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The binding interactions between bovine serum albumin (BSA) and three pyridine derivatives, i.e., 2-(5-bromopyridin-3-yl) acetic acid (L1), 3-bromo-5-nitropyridine (L2) and 2-chloro-4-nitropyridine (L3), have been carried out using UV-Vis and fluorescence spectroscopic methods. Fluorescence intensity quenching is observed by adding L2 and L3 to the BSA solution. The quenched fluorescence emission is due to the static nature. An isothermal titration calorimetry (ITC) experiment shows the binding ability of L1 with BSA. The binding constants are found to be 7.23 ± 0.32 × 10 5 M -1 for L1. The thermodynamic parameters were calculated from ITC measurements (i.e., ∆H = -2.78 ± 0.08 kcal/mol, ∆G = -5.65 ± 0.25 kcal/mol, and -T∆S = -2.87 ± 0.11 kcal/mol), which indicated that the protein-ligand complex formation between L1 and BSA is mainly due to the hydrogen bonds and van der Waals interactions. Cyclic voltammetry (CV) and structure activity and relationship (SAR) studies have been carried out to establish the relationship between ligands and proteins. Additionally, we conducted an antibacterial assay with gram-positive Staphylococcus aureus, Enterococcus faecalis, and negative bacterial strains Acinetobacter baumannii and Escherichia coli against L1, L2, and L3, aiming to address the challenges posed by the co-existence of multidrug-resistant bacteria. Finally, drosophila is used to test the cytotoxicity of ligands L1, L2, and L3's in vitro., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This study describes phycocompounds of the non-N 2 -fixing filamentous cyanobacterium Lyngbya sp., which has potential bio-reducing and stabilizing heavy metal-accumulating properties for synthesizing silver nanoparticles (AgNPs), whose formation was confirmed by the colour change of the Lyngbya sp.-AgNP solution from pale green to deep brown. The reduction of 'Lyngbya sp.-AgNPs', called Lsp-AgNPs, was proved by UV-visible photo-spectrometry analysis with an obtained peak value at 426 nm. Lsp-AgNPs were characterised by analytical techniques, XRD, FESEM, DLS and FTIR. The XRD analysis with 5-70 theta was obtained at 2ϴ angles ranging from 38.79º with intensity, indicating the crystal structure of Lsp-AgNPs. The FESEM analysis indicated the area size at 20-50 µm; in the DLS analysis, the peak at 400 d nm indicated the size and distribution of Lsp-AgNPs. In FTIR analysis, the peaks were obtained at wavenumbers 3338, 1639, and 542 cm -1 , which indicated the presence of N-H, -OH and C=O functional groups in Lsp-AgNPs. Those had in vitro antibacterial activities against Gram-negative Escherichia coli (MTCC 443) and Pseudomonas aeruginosa (MTCC 1688) and Gram-positive Staphylococcus aureus (MTCC 7443) bacterial strains with zone of inhibitions (ZOI) of 16, 12 and 14 mm, respectively, with comparing the antibiotic gentamycin as a positive control, as was monitored with agar-well diffusion method. Furthermore, the MIC value was 50 mg/ml, and MBC values of 65 mg/ml of Lsp-AgNPs were effective against those bacteria. Thus, Lsp-AgNPs had potential antibacterial activities against MDR pathogenic S. aureus, E. coli and P. aeruginosa. In conclusion, MDR pathogenic bacteria could be controlled as prodrugs in the future., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Two pyrrolo-based compounds, 1H-pyrrolo[3,2-b]pyridine-3-carboxylic acid (L1) and 1H-pyrrolo[3,2-c]pyridine-4-carboxylic acid (L2), were employed for the detection of bovine serum albumin (BSA) by UV-Vis and fluorescence spectroscopic methods in phosphate buffer solution (pH = 7). In the presence of L1 and L2, the fluorescence emission of BSA at 340 nm was quenched and concomitantly a red-shifted emission band appeared at 420 nm (L1)/450 nm (L2). The fluorescence spectral changes indicate the protein-ligand complex formation between BSA and L1/L2. An isothermal titration calorimetry (ITC) experiment was conducted to determine the binding ability between BSA and L1/L2. The binding constants are found to be 4.45 ± 0.22 × 10 4 M -1 for L1 and 2.29 ± 0.11 × 10 4 M -1 for L2, respectively. The thermodynamic parameters were calculated from ITC measurements (i.e. ∆rH = -40 ± 2 kcal/mol, ∆rG = -4.57 ± 0.22 kcal/mol and -T∆rS = 35.4 ± 1.77 kcal/mol), which indicated that the protein-ligand complex formation between L1/L2 with BSA is mainly due to the electrostatic interactions. The protein-ligand interactions were studied by performing molecular docking. Further, the antibacterial assay of L1 and L2 was conducted against gram-positive and gram-negative bacterial strains in an effort to address the difficulties caused by the co-occurrence of antimicrobial and multidrug-resistant bacteria. E. coli and S. aureus were significantly inhibited by L1 and L2. The L1 exhibits 13, 12 and 15 mm, whereas L2 exhibits a 2, 3 and 5 mm zone of inhibition against S. aureus, S. pyogenes and E. coli, respectively. In silico molecular docking of L1 and L2 was performed with bacterial DNA gyrase to establish the intermolecular interactions. Finally, the in vitro cytotoxicity activities of the ligands L1 and L2 have been carried out using drosophila., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The 2,4-dinitrophenylhydrazine based Schiff base (L) acts as an effective fluorescence sensor for the selective detection of maleic acid. The detection limit of L towards maleic acid is observed to be 1.29 × 10 -7 M. A 1:1 binding stoichiometry between L and maleic acid was obtained using Bensi-Hilderbrand method. The binding constant (K a ) was measured to be 5.17 × 10 6 M -1 . The sensing behavior of L was confirmed through analysis using FT-IR, DLS and SEM analysis, alongside DFT calculations. Theoretical assessments clearly suggest that the L's mono-protonation and complexation in the solvent medium are the primary mechanisms in the sensing process. Additionally, L is used to imaging the maleic acid in living cells, demonstrating its potential biological uses. In addition, recognition of maleic acid in food additives was reported., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

