Background The ability to produce microbial bioactive compounds makes actinobacteria one of the most explored microbes among prokaryotes. The secondary metabolites of actinobacteria are known for their role in various physiological, cellular, and biological processes. Main body Actinomycetes are widely distributed in natural ecosystem habitats such as soil, rhizosphere soil, actinmycorrhizal plants, hypersaline soil, limestone, freshwater, marine, sponges, volcanic cave—hot spot, desert, air, insects gut, earthworm castings, goat feces, and endophytic actinomycetes. The most important features of microbial bioactive compounds are that they have specific microbial producers: their diverse bioactivities and their unique chemical structures. Actinomycetes represent a source of biologically active secondary metabolites like antibiotics, biopesticide agents, plant growth hormones, antitumor compounds, antiviral agents, pharmacological compounds, pigments, enzymes, enzyme inhibitors, anti-inflammatory compounds, single-cell protein feed, and biosurfactant. Short conclusions Further highlight that compounds derived from actinobacteria can be applied in a wide range of industrial applications in biomedicines and the ecological habitat is under-explored and yet to be investigated for unknown, rare actinomycetes diversity.

Background: Natural products have been viewed as essential sources that could create potential chemotherapeutic agents. In the look for new bioactive substances, examinations were extended to marine territories. Results: Humanity has known for the last few thousand years that a marine organism contains substances fit for strong biological activity. However, the main genuine examination of marine living beings began just 50 years prior. Since then, all types of life in the marine condition (e.g., bacteria, algae, and fungi) have been researched for their bioactive content. Conclusions: Exopolymers can be applied in a wide range of industrial applications in biomedicines.

Background The study investigated the phytochemical constituents and antibacterial activity of Citrus lemon volatile oil extracted from pruning leaves collected from a private farm at Nobariya district against Gram-positive "Staphylococcus aureus NRRL B-313 and Bacillus cereus NRC" and Gram-negative "Pseudomonas aeruginosa NRC B-32 and Escherichia coli NRC B-3703". Results The oil obtained from powdered dried C. lemon leaves was analyzed by GC–MS to identify their constituents. The analysis revealed the presence of sabinene, carene, limonene, and β-ocimene. The leaves volatile oil showed a remarkable inhibition against S. aureus (32 ± 0.01 mm) and P. aeruginosa (49 ± 0.01 mm) and it had a strong effect on the DNA, RNA, lipids, and protein biosynthesis in cells of S. aureus and had a strong effect on the lipids biosynthesis in cells of P. aeruginosa. Conclusion The results in this study suggested that C. lemon leaves could be beneficial in developing a novel antibiotic and studied its mode of action on the pathogenic microorganism’s cells.

The present work aims to design and synthesize novel series of spiro pyrazole-3,3'-oxindoles analogues and investigate their bioactivity as antioxidant and antimicrobial agents, as well as antiproliferative potency against selected human cancerous cell lines (i.e., breast, MCF-7; colon, HCT-116 and liver, HepG-2) relative to healthy noncancerous control skin fibroblast cells (BJ-1). The mechanism of their cytotoxic activity has been also examined by immunoassaying the levels of key anti-and proapoptotic protein markers. The analytical and spectral data of the all synthesized target congeners were compatible with their structures. Synthesized compounds showed diverse moderate to powerful antimicrobial and antioxidant activities. Results of MTT assay revealed that seven synthesized compounds (i.e., 11a, 11b, 12a, 12b, 13b, 13c and 13h) particularly exhibited significant cytotoxicity against the three cancerous cell lines under investigation. Ranges of IC 50 values obtained were 5.7-21.3 and 5.8-37.4 µg/mL against HCT-116 and MCF-7, respectively; which is 3.8 and 6.5-fold (based on the least IC 50 values) more significant relative to the reference chemotherapeutic drug doxorubicin. In HepG-2 cells, the analogue 13h exhibited the highest cytotoxicity with IC 50 value of 19.2µg/mL relative to doxorubicin (IC 50 = 21.6µg/mL). The observed cytotoxicity was specific to cancerous cells, as evidenced by the minimal toxicity in the noncancerous control skin-fibroblast cells. ELISA results indicated that the observed antiproliferative effect against examined cancer cell lines is mediated via engaging the activation of apoptosis as illustrated by the significant increase in proapoptotic protein markers (p53, bax and caspase-3) and reduction in the antiapoptotic marker bcl-2. Taken together, results of the present study emphasize the potential of spiro pyrazole-oxindole analogues as valuable candidate anticancer agents against human cancer cells.

Background Carbohydrates are known as the main natural products of life activities. Results Streptomyces rochie strain OF1 isolated from a mangrove tree produced exopolysaccharide S5 (EPSS5) (14.2 gl−1) containing uronic acid 21.98% sulfate content of 11.65 mg/ml, and a viscosity of 1.35 mm2/s. while total hexose amine content was 24.72%. The high performance liquid chromatography (HPLC) analysis of mono sugars revealed that EPS was composed of manouronic acid, glucuronic acid, xylose, and fructose at a molar ratio of 1.0:0.5:1.0:2.0, respectively. It showed that the whole antioxidant activity was 92.06%. It showed antibacterial activity against Staphylococcus aureus, and E. coli, MRSA and Klebsiella pneumoniae. But, EPSS5 displayed low antifungal activity against Candida albicans. While no antifungal activity has been detected against Aspergillus niger. EPSS5 has antibiofilm action that is noticeable toward S. aureus with an inhibition ratio of biofilm up to 50%. Effect of EPS on serum levels of TNF-α and COX2 by 2 fold and 1.9 fold of EPS reduced serum levels of Tumor necrosis factor-α (TNF-α) by 38%, 12%, 49%, and Cyclooxygenase-2 (COX2) by 61%, 34%, and 62%, respectively. By affected of EPSS5 on arthritis in rats stimulated by carrageenan. Conclusions Administration of EPS ameliorated carrageen-induced elevation in inflammatory mediators; TNF-α/COX and suppressed the expressions of metalloproteinase 9 (MMP9) by 68%, 86%, and 75% correspondingly in comparison to the group of carrageenans. Then again, therapy involving a high dose only reduced MMP9 level by 57%, compared to free drug suggesting that EPSS5 is a good inhibitor of the MMP9, as it brought MMP9 back to normal levels via the signaling pathway.