Synthesis and biological evaluation of sulfur-containing shikonin oxime derivatives as potential antineoplastic agents

Discovery of polycyclic polyprenylated acylphloroglucinols with antitumor activities from Garcinia pedunculata Roxb. fruits based on molecular networking

Garpedvinin A (1), a novel polycyclic polyprenylated acylphloroglucinol (PPAP) with a bicyclo[4,2,1]nonane core, 13 previously undescribed PPAPs, garpedvinins B-N (2-14) and 6 known analogs (15-20) were isolated from Garcinia pedunculata by various chromatographic methods combined with Global Natural Products Social Molecular Networking. The structures were identified by the analyses of spectral characteristics, computational chemistry calculations and single-crystal X-ray diffraction. A plausible biosynthetic pathway for garpedvinin A was suggested based on the isolated precursor, cambogin. Compounds 2-6, 8, 11, 13, 15-18 and 20 displayed cytotoxic effects on three cancer cell lines, HepG2, A549 and MCF-7. 6 showed the strong inhibitory effect on the proliferation of HepG2 cells in vitro, inducing cell apoptosis in a concentration-dependent manner and blocking the cell cycle at the S phase. Furthermore, 6 affected the expression of apoptosis-related proteins Bax, Bcl2 and pro-Caspase-3.

Flow Cytometry and Gene Expression Modulation by Euphorbia rigida Methanol Extract in A549 Lung Cancer Cells: Induction of Apoptosis Through Bax, Caspase-9, and Bcl-2 Pathways

Non-small cell lung cancer (NSCLC) remains a major cause of cancer-related mortality. This study investigates the cytotoxic effects of Euphorbia rigida extract on A549 NSCLC cells and its potential as a therapeutic agent. Cellular morphology was observed microscopically, and cell viability was evaluated using dose-dependent proliferation assays. Apoptosis-related gene expression-including Bax, Bcl-2, and Caspase-9-was analyzed via quantitative PCR (qPCR). Chromatographic methods identified bioactive flavonoids, and molecular docking assessed their binding to cancer-related proteins. Additionally, absorption, distribution, metabolism, excretion, and toxicity (ADMET) profiles were evaluated. The extract induced apoptotic morphological changes such as cell shrinkage and loss of intercellular contact. A dose-dependent reduction in A549 viability was observed, with an IC50 of 0.5 mg mL-1. Gene expression indicated activation of the intrinsic mitochondrial apoptotic pathway, with increased Bax and Caspase-9 and decreased Bcl-2 expression. Flow cytometry using Annexin V-allophycocyanin (V-APC) staining revealed selective cytotoxicity: significant apoptosis in A549 cells while preserving viability in BEAS-2B normal lung epithelial cells. Identified flavonoids included quercetin, apigenin, and myricetin, which showed strong binding affinities in docking studies. ADMET profiling supported their drug-likeness. These findings highlight E. rigida potential in NSCLC treatment via apoptosis induction and selective cytotoxicity.

Exploiting the Anticancer, Antimicrobial and Antiviral Potential of Naphthoquinone Derivatives: Recent Advances and Future Prospects

Cancer remains a primary cause of mortality, with over 18.1 million new cases and 9.6 million deaths globally in 2018. Chemotherapy, which utilizes a spectrum of cytotoxic drugs targeting the rapidly dividing cancer cells, is a predominant treatment modality. However, the tendency of chemotherapeutics to induce drug resistance and exhibit non-specific cytotoxicity necessitates the development of new anticancer agents with heightened efficacy and minimized toxicity. In recent years, the discovery of safe and effective antibacterial/antiviral agents has also been a hot spot in medicinal chemistry. This paper comprehensively reviews the synthesis, anticancer/antibacterial/antiviral activity, and structure-activity relationships of natural 1,4-naphthoquinones and their derivatives. It highlights their potential as efficient and low-toxicity antitumor and anti-infectious drug candidates.

Shikonin from lithospermum erythrorhizon induces pyroptosis in trophoblast cells by activating the CTSB-NLRP3 inflammasome

BACKGROUND

With the decline of global fertility, drug therapeutic of ectopic pregnancy is of great significance. Lithospermum erythrorhizon is using for embryo killing as herbal medicine. Shikonin is the critical nucleus of Lithospermum erythrorhizon; however, the mechanism is still unclear. The study aimed to explore the mechanism of shikonin against ectopic pregnancy.

MATERIAL AND METHODS

In this study, we examined the viability and LDH release of HTR-8/SVneo cells by assays, observed pore formation in cell membranes by microscopy imaging and PI staining, and IL-1β release by WB and ELISA assay kit. Then, we used network pharmacology to analyse the potential interaction between shikonin, ectopic pregnancy and pyroptosis and used molecular docking techniques to verify interactions between shikonin and core common targets. Finally, western blotting and immunofluorescence assay were used to explore the mechanism of shikonin-inducing pyroptosis of HTR-8/SVneo cells.