In this study, we aimed to explore the interaction mechanism between bovine serum albumin (BSA) and a Schiff base compound derived from 2,4-dinotrophenyl hydrazine (L) using various spectroscopic techniques. The interaction between BSA and synthesizing molecule can provide insights into binding affinity, conformational changes and potential applications in drug delivery or biochemistry. The interaction between BSA and L was studied by using UV-Vis and fluorescence titration analysis. The fluorescence quenching emission was observed at 343 nm, upon addition of L to the buffer solution of BSA. The binding between BSA and ligand is static in nature using fluorescence quenching emission. The thermodynamic parameters were calculated from the temperature-dependent binding constants (i.e., ∆H = -0.318 kcal/mol, ∆G = -7.857 kcal/mol and ∆S = 0.023 kcal/mol), which indicated that the protein-ligand complex formation between L and BSA is mainly due to the electrostatic interactions. The experimental and theoretical results showed excellent agreement with respect to the mechanism of binding and binding constants. The molecular docking and molecular dynamic analysis experiments were performed to establish the interaction between protein and ligand., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

An easy-to-prepare pyrene-based Schiff base PNZ was synthesized by condensing equimolar amount of 1-pyrenebutyric hydrazide with 2-hydroxy-naphthaldehyde, and employed as a fluorescent chemosensor for in-situ cascade detection of aluminium (Al3+) and fluoride (F-) ions. In DMSO:H2O (1:1, v/v), the weakly emissive PNZ showed a significant fluorescence enhancement at 455 nm selectively upon the addition of Al3+ due to the complexation-induced formation of a pyrene excimer. Schiff base PNZ and Al3+ formed a complex in 2:1 binding ratio with the estimated binding constants of K1:1 = 9826.01 M-1 and K2:1 = 3188.49 M-1. The sensing mechanism was explored by performing quantum mechanical calculations and 1H NMR titration of PNZ with Al3+. The in-situ formed PNZ-Al3+ complex species enabled the fluorescent turn-off detection of F-. Using PNZ and PNZ-Al3+, the concentrations of Al3+ and F- ions can be detected down to 2.89×10-7 M and 1.88×10-7 M, respectively. The cytotoxicity of the PNZ and its ability to bioimage Al3+ and F- ions was examined in the human cervical cancer cell line. Finally, the receptor PNZ was applied for the quantification of Al3+ and F- ions in various real samples, such as tap water, river water, rainwater, mouthwash, and toothpaste., (© 2024 Wiley‐VCH GmbH.)

