Styryllactones, a class of compounds obtained from the genus Goniothalamus (Annonaceae), have demonstrated in vitro antitumor activity. However, the aqueous solubility of these compounds is poor. In this study, we identified the absolute configurations of the previously isolated compounds, which were first isolated in our laboratory, by single-crystal X-ray diffraction analysis using Cu Ka radiation. Subsequently, the antitumor activities of the compounds were evaluated by 3-(4,5dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide staining in four tumor cell lines. The induced apoptosis activity of leiocarpin E-7ʹ-Monoacetate was studied by an annexin V fluorescein isothiocyanate/propidium iodide double-staining experiment, and the caspase activity was tested in the SW1116 cell line. The results demonstrated that the antitumor activities of cheliensisin A and goniodiol-7-monoacetate were limited by their poor water solubility. To address this issue, hydroxypropyl-b-cyclodextrin (HP-b-CD) complexes of the compounds were synthesized by the saturated aqueous method. The complexes were then analyzed using a differential scanning calorimeter. The IC 50 of cheliensisin A was reduced by 45% and 58% against SW1116 and SMMC-7721 cell lines, respectively. Similarly, the IC 50 of goniodiol-7-monoacetate was reduced by 55% and 34% against the two tumor cell lines, respectively. To further evaluate whether the styryllactones and complexes possessed selectivity against cancer cell lines and normal cell lines, toxicity against human normal cell line (HEK293T) was evaluated. The results demonstrated that the HP-b-CD complexes displayed more cytotoxicity than the respective pristine compounds against the HEK293T cell line. However, there existed a therapeutic window when the complexes were applied against cancer cell lines. In summary, the synthesis of several styryllactone compounds complexed with HP-b-CD was reported for the first time. These complexes could significantly enhance the cytotoxic effects of styryllactone compounds.
Our previous study reported a cyclic peptide, GG‐8‐6, possessing effective activity against hepatocellular carcinoma both in vitro and in vivo. In order to seek out better analogues in synthetic yield or bioactivity, we synthesized 15 cyclopeptide GG‐8‐6 analogues. Their purities were detected by HPLC, and their structures were characterized by HR‐QTOF‐MS, 1H and 13C NMR together with X‐ray crystal analysis. Among these analogues, compound 8, containing two d‐amino acids, gave the highest total yield of 72.5%. Moreover, all analogues were evaluated for their antihepatocellular carcinoma activities by MTT experiments. Compound 14 showed better specificity against Huh7 and HepG2 cell lines with IC50 values of 8.59 ± 0.97 μM and 7.34 ± 0.33 μM, respectively, while possessing more than four times total yield compared to the lead compound GG‐8‐6. In addition, an ATP assay for some representative compounds was carried out to confirm their anti‐hepatocellular carcinoma activity.
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