Endophytic microbes are microorganisms that colonize the intracellular spaces within the plant tissues without exerting any adverse or pathological effects. Currently, the world population is facing devastating chronic diseases that affect humans. The resistance of pathogens to commercial antibiotics is increasing, thus limiting the therapeutic potential and effectiveness of antibiotics. Consequently, the need to search for novel, affordable and nontoxic natural bioactive compounds from endophytic fungi in developing new drugs with multifunction mechanisms to meet human needs is essential. Fungal endophytes produce invaluable bioactive metabolic compounds beneficial to humans with antimicrobial, anticancer, antidiabetic, anti-inflammatory, antitumor properties, etc. Some of these bioactive compounds include pestacin, taxol, camptothecin, ergoflavin, podophyllotoxin, benzopyran, isopestacin, phloroglucinol, tetrahydroxy-1-methylxanthone, salidroside, borneol, dibenzofurane, methyl peniphenone, lipopeptide, peniphenone etc. Despite the aforementioned importance of endophytic fungal metabolites, less information is available on their exploration and pharmacological importance. Therefore, in this review, we shall elucidate the fungal bioactive metabolites from medicinal plants and their pharmacological potential.

Pharmacological Potential of Fungal Endophytes Associated with Medicinal Plants: A Review

Enhanced bioremediation of diesel oil-contaminated seawater by a biochar-immobilized biosurfactant-producing bacteria Vibrio sp. LQ2 isolated from cold seep sediment.

Endophytic bacilli from medicinal-aromatic perennial Holy basil (Ocimum tenuiflorum L.) modulate plant growth promotion and induced systemic resistance against Rhizoctonia solani in rice (Oryza sativa L.)

Decrease of growth, biofilm and secreted virulence in opportunistic nosocomial Pseudomonas aeruginosa ATCC 25619 by glycyrrhetinic acid.

Secondary metabolites produced by endophytic Pantoea ananatis derived from roots of Baccharoides anthelmintica and their effect on melanin synthesis in murine B16 cells.

Medicinal plants have been used as an alternative medicine to promote human health and longevity in many regions of the world since ancient times. In recent years, many novel secondary metabolites ...

Bioactive potential of secondary metabolites derived from medicinal plant endophytes

In the present study lipopeptide biosurfactant with high emulsification capacity produced by human skin bacterium Paenibacillus thiaminolyticus was purified and subjected to FTIR and NMR spectral analysis which gave evidence of the active characteristics of the surfactant. To augment the antivirulent potential further, the mixer of copper and copper oxide nanoparticles (CuNPs) was synthesized, and characterized by UV-Visible spectroscopy, SEM-EDAX, TEM, and Zeta analysis. Here, we attempted to enhance the antimicrobial and antibiofilm activity with the assistance of encapsulated preparation of lipopeptide and CuNPs in multilamellar liposomes. The proposed mechanism of action of lipopeptide and CuNPs liposomal preparation negatively influences the cell metabolism, secreted virulence such as staphyloxanthin, pyocyanin, and extracellular polysaccharides. The significant decline in the growth of MRSA and P. aeruginosa in both planktonic form and biofilm by lipopeptide and CuNPs treatment were visualized using scanning electron microscopy and High content screening imaging system. In vivo studies revealed that treatment with lipopeptide and CuNPs in multilamellar liposomes extended the lifespan of infected Caenorhabditis elegans by about 75%. Therefore, this study typifies lipopeptide and CuNPs could credibly be a substantial substitute over conventional antibiotics in averting the biofilm associated pathogenesis of MRSA and P. aeruginosa.

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Liposome encapsulated surfactant abetted copper nanoparticles alleviates biofilm mediated virulence in pathogenic Pseudomonas aeruginosa and MRSA.

Vibrio harveyi is a marine luminous pathogen, which causes biofilm-mediated infections, pressures the search for an innovative alternate approach to strive against vibriosis in aquaculture. This study anticipated to explore the effect of glycolipid biosurfactant as an antipathogenic against V. harveyi to control vibriosis. In this study, 27 bacterial strains were isolated from marine soil sediments. Out of these, 11 strains exhibited surfactant activity and the strain MK3 showed high emulsification index. The potent strain was identified as Vibrio natriegens and named as V. natriegens MK3. The extracted biosurfactant was purified using high-performance liquid chromatography and it was efficient to decrease the surface tension of the growth medium up to 21 mN/m. The functional group and composition of the biosurfactant were determined by Fourier-transform infrared spectroscopy and nuclear magnetic resonance spectroscopy spectral studies and the nature of the biosurfactant was identified as glycolipid. The surfactant was capable of reducing the biofilm formation, bioluminescence, extracellular polysaccharide synthesis, and quorum sensing in marine shrimp pathogen V. harveyi. The antagonistic effect of biosurfactant was evaluated against V. harveyi-infected brine shrimp Artemia salina. This study reveals that biosurfactant can be considered for the management of biofilm-related aquatic infections.

