor cytotoxicity needs further investigation. Furthermore, the here performed anti-infective assays disclosed that the symmetry of the valinomycin molecule is most important for its bioactivity, a fact that has not been reported so far.

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