Hispolon (HS), a natural polyphenol found in medicinal mushrooms, and its isoxazole (HI) and pyrazole (HP) derivatives have been examined for free radical reactions and in vitro antioxidant activity. Reaction of these compounds with one-electron oxidant, azide radicals ([Formula: see text]) and trichloromethyl peroxyl radicals ([Formula: see text]), model peroxyl radicals, studied by nanosecond pulse radiolysis technique, indicated formation of phenoxyl radicals absorbing at 420 nm with half life of few hundred microseconds (μs). The formation of phenoxyl radicals confirmed that the phenolic OH is the active centre for free radical reactions. Rate constant for the reaction of these radicals with these compounds were in the order k ≅ k>k. Further the compounds were examined for their ability to inhibit lipid peroxidation in model membranes and also for the scavenging of 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical and superoxide ([Formula: see text]) radicals. The results suggested that HP and HI are less efficient than HS towards these radical reactions. Quantum chemical calculations were performed on these compounds to understand the mechanism of reaction with different radicals. Lower values of adiabatic ionization potential (AIP) and elevated highest occupied molecular orbital (HOMO) for HI and HP compared with HS controlled their activity towards [Formula: see text] and [Formula: see text] radicals, whereas the contribution of overall anion concentration was responsible for higher activity of HS for DPPH, [Formula: see text], and lipid peroxyl radical. The results confirm the role of different structural moieties on the antioxidant activity of hispolon derivatives.

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The objective of this study was to characterise the putative phytochemical constituents from petroleum ether (CC-P) and chloroform (CC-C) extracts of Curcuma. caesia rhizome by GC-MS analysis and to compare their bioactivities. GC-MS analysis facilitated the documentation of a total of 16 and 20 volatile constituents in CC-P and CC-C extracts respectively. Of these the major constituents present in CC-P were cycloisolongifolence, 8, 9-dehydro-9 formyl- (19.64%), 4-oxo- β-isodamascol (16.05%), 6,10-dimethyl-3- (1-methylethyl) -6-cyclodecene-1,4-dione (13.80%), 2H-cyclohepta[b]furan-2-one,6-[1-(acetyloxy) -3-oxobutyl]- 3,3a,4,7,8,8a- hexahydro-7-methyl- 3-methylene- (9.08%), tricycle [5.1.0.0(2,4)] oct-5-ene-5-propanoic acid,3,3,8.8-tetramethyl- (6.39%), 2(3H)-benzofuranone,6-ethenylhexahydro-3,6-dimethyl-7-(1- methyl ethenyl)-, [3S-(3α,3aα,6α,7β,7aβ) (4.18%) and 7a-isopropenyl-4,5-dimethy loctahydroindene-4-carboxylic acid (4.01%). Similarly, the major constituents present in CC-C were cycloisolongifolence,8,9- dehydro-9-formyl-(15.69%), 6,10-dimethyl-3-(1-methylethyl)-6-cyclodecene-1, 4-dione (13.38%), 2H-cyclohepta [b]furan-2-one,6-[1- (acetyloxy)-3-oxobutyl] -3,3a,4,7,8,8a- hexa hydro -7-methyl - 3-methylene- (4.55%), tricycle [5.1.0.0(2,4)] oct-5-ene-5- propanoic acid,3,3,8.8-tetramethyl- (7.50%), 2(3H)-benzofuranone, 6-ethenylhexahydro-3,6-dimethyl-7-(1-methylethenyl)-,[3S- (3α,3aα,6α,7β,7aβ) (6.15%), 7a-isopropenyl-4,5-dimethyl octahydroindene-4-carboxylic acid (6.43%) and 2-(4a,8- Dimethyl-6- oxo-1,2,3,4-4a,5,6,8a-octahydro-naphthalen-2-yl) propionaldehyde (6.57%). The extracts, CC-P and CC-C exhibited almost similar antibacterial and antifungal potentials but differed with respect to antioxidant activity. The IC50 values of CC-P and CC-C extracts for DPPH scavenging were 0.68±0.02 mg ml-1 and 0.13±0.01 mg ml-1 respectively. Together, above results provide an important basis for the isolation of bioactive compounds from C. caesia rhizome extract and their use as traditional medicine.

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Background: Antibiotic resistance of various bacterial communities remains a global burden in healthcare industry. Biofilm formation is one of the resistance mechanisms acquired by bacterial communities in order to reverse the action of antibiotics. There is an urgent need for the discovery of novel antimicrobials and novel approaches to tackle this problem. However, it is very expensive and challenging to develop new antibiotics. Drug repurposing is an efficient strategy which reduces time and cost associated with drug discovery. Objective: In the current study, anti-microbial and antibiofilm potential of an organoselenium clinical molecule Ebselen against Neisseria mucosa has been elucidated. Methods: Ebselen Antibacterial studies include Minimum Inhibitory Concentration (MIC), growth-kill, Colony Forming Unit (CFU) assays and intracellular Reactive Oxygen Species (ROS) accumulation studies. Antibiofilm studies include inhibition, eradication and cell surface hydrophobicity assays, quantification of Extracellular Polymeric Substance (EPS) and eDNA and for anti-quorum sensing activity protease and urease enzyme activities were elucidated. Results: Ebselen showed efficient bactericidal activity as indicated by its low MIC values, bacterial growth inhibition over time and its ability to prevent clonal propagation in this bacterium. Increased accumulation of ROS in Ebselen treated cells indicates radical mediated induction of bacterial death. Interestingly, Ebselen inhibited and distorted matured biofilms by degrading the eDNA component of the EPS layer. Ebselen also attenuated quorum-sensing pathway as indicated by decreased urease and protease enzyme activities. Conclusion: Taken together, these results paved the way to repurpose Ebselen as a potential drug target to curb Neisseria mucosa infections.