Characterization of pumilacidin, a lipopeptide biosurfactant produced from Bacillus pumilus NITDID1 and its prospect in bioremediation of hazardous pollutants.

Highly hydrophobic compounds like petroleum and their byproducts, once released into the environment, can persist indefinitely by virtue of their ability to resist microbial degradation, ultimately paving the path to severe environmental pollution. Likewise, the accumulation of toxic heavy metals like lead, cadmium, chromium, etc., in the surroundings poses an alarming threat to various living organisms. To remediate the matter in question, the applicability of a biosurfactant produced from the mangrove bacterium Bacillus pumilus NITDID1 (Accession No. KY678446.1) is reported here. The structural characterization of the produced biosurfactant revealed it to be a lipopeptide and has been identified as pumilacidin through FTIR, NMR, and MALDI-TOF MS. The critical micelle concentration of pumilacidin was 120 mg/L, and it showed a wide range of stability in surface tension reduction experiments under various environmental conditions and exhibited a high emulsification index of as much as 90%. In a simulated setup of engine oil-contaminated sand, considerable oil recovery (39.78%) by this biosurfactant was observed, and upon being added to a microbial consortium, there was an appreciable enhancement in the degradation of the used engine oil. As far as the heavy metal removal potential of biosurfactant is concerned, as much as 100% and 82% removal was observed for lead and cadmium, respectively. Thus, in a nutshell, the pumilacidin produced from Bacillus pumilus NITDID1 holds promise for multifaceted applications in the field of environmental remediation.

Low circulatory Fe and Se levels with a higher IL-6/IL-10 ratio provide nutritional immunity in tuberculosis.

Tuberculosis (TB) patients show dysregulated immunity, iron metabolism, and anemia. In this study, circulatory cytokines, trace metals, and iron-related proteins (hepcidin, ferroportin, transferrin, Dmt1, Nramp1, ferritin, ceruloplasmin, hemojuvelin, aconitase, and transferrin receptor) were monitored in case (active tuberculosis patients: ATB) and control (non-tuberculosis: NTB and healthy) study populations (n = 72, male: 100%, mean age, 42.94 years; range, 17-83 years). Using serum elemental and cytokine levels, a partial least square discriminate analysis model (PLS-DA) was built, which clustered ATB patients away from NTB and healthy controls. Based on the PLS-DA variable importance in projection (VIP) score and analysis of variance (ANOVA), 13 variables were selected as important biosignatures [IL-18, IL-10, IL-13, IFN-γ, TNF-α, IL-5, IL-12 (p70), IL-1ß, copper, zinc, selenium, iron, and aluminum]. Interestingly, low iron and selenium levels and high copper and aluminum levels were observed in ATB subjects. Low circulatory levels of transferrin, ferroportin, and hemojuvelin with higher ferritin and ceruloplasmin levels observed in ATB subjects demonstrate an altered iron metabolism, which partially resolved upon 6 months of anti-TB therapy. The identified biosignature in TB patients demonstrated perturbed iron homeostasis with anemia of inflammation, which could be useful targets for the development of host-directed adjunct therapeutics.

Synthesis and Biological Evaluation of Calothrixins B and their Deoxygenated Analogues.

A series of calothrixin B (2) analogues bearing substituents at the 'E' ring and their corresponding deoxygenated quinocarbazoles lacking quinone unit were synthesized. The cytotoxicities of calothrixins 1, 2, and 15b-p and quinocarbazole analogues were investigated against nine cancer cell lines. The quinocarbazoles 21a and 25a inhibited the catalytic activity of human topoisomerase II. The plasmid DNA cleavage abilities of calothrixins 1, 2, and 15b-p identified compound 15h causing DNA cleavage comparable to that of calothrixin A (1). Calothrixin A (1), 3-fluorocalothrixin 15h and 4-fluoroquinocarbazole 21b induced extensive DNA damage followed by apoptotic cell death. Spectral and plasmid unwinding studies demonstrated an intercalative mode of binding for quinocarbazoles. We identified two promising drug candidates, the 3-fluorocalothrixin B 15h with low toxicity in animal model and its deoxygenated derivative 4-fluoroquinocarbazole 21b as having potent cytotoxicity against NCI-H460 cell line with a GI50 of 1 nM.

A Novel Spirooxindole Derivative Inhibits the Growth of Leishmania donovani Parasites both In Vitro and In Vivo by Targeting Type IB Topoisomerase.

Visceral leishmaniasis is a fatal parasitic disease, and there is an emergent need for development of effective drugs against this neglected tropical disease. We report here the development of a novel spirooxindole derivative, N-benzyl-2,2'α-3,3',5',6',7',7α,α'-octahydro-2methoxycarbonyl-spiro[indole-3,3'-pyrrolizidine]-2-one (compound 4c), which inhibits Leishmania donovani topoisomerase IB (LdTopIB) and kills the wild type as well as drug-resistant parasite strains. This compound inhibits catalytic activity of LdTopIB in a competitive manner. Unlike camptothecin (CPT), the compound does not stabilize the DNA-topoisomerase IB cleavage complex; rather, it hinders drug-DNA-enzyme covalent complex formation. Fluorescence studies show that the stoichiometry of this compound binding to LdTopIB is 2:1 (mole/mole), with a dissociation constant of 6.65 µM. Molecular docking with LdTopIB using the stereoisomers of compound 4c produced two probable hits for the binding site, one in the small subunit and the other in the hinge region of the large subunit of LdTopIB. This spirooxindole is highly cytotoxic to promastigotes of L. donovani and also induces apoptosis-like cell death in the parasite. Treatment with compound 4c causes depolarization of mitochondrial membrane potential, formation of reactive oxygen species inside parasites, and ultimately fragmentation of nuclear DNA. Compound 4c also effectively clears amastigote forms of wild-type and drug-resistant parasites from infected mouse peritoneal macrophages but has less of an effect on host macrophages. Moreover, compound 4c showed strong antileishmanial efficacies in the BALB/c mouse model of leishmaniasis. This compound potentially can be used as a lead for developing excellent antileishmanial agents against emerging drug-resistant strains of the parasite.