Vanillin and ortho-vanillin are the most important flavoring additives used in the food industry at a large scale. Herein, the aggregation-induced emission (AIE) behavior of commercially available 3-hydroxy-2-naphthohydrazide (3HN) was explored and applied for the detection of vanillin and ortho-vanillin. The weakly fluorescent 3HN in DMSO showed fluorescence enhancement at 500 nm with the increase in HEPES or PBS buffer (pH 7.4) fractions in DMSO. The 3HN in DMSO containing 30% HEPES buffer is used as Probe 1 for the selective detection of ortho-vanillin. Probe 1 showed a new fluorescence emission at 415 nm for ortho-vanillin without altering the probe emission at 500 nm. With high specificity, Probe 1 can detect ortho-vanillin down to 0.3 μM. In contrast, 3HN in DMSO containing 20% PBS buffer is used as Probe 2 for the selective turn-off detection of vanillin. The green fluorescence emission of Probe 2 at 500 nm is selectively quenched by vanillin with a detection limit of 0.8 μM. Finally, the analytical novelty of the developed probes was examined by quantifying ortho-vanillin and vanillin in spiked food samples with good recovery percentages., (© 2024 John Wiley & Sons Ltd.)

The excessive use of antibiotic ofloxacin (Oflx) can cause serious detrimental effects to human health. Therefore, the utmost research priority is required to develop facile methods to detect Oflx. Herein, a V-shaped aggregation-induced emission (AIE) active Schiff base SDANA was introduced for the fluorescent turn-on detection of Oflx. The Schiff base SDANA was synthesized by condensing 4,4'-sulfonyldianiline with two equivalents of 2-hydroxy-1-naphthaldehyde. The nearly non-fluorescent SDANA in DMSO showed strong orange emission with the increase in HEPES buffer (H 2 O, 10 mM, pH 7.4) fractions in DMSO from 70 %-95 % due to the combined effects of AIE and ESIPT. The DLS and SEM analyses were performed to complement the formation of self-aggregates of SDANA. With the addition of Oflx, the fluorescence emission of AIE luminogen (AIEgen) SDANA (λ em =575 nm, λ ex =400 nm) was blue-shifted and enhanced at 530 nm. The interactions of Oflx over the surface of SDANA aggregates disrupted the intramolecular charge transfer and aggregation morphology of SDANA, which gave a distinct fluorescence response to detect Oflx. The detection limit for Oflx was estimated as 0.81 μM, and the developed probe AIEgen SDANA was applied for the quantification of Oflx in human blood serum., (© 2024 Wiley-VCH GmbH.)

Oral squamous cell carcinoma (OSCC) is a disease of significant concern with higher mortality rates. Conventional treatment approaches have several drawbacks, leading to the opening of new research avenues in the field of nanoparticle-based cancer therapeutics. The study aimed at the synthesis of gold nanoparticles (Pm-AuNPs) from the aqueous bark extract of Pterocarpus marsupium , followed by its characterization and in vitro anticancer evaluation against OSCC. The synthesized Pm-AuNPs were characterized using UV-visible spectroscopy, particle size analyser, zeta potential, FTIR and SEM techniques. The anticancer potential of the Pm-AuNPs was evaluated against OSCC cell lines (SCC29b, SSC154 and OECM-1) through in vitro assays. The IC 50 value was found to be 25 ± 1.2, 45 ± 1.5 and 75 ± 2.1 µg/mL for the three OSCC cell lines, elucidating Pm-AuNPs cytotoxic effects and mechanism of action. Intracellular ROS and SOX detection, mitochondrial transmembrane potential analysis and apoptosis detection were used to confirm the activity of Pm-AuNPs against OSCC. Acute toxicity studies on Wistar rats confirmed the non-toxic nature of the Pm-AuNPs at a higher dose concentration up to 2000 mg/kg body weight. The findings underscore Pm-AuNPs as promising candidates for future anticancer therapeutics, providing insights into their mechanism of action and therapeutic efficacy against OSCC.

