Determination of Inhibitory Effect of PKM2 Enzyme and Antitumoral Activity of Novel Coumarin-Naphthoquinone Hybrids.

BACKGROUND: Oral squamous cell carcinoma (OSCC) represents the primary form of oral cancer, posing a significant global health threat. The existing chemotherapy options are accompanied by notable side effects impacting patient treatment adherence. Consequently, the exploration and development of novel substances with enhanced anticancer effects and fewer side effects have become pivotal in the realms of biological and chemical science. OBJECTIVE: This work presents the pioneering examples of naphthoquinone-coumarin hybrids as a new category of highly effective cytotoxic substances targeting oral squamous cell carcinoma (OSCC). METHODS: Given the significance of both naphthoquinones and coumarins as essential pharmacophores/ privileged structures in the quest for anticancer compounds, this study focused on the synthesis and evaluation of novel naphthoquinones/coumarin hybrids against oral squamous cell carcinoma. RESULTS: By several in vitro, in silico, and in vivo approaches, we demonstrated that compound 6e was highly cytotoxic against OSCC cells and several other cancer cell types and was more selective than current chemotherapeutic drugs (carboplatin) and the naphthoquinone lapachol. Furthermore, compound 6e was non-hemolytic and tolerated in vivo at 50 mg/kg with an LD50 of 62.5 mg/kg. Furthermore, compound 6e did not induce apoptosis and cell cycle arrest but led to intracellular vesicle formation with LC3 aggregation in autophagosomes, suggesting an autophagic cell death. Additionally, 6e had a high-affinity potential for PKM2 protein, higher than the known ligands, such as lapachol or shikonin, and was able to inhibit this enzyme activity in vitro. CONCLUSION: We assert that compound 6e shows promise as a potential lead for a novel chemotherapeutic drug targeting OSCC, with potential applicability to other cancer types.

Chemoselective Synthesis of Mannich Adducts from 1,4-Naphthoquinones and Profile as Autophagic Inducers in Oral Squamous Cell Carcinoma.

Oral squamous cell carcinoma (OSCC) is a worldwide public health problem, accounting for approximately 90% of all oral cancers, and is the eighth most common cancer in men. Cisplatin and carboplatin are the main chemotherapy drugs used in the clinic. However, in addition to their serious side effects, such as damage to the nervous system and kidneys, there is also drug resistance. Thus, the development of new drugs becomes of great importance. Naphthoquinones have been described with antitumor activity. Some of them are found in nature, but semi synthesis has been used as strategy to find new chemical entities for the treatment of cancer. In the present study, we promote a multiple component reaction (MCR) among lawsone, arylaldehydes, and benzylamine to produce sixteen chemoselectively derivated Mannich adducts of 1,4-naphthoquinones in good yield (up to 97%). The antitumor activities and molecular mechanisms of action of these compounds were investigated in OSCC models and the compound 6a induced cytotoxicity in three different tumor cell lines (OSCC4, OSCC9, and OSCC25) and was more selective (IS > 2) for tumor cells than the chemotropic drug carboplatin and the controls lapachol and shikonin, which are chemically similar compounds with cytotoxic effects. The 6a selectively and significantly reduced the amount of cell colony growth, was not hemolytic, and tolerable in mice with no serious side effects at a concentration of 100 mg/kg with a LD50 of 150 mg/kg. The new compound is biologically stable with a profile similar to carboplatin. Morphologically, 6a does not induce cell retraction or membrane blebs, but it does induce intense vesicle formation and late emergence of membrane bubbles. Exploring the mechanism of cell death induction, compound 6a does not induce ROS formation, and cell viability was not affected by inhibitors of apoptosis (ZVAD) and necroptosis (necrostatin 1). Autophagy followed by a late apoptosis process appears to be the death-inducing pathway of 6a, as observed by increased viability by the autophagy inhibitor (3-MA) and by the appearance of autophagosomes, later triggering a process of late apoptosis with the presence of caspase 3/7 and DNA fragmentation. Molecular modeling suggests the ability of the compound to bind to topoisomerase I and II and with greater affinity to hPKM2 enzyme than controls, which could explain the mechanism of cell death by autophagy. Finally, the in-silico prediction of drug-relevant properties showed that compound 6a has a good pharmacokinetic profile when compared to carboplatin and doxorubicin. Among the sixteen naphthoquinones tested, compound 6a was the most effective and is highly selective and well tolerated in animals. The induction of cell death in OSCC through autophagy followed by late apoptosis possibly via inhibition of the PKM2 enzyme points to a promising potential of 6a as a new preclinical anticancer candidate.

Cytotoxicity and selectiveness of Brazilian Piper species towards oral carcinoma cells.

BACKGROUND: Oral squamous cell carcinoma (OSCC) is one of the ten most common types of cancer worldwide. Plants of the genusPiper are used in traditional medicine to treat cancer, and they have a vast diversity of phytochemicals with cytotoxic potential. Purpose and Study Design: In this work, we analyzed the cytotoxic and selective potential of extracts and semipurified fractions of Piper mollicomum (PM), Piper truncatum (PT), Piper cernuum (PC), Piper arboreum (PA), and Piper cabralanum (PCa) using three different OSCC cell lines (SCC4, SCC9 and SCC25), and we measured their in vivo toxicities and conducted chemical analyses of their active fractions. RESULTS: The dichloromethane fractions of the crude methanolic extracts of the leaves of PM(-L-D), PC(-L-D) and PCa(-L-D) exhibited notable IC50 values of 94.2, 47.2 and 47.5 µg/mL, respectively, and all three of these extracts were more active than carboplatin (172.3 µg/mL). The most selective fraction was PC-L-D, which exhibited SI > 4.5; less than 5% hemolysis; and no significant alterations in in vivo acute toxicology. The major constituents in active fractions were lignans (PC-L-D and PCa-L-D) and chromenes (PM-L-D). CONCLUSION: PC-L-D demonstrated great potential for further development as an anticancer drug and could be the key to developing more effective and less toxic therapies against oral cancer.