RESULTS

Shikonin could cause a significant inhibition of HTR-8/SVneo cell viability in a concentration- and time-dependent manner. In HTR-8/SVneo cells, shikonin-induced cell swelling, bubble formation, an increase in the release of lactate dehydrogenase (LDH) and up-regulation of several pyroptosis-associated factors. And network pharmacology showed that The main targets of shikonin-ectopic pregnancy-pyroptosis were IL-1β and caspase-1, and molecular docking results showed that shikonin can closely bind to IL-1β, caspase-1 and GSDMD. Additionally, the necroptosis inhibitor GSK'872 could not suppress the expression of mature-IL-1β and prevent the pyroptosis phenotype from developing. However, the nucleotide oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inhibitor MCC-950 could downregulate the expression of pyroptosis-associated factors and prevent the pyroptosis phenotype from developing. Shikonin led to an elevation in the expression of cathepsin B (CTSB), and the CTSB inhibitor CA-074 abolished pyroptosis induced by shikonin; however, the NLRP3 inhibitor MCC-950 could not inhibit the expression of CTSB.

CONCLUSIONS

Our results suggest that shikonin activates CTSB to induce NLRP3-dependent pyroptosis in HTR-8/SVneo cells. This study has important clinical implications for the treatment of ectopic pregnancy.

Shikonin Induces Autophagy and Apoptosis in Esophageal Cancer EC9706 Cells by Regulating the AMPK/mTOR/ULK Axis

Shikonin is a plant medicine extracted from Lithospermum, which dominate influential antioxidant and antitumor effect. Here, we report that shikonin was capable of inducing human esophageal cancer EC9706 cell apoptosis and autophagy, in a time- and dose-dependent manner. Shikonin exposure repressed cell viability and migration and invasion capabilities and caused EC9706 cell autophagy and apoptosis by activating the AMPK/mTOR/ULK axis. Autophagy inhibition secured EC9706 cells against shikonin-induced autophagy and apoptosis and reversed the upregulation of AMPK and ULK phosphorylation and downregulation of mTOR phosphorylation provoked by shikonin. In summary, shikonin instigates EC9706 cell apoptosis and autophagy using the target AMPK/mTOR/ULK signal pathway axis, which provides a potential new target to treat human esophageal cancer.

QSAR modeling for cytotoxicity of sulfur-containing Shikonin oxime derivatives targeting HCT-15, MGC-803, BEL-7402, and MCF-7 cell lines

Targeting cancer cells through drug-based treatment or combination therapy protocols involving chemical compounds can be challenging due to multiple factors, including their resistance to bioactive compounds and the potential of drugs to damage healthy cells. This study aims to investigate the relationship between the structure of novel sulfur-containing shikonin oxime compounds and the corresponding cytotoxicity against four cancer types, namely colon, gastric, liver, and breast cancers, through computational chemistry tools. This investigation is suggested to help build insights into how the structure of the compounds influences their activity and understand the mechanisms behind it and subsequently might be used in multi-cancer drug design process to propose novel optimized compounds that potentially exhibit the desired activity. The findings showed that the cytotoxic activity against the four cancer types was accurately predictable (R2 > 0.7, NRMSE <20%) by a combination of search and machine learning algorithms, based on the information on the structure of the compounds, including their lipophilicity, surface area, and volume. Overall, this study is supposed to play a crucial role in effective multi-cancer drug design in cancer research areas.

Unlocking the potential of 1,4-naphthoquinones: A comprehensive review of their anticancer properties

Cancer encompasses a group of pathologies with common characteristics, high incidence, and prevalence in all countries. Although there are treatments available for this disease, they are not always effective or safe, often failing to achieve the desired results. This is why it is necessary to continue the search for new therapies. One of the strategies for obtaining new antitumor drugs is the use of 1,4-naphthoquinone as a scaffold in synthetic or natural products with antitumor activity. This review focuses on compiling studies related to the antitumor activity of 1,4-naphthoquinone and its natural and synthetic derivatives over the last 10 years. The work describes the main natural naphthoquinones with antitumor activity and classifies the synthetic naphthoquinones based on the structural modifications made to the scaffold. Additionally, the formation of metal complexes using naphthoquinones as a ligand is considered. After a thorough review, 197 synthetic compounds with potent biological activity against cancer have been classified according to their chemical structures and their mechanisms of action have been described.

