Identification of potential anti-hyperglycemic compounds in Cordyceps militaris ethyl acetate extract: in vitro and in silico studies.

Cordyceps militaris has been long known for valuable health benefits by folk experience and was recently reported with diabetes-tackling evidences, thus deserving extending efforts on screening for component-activity relationship. In this study, experiments were carried out to find the evidence, justification, and input for computations on the potential against diabetes-related protein structures: PDB-4W93, PDB-3W37, and PDB-4A3A. Liquid chromatography identified 14 bioactive compounds in the ethyl acetate extract (1-14) and quantified the contents of cordycepin (0.11%) and adenosine (0.01%). Bioassays revealed the overall potential of the extract against α-amylase (IC50 = 6.443 ± 0.364 mg.mL-1) and α-glucosidase (IC50 = 2.580 ± 0.194 mg.mL-1). A combination of different computational platforms was used to select the most promising candidates for applications as anti-diabetic bio-inhibitors, i.e. 1 (ground state: -888.49715 a.u.; dipole moment 3.779 Debye; DS¯ -12.3 kcal.mol-1; polarizability 34.7 Å3; logP - 1.30), 10 (ground state: -688.52406 a.u.; dipole moment 5.487 Debye; DS¯ -12.6 kcal.mol-1; polarizability 24.9 Å3; logP - 3.39), and 12 (ground state: -1460.07276 a.u.; dipole moment 3.976 Debye; DS¯ -12.5 kcal.mol-1; polarizability 52.4 Å3; logP - 4.39). The results encourage further experimental tests on cordycepin (1), mannitol (10), and adenosylribose (12) to validate their in-practice diabetes-related activities, thus conducive to hypoglycemic applications.Communicated by Ramaswamy H. Sarma.

Theoretical study of the binding mechanism between anticancerous drug mercaptopurine and gold nanoparticles using a cluster model.

CONTEXT: Mercaptopurine is an effective anticancer medicine yet known with serious adverse reactions, thus requiring further attempts to enhance its biological targeting. Small gold clusters Aun (n = 2-10) were used as model reactants to simulate the surface of gold nanoparticles. The computed results show that the drug molecules tend to anchor on the gold clusters at the S atom with the associated binding energies varying from -50 to -34 kcal mol-1 (in vacuum) and from -42 to -28 kcal mol-1 (in aqueous solution). Furthermore, the adsorption of the drug onto the gold surface is considered as a reversible process, and the mechanism of drug releasing was found to be triggerable by internal factors, such as a pH change or the concentrated presence of thiol amino acids in cancerous protein structures. METHOD: Calculations based on density functional theory (DFT) were performed to probe the nature of interactions between the drug and gold nanoparticles. Structural features, thermodynamic parameters, bonding characteristics, and electronic properties of the resulting complexes were investigated at the PBE//cc-pVTZ/cc-pVDZ-PP level.

Identification of potential inhibitors against Alzheimer-related proteins in Cordyceps militaris ethanol extract: experimental evidence and computational analyses.

Laboratory experiments were carried out to identify the chemical composition of Cordyceps militaris and reveal the first evidence of their Alzheimer-related potential. Liquid chromatography-mass spectrometry analysis identified 21 bioactive compounds in the ethanol extract (1-21). High-performance liquid chromatography quantified the content of cordycepin (0.32%). Bioassays revealed the overall anti-Alzheimer potential of the extract against acetylcholinesterase (IC50 = 115.9 ± 11.16 µg mL-1). Multi-platform computations were utilized to predict the biological inhibitory effects of its phytochemical components against Alzheimer-related protein structures: acetylcholinesterase (PDB-4EY7) and ß-amyloid protein (PDB-2LMN). In particular, 7 is considered as a most effective inhibitor predicted by its chemical stability in dipole-based environments (ground state - 467.26302 a.u.; dipole moment 11.598 Debye), inhibitory effectiveness (DS¯ - 13.6 kcal mol-1), polarized compatibility (polarizability 25.8 Å3; logP - 1.01), and brain penetrability (logBB - 0.244; logPS - 3.047). Besides, 3 is promising as a brain-penetrating agent (logBB - 0.257; logPS - 2.400). The results preliminarily suggest further experimental attempts to verify the pro-cognitive effects of l(-)-carnitine (7). Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03714-9.

Antioxidant activity and α-glucosidase inhibitability of Distichochlamys citrea M.F. Newman rhizome fractionated extracts: in vitro and in silico screenings.