Water, although an important part of everyday life, is acts as one of the most significant contaminants in various applications such as biomedical monitoring, chemical production, petroleum-based fuel and food processing. In fact, the presence of water in other solvents is a huge concern. For the quantification of trace water content, different methods such as Karl-Fischer, electrochemical, nuclear magnetic resonance, chromatography, and thermogravimetric analysis have been used. Although every technique has its own benefit, each one suffers from several drawbacks that include high detection costs, lengthy procedures and specialized operations. Nowadays, the development of fluorescence-based chemical probes has become an exciting area of research for the quick and accurate estimation of water content in organic solvents. A variety of chemical processes such as hydrolysis reaction, metal ions promoted oxidation reaction, suppression of the -C═N isomerization, protonation and deprotonation reactions, and molecular aggregation have been well researched in the last few years for the fluorescent detection of trace water. These chemical processes eventually lead to different photophysical events such as aggregation-induced emission (AIE), aggregation-induced emission enhancement (AIEE), aggregation-caused quenching (ACQ), fluorescent resonance energy transfer (FRET), charge transfer, photo-induced electron transfer (PET), excited state intramolecular proton transfer (ESIPT) that are responsible for the detection. This review presents a summary of the fluorescence-based chemosensors reported in recent years. The design of water sensors, sensing mechanisms and their potential applications are reviewed and discussed., Competing Interests: Declaration of competing interest All the authors declare that they have no established conflicting financial interests or personal relationships that may have influenced the research presented in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

A thiourea functionalised fluorescent probe 1-phenyl-3-(pyridin-4-yl)thiourea was synthesized and utilised as a fluorescent turn-on chemosensor for the selective recognition of Hg 2+ ion over competitive metal ions including Na + , Mn 2+ , Li + , Cr 2+ , Ni 2+ , Ca 2+ , Cd 2+ , Mg 2+ , K + , Co 2+ , Cu 2+ , Zn 2+ , Al 3+ and Fe 2+ ions based on the inter-molecular charge transfer (ICT). Intriguingly, the receptor demonstrated unique sensing capabilities for Hg 2+ in DMSO: H 2 O (10:90, v/v). The addition of Hg 2+ ions to the sensor resulted in a blue shift in the absorption intensity and also enhancement in fluorescence intensity at 435 nm. Fluorescence emission intensity increased linearly with Hg 2+ concentration ranging from 0 to 80 µL. The detection limit and binding constant were determined as 0.134 × 10 -6  M and 1.733 × 10 7  M -1 , respectively. The sensing behavior of Hg 2+ was further examined using DLS, SEM and FTIR. The probe could detect Hg 2+ ions across a wide pH range. Furthermore, the receptor L demonstrated good sensing performance for Hg 2+ in bovine serum albumin and actual water samples., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

A great deal of effort has been put into developing a novel and cost-effective molecular probe for selective and sensitive recognition of trace amounts of water in organic solvents due to their tremendous advantages in industrial, pharmaceutical, and laboratory-scale chemistry. Herein, a cost-effective chemosensor L has been designed and studied for the detection of trace amounts of water. The addition of water to the DMSO solution of L exhibited an enhancement of fluorescence emission at 460 nm along with a color change from green to colorless. The spectral and color changes occurred due to the self-aggregation of L. The interaction between water and L was performed by dynamic light scattering (DLS), scanning electron microscope (SEM) and finally complemented by quantum mechanical calculation. The detection limit was found to be 0.0093 wt% in DMSO. The L also exhibits a fast visual response and is effectively applied to detect trace amounts of moisture in various food materials (salt, sugar, wheat and honey) and building materials (cement, fly ash, limestone and sand)., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

An anthracene thiazole based Schiff base L was synthesized and employed for fluorescence switch-on detection of maleic acid in aqueous DMSO. The non-fluorescent L (10 -5  M) showed an instantaneous and selective fluorescence enhancement at 506 nm upon interaction with maleic acid (10 -5  M). Other potential carboxylic acids (10 -5  M), such as malic acid, citric acid, acetic acid, cinnamic acid, tartaric acid, succinic acid, fumaric acid, oxalic acid and malonic acid failed to alter the chromo-fluorogenic properties of L. Probe L can be employed to detect maleic acid down to 2.74 × 10 -6  M. The probe L showed good linearity from 2.97 to 6.87 µM. Analytical utility of L was examined by detecting maleic acid in various food additives and drosophila larvae., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

This research investigates the biogenic synthesis of silver nanoparticles (AgNPs) using the leaf extract of Chromolaena odorata (Asteraceae) and their potential as antibacterial and antifungal agents. Characterization techniques like ultraviolet-visible, Fourier transform infrared (FTIR), Dynamic light scattering and zeta potential (DLS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy (FESEM-EDX) confirmed the formation of spherical (AgNPs). UV-vis spectroscopy reaffirms AgNP formation with a peak at 429 nm. DLS and zeta potential measurements revealed an average size of 30.77 nm and a negative surface charge (- 0.532 mV). Further, XRD analysis established the crystalline structure of the AgNPs. Moreover, the TEM descriptions indicate that the AgNPs are spherical shapes, and their sizes ranged from 9 to 22 nm with an average length of 15.27 nm. The X-ray photoelectron spectroscopy (XPS) analysis validated the formation of metallic silver and elucidated the surface state composition of AgNPs. Biologically, CO-AgNPs showed moderate antibacterial activity but excellent antifungal activity against Candida tropicalis (MCC 1559) and Trichophyton rubrum (MCC 1598). Low MIC values (0.195 and 0.390 mg/mL) respectively, suggest their potential as effective antifungal agents. This suggests potential applications in controlling fungal infections, which are often more challenging to treat than bacterial infections. Molecular docking results validated that bioactive compounds in C. odorata contribute to antifungal activity by interacting with its specific domain. Further research could pave the way for the development of novel and safe antifungal therapies based on biogenic nanoparticles., (© 2024. The Author(s).)

