Kingianic acids A-G, Endiandric acid analogues from Endiandra kingiana.

A phytochemical investigation of the methanolic extract of the bark of Endiandra kingiana led to the isolation of seven new tetracyclic endiandric acid analogues, kingianic acids A-G (1-7), together with endiandric acid M (8), tsangibeilin B (9) and endiandric acid (10). Their structures were determined by 1D- and 2D-NMR analysis in combination with HRMS experiments. The structure of compounds 9 and 10 were confirmed by single-crystal X-ray diffraction analysis. These compounds were screened for Bcl-xL and Mcl-1 binding affinities and cytotoxic activity on various cancer cell lines. Compound 5 showed moderate cytotoxic activity against human colorectal adeno-carcinoma (HT-29) and lung adenocarcinoma epithelial (A549) cell lines, with IC50 values in the range 15-17 µM, and compounds 3, 6 and 9 exhibited weak binding affinity for the anti-apoptotic protein Mcl-1.

3-(2-Hy-droxy-phen-yl)-1-{(E)-[1-(pyrazin-2-yl)ethyl-idene]amino}-thio-urea monohydrate.

In the title compound, C(13)H(13)N(5)OS·H(2)O, the thio-urea mol-ecules closely resemble each other and are approximately planar; the dihedral angles formed between the terminal benzene rings are 7.88 (8) and 7.20 (8)°, respectively. The observed planarity correlates with the presence of bifurcated N-H⋯(O,N) hydrogen bonds. In the crystal, the mol-ecules are connected into supra-molecular double chains via a combination of N-H⋯S (linking the two independent mol-ecules), O-H⋯O and O-H⋯N (linking dimeric aggregates into a supra-molecular chain via hy-droxy-water, water-water and water-pyrazine inter-actions) and O-H⋯S hydrogen bonds (connecting two chains). The chains are further connected by C-H⋯N and C-H⋯S inter-actions.