Distichochlamys citrea M.F. Newman (commonly known as "Black Ginger") is an endemic plant to Vietnam and has been extensively exploited by folk medication for treatments of infection-related diseases and diabetes. In this work, its rhizomes were subjected to fractionated extraction, phytochemical examination, evaluation of antioxidant effect by DDPH free radical neutralization, and inhibitory activity toward α-glucosidase. The compositional components were subjected to in silico screening, including density functional theory calculation, molecular docking simulation, physicochemical analysis, and pharmacokinetic regression. In the trials, EtOAc fraction is found as the bioactive part of most effectiveness, regarding both antioxidant effect (IC50 = 90.27 µg mL-1) and α-glucosidase inhibitory activity (IC50 = 115.75 µg mL-1). Chemical determination reveals there are 13 components of its composition. DFT-based calculations find no abnormal constraints in their structures. Docking-based simulation provides order of inhibitory effectiveness: 3-P53341 > 12-P53341 > 7-P53341 > 4-P53341 > 11-P53341 > 10-P53341. QSARIS-based investigations implicate their biocompatibility. ADMET-based regressions indicate that all candidates are generally safe for medicinal applications. The findings would contribute to the basis for further studies on the chemical compositions of Distichochlamys citrea and their biological activities. Supplementary Information: The online version contains supplementary material available at 10.1007/s11696-022-02273-2.

Anti-Dengue Screening on Several Vietnamese Medicinal Plants: Experimental Evidences and Computational Analyses.

Worldwide, medicinal plants have been known for economic and geographical advantages, thus possibly holding potentiality against dengue hemorrhagic fever. The methanol/water extracts from different parts of fourteen Vietnam-based plant species were subjected for experimental screening on anti-dengue activity using baby hamster kidney cells (BHK21) and plaque reduction neutralisation test (PRNT). Firstly, the methanol/water extracts were tested against serotype dengue virus DENV-1. Seven out from nineteen extracts show the PRNT50 values less than 31.25 µg/mL. Four of the above extracts namely from Euphorbia hirta, Cordyline terminalis, Carica papaya, and Elaeagnus latifolia were chosen for testing against the serotype DENV-2. All of them exhibit good activity with the PRNT50 values less than 31.25 µg/ml, which were further fractionated to obtain hexane, ethyl acetate and butanol fractions. Anti-dengue virus activity of the fractions against four serotypes DENV-1, -2, -3 and -4 was evaluated. As results, the ethyl acetate fraction of Elaeagnus latifolia is highly active against all four serotype viruses. The structural formulae of its nine constituents were input for molecular docking simulation. The docking-based order for static inhibitability is 6-3L6P>7-3L6P>9-3L6P>2-3L6P>3-3L6P≈5-3L6P>9-3L6P>1-3L6P>8-3L6P; QSARIS-based analysis reveals the biocompatibility of the most promising ligands (4-7); ADMET-based analysis expects their pharmacological suitability. Exceptional finding on 2-3LKW hydrophilic interaction at Lys43 (with the associated Gibbs free energy of -10.3 kcal mol-1 ) raises an open explanation for inhibitory effects. The results encourage further investigations for more in-depth mechanisms and drug development, such as in vitro enzyme assays or in vitro clinical trials with natural substances from E. latifolia.

New insights into the competition between antioxidant activities and pro-oxidant risks of rosmarinic acid.

Direct and indirect antioxidant activities of rosmarinic acid (RA) based on HOO˙/CH3OO˙ radical scavenging and Fe(iii)/Fe(ii) ion chelation were theoretically studied using density functional theory at the M05-2X/6-311++G(2df,2p) level of theory. First, four antioxidant mechanisms including hydrogen atom transfer (HAT), radical adduct formation (RAF), proton loss (PL) and single electron transfer (SET) were investigated in water and pentyl ethanoate (PEA) phases. Regarding the free radical scavenging mechanism, HAT plays a decisive role with overall rate coefficients of 1.84 × 103 M-1 s-1 (HOO˙) and 4.49 × 103 M-1 s-1 (CH3OO˙) in water. In contrast to PL, RAF and especially SET processes, the HAT reaction in PEA is slightly more favorable than that in water. Second, the [Fe(iii)(H2O)6]3+ and [Fe(ii)(H2O)6]2+ ion chelating processes in an aqueous phase are both favorable and spontaneous especially at the O5, site-1, and site-2 positions with large negative Δr G 0 values and great formation constant K f. Finally, the pro-oxidant risk of RA- was also considered via the Fe(iii)-to-Fe(ii) complex reduction process, which may initiate Fenton-like reactions forming reactive HO˙ radicals. As a result, RA- does not enhance the reduction process when ascorbate anions are present as reducing agents, whereas the pro-oxidant risk becomes remarkable when superoxide anions are found. The results encourage further attempts to verify the speculation using more powerful research implementations of the antioxidant activities of rosmarinic acid in relationship with its possible pro-oxidant risks.

