Curcumin Analogues as a Potential Drug against Antibiotic Resistant Protein, β-Lactamases and L, D-Transpeptidases Involved in Toxin Secretion in Salmonella typhi: A Computational Approach

Typhoid fever caused by the bacteria Salmonella typhi gained resistance through multidrug-resistant S. typhi strains. One of the reasons behind β-lactam antibiotic resistance is -lactamase. L, D-Transpeptidases is responsible for typhoid fever as it is involved in toxin release that results in typhoid fever in humans. A molecular modeling study of these targeted proteins was carried out by various methods, such as homology modeling, active site prediction, prediction of disease-causing regions, and by analyzing the potential inhibitory activities of curcumin analogs by targeting these proteins to overcome the antibiotic resistance. The five potent drug candidate compounds were identified to be natural ligands that can inhibit those enzymes compared to controls in our research. The binding affinity of both the Go-Y032 and NSC-43319 were found against β-lactamase was −7.8 Kcal/mol in AutoDock, whereas, in SwissDock, the binding energy was −8.15 and −8.04 Kcal/mol, respectively. On the other hand, the Cyclovalone and NSC-43319 had an equal energy of −7.60 Kcal/mol in AutoDock, whereas −7.90 and −8.01 Kcal/mol in SwissDock against L, D-Transpeptidases. After the identification of proteins, the determination of primary and secondary structures, as well as the gene producing area and homology modeling, was accomplished. The screened drug candidates were further evaluated in ADMET, and pharmacological properties along with positive drug-likeness properties were observed for these ligand molecules. However, further in vitro and in vivo experiments are required to validate these in silico data to develop novel therapeutics against antibiotic resistance.

Neuroprotective Potential of Synthetic Mono-Carbonyl Curcumin Analogs Assessed by Molecular Docking Studies

Cognitive decline in dementia is associated with deficiency of the cholinergic system. In this study, five mono-carbonyl curcumin analogs were synthesized, and on the basis of their promising in vitro anticholinesterase activities, they were further investigated for in vivo neuroprotective and memory enhancing effects in scopolamine-induced amnesia using elevated plus maze (EPM) and novel object recognition (NOR) behavioral mice models. The effects of the synthesized compounds on the cholinergic system involvement in the brain hippocampus and their binding mode in the active site of cholinesterases were also determined. Compound h2 (p < 0.001) and h3 (p < 0.001) significantly inhibited the cholinesterases and reversed the effects of scopolamine by significantly reducing TLT (p < 0.001) in EPM, while (p < 0.001) increased the time exploring the novel object. The % discrimination index (DI) was significantly increased (p < 0.001) in the novel object recognition test. The mechanism of cholinesterase inhibition was further validated through molecular docking study using MOE software. The results obtained from the in vitro, in vivo and ex vivo studies showed that the synthesized curcumin analogs exhibited significantly higher memory-enhancing potential, and h3 could be an effective neuroprotective agent. However, more study is suggested to explore its exact mechanism of action.

The Two Mono-Carbonyl Curcumin Analogs, PGV-1 and CCA-1.1: The Chemopreventive Activity Against DMH-Induced Colorectal Cancer Rat and Proteins Target Candidate Involved

Pentagamavunone-1 and its newest derivatives, CCA-1.1, possess an outstanding cytotoxic activity against several cancer cell lines, especially colorectal cancer. We are continuing to explore the anti-colorectal cancer properties of PGV-1 and CCA-1.1 against DMH-induced colorectal cancer rats and expound the potential protein target in colorectal adenocarcinoma. We utilized DMH 60 mg/kg (subcutaneous injection once a week for 16 weeks) to induce colorectal cancer. PGV-1 and CCA-1.1 at 10 and 20 mg/kg (orally twice a week for 16 weeks) were co-administered with DMH. The WBC count increased in a single DMH group and was countered by co-administration of PGV-1 and CCA-1.1, but no significant differences in RBC. Single DMH treatment for 16 weeks resulted in 80% adenocarcinoma. In contrast, co-administration with PGV-1 and CCA-1.1 suppressed most of the carcinogenic characteristics and symptoms of the pre-malignancy condition. Furthermore, bioinformatics analysis showed that CCA-1.1 has more specific targets than PGV-1, including CDK1, CDK2, MMP3, MMP14, and CYP3A4, which regulate the cell cycle arrest, cancer cell migration, and xenobiotic metabolism, respectively. Interestingly, CCA-1.1 targets CYP3A4, which possibly interrupts DMH metabolism and prevents the initiation of DMH-colorectal carcinogenesis. In conclusion, CCA-1.1 performed better chemopreventive effects against DMH colorectal cancer and might replace PGV-1 to be promoted as a more effective anti-colorectal cancer agent.