Effect of biosurfactant derived from Vibrio natriegens MK3 against Vibrio harveyi biofilm and virulence

In recent times gastrointestinal infections caused by bacterial pathogens have become potentially life-threatening. Particularly, biofilm assembly participates in stimulating the ailments. Bacterial biofilms hold a pivotal role in disease dispersion, pathogenesis and consortia formation. This study reports the antimicrobial and anti-biofilm efficacy of the native gut bacterium Proteus mirabilis DMTMMK1 effected by the production of biosurfactant. Biosurfactant-producing isolates were screened by preliminary assays, and a surfactant with high emulsification capacity produced by Proteus mirabilis DMTMMK1 was purified and subjected to FTIR and NMR spectral analysis which gave evidence of the active characteristics of the surfactant. In the presence of such bioactive compounds an exponential reduction in secreted protease, haemolysis, quorum sensing, and phenotypic inhibition of swarming motility in pathogenic Vibrio cholerae was observed. Further, SEM and HCS (high-content screening) analysis revealed the hampered and disrupted nature of biofilm and cytometry results emphasized a sizeable dead cell population in Vibrio cholerae that had been treated with biosurfactant. Cytotoxicity assay on Vero cell lines evaluated the LD50 value (600 μg mL−1), which showed significant reduction in cell viability and proliferation upon exposure up to 48 h. Furthermore, challenge survival studies provided evidence of biosurfactant effectively inhibiting intestinal colonization of Vibrio cholerae in the nematode Caenorhabditis elegans.

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Monitoring surfactant mediated defence of gastrointestinal Proteus mirabilis DMTMMK1 against pathogenic consortia of Vibrio cholerae

This study focused on the evaluation of fungal compound for their anti-pathogenic potential against respiratory pathogens Soil samples were collected from various geographical regions in Madurai, fungal strain was isolated and identified as Aspergillus terreusDMTMGK004 (MGK004) Secondary metabolites were extracted and evaluated for antioxidant potential It exhibited significantly high anti-proliferative property against gastric adenocarcinoma (AGS) cell lines Antimicrobial activity against Gram positive (Streptococcus pneumoniae) and Gram negative (Klebsiella pneumoniae and Haemophilus influenzae) respiratory pathogens were analysed and the minimum inhibitory concentration (MIC) values were determined Furthermore, the time-killing assay illustrated that the metabolite eliminates 50% of the vegetative cells within few hours of the treatment From the spectral data, the major functional groups present in the compound were determined as carbonyl group and phenolic hydroxyl group which contribute towards its bioactivity The compound significantly depreciates the production of extracellular polysaccharides which results in the weakening of biofilm architecture and resistance towards serum killing and phagocytosis It also induced cell membrane damage which leads to protein and nucleic acid leakage Hence, the results of the present study could provide a better insinuation towards the formulation of new drug targeting respiratory pathogens SIGNIFICANCE AND IMPACT OF THE STUDY: The ubiquitous fungi Aspergillus terreus is well known for its secondary metabolite production The fungus was evaluated for production of antagonistic molecule to reduce the growth of infectious agents causing respiratory infections It exhibited the biological means of antioxidant, anti-proliferative and anti-pathogenic compound production The compound exhibits killing effect against respiratory pathogens within two hours It induced cell membrane damage leading to protein and nucleic acid leakage It significantly reduced the production of extracellular polysaccharides The results provide needed information to design innovative strategies for targeting pathogenic factors of the respiratory pathogens instead of killing it precisely

Govindan Krishnamoorthy

Papers

Bioactive potential of secondary metabolites derived from medicinal plant endophytes

Liposome encapsulated surfactant abetted copper nanoparticles alleviates biofilm mediated virulence in pathogenic Pseudomonas aeruginosa and MRSA.

Effect of biosurfactant derived from Vibrio natriegens MK3 against Vibrio harveyi biofilm and virulence

Monitoring surfactant mediated defence of gastrointestinal Proteus mirabilis DMTMMK1 against pathogenic consortia of Vibrio cholerae

Bioactive compound from Aspergillus terreusDMTMGK004 synergistically contributes towards potential anti-pathogenicity.