The formation of well-ordered nanostructures through self-assembly of diverse organic and inorganic building blocks has drawn much attention owing to their potential applications in biology and chemistry.

A number of cyclic peptides including [FR]₄, [FK]₄, [WK]₅, [CR]₄, [AK]₄, and [WR]_n (n = 3–5) containing L-amino acids were produced using solid-phase peptide synthesis. We hypothesized that an optimal balance of hydrophobicity and charge could generate self-assembled nanostructures in aqueous solution by intramolecular and/or intermolecular interactions. Among all the designed peptides, [WR]_n (n = 3–5) generated self-assembled vesicle-like nanostructures at room temperature as shown by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and/or dynamic light scattering (DLS). This class of peptides represents the first report of surfactant-like cyclic peptides that self-assemble into nanostructures. A plausible mechanistic insight into the self-assembly of [WR]₅ was obtained by molecular modeling studies. Modified [WR]₅ analogues, such as [W_MeR]₅, [WR_(Me)2]₅, [W_MeR_(Me)2]₅, and [WdR]₅, exhibited different morphologies to [WR]₅ as shown by TEM observations. [WR]₅ exhibited a significant stabilizing effect for generated silver nanoparticles and glyceraldehyde-3-phosphate dehydrogenase activity. These studies established a new class of surfactant-like cyclic peptides that self-assembled into nanostructures and could have potential applications for the stabilization of silver nanoparticles and protein biomolecules.

Background: A series of 2-amino-4-aryl-4H-benzo[h or f]chromene-3-carbonitrile derivatives were synthesized and evaluated for inhibition of Src kinase and cell proliferation in breast carcinoma (BT-20) cell lines.Methods: The one-pot, three-component reaction of α or β-naphthol, malonitrile and an aromatic aldehyde in the presence of diammonium hydrogen phosphate was afforded the corresponding 2-amino-4-aryl-4H-benzo[h or f]chromene-3-carbonitrile derivatives, All target compounds were evaluated for inhibition of Src kinase and cell proliferation in breast carcinoma (BT-20) cell lines.Results: Among all tested compounds, unsubstituted 4-phenyl analog4ashowed Src kinas inhibitory effect with IC₅₀value of 28.1 μM and was the most potent compound in this series. In general, the compounds were moderately active against BT-20. 3-Nitro-phenyl4eand 3-pyridinyl4hderivatives inhibited the cell proliferation of BT-20 cells by 33% and 31.5%, respectively, and found to be more potent compared to doxorubicin (25% inhibition of cell growth).Conclusion: The data indicate that 4-aryl-4H-naphthopyrans scaffold has the potential to be optimized further for designing more potent Src kinase inhibitors and/or anticancer lead compounds.

Previously, we have reported the synthesis of a homochiral l-cyclic peptide [WR]₅ and its use for delivery of anti-HIV drugs and biomolecules. A physical mixture of HAuCl₄ and the peptide generated peptide-capped gold nanoparticles. Here, [WR]₅ and [WR]₅-AuNPs were tested for their efficiency to deliver a small interfering RNA molecule (siRNA) in human cervix adenocarcinoma (HeLa) cells. Flow cytometry investigation revealed that the intracellular uptake of a fluorescence-labeled non-targeting siRNA (200 nM) was enhanced in the presence of [WR]₅ and [WR]₅-AuNPs by 2- and 3.8-fold when compared with that of siRNA alone after 24 h incubation. Comparative toxicity results showed that [WR]₅ and [WR]₅-AuNPs were less toxic in cells compared to other available carrier systems, such as Lipofectamine.