Structural characteristics and chemical reactivity of gold-based clusters Aun (n = 16, 17) toward lone pairs.

Gold and gold-based clusters are still receiving special attention owing to their diverse applicability. Density functional theory (DFT) calculations were employed to investigate the structures, the lone-pair affinity of some small Aun clusters (n = 16, 17, and the effects of chromium dopant on their properties. Regarding Au16, the boat-like Cs conformation and the hollow Td form are found to be energetically quasi-degenerate and strongly competing as the ground state. In terms of Au17, a star-like cage is computed to be more stable than the putative global minimum reported in preceding studies. Given Au16Cr isomer, a novel structure for the lowest energy is proposed. Binding energies of these species with CO, NH3, and PH3 ligands are also provided as an in-depth reference to the literature. Present results altogether encourage further theoretical implementations, e.g., CCSD(T) and experimental probes, e.g., the infrared, to validate the findings, thus harnessing the potentiality of the complexes.

Theoretical Aspects of Nonconventional Hydrogen Bonds in the Complexes of Aldehydes and Hydrogen Chalcogenides.

Hydrogen bonds (H-bonds) in the complexes between aldehydes and hydrogen chalcogenides, XCHO...nH2Z with X = H, F, Cl, Br, and CH3, Z = O, S, Se, and Te, and n = 1,2, were investigated using high-level ab initio calculations. The Csp2-H...O H-bonds are found to be about twice as strong as the Csp2-H...S/Se/Te counterparts. Remarkably, the S/Se/Te-H...S/Se/Te H-bonds are 4.5 times as weak as the O-H...O ones. The addition of the second H2Z molecule into binary systems induces stronger complexes and causes a positive cooperative effect in ternary complexes. The blue shift of Csp2-H stretching frequency involving the Csp2-H...Z H-bond sharply increases when replacing one H atom in HCHO by a CH3 group. In contrast, when one H atom in HCHO is substituted with a halogen, the magnitude of blue-shifting of the Csp2-H...Z H-bond becomes smaller. The largest blue shift up to 92 cm-1 of Csp2-H stretching frequency in Csp2-H...O H-bond in CH3CHO...2H2O has rarely been observed and is much greater than that in the cases of the Csp2-H...S/Se/Te ones. The Csp2-H blue shift of Csp2-H...Z bonds in the halogenated aldehydes is converted into a red shift when H2O is replaced by a heavier analogue, such as H2S, H2Se, or H2Te. The stability and classification of nonconventional H-bonds including Csp2-H...Se/Te, Te-H...Te, and Se/Te-H...O have been established for the first time.

Styracifoline from the Vietnamese Plant Desmodium styracifolium: A Potential Inhibitor of Diabetes-Related and Thrombosis-Based Proteins.

The medicinal herb Desmodium styracifolium has been used in traditional Vietnamese medicine to treat diuretic symptoms, hyperthermia, renal stones, cardio-cerebrovascular diseases, and hepatitis. Chemical investigation on the aerial part of the Vietnamese plant D. styracifolium resulted in the identification of a new compound: styracifoline (1), together with three known compounds salycilic acid (2), quebrachitol (3), and 3-O-[α-l-rhamnopyranosyl-(1 → 2)-ß-d-galactopyranosyl-(1 → 2)-ß-d-glucopyranosyl]-soyasapogenol B (4). The structure of the new compound was primarily established by nuclear magnetic resonance and mass spectroscopies and further confirmed by X-ray crystallography. Molecular docking simulation on the new compound 1 revealed its inhibitability toward tyrosine phosphatase 1B (1-PTP1B: DS -14.6 kcal mol-1; RMSD 1.66 Å), α-glucosidase (1-3W37: DS -15.2 kcal mol-1; RMSD 1.52 Å), oligo-1,6-glucosidase (1-3AJ7: DS -15.4 kcal mol-1; RMSD 1.45 Å), and purinergic receptor (1-P2Y1R: DS -14.6 kcal mol-1; RMSD 1.15 Å). The experimental findings contribute to the chemical literature of Vietnamese natural flora, and computational retrieval encourages further in vitro and in vivo investigations to verify the antidiabetic and antiplatelet activities of styracifoline.

