BCESA: a nano-scaled intercalator capable of targeting tumor tissue and releasing anti-tumoral β-carboline-3-carboxylic acid

(1R,3S)-THCCA-Asn: To show the discovery of selective inhibitor of thrombin by successfully combining virtual screening and biological assay

Thrombin is the most potent platelet aggregator. To discover the selective inhibitor of thrombin that is important to curing platelet aggregation-related diseases, docking experiments were performed to dock (1R,3S)-2,3,4,9-tetrahydro-β-carboline-3- carboxylic acid, [(1R,3S)-THCCA], and (1S,3S)-2,3,4,9-tetrahydro-β-carboline-3- carboxylic acid, [(1S,3S)-THCCA], into the p pocket of bovine thrombin. The ideal match supported that (1R,3S)-THCCA could be used as a potential lead compound. In this case 20 natural amino acids were theoretically introduced into the 3-carboxyl of (1R,3S)-THCCA and 20 derivatives, (1R,3S)-THCCA-amino acids, were docked into p pocket of bovine thrombin to perform virtual screening. The screening revealed that comparing to (1R,3S)-THCCA itself the DockScores of 16 derivatives were higher, and (1R,3S)-THCCA-Asn (4j) got the highest DockScore. Thus, 16 derivatives were synthesized for experimental study. The in vitro anti-platelet aggregation assay showed that at 100 μM of concentration the 16 derivatives failed to inhibit the platelet aggregation induced by both adenosine diphosphate and arachidonic acid. On the other hand, however, the IC₅₀ value of the 16 derivatives inhibiting the platelet aggregation induced by platelet activating factor and thrombin ranged from 9.44 μM to 194.64 μM and from 0.07 μM to 9.56 μM, respectively. The in vitro anti-platelet aggregation assay suggested that the 16 derivatives selectively inhibited the platelet aggregation induced by thrombin. In particular, the IC₅₀ of (1R,3S)-THCCA-Asn (4j) had the lowest value. On rat model at 1 nmol/kg of dosage the 16 derivatives effectively prevented thrombus formation. It is worth pointing out that even at 0.01 nmol/kg of dosage, 4j still effectively prevented thrombus formation. 4j hardly has effects on the proliferation of mammalian cells and rat tail bleeding time. In conclusion, the combination of virtual screening and biological assays successfully lead to the discovery of 4j as a promising candidate of selective inhibitor of thrombin.

Modifying ICCA with Trp-Phe-Phe to Enhance in vivo Activity and Form Nano-Medicine

BACKGROUND

1-(4-isopropylphenyl)-β-carboline-3-carboxylic acid (ICCA) was modified by Trp-Phe-Phe to form 1-(4-isopropylphenyl)-β-carboline-3-carbonyl-Trp-Phe-Phe (ICCA-WFF).

PURPOSE

The object of preparing ICCA-WFF was to enhance the in vivo efficacy of ICCA, to explore the possible targeting action, and to visualize the nano-feature.

METHODS

The advantages of ICCA-WFF over ICCA were demonstrated by a series of in vivo assays, such as anti-tumor assay, anti-arterial thrombosis assay, anti-venous thrombosis assay, P-selectin expression assay, and GPIIb/IIIa expression assay. The nano-features of ICCA-WFF were visualized by TEM, SEM and AFM images. The thrombus targeting and tumor-targeting actions were evidenced by FT-MS spectrum analysis.

RESULTS

The minimal effective dose of ICCA-WFF slowing tumor growth and inhibiting thrombosis was 10-fold lower than that of ICCA. ICCA-WFF, but not ICCA, formed nano-particles capable of safe delivery in blood circulation. In vivo ICCA-WFF, but not ICCA, can target thrombus and tumor. In thrombus and tumor, ICCA-WFF released Trp-Phe-Phe and/or ICCA.

CONCLUSION

Modifying ICCA with Trp-Phe-Phe successfully enhanced the anti-tumor activity, improved the anti-thrombotic action, formed nano-particles, targeted tumor tissue and thrombus, and provided an oligopeptide modification strategy for heterocyclic compounds.