Molecular Engineering of Curcumin, an Active Constituent of Curcuma longa L. (Turmeric) of the Family Zingiberaceae with Improved Antiproliferative Activity

Cancer is the world’s second leading cause of death, accounting for nearly 10 million deaths and 19.3 million new cases in 2020. Curcumin analogs are gaining popularity as anticancer agents currently. We reported herein the isolation, molecular engineering, molecular docking, antiproliferative, and anti-epidermal growth factor receptor (anti-EGFR) activities of curcumin analogs. Three curcumin analogs were prepared and docked against the epidermal growth factor receptor (EGFR), revealing efficient binding. Antiproliferative activity against 60 NCI cancer cell lines was assessed using National Cancer Institute (NCI US) protocols. The compound 3b,c demonstrated promising antiproliferative activity in single dose (at 10 µM) as well as five dose (0.01, 0.10, 1.00, 10, and 100 µM). Compound 3c inhibited leukemia cancer panel better than other cancer panels with growth inhibition of 50% (GI50) values ranging from 1.48 to 2.73 µM, and the most promising inhibition with GI50 of 1.25 µM was observed against leukemia cell line SR, while the least inhibition was found against non-small lung cancer cell line NCI-H226 with GI50 value of 7.29 µM. Compounds 3b,c demonstrated superior antiproliferative activity than curcumin and gefitinib. In molecular docking, compound 3c had the most significant interaction with four H-bonds and three π–π stacking, and compound 3c was found to moderately inhibit EGFR. The curcumin analogs discovered in this study have the potential to accelerate the anticancer drug discovery program.

Novel Chemically Modified Curcumin (CMC) Analogs Exhibit Anti-Melanogenic Activity in Primary Human Melanocytes

Hyperpigmentation is a dermatological condition characterized by the overaccumulation and/or oversecretion of melanin pigment. The efficacy of curcumin as an anti-melanogenic therapeutic has been recognized, but the poor stability and solubility that have limited its use have inspired the synthesis of novel curcumin analogs. We have previously reported on comparisons of the anti-melanogenic activity of four novel chemically modified curcumin (CMC) analogs, CMC2.14, CMC2.5, CMC2.23 and CMC2.24, with that of parent curcumin (PC), using a B16F10 mouse melanoma cell model, and we have investigated mechanisms of inhibition. In the current study, we have extended our findings using normal human melanocytes from a darkly pigmented donor (HEMn-DP) and we have begun to study aspects of melanosome export to human keratinocytes. Our results showed that all the CMCs downregulated the protein levels of melanogenic paracrine mediators, endothelin-1 (ET-1) and adrenomedullin (ADM) in HaCaT cells and suppressed the phagocytosis of FluoSphere beads that are considered to be melanosome mimics. All the three CMCs were similarly potent (except CMC2.14, which was highly cytotoxic) in inhibiting melanin production; furthermore, they suppressed dendricity in HEMn-DP cells. CMC2.24 and CMC2.23 robustly suppressed cellular tyrosinase activity but did not alter tyrosinase protein levels, while CMC2.5 did not suppress tyrosinase activity but significantly downregulated tyrosinase protein levels, indicative of a distinctive mode of action for the two structurally related CMCs. Moreover, HEMn-DP cells treated with CMC2.24 or CMC2.23 partially recovered their suppressed tyrosinase activity after cessation of the treatment. All the three CMCs were nontoxic to human dermal fibroblasts while PC was highly cytotoxic. Our results provide a proof-of-principle for the novel use of the CMCs for skin depigmentation, since at low concentrations, ranging from 5 to 25 µM, the CMCs (CMC2.24, CMC2.23 and CMC2.5) were more potent anti-melanogenic agents than PC and tetrahydrocurcumin (THC), both of which were ineffective at melanogenesis at similar doses, as tested in HEMn-DP cells (with PC being highly toxic in dermal fibroblasts and keratinocytes). Further studies to evaluate the efficacy of CMCs in human skin tissue and in vivo studies are warranted.