The Fundamental Role of Oxime and Oxime Ether Moieties in Improving the Physicochemical and Anticancer Properties of Structurally Diverse Scaffolds

The present review explores the critical role of oxime and oxime ether moieties in enhancing the physicochemical and anticancer properties of structurally diverse molecular frameworks. Specific examples are carefully selected to illustrate the distinct contributions of these functional groups to general strategies for molecular design, modulation of biological activities, computational modeling, and structure-activity relationship studies. An extensive literature search was conducted across three databases, including PubMed, Google Scholar, and Scifinder, enabling us to create one of the most comprehensive overviews of how oximes and oxime ethers impact antitumor activities within a wide range of structural frameworks. This search focused on various combinations of keywords or their synonyms, related to the anticancer activity of oximes and oxime ethers, structure-activity relationships, mechanism of action, as well as molecular dynamics and docking studies. Each article was evaluated based on its scientific merit and the depth of the study, resulting in 268 cited references and more than 336 illustrative chemical structures carefully selected to support this analysis. As many previous reviews focus on one subclass of this extensive family of compounds, this report represents one of the rare and fully comprehensive assessments of the anticancer potential of this group of molecules across diverse molecular scaffolds.

Anti-tumor effects of novel alkannin derivatives with potent selectivity on comprehensive analysis

BACKGROUND

Therapeutic approaches based on glycolysis and energy metabolism of tumor cells are new promising strategies for the treatment of cancer. Currently, researches on the inhibition of pyruvate kinase M2, a key rate limiting enzyme in glycolysis, have been corroborated as an effective cancer therapy. Alkannin is a potent pyruvate kinase M2 inhibitor. However, its non-selective cytotoxicity has affected its subsequent clinical application. Thus, it needs to be structurally modified to develop novel derivatives with high selectivity.

PURPOSE

Our study aimed to ameliorate the toxicity of alkannin through structural modification and elucidate the mechanism of the superior derivative 23 in lung cancer therapy.

METHODS

On the basis of the principle of collocation, different amino acids and oxygen-containing heterocycles were introduced into the hydroxyl group of the alkannin side chain. We examined the cell viability of all derivatives on three tumor cells (HepG2, A549 and HCT116) and two normal cells (L02 and MDCK) by MTT assay. Besides, the effect of derivative 23 on the morphology of A549 cells as observed by Giemsa and DAPI staining, respectively. Flow cytometry was performed to assess the effects of derivative 23 on apoptosis and cell cycle arrest. To further assess the effect of derivative 23 on the Pyruvate kinase M2 in glycolysis, an enzyme activity assay and western blot assay were performed. Finally, in vivo the antitumor activity and safety of the derivative 23 were evaluated by using Lewis mouse lung cancer xenograft model.

RESULTS

Twenty-three novel alkannin derivatives were designed and synthesized to improve the cytotoxicity selectivity. Among these derivatives, derivative 23 showed the highest cytotoxicity selectivity between cancer and normal cells. The anti-proliferative activity of derivative 23 on A549 cells (IC₅₀ = 1.67 ± 0.34 μM) was 10-fold higher than L02 cells (IC₅₀ = 16.77 ± 1.44 μM) and 5-fold higher than MDCK cells (IC₅₀ = 9.23 ± 0.29 μM) respectively. Subsequently, fluorescent staining and flow cytometric analysis showed that derivative 23 was able to induce apoptosis of A549 cells and arrest the cell cycle in the G0/G1 phase. In addition, the mechanistic studies suggested derivative 23 was an inhibitor of pyruvate kinase; it could regulate glycolysis by inhibiting the activation of the phosphorylation of PKM2/STAT3 signaling pathway. Furthermore, studies in vivo demonstrated derivative 23 significantly inhibited the growth of xenograft tumor.

CONCLUSION

In this study, alkannin selectivity is reported to be significantly improved following structural modification, and derivative 23 is first shown to be able to inhibit lung cancer growth via the PKM2/STAT3 phosphorylation signaling pathway in vitro, indicating the potential value of derivative 23 in treating lung cancer.

Fe(III)-Shikonin Supramolecular Nanomedicine for Combined Therapy of Tumor via Ferroptosis and Necroptosis

Most of the antitumor chemotherapeutic drugs execute the therapeutic performance upon eliciting tumor cell apoptosis, which may cause chemoresistance of tumors. Design of novel drugs to eradicate apoptosis-resistant tumors via non-apoptotic cell death pathways is promising for improving the long-term chemotherapeutic efficacy. Herein, a Fe(III)-Shikonin metal-polyphenol-coordinated supramolecular nanomedicine for combined therapy of tumor via ferroptosis and necroptosis is designed. The construction of the nanomedicine based on the coordinated self-assembly between Fe³⁺ and Shikonin not only overcomes the shortcomings of Shikonin including its low bioavailability and high toxicity toward normal tissues, but also integrates the theranostics functions of Fe ions. Under the exposure of the high concentration of glutathione (GSH) in tumor cells, the as-prepared nanomedicine will disassemble into Fe²⁺ and Shikonin, followed by stimulating the tumor cell death through ferroptosis and necroptosis. In addition, benefiting from the stealth effect of polyethylene glycol (PEG) and the targeting ability of cyclo(Arg-Gly-Asp-d-Phe-Lys) (cRGD) to α_v β₃ -integrin, NH₂ -PEG-cRGD-modified nanomedicine exhibits a GSH-responsive therapy toward 4T1 tumor in vivo and self-enhanced longitudinal relaxation (T₁ )-weighted imaging property. Since the self-assembly of natural Shikonin and human body-necessary Fe element is facile and feasible, the work may provide a promising supramolecular nanomedicine for next-generation chemotherapeutic applications.

