A bio-compatible pyridine-pyrazole hydrazide based compartmental receptor for Al3+ sensing and its application in cell imaging.

For practical applications, the development of bio-compatible organic molecules as p-block ion chemosensors is critical. Herein, we report the single crystal (SC) of new pyridine-pyrazole derived Al3+ sensor H2PPC [(Z)-N'-(2,3-dihydroxybenzylidene)-5-methyl-1-(pyridin-2-yl)-1H-pyrazole-3-carbohydrazide] as well as its Cu-complex SC. The probe exhibits an "off-on" fluorescence response towards Al3+ ions, and this has been modulated with different solvents. For selective detection of Al3+ ions, a special coordination pocket in the structural backbone is advantageous. The chemosensor exhibits a submicromolar detection level (LOD = 4.78 µM) for Al3+. The density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations of H2PPC and [Al(HPP)2]+ (1) reveal that a change of the structural conformation of probe H2PPC upon complexation causes the pyrazole and pyridine units to create a specific cavity to tether Al3+, and consequently H2PPC proves to be a promising molecule for Al3+ detection. Furthermore, the probe has been successfully used to evaluate Al3+ as a low-cost kit using filter paper strips, and the in situ Al3+ ion imaging in Vero cells as well as A549 cell lines shows the sensor's nuclear envelope penetrability, indicating that it has great potential for biological and environmental applications.

Fluorescein derived Schiff base as fluorimetric zinc (II) sensor via 'turn on' response and its application in live cell imaging.

A novel Schiff base L composed of fluorescein hydrazine and a phenol functionalized moiety has been designed and prepared via cost-effective condensation reaction. The L is utilized for selective sensing of Zn2+ over other environmental and biological relevant metal ions in aqueous alcoholic solution under physiological pH range. The binding of Zn2+ to the receptor L is found to causes ~23 fold fluorescence enhancement of L. The 1:1 binding mode of the metal complex is established by combined UV-Vis, fluorescence, and HRMS (high-resolution mass spectroscopy) spectroscopic methods. The binding constant (Ka) for complexation and the limit of detection (LOD) of Zn2+ is calculated to be 2.86 × 104 M-1 and 1.59 µM, respectively. Further photophysical investigations including steady-state, time-resolved fluorescence analysis and spectral investigations including NMR (nuclear magnetic resonance), IR (infrared spectroscopy) suggest introduction of CHEF (chelation enhance fluorescence) with the suppression of CN isomerization and PET (photo-induced electron transfer) mechanism for the strong fluorescent response towards Zn2+. Finally, the sensor L is successfully employed to monitor a real-time detection of Zn2+ by means of TLC (thin layer chromatography) based paper strip. The L is used in the cell imaging study using African green monkey kidney cells (Vero cells) for the determination of exogenous Zn2+ by Immunofluorescence Assay (IFA) process.

An azine-based carbothioamide chemosensor for selective and sensitive turn-on-off sequential detection of Zn(II) and H2PO4-, live cell imaging and INHIBIT logic gate.

Hydrazino-carbothioamide, 1, serves as a turn-on fluorescent chemosensor to Zn2+ and the mixture shows green emission (λem 492) in presence of large number of ions with impressive limit of detection (LOD), 0.59 nM. Intense fluorescence of Zn-complex is selectively turn-off upon adding H2PO4- only to the limit of detection, 26 µM, while other anions remain silent. The sensing mechanism of 1 is established by suppressing the ESIPT of 1 and complexation with Zn2+ (CHEF) is supported by Job's plot, 1H NMR, and HR-MS data. Turn-on-off sequential detection of Zn2+ and H2PO4- also have successfully been employed for the engineering of INHIBIT molecular logic gate. The sensor is non-toxic and has been used in identifying Zn2+ in the intracellular region of African green monkey kidney cells (Vero cells).

Boswellia serrata oleo-gum-resin and ß-boswellic acid inhibits HSV-1 infection in vitro through modulation of NF-кB and p38 MAP kinase signaling.

BACKGROUND: Herpes Simplex Virus (HSV), a highly contagious pathogen, is responsible for causing lifelong oral to genital infection in human. Boswellia serrata oleo-gum-resin possesses a strong traditional background of treating diverse skin ailments including infection but its effect on HSV-1 has not been examined yet. PURPOSE: To exploit its potential, we aimed to explore the antiviral activity of methanol extract of B. serrata oleo-gum-resin (BSE) and one of its major constituent ß-boswellic acid (BA) against HSV-1 along with the underlying mechanism of action involved. METHODS: BSE was subjected to RP-HPLC analysis to quantify the active constituent. Cytotoxicity (CC50) and antiviral activity were evaluated by MTT and plaque reduction assay, followed by the determination of median effective concentration (EC50). The mode of antiviral activity was assessed by time-of-addition assay and confirmed by reverse transcriptase-PCR (RT-PCR). Further, the expressions of various cytokines were measured by RT-PCR, while the proteins by Western blot. RESULTS: BSE and BA potently inhibited wild-type and a clinical isolate of HSV-1 (EC50 5.2-6.2 and 12.1-14.63 µg/ml), with nearly-complete inhibition (EC99) at 10 and 30 µg/ml, respectively. The inhibitory effect was significant at 1 h post-infection and effective up to 4 h. Based on target analysis we examined the inhibition of NF-κB, essential for virus replication, and observed significant down-regulation of NF-κB, and p38 MAP-kinase activation, with reduced expression of tumor necrosis factor (TNF)-α, Interleukin (IL)-1ß and IL-6, involved in scheming NF-κB signaling. CONCLUSION: Thus, our results support the ethnomedicinal use of BSE in skin infection by inhibiting HSV-1 through the modulation of NF-κB and p38 MAPK pathway.