In vivo angiogenesis screening and mechanism of action of novel tanshinone derivatives produced by one-pot combinatorial modification of natural tanshinone mixture from Salvia miltiorrhiza.

BACKGROUND: Natural products present in low quantity in herb medicines constitute an important source of chemical diversity. However, the isolation of sufficient amounts of these low abundant constituents for structural modification has been a challenge for several decades and subsequently halts research on the utilization of this important source of chemical entities for drug discovery and development. And, pro-angiogenic therapies are being explored as options to treat cardio-cerebral vascular diseases and wound healing recently. The present study investigates the pro-angiogenic potential of tanshinone derivatives produced by one-pot synthesis using zebrafish model. METHODOLOGY/PRINCIPAL FINDINGS: In order to address the difficulty of chemical modification of low abundant constituents in herb medicines, a novel one-pot combinatorial modification was used to diversify a partially purified tanshinone mixture from Salvia miltiorrhiza. This led to the isolation of ten new imidazole-tanshinones (Compounds 1-10) and one oxazole-tanshinone (Compound 11), the structures of which were characterized by spectroscopic methods in combination with single-crystal X-ray crystallographic analysis. The angiogenesis activities of the new tanshinone derivatives were determined in an experimental model of chemical-induced blood vessels damage in zebrafish. Of all the tested new derivatives, compound 10 exhibited the most potent vascular protective and restorative activity with an EC50 value of 0.026 µM. Moreover, the mechanism underlying the pro-angiogenesis effect of 10 probably involved the VEGF/FGF-Src-MAPK and PI3K-P38 signalling pathways by gene expression analysis and a blocking assay with pathways-specific kinase inhibitors. CONCLUSIONS/SIGNIFICANCE: Taken together, our study demonstrated the more distinctive pro-angiogenic properties of 10 than other tanshinones and revealed 10 has potential for development as a pro-angiogenic agent for diseases associated with insufficient angiogenesis. Our results highlighted the great potential of adopting a newly modified one-pot approach to enhance the chemical diversity and biological activities of constituents from natural products regardless of their abundances.

Secohellebrigeninamide.

The title compound, C(26)H(37)NO(5), was the reaction product of hellebrigenin with N,N-dimethyl-formamide. It consists of three cyclo-hexane rings (A, B and C), one five-membered ring (D) and one dihydro-pyran ring (E). The stereochemistry of the ring junctions is is A/B cis, B/C trans, C/D cis and C/E trans. The cyclo-hexane rings A, B and C have chair conformations. Both the five-membered ring D and the dihydro-pyran ring adopt an envelope conformation. Two orientations are found for the aldehyde group with occupancies of 0.608 (10) and 0.392 (10). In the crystal, short O-H⋯O hydrogen bonds and short C-H⋯O contacts involving the hy-droxy group, terminal methyl group and carbonyl group link the mol-ecules into a three-dimensional network.

2,3,4-Trihy-droxy-benzoic acid 0.25-hydrate.

The asymmetric unit of the title compound, C(7)H(6)O(5)·0.25H(2)O, contains two mol-ecules of 2,3,4-trihy-droxy-benzoic acid, with similar conformations, and one water mol-ecule which lies on a twofold rotation axis. Both acid mol-ecules are essentially planar [maximum r.m.s deviations = 0.0324 (2) and 0.0542 (3) Šfor the two acid molecules]. The mol-ecular conformations are stabilized by intra-molecular O(phenol)-H⋯O(carbox-yl/phenol) inter-actions. A cyclic inter-molecular association is formed between the two acid and one water mol-ecule [graph set R(3) (3)(12)] involving O-H⋯O hydrogen bonds. The two acid mol-ecules are further linked through a cyclic R(2) (2)(8) carb-oxy-lic acid hydrogen-bonding association, which together with inter-molecular O-H⋯O hydrogen-bonding inter-actions involving the phenol groups and the water mol-ecule, and weak π-π inter-actions [minimum ring centroid separation = 3.731 (3) Å], give a three-dimensional network.