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Background and Purpose: Gambogic acid (GA), a promising anti-cancer agent isolated from the resin of Garcinia species in Southeast Asia, exhibits high potency in inhibiting a wide variety of cancer cells growth. Moreover, the fact that it is amenable to chemical modification makes GA an attractive molecule for the development of anticancer agents. Methods: Gambogic acid-3-(4-pyrimidinyloxy) propyl ester (compound 4) was derived from the reaction between 4-hydroxypropoxy pyrimidine and GA. Its structure was elucidated by comprehensive analysis of ESIMS, HRESIMS, 1 D NMR data. Antitumor activities of compound 4 and GA in vitro against HepG-2, A549 and MCF-7 cells were investigated by MTT assay. FITC/PI dye were used to test apoptosis. The binding affinity difference of compound 4 and GA binding to IKKβ was studied by using Discovery Studio 2016. Results: Compound 4 was successfully synthesized and showed strong inhibitory effects on HepG-2, A549 and MCF-7 cells lines with an IC50 value of 1.49±0.11, 1.37±0.06 and 0.64±0.16μM, respectively. Molecular docking study demonstrated that four more hydrogen bonds were established between IKKβ and compound 4, compared with GA. Conclusion: Our results suggested that compound 4 showed significant effects in inducing apoptosis. Further molecular docking study indicated that the introduction of pyrimidine could improve GA’s binding affinity to IKKβ. Compound 4 may serve as a potential lead compound for the development of new anti-cancer drugs.

Background Locoweeds are widely distributed all over the world. Goats and other herbivores often get poisoning if they eat a large number of locoweeds by mistake. Swainsonine (SW), the main toxin in locoweeds, can inhibit lysosomes α-Mannosidase (LAM) competitively in animal cells. The insufficient activity of lysosomes α-Mannosidase can lead to abnormal metabolism of animals, forming alpha mannosidosis. However，the details of interaction between SW and LAM are not clear yet. Methods In this study, molecular docking was used to predict the interaction points between SW and LAM. The effect of putative points was investigated by constructing mutated LAM (LAMM) and analyzing its biochemical characteristics. Results The results showed that the Trp at the 28th position and Tyr at the 599th position of the LAM were the candidates of interaction points. Both tryptophan at position 28 of A peptide residue and tyrosine at position 599 of D peptide residue of goat LAM were mutated into glycine, and goat lysosomes were obtained α- The mutant sequence of mannosidase; The recombinant yeast GS115 / pPIC9K LAMM was successfully constructed; After SW induction, the sensitivity of goat LAMM to SW decreased significantly, and the enzyme activity decreased about 3 times compared with wild-type LAM; The optimum temperature of LAMM decreased from 55 °C to 50 °C, and the optimum pH value increased from 4.5 to 5.0; All the trivalent metal ions (Fe3+, Al3+, Cr3+) had significant activation (P < 0.05), and EDTA had inhibitory effect on goat LAM before and after mutation. Conclusions These results indicated that the sensitivity of goat LAMM to SW was significantly reduced, but other characteristics changed little, which was consistent with the molecular docking results of goat LAMM. This study provides help for the study of interaction mechanism between SW and goat LAM, and also provides a new idea for the development of animal locoweed disease control technology.

Golgi α-mannosidase II (GMII), a key glycosyl hydrolase in the N-linked glycosylation pathway, has been demonstrated to be closely associated with the genesis and development of cancer. In this study, we cloned cDNA-encoding Capra hircus GMII (chGMII) and expressed it in Pichia pastoris expression system. The chGMII cDNA contains an open reading frame of 3432 bp encoding a polypeptide of 1144 amino acids. The deduced molecular mass and pI of chGMII was 130.5 kDa and 8.04, respectively. The gene expression profile analysis showed GMII was the highest expressed gene in the spleen. The recombinant chGMII showed maximum activity at pH 5.4 and 42 °C and was activated by Fe(2+), Zn(2+), Ca(2+), and Mn(2+) and strongly inhibited by Co(2+), Cu(2+), and EDTA. By homology modeling and molecular docking, we obtained the predicted 3D structure of chGMII and the probable binding modes of chGMII-GnMan5Gn, chGMII-SW. A small cavity containing Tyr355 and zinc ion fixed by residues Asp290, His176, Asp178, and His570 was identified as the active center of chGMII. These results not only provide a clue for clarifying the catalytic mechanism of chGMII but also lay a theoretical foundation for subsequent investigations in the field of anticancer therapy for mammals.

10, 15, 20-Triphenyl-5-{4-hydroxy-3-(trimethylammonium)methyl}phenylporphyrin 4 and its zinc complex 5 have been synthesized and antibacterial activities have been studied for 4 and its derivative. Compound 4 showed stronger inhibition than that of 10, 15, 20-triphenyl-5-{4-hydroxy-3-(dimethylamine)methyl}phenylporphyrin (2) and 10, 15, 20-triphenyl-5-{4-methoxy-3-(trimethylammonium)methyl}phenylporphyrin (6). It is possible that antibacterial activity of compound 4 involved in photoinducing both o-quinone methide intermediate and singlet oxygen formation.