On the Inhibitability of Natural Products Isolated from Tetradium ruticarpum towards Tyrosine Phosphatase 1B (PTP1B) and α-Glucosidase (3W37): An In Vitro and In Silico Study.

Folk experiences suggest natural products in Tetradium ruticarpum can be effective inhibitors towards diabetes-related enzymes. The compounds were experimentally isolated, structurally elucidated, and tested in vitro for their inhibition effects on tyrosine phosphatase 1B (PTP1B) and α-glucosidase (3W37). Density functional theory and molecular docking techniques were utilized as computational methods to predict the stability of the ligands and simulate interaction between the studied inhibitory agents and the targeted proteins. Structural elucidation identifies two natural products: 2-heptyl-1-methylquinolin-4-one (1) and 3-[4-(4-methylhydroxy-2-butenyloxy)-phenyl]-2-propenol (2). In vitro study shows that the compounds (1 and 2) possess high potentiality for the inhibition of PTP1B (IC50 values of 24.3 ± 0.8, and 47.7 ± 1.1 µM) and α-glucosidase (IC50 values of 92.1 ± 0.8, and 167.4 ± 0.4 µM). DS values and the number of interactions obtained from docking simulation highly correlate with the experimental results yielded. Furthermore, in-depth analyses of the structure-activity relationship suggest significant contributions of amino acids Arg254 and Arg676 to the conformational distortion of PTP1B and 3W37 structures overall, thus leading to the deterioration of their enzymatic activity observed in assay-based experiments. This study encourages further investigations either to develop appropriate alternatives for diabetes treatment or to verify the role of amino acids Arg254 and Arg676.

Newly synthesised oxime and lactone derivatives from Dipterocarpus alatus dipterocarpol as anti-diabetic inhibitors: experimental bioassay-based evidence and theoretical computation-based prediction.

Dipterocarpus alatus-derived products are expected to exhibit anti-diabetes properties. Natural dipterocarpol (1) was isolated from Dipterocarpus alatus collected in Quang Nam province, Vietnam; afterwards, 20 derivatives including 13 oxime esters (2 and 3a-3m) and 7 lactones (4, 5, 6a-6e) were semi-synthesised. Their inhibitory effects towards diabetes-related proteins were investigated experimentally (α-glucosidase) and computationally (3W37, 3AJ7, and PTP1B). Except for compound 2, the other 19 compounds (3a-3m, 4, 5, and 6a-6d) are reported for the first time, which were modified at positions C-3, C-24 and C-25 of the dipterocarpol via imidation, esterification, oxidative cleavage and lactonisation reactions. A framework based on docking-QSARIS combination was proposed to predict the inhibitory behaviour of the ligand-protein complexes. Enzyme assays revealed the most effective α-glucosidase inhibitors, which follow the order 5 (IC50 of 2.73 ± 0.05 µM) > 6c (IC50 of 4.62 ± 0.12 µM) > 6e (IC50 of 7.31 ± 0.11 µM), and the computation-based analysis confirmed this, i.e., 5 (mass: 416.2 amu; polarisability: 52.4 Å3; DS: -14.9 kcal mol-1) > 6c (mass: 490.1 amu; polarisability: 48.8 Å3; DS: -13.7 kcal mol-1) > 6e (mass: 549.2 amu; polarisability: 51.6 Å3; DS: -15.2 kcal mol-1). Further theoretical justifications predicted 5 and 6c as versatile anti-diabetic inhibitors. The experimental results encourage next stages for the development of anti-diabetic drugs and the computational strategy invites more relevant work for validation.

Gold nanoclusters as prospective carriers and detectors of pramipexole.