Synthesis and cytotoxicity of substituted aromatic curcuminoids against human oral epidermal carcinoma-KB cell line

Introduction: The survival rate of oral cancer, like other types of cancers, has not been improved regardless of the early diagnosis and the introduction of advanced therapies. Treatment for oral cancer includes surgery, radiation therapy, and chemotherapy. However, the effectiveness has been limited due to recurrence and undesirable side effects. Metabolites from plant sources have been shown to be relatively less toxic and thus are considered as potential anti-cancer agents. Interestingly, curcumin isolated from the rhizome of Curcuma longa L. possesses broad-spectrum bioactivities. We focused on the synthesis of curcumin-based analogs bearing -OH/-OCH3/-F groups on the phenyl rings in our continuous efforts to search for curcumin-based anti-cancer agents. The synthesized compounds were subsequently evaluated for the cytotoxic activities against KB cancer cell line (an epidermal carcinoma of the mouth). Methods: The desired curcuminoids were synthesized via aldol reactions between benzaldehyde derivatives and pentane-2,4-dione using n-butylamine as a catalyst. Structures were distinguished by NMR and MS spectra. The cytotoxic activity against KB was determined through the half-maximal inhibitory concentration (IC50, mM). Results: Six curcumin analogs (1-6) were successfully synthesized in a yield of 48-76%. The 3- hydroxy/fluoro curcumin analogs (3, IC50 = 15.61 0.13 mM; 6, IC50 = 22.65 1.76 mM) exhibited better anti-cancer activities when compared to curcumin (1, IC50 = 33.35 2.66 mM), whereas the para-fluoro substitution patterns displayed lower inhibitory activities (4, 5) against KB cancer cell line. Conclusions: The synthetic yields are dependent on the position and nature of substituents in aromatic rings. The presence of electron-donating groups gives products (1-3) in lower yields when compared to those (4-6) prepared from fluorinated benzaldehydes as starting materials. The curcuminoids bearing -OH groups at para-positions in aromatic rings (1, 2) can be responsible for better inhibition of cell growth, whereas the fluoro-substituted compounds (4, 5) make a negative contribution to inhibitory activity. Furthermore, the contributions -OH/-F groups at meta-position in aromatic rings of (3, 6) on the cytotoxicity against KB are remarkable and firstly reported in our findings.

Impact of Curcumin on Microsomal Enzyme Activities: Drug Interaction and Chemopreventive Studies

: Curcumin, a yellow pigment in Asian spice, is a natural polyphenol component of Curcuma longa rhizome. Curcuminoid components include curcumin, demethoxycurcumin (DMC), and bisdemethoxycurcumin (BDMC). Previous studies established curcumin as a safe agent based on preclinical and clinical evaluations and curcuminoids have been approved by the US Food and Drug Administration (FDA) as “Generally Recognized as Safe” (GRAS). The present review collects and summarizes clinical and preclinical studies of curcumin interactions, with an emphasis on the effect of curcumin and curcumin analogs on the mRNA and protein levels of microsomal CYP450 enzymes (phase I metabolism) and their interactions with toxicants, drugs and drug probes. The literature search was conducted using keywords in various scientific databases, including Web of Science, Scopus, PubMed, and Google Scholar. Studies concerning the impact of curcumin and curcumin analogs on microsomal enzyme activity are reviewed and include oral, topical, and systemic treatment in humans and experimental animals, as well as studies from in vitro research. When taken together the data identified some inconsistent results between various studies. The findings showed significant inhibition of CYP450 enzymes by curcumin and its analogs. However such effects often differed when curcumin and curcumin analogs were coadministered with toxicant and other drugs and drug probes. We conclude from this review that herb-drug interactions should be considered when curcumin and curcumin analogs are consumed.

Synthesis, Molecular Docking, and Evaluation of Some New Curcumin Analogs as Antimalarial Agents

This research involves the synthesis, antimalarial evaluation, and molecular docking of several curcumin analogs. A total of six curcumin analog compounds were synthesized using aldol condensation using hydrochloric acid and sodium hydroxide catalysts. The synthesized compounds were elucidated using FTIR, 1H-NMR, 13C-NMR, and LC-MS/MS. Subsequently, all curcumin analogs were tested as an antimalarial agent against Plasmodium falciparum 3D7 strain, and their mechanism of action was evaluated through a molecular docking study. Six curcumin analogs, i.e. 2,6-bis(2-hydroxybenzylidene)cyclohexanone; 2,6-bis(2-hydroxybenzylidene)cyclopentanone; 1.5-bis(2-hydroxyphenyl)penta-1,4-diene-3-one; 2,6-bis(3-hydroxybenzylidene)cyclo-hexanone; 2,6-bis(3-hydroxybenzylidene)cyclopentanone; and 1,5-bis(3-hydroxy-phenyl)penta-1,4-diene-3-one have been successfully synthesized. In addition, 2,6-bis(2-hydroxybenzylidene) cyclopentanone demonstrated the lowest IC50 value and binding affinity of 0.04 µM and -7.6 kcal/mol, respectively. Based on molecular docking studies, this compound also showed the most potent antimalarial activity targeted at PfATP6.