Synthesis, computational molecular docking analysis and effectiveness on tyrosinase inhibition of kojic acid derivatives.

Tyrosinase inhibitors have become increasingly important as whitening agents and for the treatment of pigmentary disorders. In this study, the synthesis of kojic acid derivatives having 2-substituted-3-hydroxy-6-hyroxymethyl/chloromethyl/methyl/morpholinomethylpiperidinyl- methyl/pyrrolidinylmethyl-4H-pyran-4-one structure (compounds 1-30) with inhibitory effects on tyrosinase enzyme were described. One-pot Mannich reaction was carried out by using kojic acid/chlorokojic acid/allomaltol and substituted benzylpiperazine derivatives in presence of formaline. Subsequently, cyclic amine (morpholine, piperidine and pyrrolidine) derivatives of the 6th-position of chlorokojic acid were obtained with nucleophilic substitutions in basic medium. The structures of new compounds were identified by FT-IR, 1H- and 13C NMR, ESI-MS and elemental analysis data. The potential mushroom tyrosinase inhibitory activity of the compounds were evaluated by the spectrophotometric method using l-DOPA as a substrate and kojic acid as the control agent. The potential inhibitory activity was also investigated in silico using molecular docking simulation method. Tyrosinase inhibitory action was significantly more efficacious for several compounds (IC50: 86.2-362.1 µM) than kojic acid (IC50: 418.2). Compound 3 bearing 3,4-dichlorobenzyl piperazine moiety was proven to have the highest inhibitory activity. The results of docking studies showed that according to the predicted conformation of compound 3 in the enzyme binding site, hydroxymethyl group provides a metal complex with copper ions and enzyme. Thus, this interaction explain the high inhibitory activities of the compounds 1, 3 and 4 possessing hydroxymethyl substituent supporting the mushroom assay results with docking studies. In accordance with the results, it is suggested that Mannich bases of kojic acid bearing substituted benzyl piperazine groups (compounds 1, 3, 4, 11, 13, 14, 23, 24, 28, and 29) could be promising antityrosinase agents. Additionally, considering the relationship between tyrosinase inhibitory activity results and molecular docking, a new tyrosinase inhibition mechanism can be proposed.

Evaluation of bioactivities of chlorokojic acid derivatives against dermatophytes couplet with cytotoxicity.

In an attempt to find novel antifungal agents with improved activity, a series of compounds bearing 6-chloromethyl-3-hydroxy-2-substituted 4H-pyran-4-one moiety were synthesized and examined for their cytotoxic evaluation and antifungal activities against both standard and isolated dermatophytic fungal species Microsporum gypseum, Trichophyton mentagrophytes var. erinacei and Epidermophyton floccosum.

Design, synthesis and in vivo/in vitro screening of novel chlorokojic acid derivatives.

A series of novel Mannich bases of chlorokojic acid (2-chloromethyl-5-hydroxy-4H-pyran-4-one) were synthesized and their biological activities were investigated. Anticonvulsant activity results according to phase-I tests of Antiepileptic Drug Development (ADD) Program revealed that compound 13 was the most effective one at 4 h against subcutaneous pentylenetetrazole (scPTZ)-induced seizure test. Antimicrobial activities were evaluated in vitro against bacteria and fungi by using broth microdilution method. The antitubercular activities against Mycobacterium tuberculosis and M. avium were discussed with Resazurin microplate assay (REMA). The antimicrobial activity results indicated that compounds 1 and 12 (MIC: 8-16 µg/mL) showed higher activity against Gram negative bacteria while compound 12 had MIC: 4-16 µg/mL against Gram positive bacteria. Compound 1 was the most active one with MIC values of 8-32 µg/mL against fungi. Mannich bases also exhibit significant antitubercular activity in a MIC range of 4 to 32 µg/mL, especially compound 18 against M. avium.

Design, synthesis, in vitro - In vivo biological evaluation of novel thiazolopyrimidine compounds as antileishmanial agent with PTR1 inhibition.

The leishmaniasis are a group of vector-borne diseases caused by a protozoan parasite from the genus Leishmania. In this study, a series of thiazolopyrimidine derivatives were designed and synthesized as novel antileishmanial agents with LmPTR1 inhibitory activity. The final compounds were evaluated for their in vitro antipromastigote activity, LmPTR1 and hDHFR enzyme inhibitory activities, and cytotoxicity on RAW264.7 and L929 cell lines. Based on the bioactivity results, three compounds, namely L24f, L24h and L25c, were selected for evaluation of their in vivo efficacy on CL and VL models in BALB/c mice. Among them, two promising compounds, L24h and L25c, showed in vitro antipromastigote activity against L. tropica with the IC50 values of 0.04 µg/ml and 6.68 µg/ml; against L. infantum with the IC50 values of 0.042 µg/ml and 6.77 µg/ml, respectively. Moreover, the title compounds were found to have low in vitro cytotoxicity on L929 and RAW264.7 cell lines with the IC50 14.08 µg/ml and 21.03 µg/ml, and IC50 15.02 µg/ml and 8.75 µg/ml, respectively. LmPTR1 enzyme inhibitory activity of these compounds was determined as 257.40 µg/ml and 59.12 µg/ml and their selectivity index (SI) over hDHFR was reported as 42.62 and 7.02, respectively. In vivo studies presented that L24h and L25c have a significant antileishmanial activity against footpad lesion development of CL and at weight measurement of VL group in comparison to the reference compound, Glucantime®. Also, docking studies were carried out with selected compounds and other potential Leishmania targets to detect the putative targets of the title compounds. Taken together, all these findings provide an important novel lead structure for the antileishmanial drug development.

