Embelin (2,5-dihydroxy-3-undecyl-p-benzoquinone): a bioactive molecule isolated from Embelia ribes as an effective photodynamic therapeutic candidate against tumor in vivo

Synthesis and characterisation of copper acetate mediated oxidative coupled product of naturally occurring hydroxy benzoquinone, embelin and its in vitro and in vivo cytotoxic studies in Dalton Lymphoma ascites tumour cells

Embelin is an active phytoconstituent known to exhibit a variety of biological activities, especially active against various cancer and tumour cell lines. In the present work, embelin was extracted and isolated from Embelia ribes and was structurally modified by incorporating different fluoro substituted aniline in the quinone motif with a view of enhancing the biological activity. The synthesis was carried out in presence of copper acetate catalyst in a protic solvent, glacial acetic acid to obtain EDFA, ETFA and EOCF and were characterised by various spectral techniques. Embelin and its derivatives were then subjected to in vitro studies in DLA cell lines. Antiangeogenic activities were tested using CAM assay. EOCF was identified as the most active derivative and hence subjected to in vivo studies in tumour induced albino mice. The activity was compared with currently used anticancer drug, cyclophosphamide. The study revealed that EOCF was effective in inhibiting tumour growth.

Reviewing the Traditional/Modern Uses, Phytochemistry, Essential Oils/Extracts and Pharmacology of Embelia ribes Burm

Objectives: Embelia ribes Burm. (E. ribes, Myrsinaceae), also known as Vidanga in Ayurveda, has been shown to have significant therapeutic benefits on several disorders, and its main chemical bioactive constituent, embelin, has the therapeutic potential to be converted into innovative drugs, which is why it has recently received considerable interest. In the present work, we provide a higher level of comprehension, awareness, and extensive knowledge of the traditional uses, phytochemistry, and pharmacological characteristics of E. ribes throughout the last several decades (February 1965 to June 2021), emphasizing the importance of the study of essential oils extracted from E. ribes, which show a major potential for exerting antioxidant and anti-inflammatory activity. Materials and Methods: Google Scholar, MEDLINE, EMBASE, Scifinder, Scopus, and ScienceDirect were used to conduct a thorough literature search. Results: E. ribes is high in essential oils, alkaloids, flavonoids, steroids, and phenolics, all of which have medicinal benefits. The essential oils/extracts and isolated chemical constituents exhibited antioxidant activity, wound healing, antidiabetic, central nervous system (CNS)-related disease, antiviral, antiobesity, cardioprotective, antifungal, antibacterial, and antifertility activity, among other promising pharmacological effects. Conclusion: The translation between traditional applications and modern medicine may make E. ribes a promising target for the implementation of innovative medication. To investigate the efficacy and safety profile of E. ribes, further high-quality preclinical studies using advanced methodologies are required.

Synthesis, characterization, molecular docking and anticancer studies of fluoroaniline derivatives of hydroxybenzoquinone and hydroxynaphthoquinone

Two series of fluoro substituted-anilino derivatives of naturally occurring hydroxybenzoquinone and hydroxynaphthoquinone were synthesized using TFA as catalyst to improve the product yield. Recently, fluorine containing compounds are being used as anticancer drugs. The aim of this study is to find compounds that are active against melanoma cells. This six new fluoro substituted quinone compounds were synthesized and characterized. All of these compounds were then subjected to molecular docking studies against B-raf protein using Discovery Studio 4.0 and the binding affinities were calculated. The energy scores of in silico analysis revealed that all the compounds exhibited better binding affinity towards B-raf protein. Moreover, all the derivatives and the parent compounds, embelin and plumbagin along with standard drug, PLX4032 were investigated for its in vitro cytotoxicity in A375 cell lines (Melanoma) and in vitro ELISA assay in B-raf isolated from melanoma cells. Among them, 5-(3-chloro-4-trifluoromethoxy-phenylamino)-2-hydroxy-3-undecyl-[1,4]benzoquinone exhibited lower cell viability with lowest LC₅₀ of 12.25 μg/mL and thus poses suitability to be a lead molecule for further drug discovery.Communicated by Ramaswamy H. Sarma.

The Application of Embelin for Cancer Prevention and Therapy

Embelin is a naturally-occurring benzoquinone compound that has been shown to possess many biological properties relevant to human cancer prevention and treatment, and increasing evidence indicates that embelin may modulate various characteristic hallmarks of tumor cells. This review summarizes the information related to the various oncogenic pathways that mediate embelin-induced cell death in multiple cancer cells. The mechanisms of the action of embelin are numerous, and most of them induce apoptotic cell death that may be intrinsic or extrinsic, and modulate the NF-κB, p53, PI3K/AKT, and STAT3 signaling pathways. Embelin also induces autophagy in cancer cells; however, these autophagic cell-death mechanisms of embelin have been less reported than the apoptotic ones. Recently, several autophagy-inducing agents have been used in the treatment of different human cancers, although they require further exploration before being transferred from the bench to the clinic. Therefore, embelin could be used as a potential agent for cancer therapy.

Rh-Catalyzed Reactions of 1,4-Benzoquinones with Electrophiles: C-H Iodination, Bromination, and Phenylselenation

Under Rh-catalyzed conditions, typically electrophilic 1,4-benzoquinones exhibit nucleophilic reactivity, such that exposure to appropriate electrophiles generates products of C-H iodination, bromination, and phenylselenation. This provides a mild and general method for direct halofunctionalization, and the first method that can achieve direct C-H phenylselenation of this compound class. The scope and limitations of the new protocols are outlined, and representative derivatizations are highlighted.