Anti-cancer Research on Arnebiae Radix-derived Naphthoquinone in Recent Five Years

BACKGROUND

In recent years, many naphthoquinone compounds with anticancer activity have been identified in Arnebiae Radix, and some of them have the potential to be developed into anticancer drugs.

OBJECTIVE

This article aimed to provide a comprehensive overview of the anticancer effects of naphthoquinone compounds through a detailed review of literature and Chinese patents, and discuss their potential to be developed as anticancer drugs for clinical application.

METHODS

Research papers were collected through the databases of PubMed, Cnki and SciDirect using keyword searches "naphthoquinone compounds" and "anticancer". The keywords of "shikonin" and "shikonin derivatives" were also used in PubMed, Cnki and SciDirect databases to collect research articles. The Chinese patents were collected using the Cnki patent database.

RESULTS

Naphthoquinone compounds have been found to possess anti-cancer activity, and their modes of action are associated with inducing apoptosis, inhibiting cancer cell proliferation, promoting autophagy in cancer cells, anti-cancer angiogenesis and inhibition of cell adhesion, invasion and metastasis, inhibiting glycolysis and inhibiting DNA topoisomerase activity.

CONCLUSION

Most of the naphthoquinone compounds show effective anti-cancer activity in vitro. The structure modification of naphthoquinone aims to develop anti-cancer drugs with high efficacy and low toxicity.

Novel Derivatives of Nicotinic Acid as Promising Anticancer Agents

BACKGROUND

Cancer has become the second leading cause of death worldwide. Despite of the availability of significant number of anticancer agents, cancer is still incurable especially at the last stages. Remarkable targets for anticancer research and drug discovery are heterocyclic compounds, and among them, superior effect has been shown by the nitrogen containing compounds than non-nitrogen containing compounds. Nicotinic acid, a nitrogen containing moiety and its derivatives have gained an immense importance in the development of anticancer drugs owing to the wide variety of biological properties displayed by them.

OBJECTIVE

The objective of this review is to provide researchers the information about various synthetic approaches used for the synthesis of anticancer drugs of nicotinic acid from 2001 onwards and to reveal their application and importance in the treatment of this dreadful disease.

CONCLUSION

As indicated by this review, considerable work has been done in terms of synthesis and investigation of anticancer potential of nicotinamide derivatives. The information provided in this article may be of great value for the researchers seeking to develop efficient anticancer drugs.

Assessment of Skin Photoallergy Risk in Cosmetics Containing Herbal Extract Ingredients

BACKGROUND/OBJECTIVE

In recent years, herbal extracts are becoming increasingly popular ingredients added in cosmetics; however, the assessment of their potential adverse effects on the skin remains unclear. As Coptis, Phellodendron amurense, curcumin, and shikonin are herbs currently used in cosmetic ingredients, the aim of this study was to assess their skin photoallergy (PA) potential and the concentrations at which they could safely be used.

METHODS

In the patch test, Coptis, P. amurense, curcumin, and shikonin with 5, 10, 25, and 50% concentration were applied on 33 healthy Chinese subjects using the T.R.U.E. TEST® patch test system for 48 h. Photopatch testing was performed on 206 Chinese subjects with predisposed photosensitivity history using the Scandinavian photopatch series, and subjects were irradiated by 50% UVA minimum erythema dose. Photopatch testing of herbal extracts was then performed on subjects diagnosed with PA.

