Combining chemometric and phytochemical tools to isolate and characterize activity of Vismia gracilis compounds against Aedes aegypti

Vismia gracilis extracts were tested against Aedes aegypti to assess mortality and behavioural effects. The leaf hexanic extract (L-Hex) presented increased larvicidal activity with exposure period: LC₅₀ 46.48 µg/mL (24 h) and LC₅₀ 20.57 µg/mL (48 h). Eight compounds were annotated/isolated from the L-Hex active extract, 4 benzophenones and 4 anthraquinones. Considering chemometric findings, the benzophenone moiety, tested as the commercial benzophenone, promoted larval mortality (LC₅₀ 16.35 µg/mL). Both the L-Hex extract and benzophenone induced intestinal damage in larvae. Benzophenone also promoted toxicity and behavioural effects in female adults. These findings highlighted the potential use of this class of compounds for developing vector-control products.

Multispectral studies of DNA binding, antioxidant and cytotoxic activities of a new pyranochromene derivative

The binding properties of a new pyranochromene derivative, 2-amino-4-(3-hydroxyphenyl)-5-oxo-4H, 5H-pyrano-[3, 2-c] chromene-3-carbonitrile (3-HC) with calf thymus DNA (ctDNA) have been investigated by UV-vis absorption, circular dichroism, fluorescence spectroscopy and viscosity measurement. These results indicated that 3-HC can interact with DNA through non-intercalative mode and the intrinsic binding constant (Kb) for 3-HC with DNA was estimated to be 3.6 × 10(3)M(-1). The antioxidant activity experiments show that 3-HC also exhibit good antioxidant activity in DPPH free radical scavenging and ferric reducing ability methods. Moreover, 3-HC exhibited cytotoxic activity against K562, human chronic myelogenous leukemia cells, with IC50 value of 146 μM and the cells responded to the treatment with mostly through apoptosis.

Synthesis and structure elucidation of a series of pyranochromene chalcones and flavanones using 1D and 2D NMR spectroscopy and X-ray crystallography

A series of novel pyranochromene chalcones and corresponding flavanones were synthesized. This is the first report on the confirmation of the absolute configuration of chromene-based flavanones using X-ray crystallography. These compounds were characterized by 2D NMR spectroscopy, and their assignments are reported herein. The 3D structure of the chalcone 3b and flavanone 4g was determined by X-ray crystallography, and the structure of the flavanone was confirmed to be in the S configuration at C-2.

1-(5-Hy-droxy-2,2,8,8-tetra-methyl-2H,8H-pyrano[2,3-f]chromen-6-yl)-3-(4-meth-oxy-phen-yl)prop-2-en-1-one

In the biologically active title compound, C₂₆H₂₆O₅, the pyran ring of the chromene unit adopts a half-chair conformation. The C=C double bond of the propenone unit exhibits a trans conformation and the carbonyl group is syn conformation to the double bond. The dihedral angle between the benzene ring and the benzopyran­one moiety is 31.54 (4)°. The mol­ecular structure is stabilized by an intra­molecular C=O⋯H—O hydrogen bond.

1-(5-Hy-droxy-2,2,8,8-tetra-methyl-2H,8H-pyrano[2,3-f]chromen-6-yl)ethanone

In the title compound, C₁₈H₂₀O₄,the pyran ring of the chromene unit adopts a half-chair conformation. An intra­molecular O—H⋯O hydrogen bond occurs. In the crystal, mol­ecules are linked along the b axis by C—H⋯O hydrogen bonds.