Diversity of Myxobacteria Isolated from Indonesian Mangroves and Their Potential for New Antimicrobial Sources

Mangroves are unique intertidal ecosystems that provide ecological niches to different microbes, which play various roles in nutrient recycling and diverse environmental activities. The association between myxobacteria and mangroves are hitherto poorly understood. The aim of our study was to evaluate the myxobacterial community composition as well as isolate myxobacteria and to characterize the antimicrobial activity of myxobacteria isolates from Indonesian mangroves. Twenty-five cultivable myxobacteria were affiliated in six genera: Myxococcus, Corallococcus, Archangium, Chondromyces, Racemicystis and Nannocystis of the order Myxococcales based on partial 16S rRNA gene sequences. Thirteen crude extracts showed moderate activities against at least one of human pathogenic microorganisms. The crude extract of Racemicystis sp. strain 503MSO indicated a novel compound, which has not been reported in the database yet and the identification of this compound needs further study. The myxobacterial communities of three different sampling sites were analyzed using primers adapted for the myxobacteria group identification. The results showed that myxobacterial communities are more diverse than assumed. Therefore, our study has highlighted the importance of the mangrove habitat as promising harbor of myxobacteria as well as novel antimicrobial compounds with activity against pathogenic microorganisms.

Paederia foetida Linn Leaves-Derived Extract Showed Antioxidant and Cytotoxic Properties Against Breast Carcinoma Cell

Paederia foetida Linn. is a rich source of active compounds, yet its antioxidant and cytotoxic properties remain poorly studied. This current research aimed to investigate the chemical profiles of a crude extract derived from P. foetida leaves, its fractionated substances, and their antioxidant and cytotoxic properties on MCF-7 cells, a breast carcinoma cell. Six fractionated substances have been separated in thin layer chromatography (TLC) plate. Five fractions showed antioxidant properties, as indicated by the formation of the yellowish band on the TLC plate after spraying with the DPPH reagent. Furthermore, crude extract of P. foetida leaves and its fractions are also characterized by antioxidant properties against 2, 2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals. F1 fraction exhibited the most potent antioxidant activity with IC50 values of 10.94±2.67 and 50.04±0.48 µg/ml, respectively, toward DPPH and ABTS radicals. Crude extract and all six fractions also varied in their cytotoxic properties against MCF-7 cells, with IC50 values ranging from 410.24±0.30 to 831.57±6.91 µg/ml. F3 fractions showed the strongest cytotoxicity (IC50 value: 410.24±0.30 µg/ml). Methanolic extract and active plant leaf fractions contained flavonoid and phenolic compounds, as measured by aluminum chloride and Folin-Ciocalteu reagent, respectively. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis showed that phenol, flavonoid, alkaloid, limonoid, and steroid were the major compound found in the crude extract and fractions. In conclusion, the present study proved that crude extract of P. foetida leaves and its fractionated substances were potential as antioxidant and cytotoxic agents.

Quality control standardization of Indonesian noni fruit (Morinda citrifolia) extract and evaluation of their angiotensin-converting enzyme inhibitory activity

Morinda citrifolia fruit (Noni) has been used as a folk medicine in several countries. Noni possessed various pharmacological activities such as; anticancer, antidiabetic, antihypertensive, antarthritic, and antioxidants. The present study evaluated pharmacognostic properties, profiling of active constituent through High-Performance Thin Layer Chromatography (HPTLC) and Liquid Chromatography-High Resolution Mass Spectrometer (LC-HRMS) run for quantitative and qualitative phytochemical analysis and determining angiotensin-converting enzyme (ACE) inhibitor activity of Noni from three different locations. The physicochemical parameters of crude drugs and extracts met the requirement of Indonesian Herbal Pharmacopeia. Total phenol content was 2.16-3.08 mg GAE/g extract and total flavonoid content was 0.11 - 1.58 mg QE/g extract. HPTLC analysis revealed that scopoletin content in Noni was in the range of 0.44 - 0.51%. The results were also corresponding well with LC-HRMS fingerprint analysis. In addition, Noni fruit extract from Bogor potential exhibited activity in inhibiting ACE with an IC50 value of 206.26 µg/mL.

Five Tetramic Acid Derivatives Isolated from the Iranian Fungus Colpoma quercinum CCTU A372

Submerged mycelial cultures of the ascomycete Colpoma quercinum CCTU A372 were found to produce five previously undescribed tetramic acids, for which we propose the trivial names colposetins A-C (1-3) and colpomenoic acids A and B (4 and 5), along with the known compounds penicillide (6) and monodictyphenone (7). The planar structures of 1-5 were determined by high-resolution electrospray ionization mass spectrometry (HR-ESIMS) and extensive 1D and 2D nuclear magnetic resonance (NMR) spectroscopy. Their absolute configurations were determined by the combination of electronic circular dischroism (ECD) analysis, J-based configurational analysis, and a rotating-frame Overhauser effect spectroscopy (ROESY) experiment. Colposetin B displayed weak antimicrobial activity against Bacillus subtilis and Mucor hiemalis (MIC 67 µg/mL).

Amycolatomycins A and B, Cyclic Hexapeptides Isolated from an Amycolatopsis sp. 195334CR

The rare actinobacterium Amycolatopsis sp. strain 195334CR was found to produce previously undescribed cyclic hexapeptides, which we named amycolatomycin A and B (1 and 2). Their planar structures were determined by high-resolution mass spectrometry as well as extensive 1D and 2D NMR spectroscopy, while the absolute stereochemistry of its amino acids were determined by Marfey's method. Moreover, 1 and 2 differ by the incorporation of l-Ile and l-allo-Ile, respectively, whose FDVA (Nα-(2,4-Dinitro-5-fluorphenyl)-L-valinamide) derivatives were separated on a C4 column. Their hallmark in common is a unique 2,6-dichloro-tryptophan amino acid unit. Amycolatomycin A (1) exhibited weak activity against Bacillus subtilis DSM 10 (minimum inhibitory concentration (MIC) = 33.4 µg/mL).

Nonocarbolines A-E, β-Carboline Antibiotics Produced by the Rare Actinobacterium Nonomuraea sp. from Indonesia

During the course of our ongoing screening for novel biologically active secondary metabolites, the rare Actinobacterium, Nonomuraea sp. 1808210CR was found to produce five unprecedented β-carboline derivatives, nonocarbolines A-E (1-5). Their structures were elucidated from high-resolution mass spectrometry, 1D and 2D nuclear magnetic resonance spectroscopy, and the absolute configuration of 4 was determined by using the modified Mosher method. Nonocarboline B (2) displayed moderate antifungal activity against Mucor hiemalis, while nonocarboline D (4) exhibited significant cytotoxic activity against the human lung carcinoma cell line A-549 with the IC50 value of 1.7 µM.

Structurally diverse metabolites from the rare actinobacterium Saccharothrix xinjiangensis

The bioassay-guided fractionation from cultures of the actinobacterium Saccharothrix xinjiangensis Act24Zk, collected from the Caspian Sea beach in Iran led to the isolation of three new compounds, caerulomycin M (1), saccharopyrone (2), and saccharonoic acid (3), together with the known compound, caerulomycin A (4). Their structures were elucidated from HR-ESIMS and 1D and 2D NMR data. Compound 2 displayed moderate cytotoxic activity against the human cervix carcinoma HeLa cells KB3.1 with an IC₅₀ value of 5.4 µM.