RESULTS

Thirty-three subjects (14 with type III skin and 19 with type IV skin) completed contact patch testing of herbal extracts. Coptis induced a contact allergy (CA) reaction on 2 subjects at 25% concentration and on 2 subjects at 10% concentration. P. amurense induced a CA reaction on 1 subject at 10% concentration and on 1 subject at 5% concentration. Shikonin induced a stimulating reaction on 1 subject at 10% concentration. Curcumin induced a stimulating reaction on 1 subject at 10% concentration. Of the 206 Chinese subjects predisposed for photosensitivity, 10.19% had PA, 16.5% showed CA, and 1.45% had both PA + CA. PA-induced substances were promethazine hydrochloride (15%, n = 31), chlorpromazine hydrochloride (10.84%, n = 19), perfume mix (5.82%, n = 12), atranorin (3.39%, n = 7), 6-methyl coumarine (3.39%, n = 7), balsam Peru (1.94%, n = 4), fentichlor (1.94%, n = 4), 3,3',4',5-tetrachloro salicylanilide (0.97%, n = 2), hexachlorophene (0.97%, n = 2), chlorhexidine digluconate (0.97%, n = 2), and 4-aminobenzoic acid 2-hydroxy-4-methoxybenzophenone (0.97%, n = 2). Coptis at 25, 10, and 5% concentration and P. amurense, shikonin, and curcumin each at 10 and 5% concentration induced negative photopatch test results in all 10 photosensitive subjects.

CONCLUSION

We have shown that Coptis, shikonin, or curcumin at 5% concentration in cosmetics could be applied safely without inducing contact allergic and photosensitive reactions on the skin. These findings advance the understanding of herbal extract use in cosmetic ingredients as related to the fields of dermatopharmacology and dermatotoxicology.

Synthesis and Pharmacological In Vitro Investigations of Novel Shikonin Derivatives with a Special Focus on Cyclopropane Bearing Derivatives

Melanoma is the deadliest form of skin cancer and accounts for about three quarters of all skin cancer deaths. Especially at an advanced stage, its treatment is challenging, and survival rates are very low. In previous studies, we showed that the constituents of the roots of Onosma paniculata as well as a synthetic derivative of the most active constituent showed promising results in metastatic melanoma cell lines. In the current study, we address the question whether we can generate further derivatives with optimized activity by synthesis. Therefore, we prepared 31, mainly novel shikonin derivatives and screened them in different melanoma cell lines (WM9, WM164, and MUG-Mel2 cells) using the XTT viability assay. We identified (R)-1-(1,4-dihydro-5,8-dihydroxy-1,4-dioxonaphthalen-2-yl)-4-methylpent-3-enyl 2-cyclopropyl-2-oxoacetate as a novel derivative with even higher activity. Furthermore, pharmacological investigations including the ApoToxGlo^TM Triplex assay, LDH assay, and cell cycle measurements revealed that this compound induced apoptosis and reduced cells in the G1 phase accompanied by an increase of cells in the G2/M phase. Moreover, it showed hardly any effects on the cell membrane integrity. However, it also exhibited cytotoxicity against non-tumorigenic cells. Nevertheless, in summary, we could show that shikonin derivatives might be promising drug leads in the treatment of melanoma.

Design, synthesis, antibacterial evaluation, molecular docking and computational study of 4-alkoxy/aryloxyphenyl cyclopropyl methane oxime derivatives

A series of new 4-alkoxy/aryloxyphenyl cyclopropyl methane oxime derivatives 2(a-k) were synthesized and fully characterized by FT-IR, 1H-NMR, 13C-NMR and Mass spectrometry techniques. All the synthesized compounds 2(a-k) were assayed for in vitro antibacterial activity against a selected bacterial strain and the compound (2 h) and (2k) exerted excellent activity against Staphylococcus aureus, Escherichia coli and Salmonella typhi strains. The potency of inhibitors and possible interaction mechanism of synthetic oxime (2k) with 1GQN enzyme on Salmonella typhi was explored by molecular docking method. Amongst the all synthesized compounds, the quantum chemical calculations were done for Cyclopropyl(4-(pyridin-3-ylmethoxy)phenyl)methanone oxime (2k). The first hyperpolarizability calculation performed in different solvent such as CHCl₃, CH₂Cl₂ and DMSO and compared to the reference compound urea. In addition, natural bond orbital analysis (NBO), local reactivity descriptors, thermodynamic properties, Mulliken charges, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis were explored using theoretical calculations.

Selective Antitumor Effect of Shikonin Derived DMAKO-20 on Melanoma through CYP1B1

BACKGROUND

CYP1B1 is recognized as a valuable target for chemotherapy. It catalyzes the bioactivation of naphthoquinone oximes within certain cancer cell lines. However, the expression level of CYP1B1 in melanoma and the functional role regulating the activity of DMAKO-20 as a representative naphthoquinone oxime against skin carcinoma is still unknown.

OBJECTIVE

We sought to examine the expression level of CYP1B1 in melanoma and explore the molecular mechanism behind the anticancer effects of DMAKO-20 in melanoma.

METHODS

CYP1B1 expression levels in paraffin specimens taken from melanoma patients, and its expression levels in B16/F10 cancer cells were investigated using immunohistochemical staining. The molecular mechanisms behind DMAKO20 activity against melanoma was investigated by using cytotoxicity, cell scratching, apoptotic, and immunoblotting assays.

