Molecular recognition of carbonate ion using a novel turn-on fluorescent probe.

A novel turn-on fluorescent probe 3 was synthesized by condensing salicylaldehyde and nicotinic hydrazide for the selective detection of CO32- in aqueous medium. Probe 3 exhibited a turn-on fluorescence response toward CO32- with excellent selectivity, sensitivity (DL = 2.76 µM), and good reversibility. The binding constant (K) of probe 3 with CO32- was calculated to be 5 × 103 M-1 (log K 3.69). The 1:1 stoichiometry of the complex between probe 3 and CO32- ions was confirmed by Job's plot and ESI-MS spectra. Deprotonation and hydrogen-bonding interactions are involved in the recognition of CO32- ion, which was also suggested by 1H NMR, ESI-MS spectra, and Density Functional Theory (DFT) calculations. Moreover, an INHIBIT type molecular logic gate was constructed by using 3:CO32- and CH3COOH as inputs and current signal as output. Owing to the practical applications, probe 3 demonstrated its efficiency in quantifying CO32- ion in real water samples through standard addition method, thus showcasing its potential in real environment. Further, the MTT assay indicated very low cytotoxicity (IC50 = 1 mM) of probe 3 and also the cell imaging experiments demonstrated the effective sensing of CO32- ions with probe 3 in the biological systems.

Two new anticancer phenolic derivatives from leaves of Piper betle Linn.

In this study, phytochemical analyses of the chloroform extract of Piper betle L. var. haldia and maghai, Piperaceae, leaves led to the isolation of two new phenolic derivatives: 1-n-decanoyl hydroxy-benzoic acid/1-n-decanoyl phenol (H2) and 3-butylphenol (M1) on the basis of spectroscopic data 1D NMR (1H, 13C) and 2D NMR (1H - 1H COSY, HMBC) as well as ESI-MS, FT-IR and HR-ESI-MS analyses. Compounds H2 and M1 showed excellent antioxidant DPPH free radical scavenging activity with IC50 values of 10.66 µ/mL and 13.65 µg/mL compared to ascorbic acid as a standard antioxidant with an IC50 value of 2.52 µg/mL. Evaluation of cytotoxic activity against two human oral cancer cell lines (SCC-40 and SCC-29B) showed significant effect with GI50 values of 24.08 and 33.08 µg/mL for compound H2 and 35.03 and 47.06 µg/mL for compound M1, compared to Doxorubicin® as a standard cytotoxic drug with GI50 value of < 10 µg/mL.

New chemical constituents from the Piper betle Linn. (Piperaceae).

The phytochemical investigation of chloroform extract from Piper betle var. haldia, Piperaceae, leaves has resulted in the isolation of two new chemical constituents which were identified as 1-n-dodecanyloxy resorcinol (H1) and desmethylenesqualenyl deoxy-cepharadione-A (H4), on the basis of spectroscopic data 1D NMR (1H and 13C) and 2D NMR (1H-1H COSY and HMBC) as well as ESI-MS, FT-IR and HR-ESI-MS analyses. Compounds H1 and H4 showed excellent antioxidant DPPH free radical scavenging activity with IC50 values of 7.14 µg/mL and 8.08 µg/mL compared to ascorbic acid as a standard antioxidant drug with IC50 value of 2.52 µg/mL, respectively. Evaluation of cytotoxic activity against human hepatoma cell line (PLC-PRF-5) showed moderate effect with the GI50 values of 35.12 µg/mL for H1, 31.01 µg/mL for H4, compared to Doxorubicin® as a standard cytotoxic drug with GI50 value of 18.80 µg/mL.