Here, straightforward and environmentally friendly fluorescent nitrogen doped carbon quantum dots (N-CQDs) with a high blue fluorescence emission at 455 nm are used for ultrasensitive Hg 2+ ion detection. Folic acid and urea are used as carbon sources in the carbonization process. Two broad absorption bands at around 280 and 370 nm from UV-Vis spectrum and characteristic absorption peaks from infrared spectrum confirms the successful synthesis of the N-CQDs. Energy dispersive X-Ray analysis confirmed the elemental composition of the N-CQDs. Transmission electron microscopy showed the homogeneous globular morphology of the N-CQDs with an average particle size of 65 nm. Zeta potential measurement established the stability and surface charge of N-CQDs. Dynamic light scattering measurement showed the average size of N-CQDs. With the addition of Hg 2+ ion to N-CQDs, the blue fluorescence emission is quenched. Moreover, the N-CQDs can be applied to real water sample such as pond water, river water, and tap water. The detection limit is approximately calculated to be 12 nM and linear range is 0-30 parts per billion., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

A novel chromone-based Schiff base L was designed and synthesized by condensing an equimolar amount of 3-formyl chromone and 2,4-dinitro phenyl hydrazine. Schiff base L was developed as a potent colorimetric and fluorescent molecular probe to recognize Hg 2+ ions over other competitive metal ions. In the presence of Hg 2+ , Schiff base L displays a naked-eye detectable color change under day and UV 365 nm light. Various UV-Vis and fluorescence studies of L were performed in the absence and presence of Hg 2+ to determine the sensitivity and the sensing mechanism. With high selectivity and specificity, the detection limit and association constant of L for Hg 2+ were estimated at 1.87 µM and 1.234 × 10 7  M -1 , respectively. The developed sensor L was applied to real soil samples for the detection of Hg 2+ ., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Resistance to antibiotics/antibacterials/antifungals in pathogenic microbes has been developing over the past few decades and has recently become a commonplace public-health peril. Thus, alternative nontoxic potent antibiotic agents are covertly needed to control antibiotic-resistant outbreaks. In an effort to combat the challenges posed by the co-occurrence of multidrug resistance, two terpyridine ligands 4'-(4- N , N '-dimethylaminophenyl)-2,2':6',2″-terpyridine ( L1 ) and 4'-(4-tolyl)-2,2':6',2″-terpyridine ( L2 ) have been designed, prepared and confirmed their structure by spectral studies. Thereafter, antimicrobial assay was performed against gram positive and negative bacterial strains along with fungal strains. Both compounds L1 and L2 exhibited remarkable inhibitory activities against bacteria, Escherichia coli and Staphylococcus aureus at MIC values 6.25 and 3.125 µg/ml, respectively. In addition, in silico molecular docking studies were ascertained with bacterial DNA gyrase and fungal demethylase. Furthermore, both L1 and L2 could bind Bovine Serum Albumin (BSA) protein and binding interaction has been studied with the help of UV-Visible and fluorescence spectroscopy. While fluorescence of BSA unperturbed in the presence of L2 , an addition of L1 to the solution of BSA resulted significant quenching. The binding constant calculations at different temperature confirmed that the fluorescence quenching between BSA and L1 is predominantly static in nature. The toxicity of L1 and L2 was checked using Drosophila melanogaster . The toxicity analysis suggest both the dyes are non-cytotoxic in nature.Communicated by Ramaswamy H. Sarma.