RESULTS

CYP1B1, the P450 isoform was expressed at high levels in melanoma tissues and cultured B16/F10 cells, but was undetectable in normal tissues or fibroblasts. In cell proliferation assays, the shikonin oxime DMAKO-20 exhibited potent and selective antiproliferative effects against B16/F10 melanoma cells and inhibited migration. Several mechanisms for the anticancer effects of DMAKO-20 have been identified in B16/F10 melanoma cells, including apoptosis, upregulation of mitochondrial apoptotic Bax proteins and downregulation of anti-apoptotic Bcl-2. The results from these mechanistic investigations indicated that DMAKO-20 underwent CYP1B1-mediated metabolic activation to activate anticancer metabolites within melanoma cells.

CONCLUSION

DMAKO-20 exhibited a selective cytotoxic effect on melanoma cells through CYP1B1-mediated activation. Using DMAKO-20 as a lead compound, further structural optimization may provide new drug entities for the treatments of malignant skin carcinomas.

Synthesis and Biological Evaluation of New Naphthoquinones Derivatives

:

New substituted 1,4-naphthoquinones have been prepared in good overall yields through the naphthol route. The cytotoxicity of these compounds was tested in vitro on MCF-7 breast tumor cells. The most active compound 14 displayed an IC50 of 15μM.

Objective:

To investigate the cytotoxicity of new naphthoquinones derivatives on MCF-7 cells.

Methods:

Synthesis of new naphtoquinones derivatives and in vitro evaluation of their cytotoxicity on MCF-7 cells (rezasurin cell-based assay).

Results:

Starting from Ethyl 4-hydroxy-6,7-dimethoxy-2-naphthoate, four naphthoquinones were prepared and exhibited substantial cytotoxicity against MCF-7 cells.

Conclusion:

Preliminary studies of the structure-activity relationship have shown the influence of the structural parameters and, in particular, the nature of the naphthoquinone side chain.

Anticancer activities of vitamin K3 analogues

In a previous study we reported on the synthesis of 1,4-naphthoquinone-sulfides by thiolation of 1,4-naphthohydroquinones with primary aryl and alkyl thiols using laccase as catalyst. These compounds were synthesized as Vitamin K3 analogues. Vitamin K3 (VK3; 2-methyl-1,4-naphthoquinone; menadione) is known to have potent anticancer activity. This investigation reports on the anticancer activity of these VK3 analogues against TK10 renal, UACC62 melanoma, MCF7 breast, HeLa cervical, PC3 prostate and HepG2 liver cancer cell lines to evaluate their cytostatic effects. A 1,4-naphthohydroquinone derivative exhibited potent cytostatic effects (GI₅₀ = 1.66-6.75 μM) which were better than that of etoposide and parthenolide against several of the cancer cell lines. This compound produces reactive oxygen species and disrupts the mitochondrial membrane potential in the MCF7 breast cancer cell line which is an indication that the cells undergo apoptosis. The 1,4-naphthoquinone sulfides also had potent cytostatic effects (GI₅₀ = 2.82-9.79 μM) which were also better than that of etoposide, parthenolide and VK3 against several of the cancer cell lines. These compounds are generally more selective for cancer cells than for normal human lung fetal fibroblasts (WI-38). They also have moderate to weak cytostatic effects compared to etoposide, parthenolide and VK3 which have potent cytostatic effects against WI-38. One analogue induces apoptosis by activating caspases without arresting the cell cycle in the MCF7 breast cancer cell line. These results inspire further research for possible application in cancer chemotherapy.

Pharmacological properties and derivatives of shikonin-A review in recent years

Shikonin is the major bioactive component extracted from the roots of Lithospermum erythrorhizon which is also known as "Zicao" in Traditional Chinese Medicine (TCM). Recent studies have shown that shikonin demonstrates various bioactivities related to the treatment of cancer, inflammation, and wound healing. This review aimed to provide an updated summary of recent studies on shikonin. Firstly, many studies have demonstrated that shikonin exerts strong anticancer effects on various types of cancer by inhibiting cell proliferation and migration, inducing apoptosis, autophagy, and necroptosis. Shikonin also triggers Reactive Oxygen Species (ROS) generation, suppressing exosome release, and activate anti-tumor immunity in multiple molecular mechanisms. Examples of these effects include modulating the PI3K/AKT/mTOR and MAPKs signaling; inhibiting the activation of TrxR1, PKM2, RIP1/3, Src, and FAK; and regulating the expression of ERP57, MMPs, ATF2, C-MYC, miR-128, and GRP78 (Bip). Next, the anti-inflammatory and wound-healing properties of shikonin were also reviewed. Furthermore, several studies focusing on shikonin derivatives were reviewed, and these showed that, with modification to the naphthazarin ring or side chain, some shikonin derivatives display stronger anticancer activity and lower toxicity than shikonin itself. Our findings suggest that shikonin and its derivatives could serve as potential novel drug for the treatment of cancer and inflammation.

