Methanolic fraction of Cassia fistula L. bark exhibits potential to combat oxidative stress and possess antiproliferative activity.

Cassia fistula L. is well known for its traditional medicinal properties as an anti-inflammatory, hepatoprotective, antifungal, antibacterial, antimutagenic, and wound healing agent. The aim of the present study was to determine antioxidant, genoprotective, and cytotoxic potential of different fractions of C. fistula bark including hexane (CaMH), chloroform (CaMC), ethyl acetate (CaME), and methanol (CaMM). Among all the fractions studied, CaMM exhibited maximal radical scavenging activity in antioxidant DPPH assay, Superoxide anion radical scavenging assay and nitric oxide radical scavenging assay displayed an IC50 value of 18.95, 29.41, and 13.38 µg/ml, respectively. CaMM fraction possessed the highest phenolic (130.37 mg gallic acid equivalent/g dry weight of extract) and flavonoid (36.96 mg rutin equivalent/g dry weight of fraction) content. Data demonstrated significant positive correlation between polyphenol levels and radical scavenging activity. Single cell gel electrophoresis (Comet assay) exhibited genoprotective potential of C. fistula bark fractions against DNA damage induced by hydrogen peroxide (H2O2) in human lymphocytes. CaMM fraction displayed highest protective ability against H2O2 induced-toxicity as evidenced by significant decrease in % tail DNA content from 30 to 7% at highest concentration (200 µg/ml). CaMM was found to be rich in catechin, gallic acid, chlorogenic acid, and kaempferol. The phenolic content and antioxidant ability of the fractions was markedly negatively correlated with H2O2- induced DNA damage in human lymphocytes. Cytotoxic potential was evaluated against dermal epidermoid carcinoma (A431), pancreatic (MIA PaCa-2) and brain glioblastoma (LN-18) cancer cell lines using MTT assay. Results showed that C. fistula bark fractions possessed highest toxicity against the skin carcinoma cells. CaMM fraction reduced over 50% cell growth at the concentration of 76.72 µg/ml in A431 cells. These findings suggest that fractions of C. fistula bark exhibit potential to be considered as therapeutic agents in various carcinomas.

ESIPT+TICT-based Near-IR Detection of Al3+ and F- in Live Cells: Molecular Docking with Acetylcholinesterase.

The interplay of ESIPT+TICT mechanisms in 1,8-naphthalimide-hydroxyquinoline (NQ-OH) molecular rotor were reported for the near-IR 'turn-on' emission (λmax 600 nm) and ratiometric (A405nm/A345nm) absorbance-based detection of Al3+ ions in aqueous medium and live cells which were supported by NMR, IR and CV techniques. The limit of detection (LOD) for Al3+ ions is 100 nM and 14.57 nM. The self-assembled spherical aggregates of NQ-OH transformed into cuboidal aggregates upon coordination with Al3+ ions supported by microscopic and dynamic light scattering (DLS) techniques. The complex NQ-OH+Al3+ was further used for the secondary detection of F- ions in aqueous medium via displacement approach with LOD as low as 2.67 nM. A deeper study revealed that the NQ-OH is a solvatochromic dye. Probably, the NQ-OH either in the aggregated state or in the coordination state with Al3+ ions, showed an increase in the emission intensity at 600 nm due to inhibition of the ESIPT process and trigger of the TICT process. We have demonstrated the utility of NQ-OH for the detection of Al3+ ions and NQ-OH+Al3+ complex for the detection of F- ions in MCF7 live cells. We have also discussed the molecular docking studies of NQ-OH with acetylcholinesterase enzyme.