A kojic acid derivative promotes intrinsic apoptotic pathway of hepatocellular carcinoma cells without incurring drug resistance.

Hepatocellular carcinoma is one of the most pervasive cancers with low prognosis, high frequency of recurrence, and metastasis. Studies conducted have focused on extricating novel strategies for successful treatment. Kojic acid and its derivatives are already proven to have depigmenting, anti-inflammatory, and anti-neoplastic properties. In the present study, kojic acid and its 10 distinct derivatives were tested on HEPG2 cell line for their possible anti-cancer effect and seven of them were observed to be cytotoxic. Compound 6 was chosen to proceed as the IC50 dosage for HEPG2 cells was lower in comparison with the other derivatives and kojic acid itself. Further experiments pointed out that intrinsic apoptotic pathway was triggered with the exposure of the cells to IC50 concentration of the derivative as the treatment led to escalation of intracellular ROS, induction of TP53 gene, and activation of caspase 3/7. Pro-apoptotic Jnk and Bax genes were not triggered suggesting that the apoptotic pathway advance through an alternative route. Complementary experiments are in need; howbeit, the current findings suggest that the derivative offers a novel promising approach against hepatocellular carcinoma as it is not detrimental to healthy cells within the concentrations applied, and it does not induce drug resistance.

Synthesis and Cytotoxic Evaluation of Kojic Acid Derivatives with Inhibitory Activity on Melanogenesis in Human Melanoma Cells.

BACKGROUND: Malignant melanoma is an agressive tumour related to the overproduction of melanin, which provides colors of skin, eyes and hair. In addition contributing to the risk of malignant melanoma, abnormal production of melanin has many drawbacks, including hyperpigmentation, post-inflammatory pigmentation, melasma and skin aging. Kojic acid is currently employed in order to lighten skin pigmentation and provide depigmentation. OBJECTIVE: Mannich bases of kojic acid with the structure of 2-substituted-3-hydroxy-6-hyroxymethyl/chloromethyl/ methyl/morpholinomethyl/piperidinylmethyl/pyrrolidinylmethyl-4H-pyran-4-one (compounds 1-23) were synthesized by the reaction of kojic acid/chlorokojic acid/allomaltol and substituted benzylpiperazine derivatives in the presence of formaline. To obtain the cyclic amine (morpholine, piperidine and pyrrolidine) derivatives, nucleophilic substitutions were carried out. METHOD: Cytotoxic effects on A375 human malignant melanoma, HGF-1 human gingival fibroblasts, and MRC-5 human lung cell lines were investigated by sulphorhodamine B assay. Control agents were vemurafenib, dacarbazine, temozolomide, and lenalidomide, which are the commercially available drugs for the treatment of malignant melanoma. RESULTS: Cytotoxic action against melanoma cells was significantly more efficacious (IC50: 11.26-68.58 µM) than the FDA-approved drugs except for vemurafenib. Fourteen of the compounds were proven to have higher IC50 values for the non-cancerous cell lines, HGF-1, and MRC-5 cells. Melanogenesis inhibition assay was performed to observe the ability of the drugs to inhibit melanin production and certain compounds were shown to be capable of actively inhibiting melanin production in melanoma cells. CONCLUSION: Mannich bases of kojic acid derivatives may be promising therapeutic agents, since some have more potent effects on melanoma cells than previously FDA-approved drugs for the treatment of malignant melanoma.

Identifying (Quasi) Equally Informative Subsets in Feature Selection Problems for Classification: A Max-Relevance Min-Redundancy Approach.

An emerging trend in feature selection is the development of two-objective algorithms that analyze the tradeoff between the number of features and the classification performance of the model built with these features. Since these two objectives are conflicting, a typical result stands in a set of Pareto-efficient subsets, each having a different cardinality and a corresponding discriminating power. However, this approach overlooks the fact that, for a given cardinality, there can be several subsets with similar information content. The study reported here addresses this problem, and introduces a novel multiobjective feature selection approach conceived to identify: 1) a subset that maximizes the performance of a given classifier and 2) a set of subsets that are quasi equally informative, i.e., have almost same classification performance, to the performance maximizing subset. The approach consists of a wrapper [Wrapper for Quasi Equally Informative Subset Selection (W-QEISS)] built on the formulation of a four-objective optimization problem, which is aimed at maximizing the accuracy of a classifier, minimizing the number of features, and optimizing two entropy-based measures of relevance and redundancy. This allows conducting the search in a larger space, thus enabling the wrapper to generate a large number of Pareto-efficient solutions. The algorithm is compared against the mRMR algorithm, a two-objective wrapper and a computationally efficient filter [Filter for Quasi Equally Informative Subset Selection (F-QEISS)] on 24 University of California, Irvine, (UCI) datasets including both binary and multiclass classification. Experimental results show that W-QEISS has the capability of evolving a rich and diverse set of Pareto-efficient solutions, and that their availability helps in: 1) studying the tradeoff between multiple measures of classification performance and 2) understanding the relative importance of each feature. The quasi equally informative subsets are identified at the cost of a marginal increase in the computational time thanks to the adoption of Borg Multiobjective Evolutionary Algorithm and Extreme Learning Machine as global optimization and learning algorithms, respectively.