Apoptotic Pathway as the Therapeutic Target for Anticancer Traditional Chinese Medicines

Cancer is a leading cause of morbidity and mortality worldwide. Apoptosis is a process of programmed cell death and it plays a vital role in human development and tissue homeostasis. Mounting evidence indicates that apoptosis is closely related to the survival of cancer and it has emerged as a key target for the discovery and development of novel anticancer drugs. Various studies indicate that targeting the apoptotic signaling pathway by anticancer drugs is an important mechanism in cancer therapy. Therefore, numerous novel anticancer agents have been discovered and developed from traditional Chinese medicines (TCMs) by targeting the cellular apoptotic pathway of cancer cells and shown clinically beneficial effects in cancer therapy. This review aims to provide a comprehensive discussion for the role, pharmacology, related biology, and possible mechanism(s) of a number of important anticancer TCMs and their derivatives mainly targeting the cellular apoptotic pathway. It may have important clinical implications in cancer therapy.

Shikonin derivatives for cancer prevention and therapy

Phytochemicals gained considerable interest during the past years as source to develop new treatment options for chemoprevention and cancer therapy. Motivated by the fact that a majority of established anticancer drugs are derived in one way or another from natural resources, we focused on shikonin, a naphthoquinone with high potentials to be further developed as preventive or therapeutic drug to fight cancer. Shikonin is the major chemical component of Lithospermum erythrorhizon (Purple Cromwell) roots. Traditionally, the root extract has been applied to cure dermatitis, burns, and wounds. Over the past three decades, the anti-inflammatory and anticancer effects of root extracts, isolated shikonin as well as semi-synthetic and synthetic derivatives and nanoformulations have been described. In vitro and in vivo experiments were conducted to understand the effect of shikonin at cellular and molecular levels. Preliminary clinical trials indicate the potential of shikonin for translation into clinical oncology. Shikonin exerts additive and synergistic interactions in combination with established chemotherapeutics, immunotherapeutic approaches, radiotherapy and other treatment modalities, which further underscores the potential of this phytochemical to be integrated into standard treatment regimens.

Different substituent effects on the supramolecular arrays in some (E)-halo- and nitro-benzaldehyde oximes: confirmation of attractive π(C=N)···π(phenyl) interactions

The crystal structures and Hirshfeld surface analyses are reported for four aldoximes, (E)-X–C6H4CH=N–OH [X = 3-Cl (1), 4-F (2), 2-O2N (3) and 4-O2N (4)]. The strong classical O–H · · · N hydrogen bonds involving the oxime group generate C(3) chains in compound 1, in contrast to the R2 2(6) dimers formed in compounds 2–4; such arrangements have been shown to be the most frequently found for oximes other than salicylaldoximes (2-hydroxybenzaldehyde oximes). In general, weaker intermolecular interactions involving the X substituents, as well as C–H · · · O and π · · · π interactions have significant effects on the supramolecular arrays generated in the aggegation. A further important interaction in compound 1, and to a lesser extent in compound 4, is a π(C=N) · · · π(phenyl) molecular stacking. A data base search has indicated that short Cg(C=N) · · · Cg(phenyl) distances, <3.3 Å (Cg = centre of gravity), have been found in various compounds, including other oximes. A theoretical study was carried out starting from the crystal structure data of compound 1, with optimisation at the BLYP-D3/def2-DZVP level, as well as at the higher PBE0/ma-def2-TZVP level. Breakdown of the interaction energy into separate contributions was achieved using SAPT (using the jun-cc-pvdz basis set). Overall, the calculations indicate that the π(C=N) ·· · π(phenyl) interaction is attractive, with a magnitude of 14–18 kJ mol−1.

Novel naphthalene-enoates: Design and anticancer activity through regulation cell autophagy

Eleven dihydroxy-2-(1-hydroxy-4-methylpent-3-enyl)naphthalene derivatives as anticancer agents through regulating cell autophagy were designed and synthesized. The anticancer activity results indicated that most compounds manifested obvious un-toxic effect on GES-1 and L-02 with IC₅₀ from 0.58 to 1.41 mM. Among them, (S,Z)-1-(5,8-dihydroxy-1,4-dioxo-1,4-dihydronaphthalen-2-yl)-4-methylpent-3-enyl 4-(3,4- dihydroisoquinolin-2(1 H)-yl)-4-oxobut-2-enoate (compound 4i) could induce cancer cells apoptosis. Further experiments showed that autophagy played an important role in the pro-apoptotic effect of this compound. Preliminary mechanism indicated that this compound could inhibit phosphoinositide 3-kinase/protein kinase B and the mammalian target of rapamycin (PI3K/AKT/mTOR) pathway by mediating apoptosis in an autophagy-dependent manner.

