Huacan Song

Synthesis and biological evaluation of novel 4-hydroxybenzaldehyde derivatives as tyrosinase inhibitors.

A series of novel 4-hydroxybenzaldehyde derivatives were synthesized and their inhibitory effects on the diphenolase activity of mushroom tyrosinase were investigated. Most of target compounds had more potent inhibitory activities than the parent compound 4-hydroxybenzaldehyde (IC(50)=1.22 mM). Interestingly, compound 3c bearing a dimethoxyl phosphate was found to be the most potent inhibitor with IC(50) value of 0.059 mM. The inhibition kinetics analyzed by Lineweaver-Burk plots revealed that compound 3c was a non-competitive inhibitor (K(I)=0.0368 mM). In particular, compound 3c showed no side effects at dose of 1600 mg/kg in mice. These results suggested that such compounds might be served as lead compounds for further designing new potential tyrosinase inhibitors.

Inhibitory effects of 5-benzylidene barbiturate derivatives on mushroom tyrosinase and their antibacterial activities

A series of novel 5-benzylidene barbiturate and thiobarbiturate derivatives were synthesized and evaluated as tyrosinase inhibitors and antibacterial agents. The results demonstrated that some compounds had more potent inhibitory activities than the parent compound 4-hydroxybenzaldehyde (IC(50)=1.22 mM). Particularly, compounds 1a and 2a were found to be the most potent inhibitors with IC(50) value of 13.98 microM and 14.49 microM, respectively. The inhibition mechanism study revealed that these compounds were irreversible inhibitors. The circular dichroism spectra indicated that these compounds induced conformational changes of mushroom tyrosinase upon binding. In addition, these compounds exhibited selectively antibacterial activity against Staphylococcus aureus. All these results suggested that further development of such compounds may be of interest.

A class of potent tyrosinase inhibitors: alkylidenethiosemicarbazide compounds.

A series of alkylidenethiosemicarbazide compounds were synthesized and their inhibitory effects on the diphenolase activity of mushroom tyrosinase were evaluated. The results showed that most of the synthesized compounds exhibited significant inhibitory activities. Especially, compound 1f was found to be the most potent inhibitor with IC(50) value of 0.086 microM, suggesting that further development of such compounds may be of interest.

Design, synthesis and 3D-QSAR of β-carboline derivatives as potent antitumor agents

In a continuing effort to develop novel beta-carbolines endowed with better pharmacological profiles, a series of beta-carboline derivatives were designed and synthesized based on the previously developed SARs. Cytotoxicities in vitro of these compounds against a panel of human tumor cell lines were also investigated. The results demonstrated that the N2-benzylated beta-carbolinium bromides 56-60 represented the most potent compounds with IC50 values lower than 10 microM. The application of 3D-QSAR to these compounds explored the structural basis for their biological activities. CoMFA (q2=0.513, r2=0.862) and CoMSIA (q2=0.503, r2=0.831) models were developed for a set of 47 beta-carbolines. The results indicated that the antitumor pharmacophore of these molecules were marked at position-1, -2, -3, -7 and -9 of beta-carboline ring.

Synthesis, cytotoxic activities and DNA binding properties of β-carboline derivatives

In a continuing effort to develop novel β-carbolines endowed with better pharmacological profile, a series of water-soluble β-carbolines bearing a flexible amino side chain was designed and synthesized, and the cytotoxic activities in vitro of these compounds were evaluated. The N(9)-arylated alkyl substituted β-carbolines represented the most interesting cytotoxic agents, and compounds 4c and 4d were found to be the most potent compounds with IC(50) values lower than 10 μM against ten human tumor cell lines. The results confirmed that the N(9)-arylated alkyl substituents of β-carboline played a very important role in the modulation of the cytotoxic potencies. In addition, the interaction with DNA of these compounds was also investigated, these compounds were found to exhibit significant DNA binding affinity.

Synthesis and biological evaluation of 1,9-disubstituted β-carbolines as potent DNA intercalating and cytotoxic agents

A series of novel 1,9-disubstituted β-carbolines was designed, synthesized and evaluated as cytotoxic and DNA intercalating agents. Compounds 7b, 7c, 8b and 8c exhibited the most potent cytotoxic activities with IC(50) values of lower than 20 μM against ten human tumor cell lines. The results indicated that (1) the 3-chlorobenzyl and 3-phenylpropyl substituents in position-9 of β-carboline nucleus were the suitable pharmacophoric group giving rise to significant antitumor agents; (2) the length of the alkylamino side chain moiety affected their cytotoxic potencies, and three CH(2) units were more favorable. In addition, these compounds were found to exhibit remarkable DNA intercalating effects.

Refinement of arylthiosemicarbazone pharmacophore in inhibition of mushroom tyrosinase.

Melanin play a major role in human skin protection and their biosynthesis is vital. Due to their color, they contribute to the skin pigmentation. Tyrosinase is a key enzyme involved in the first stage of melanin biosynthesis, it catalyzes the transformation of tyrosine into l-dopaquinone. The aim of the present study was to study molecules able to inhibit tyrosinase to be used in treating depigmentation-related disorders. In this study, we targeted arylthiosemicarbazone analogs with the aim to contribute to the identification of the optimal aryl ring to be linked to the thiosemicarbazone moiety. The biological activity was evaluated on commercial mushroom tyrosinase which was purified prior use. The results demonstrated that several of our compounds (1a-h, 1j, 1r and 5) had more potent inhibitory activities than kojic acid which was used as the reference inhibitor.

Synthesis and biological evaluation of helicid analogues as mushroom tyrosinase inhibitors

A series of helicid analogues were synthesized and evaluated as tyrosinase inhibitors. The results demonstrated that some compounds had more potent inhibitory activities than arbutin (IC(50) 7.3 mM). In particular, compound 1c bearing 4,6-O-benzylidene substituent on the sugar moiety was found to be the most potent inhibitor with IC(50) value of 0.052 mM. The inhibition kinetics analyzed by Lineweaver-Burk plots revealed that helicid analogues were competitive inhibitors. The Circular dichroism spectra indicated that those compounds induced conformational changes of mushroom tyrosinase upon binding.

Design, synthesis and in vitro and in vivo antitumor activities of novel bivalent β-carbolines

A series of bivalent β-carbolines with a spacer of three to ten methylene units between the indole nitrogen was synthesized and evaluated as antitumor agents. The results demonstrated that compounds 18c, 21b, 25a and 31b exhibited strong cytotoxic activities with IC(50) value of lower than 20 μM against four tumor cell lines. Acute toxicities and antitumor efficacies of the selected compounds in mice were also evaluated, compounds 18b, 21b, 26a and 31b exhibited potent antitumor activities with tumor inhibition rate of over 40% in animal models. Preliminary structure-activity relationships analysis indicated that (1) the spacer length affected antitumor potencies, and four to six methylene units were more favorable; (2) the introduction of appropriate substituent into position-1 of β-carboline facilitated antitumor potencies.

Synthesis of novel β-carbolines with efficient DNA-binding capacity and potent cytotoxicity

A series of water-soluble beta-carbolines, bearing a flexible amino side chain, was prepared and evaluated in vitro against a panel of human tumor cell lines. The N(9)-arylated alkyl substituted beta-carbolines represented the most interesting cytotoxic activities, and compound 7b was found to be the most potent antitumor agent with IC(50) values lower than 10microM against eight human tumor cell lines. The results confirmed that the N(9)-arylated alkyl substituents of beta-carboline nucleus played an important role in the modulation of the cytotoxic potencies. In addition, these compounds were found to exhibit significant DNA-binding affinity.