This manuscript introduces a pyrene-based Schiff base L by reacting pyrenecarboxaldehyde with 2-aminothiazole in equimolar ratio. The ligand L was characterized by various spectral data and single crystal. The water sensing ability of L was examined in different organic solvents. The weakly emissive L in DMSO showed a fluorescence enhancement upon the addition of water. The water-induced fluorescence enhancement of L was occurred due to the combined effect of aggregation-induced emission (AIE) phenomenon and suppression of photo-induced electron transfer (PET) process. Using L, the water in DMSO can be detected down to 0.50 wt% with a quantification limit of 1.52 wt%. The analytical novelty of the developed sensor L was validated by detecting moisture in a variety of raw food products., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The cyanobacteria are the promising candidate for synthesizing gold nanoparticles (AuNPs), due to their ability to accumulate heavy metals from the cellular environment and additionally contain varied bioactive compounds as reducing and stabilizing agents. This study describes the N 2 -fixing cyanobacterium Nostoc calcicola-mediated bioreduction of AuNPs and the inherent antimicrobial, antioxidant, and antiproliferative activities in vitro. Biosynthesized Nc-AuNPs were characterized by spectral characterization techniques. The formation of AuNPs was physically confirmed by the colour change from pale green to dark violet. The UV-Vis analysis, further, proved the reduction in Nc-AuNPs with the cyanobacterium and showed a spectral peak at 527 nm. FESEM-EDX images suggested the surface morphology of the NPs as spherical, cuboidal, and size between 20 and 140 nm. The antimicrobial studies of Nc-AuNPs were carried out by agar-well diffusion method and MIC values against five pathogenic bacterial and two fungal strains were noted. The AuNPs exhibited potential antimicrobial activity against h-pathogenic bacteria with inhibitory zones ranging at 11-18 mm; against fungi ranging at 13-17 mm. Significant antioxidant potentialities were explored by a DPPH assay with an IC 50 value of 55.97 μg/ mL. Furthermore, in the anticancer efficacy assay, the Nc-AuNPs inhibited cellular proliferation in human breast adenocarcinoma and cervical cancer cell lines at IC 50 concentration, 37.3 μg/ml, and 44.5 μg/ml, respectively. Conclusively, N. calcicola would be an excellent source for synthesizing stable colloidal AuNPs that had significant credibility as phycological (algal) nanomedicines as novel prodrugs with multiple bioactivities., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Naphthoquinone derivatives such as lapachol, plumbagin, dichloroallyl lawsone show anticancer activity and generally cytotoxicity measurements are carried out in presence of bovine serum albumin; so understanding on the ability of serum albumin binding with such derivatives are essential. We have investigated cytotoxicity and serum albumin binding of a series of structurally related naphthoquinone derivatives. Substrate dependency and high selectivity in binding of naphthoquinone tethered carboxylic acids or pyridines with bovine serum albumin (BSA) and human serum albumin (HSA) are observed. For example, the binding constant of BSA with 3-(1,4-dihydro-2-methyl-1,4-dioxonaphthalen-3yl-thio)propanoic acid is ∼594 times higher than 3-(1,4-dioxo-1,4-dihydronaphthalen-2-yl-amino)benzoic acid; whereas 4-(1,4-dioxo-1,4-dihydronaphthalen-2-yl-amino)benzoic acid shows ∼367 times higher binding constant than the latter compound. The BSA weakly bind to pyridine tethered naphthoquinones, whereas HSA does not binds with them. The binding constant of HSA with 2-(1,4-dihydro-2-methyl-1,4-dioxonaphthalene-3-ylthio)benzoic acid is 134 times higher than the HSA binding constant with 2,2'-(1,4-dihydro-1,4-dioxo-naphthalen-2,3-diylthio)dipropanoic acid. Among the naphthoquinone carboxylic acids, the 3-(1,4-dioxo-1,4-dihydronaphthalen-2-yl-amino)benzoic acid binds selectively to BSA, but it does not bind to HSA. The 2-hydroxybenzoic acid or 4-mercaptobenzoic acid strongly binds to BSA. The binding of BSA with 4-hydroxybenzoic acid or 2-mercaptobenzoic acid are insignificant. We have not observed clear relationships of structure of naphthoquinone derivatives versus serum albumin binding, but could identify the compound having the best IC50 values of cytotoxicity among the twelve naphthoquinone compounds. The compound 3-(1,2-dihydro-1,2-dioxonaphthalen-4-yl-thio)propanoic acid in four cancer cell lines has IC50 values in the range 2.7-7.6μM. This compound also has optimum binding constant with BSA (35.042×10(3)Lmol(-1)) or HSA (21.427×10(3)Lmol(-1)). The cytotoxicity values of the compounds were influenced by concentration of BSA., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)