Crystal structures and Hirshfeld surfaces of four meth-oxy-benzaldehyde oxime derivatives, 2-MeO-XC6H3C=NOH (X = H and 2-, 3- and 4-MeO): different conformations and hydrogen-bonding patterns

The crystal structures of four (E)-meth-oxy-benzaldehyde oxime derivatives, namely (2-meth-oxy-benzaldehyde oxime, 1, 2,3-di-meth-oxy-benzaldehyde oxime, 2, 4-di-meth-oxy-benzaldehyde oxime, 3, and 2,5-di-meth-oxy-benzaldehyde oxime, 4, are discussed. The arrangements of the 2-meth-oxy group and the H atom of the oxime unit are s-cis in compounds 1-3, but in both independent mol-ecules of compound 4, the arrangements are s-trans. There is also a difference in the conformation of the two mol-ecules in 4, involving the orientations of the 2- and 5-meth-oxy groups. The primary inter-molecular O-H(oxime)⋯O(hy-droxy) hydrogen bonds generate C(3) chains in 1 and 2. In contrast, in compound 3, the O-H(oxime)⋯O(hy-droxy) hydrogen bonds generate symmetric R 2 2(6) dimers. A more complex dimer is generated in 4 from the O-H(oxime)⋯O(hy-droxy) and C-H(2-meth-oxy)⋯O(hy-droxy) hydrogen bonds. In all cases, further inter-actions, C-H⋯O and C-H⋯π or π-π, generate three-dimensional arrays. Hirshfeld surface and fingerprint analyses are discussed.

Different classical hydrogen-bonding patterns in three salicylaldoxime derivatives, 2-HO-4-XC6H3C=NOH (X = Me, OH and MeO)

The crystal structures of three salicyaldoxime compounds, namely 2-hy-droxy-4-methyl-benzaldehyde oxime, C8H9NO2, 1, 2,4-di-hydroxy-benzaldehyde oxime, C7H7NO3, 2, and 2-hy-droxy-4-meth-oxy-benzaldehyde oxime, C8H9NO3, 3, are discussed. In each compound, the hydroxyl groups are essentially coplanar with their attached phenyl group. The inter-planar angles between the C=N-O moieties of the oxime unit and their attached phenyl rings are 0.08 (9), 1.08 (15) and 6.65 (15)° in 1, 2 and 3, respectively. In all three mol-ecules, the 2-hy-droxy group forms an intra-molecular O-H⋯N(oxime) hydrogen bond. In compound (1), inter-molecular O-H(oxime)⋯O(hydrox-yl) hydrogen bonds generate R 2 2(14) dimers, related by inversion centres. In compound 2, inter-molecular O-H(oxime)⋯O(4-hy-droxy) hydrogen bonds generate C9 chains along the b-axis direction, while O-H(4-hydrox-yl)⋯O(2-hydrox-yl) inter-actions form zigzag C6 spiral chains along the c-axis direction, generated by a screw axis at 1, y, 1/4: the combination of the two chains provides a bimolecular sheet running parallel to the b axis, which lies between 0-1/2 c and 1/2-1 c. In compound 3, similar C9 chains, along the b-axis direction are generated by O-H(oxime)⋯O(4-meth-oxy) hydrogen bonds. Further weaker, C-H⋯π (in 1), π-π (in 2) and both C-H⋯π and π-π inter-actions (in 3) further cement the three-dimensional structures. Hirshfeld surface and fingerprint analyses are discussed.

Targeting the SET and RING-associated (SRA) domain of ubiquitin-like, PHD and ring finger-containing 1 (UHRF1) for anti-cancer drug development

Ubiquitin-like containing PHD Ring Finger 1 (UHRF1) is a multi-domain protein with a methyl-DNA binding SRA (SET and RING-associated) domain, required for maintenance DNA methylation mediated by DNMT1. Primarily expressed in proliferating cells, UHRF1 is a cell-cycle regulated protein that is required for S phase entry. Furthermore, UHRF1 participates in transcriptional gene regulation by connecting DNA methylation to histone modifications. Upregulation of UHRF1 may serve as a biomarker for a variety of cancers; including breast, gastric, prostate, lung and colorectal carcinoma. To this end, overexpression of UHRF1 promotes cancer metastasis by triggering aberrant patterns of DNA methylation, and subsequently, silencing tumor suppressor genes. Various small molecule effectors of UHRF1 have been reported in the literature, although the mechanism of action may not be fully characterized. Small molecules that potentially bind to the SRA domain may affect the ability of UHRF1 to bind hemimethylated DNA; thereby reducing aberrant DNA methylation. Therefore, in a subset of cancers, small molecule UHRF1 inhibitors may restore normal gene expression and serve as useful anti-cancer therapeutics.