Cancer is a hard-to-treat disease with a high reoccurrence rate that affects health and lives globally. The condition has a high occurrence rate and is the second leading cause of mortality after cardiovascular disorders. Increased research and more profound knowledge of the mechanisms contributing to the disease’s onset and progression have led to drug discovery and development. Various drugs are on the market against cancer; however, the drugs face challenges of chemoresistance. The other major problem is the side effects of these drugs. Therefore, using complementary and additional medicines from natural sources is the best strategy to overcome these issues. The naturally occurring phytochemicals are a vast source of novel drugs against various ailments. The modes of action by which phytochemicals show their anti-cancer effects can be the induction of apoptosis, the onset of cell cycle arrest, kinase inhibition, and the blocking of carcinogens. This review aims to describe different phytochemicals, their classification, the role of phytochemicals as anti-cancer agents, the mode of action of phytochemicals, and their role in various types of cancer.

We describe the design and synthesis of two isatin-tethered quinolines series (Q6a–h and Q8a–h), in connection with our research interest in developing novel isatin-bearing anti-tubercular candidates. In a previous study, a series of small molecules bearing a quinoline-3-carbohydrazone moiety was developed as anti-tubercular agents, and compound IV disclosed the highest potency with MIC value equal to 6.24 µg/mL. In the current work, we adopted the bioisosteric replacement approach to replace the 3,4,5-trimethoxy-benzylidene moiety in the lead compound IV with the isatin motif, a privileged scaffold in the TB drug discovery, to furnish the first series of target molecules Q6a–h. Thereafter, the isatin motif was N-substituted with either a methyl or benzyl group to furnish the second series Q8a–h. All of the designed quinoilne-isatin conjugates Q6a–h and Q8a–h were synthesized and then biologically assessed for anti-tubercular actions towards drug-susceptible, MDR, and XDR strains. Superiorly, the N-benzyl-bearing compound Q8b possessed the best activities against the examined M. tuberculosis strains with MICs equal 0.06, 0.24, and 1.95 µg/mL, respectively.

Background/Objectives: A promising anticancer strategy is the simultaneous inhibition of the receptor tyrosine kinases VEGFR-2 and c-Met, which are essential for tumor angiogenesis, growth, and metastasis. In this study, a novel series of piperidinyl-based benzoxazole derivatives was designed and synthesized as potential dual VEGFR-2/c-Met inhibitors. Methods: The kinase inhibitory potential of the derivatives was evaluated in comparison to reference inhibitors, Sorafenib (VEGFR-2 inhibitor) and Staurosporine (c-Met inhibitor). Cytotoxicity was assessed across breast, prostate (PC-3), and lung (A549) cancer cell lines. Mechanistic studies included cell-cycle analysis, apoptosis assays, gene expression profiling of apoptosis-related markers, and molecular docking within the ATP-binding pockets of both kinases. Results: Compounds 5a, 5g, 5h, 11a, and 11b showed strong inhibition of both kinases (IC₅₀ = 0.145–0.970 μM for VEGFR-2 and 0.181–1.885 μM for c-Met). Selective cytotoxicity was observed against breast cancer cells, with compound 11b (p-fluorophenyl derivative) exhibiting high selectivity toward MCF-7 over normal breast cells (MCF-10A) and potency comparable to or exceeding Sorafenib. Mechanistically, 11b induced G₂/M cell-cycle arrest and apoptosis (total apoptosis = 48.34%), accompanied by upregulation of p53, BAX, and caspase-9 and downregulation of Bcl-2. Molecular docking confirmed stable binding within the ATP-binding sites of both kinases. Conclusions: Compound 11b was established as a novel, selective, dual VEGFR-2/c-Met inhibitor with strong potential for targeted breast cancer therapy.

Staphylococcus aureus (S. aureus) is a worldwide leading versatile pathogen that causes a wide range of serious infections. The emergence of antimicrobial resistance against S. aureus resulted in an urgent need to develop new antimicrobials in the new era. The methicillin-resistant S. aureus (MRSA) prevalence in hospital and community settings necessitates the discovery of novel anti-pathogenic agents. Staphyloxanthin (STX) is a key virulence factor for the survival of MRSA against host innate immunity. The current work aimed to demonstrate the anti-virulence properties of meloxicam (MXM) as compared to diclofenac (DC), which was previously reported to mitigate the virulence of multidrug-resistant Staphylococcus aureus and test their activities in STX production. A total of 80 S. aureus clinical isolates were included, wherein a qualitative and quantitative assessment of STX inhibition by diclofenac and meloxicam was performed. The quantitative gene expression of STX biosynthetic genes (crtM, crtN and sigB) and hla (coded for α-hemolysin) as a virulence gene with and without DC and MXM was conducted, followed by molecular docking analysis for further confirmation. DC and MXM potently inhibited the synthesis of STX at 47 and 59 µg/mL to reach 79.3–98% and 80.6–96.7% inhibition, respectively. Treated cells also revealed a significant downregulation of virulence genes responsible for STX synthesis, such as crtM, crtN and global transcriptional regulator sigB along with the hla gene. Furthermore, computational studies unveiled strong interactions between the CrtM binding site and DC/MXM. In conclusion, this study highlights the potential role and repurposing of DC and MXM as adjuvants to conventional antimicrobials and as an anti-virulent to combat MRSA infections.

Background/Objectives: In the current medical era, Topoisomerase II is recognized as an essential enzyme that regulates DNA topology during critical biological processes such as DNA replication, transcription, and repair. This study aimed to design, synthesize, and biologically evaluate a new series of pyrazolo[3,4-b]pyridines (8a–g, 10a–g, and 12) as potential anticancer agents and Topoisomerase II inhibitors. Methods: The synthesized compounds were subjected to in vitro anticancer screening at the National Cancer Institute (NCI, USA). Active derivatives were further evaluated through a five-dose screening to determine their antiproliferative potency. Selected compounds were examined for their effects on leukemia cell lines (K562 and MV4-11), and mechanistic studies were performed to assess DNA damage, cell cycle distribution, and apoptosis-related protein modulation. Additionally, enzyme inhibition assays were conducted to determine Topoisomerase IIα (TOPIIα) inhibition. Results: Initial single-dose screening identified several active compounds, notably 8b, 8c, 8e, 8f, 10b, 10c, 10e, and 10f. Among these, compound 8c exhibited potent and broad-spectrum antiproliferative activity across the NCI cancer cell line panel, with a GI₅₀ MG-MID value of 1.33 µM (range: 0.54–2.08 µM). The synthesized molecules showed moderate to good anti-leukemic efficacy against K562 and MV4-11 cells. Mechanistic investigations revealed that compound 8c induced DNA damage and S-phase cell cycle arrest, leading to apoptosis as evidenced by the modulation of PARP-1, Bax, XIAP, and Caspases. Furthermore, target-based assays confirmed that compound 8c significantly inhibited the DNA relaxation activity of TOPIIα in a dose-dependent manner, comparable to etoposide. Conclusions: The study highlights compound 8c as a promising pyrazolo[3,4-b]pyridine derivative with potent antiproliferative activity and effective inhibition of Topoisomerase IIα. These findings suggest its potential as a lead scaffold for further optimization in anticancer drug development..