Two new dihydrochalcone enantiomers (+)-1 and (−)-1, along with eight known compounds 3–10, were obtained from Pteris ensiformis. The planar structures were determined on the basis of extensive 1D and 2DNMR and HRESIMS. The resolution of (+)-1 and (−)-1 was achieved by chiral HPLC analysis. The absolute configurations of (+)-1 and (−)-1 were established by the bulkiness rule using Rh2(O2CCF3)4-induced circular dichroism (ICD) method. Compounds (+)-1, (−)-1, 8, 9 and 10 exhibited the inhibitory assay of NO production in mouse macrophages stimulated by LPS, with IC50 values of 2.0, 2.5, 8.0, 9.5 and 5.6 μM, respectively. Otherwise, compound 10 showed moderate cytotoxic activity against HCT-116, HepG-2 and BGC-823 cell lines with IC50 values of 3.0, 10.5 and 6.3 μM, respectively.

One benzoindole pentamethine cyanine dye was synthesized and characterized by 1 H NMR, IR, MS and UV-Vis spectra. The UV-Vis absorption and fluorescence spectra of the dye in chloroform, dimethyl sulfoxide, acetone, ethanol and methanol were investigated, and the l max of the dye was in the region 682.0-689.0 nm with large molar extinction coefficients (e > 10 5 M -1 cm -1 ) in different solvents. The structure of the dye was also characterized and analyzed by X-ray diffraction. Crystallographic data revealed that the dye belonged to orthorhombic, with space group P2 1 2 1 2 1 , a = 10.059(2) Å, b = 15.098(4) Å, c = 24.989(6) Å, V = 3794.8(15) Å 3 , Z = 4. The C-H ¼ F intermolecular hydrogen bonds were displayed in the molecular system, which were effective in the molecular packing. The aggregation behavior and thermodynamic properties of the dye in aqueous methanol solution were also studied by means of UV-Vis spectroscopy methods. The results indicated that the dye existed monomer-dimer equilibrium in aqueous methanol solutions. The fundamental properties of the dye, such as the dimeric association constant K D , the dimeric free energy DG D , the dimeric entropy DS D , and the dimeric enthalpy DH D were determined. The DH D of the dye was -46.0 kJ mol -1 .

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