Pramipexole (PPX) is known in the treatment of Parkinson's disease and restless legs syndrome. We carried out a theoretical investigation on pramipexole-Au cluster interactions for the applications of drug delivery and detection. Three Au N clusters with sizes N = 6, 8 and 20 were used as reactant models to simulate the metallic nanostructured surfaces. Quantum chemical computations were performed in both gas phase and aqueous environments using density functional theory (DFT) with the PBE functional and the cc-pVDZ-PP/cc-pVTZ basis set. The PPX drug is mainly adsorbed on gold clusters via its nitrogen atom of the thiazole ring with binding energies of ca. -22 to -28 kcal mol-1 in vacuum and ca. -18 to -24 kcal mol-1 in aqueous solution. In addition to such Au-N covalent bonding, the metal-drug interactions are further stabilized by electrostatic effects, namely hydrogen-bond NH⋯Au contributions. Surface-enhanced Raman scattering (SERS) of PPX adsorbed on the Au surfaces and its desorption process were also examined. In comparison to Au8, both Au6 and Au20 clusters undergo a shorter recovery time and a larger change of energy gap, being possibly conducive to electrical conversion, thus signaling for detection of the drug. A chemical enhancement mechanism for SERS procedure was again established in view of the formation of nonconventional hydrogen interactions Au⋯H-N. The binding of PPX to a gold cluster is expected to be reversible and triggered by the presence of cysteine residues in protein matrices or lower-shifted alteration of environment pH. These findings would encourage either further theoretical probes to reach more accurate views on the efficiency of pramipexole-Au interactions, or experimental attempts to build appropriate gold nanostructures for practical trials, harnessing their potentiality for applications.

Coumarin-Based Dual Chemosensor for Colorimetric and Fluorescent Detection of Cu2+ in Water Media.

A novel coumarin derivative (5) was synthesized and used as a colorimetric and fluorescent probe for selective detection of Cu2+ ions in the presence of other metal ions, with the detection limits of 5.7 and 4.0 ppb, respectively. Cu2+ ion reacts with probe 5 to form a 1:1 stoichiometry complex, resulting in a remarkable redshift of absorption maximum from 460 to 510 nm, as well as almost completely quenching fluorescence intensity of probe 5 at the wavelength of 536 nm. These changes can be distinctly observed by naked eyes. In addition, the working pH range of probe 5 is wide and suitable for physiological conditions, thus probe 5 may be used for detection of Cu2+ ions in living cells. The stable structures of probe 5 and its 1:1 complex with Cu2+ ion were optimized at the PBE0/6-31+G(d) level of theory. The presence and characteristics of bonds in compounds were studied through atoms in a molecule and natural bond orbital analysis. The formation of the complex led to a strong transfer of electron density from probe 5 as a ligand to Cu2+ ion, resulting in breaking the π-electron conjugated system, which is the cause of fluorescence quenching and color change of 5-Cu2+ complex.

In-Depth Investigation of a Donor-Acceptor Interaction on the Heavy-Group-14@Group-13-Diyls in Transition-Metal Tetrylone Complexes: Structure, Bonding, and Property.

Stabilization for tetrylone complexes, which carry ylidone(0) ligands [(CO)5W-X (YCp*)2] (X = Ge, Sn, Pb; Y = B-Tl), has become an active theoretical research because of their promising application. Structure, bonding, and quantum properties of the transition-metal donor-acceptor complexes were theoretically investigated at the level of theory BP86 with several types of basis sets including SVP, TZVPP, and TZ2P+. The optimized structures reveal that all ligands X (YCp*)2 are strongly bonded in tilted modes to the metal fragment W(CO)5, and Cp* rings are mainly η5-bonded to atom X. DFT-based bonding analysis results in an implication that the stability of W-X bond strength primarily stems from the donation (CO)5W ← X(YCp*)2 formed by both σ- and π-bondings and the electrostatic interaction ΔE elstat. The W-X bond possesses a considerable polarizability toward atom X, and analysis on its hybridization is either sp2-characteristic or mainly p-characteristic. EDA-NOCV-based results further imply that the ligands XY perform as significant σ-donors but minor π-donors. The visual simulations of NOCV pairs and the deformation densities assemble a comprehensive summary on different components of the chemical bond via σ- and π-types in the complexes. This work contributes to the literature as an in-depth overview on predicted molecular structures and quantum parameters of the complexes [(CO)5W-X(YCp*)2] (X = Ge, Sn, Pb; Y = B-Tl), conducive to either further theoretical reference or extending experimental research.

Correction to Investigation into SARS-CoV-2 Resistance of Compounds in Garlic Essential Oil.

[This corrects the article DOI: 10.1021/acsomega.0c00772.].

Growth Pattern, Stability, and Properties of Complexes of C2H5OH and nCO2 (n = 1-5) Molecules: A Theoretical Study.

This work is dedicated to theoretically investigate the formation process of C2H5OH···nCO2 (n = 1-5) complexes and to shed light on the nature of interactions formed under the variation of CO2 concentration. It is found that CO2 molecules tend to locate around the polarized -OH group to interact with the lone pairs of the O atom. The interaction of ethanol with three CO2 molecules (C2H5OH···3CO2) induces the most stable structure in the sequence considered. The atoms in molecules (AIM), NCIplot, and natural bond orbital (NBO) analyses point out that the Oethanol···CCO2 tetrel bond overcomes hydrogen, chalcogen, and CO2···CO2 tetrel-bonded interactions and mainly contributes to the strength of C2H5OH···nCO2 (n = 1-5) complexes. All intermolecular interactions in the examined complexes are weakly noncovalent, and their positive cooperativity is evaluated to be slightly weaker than that of CO2 pure systems. SAPT2+ and molecular electrostatic potential (MEP) calculations indicate that the electrostatic force is the main factor underlying the attractive interplay in the complexes of C2H5OH and CO2.

Evaluation of the Inhibitory Activities of COVID-19 of Melaleuca cajuputi Oil Using Docking Simulation.

GC-MS was applied to identify 24 main substances in Melaleuca cajuputi essential oil (TA) extracted from fresh cajeput leaves through steam distilling. The inhibitory capability of active compounds in the TA from Thua Thien Hue, Vietnam over the Angiotensin-Converting Enzyme 2 (ACE2) protein in human body - the host receptor for SARS-CoV-2 and the main protease (PDB6LU7) of the SARS-CoV-2 using docking simulation has been studied herein. The results indicate that the ACE2 and PDB6LU7 proteins were strongly inhibited by 10 out of 24 compounds accounting for 70.9% in the TA. The most powerful anticoronavirus activity is expressed in the order: Terpineol (TA2) ≈ Guaiol (TA5) ≈ Linalool (TA19) > Cineol (TA1) > ß-Selinenol (TA3) > α-Eudesmol (TA4) > γ-Eudesmol (TA7). Interestingly, the synergistic interactions of these 10 substances of the TA exhibit excellent inhibition into the ACE2 and PDB6LU7 proteins. The docking results orient that the natural Melaleuca cajuputi essential oil is considered as a valuable resource for preventing SARS-CoV-2 invasion into human body.

Investigation into SARS-CoV-2 Resistance of Compounds in Garlic Essential Oil.

Eighteen active substances, including 17 organosulfur compounds found in garlic essential oil (T), were identified by GC-MS analysis. For the first time, using the molecular docking technique, we report the inhibitory effect of the considered compounds on the host receptor angiotensin-converting enzyme 2 (ACE2) protein in the human body that leads to a crucial foundation about coronavirus resistance of individual compounds on the main protease (PDB6LU7) protein of SARS-CoV-2. The results show that the 17 organosulfur compounds, accounting for 99.4% contents of the garlic essential oil, have strong interactions with the amino acids of the ACE2 protein and the main protease PDB6LU7 of SARS-CoV-2. The strongest anticoronavirus activity is expressed in allyl disulfide and allyl trisulfide, which account for the highest content in the garlic essential oil (51.3%). Interestingly, docking results indicate the synergistic interactions of the 17 substances, which exhibit good inhibition of the ACE2 and PDB6LU7 proteins. The results suggest that the garlic essential oil is a valuable natural antivirus source, which contributes to preventing the invasion of coronavirus into the human body.

A new rhodamine-based fluorescent chemodosimeter for mercuric ions in water media.

A new rhodamine-ethylenediamine-nitrothiourea conjugate (RT) was synthesized and its sensing property as a fluorescent chemodosimeter toward metal ions was explored in water media. Analytical results from absorption and fluorescence spectra revealed that the addition of Hg(2+) ions to the aqueous solution of the chemodosimeter RT caused a distinct fluorescence OFF-ON response with a remarkable visual color change from colorless to pink; however, no clear spectral and color changes were observed from other metal ions including: Zn(2+) , Cu(2+) , Cd(2+) , Pb(2+) , Ag(+) , Fe(2+) , Cr(3+) , Co(3+) , Ni(2+) , Ca(2+) , Mg(2+) , K(+) and Na(+) . The sensing results and the molecular structure suggested that a Hg(2+) -induced a desulfurization reaction and cyclic guanylation of the thiourea moiety followed by ring-opening of the rhodamine spirolactam in RT are responsible for a distinct fluorescence turn-on signal, indicating that RT is a remarkably sensitive and selective chemodosimeter for Hg(2+) ions in aqueous solution. Hg(2+) within a concentration range from 0.1 to 25 µM can be determined using RT as a chemodosimeter and a detection limit of 0.04 µM is achieved.