Biological effects of essential oils - A review

Epithelial to mesenchymal transition (EMT) is essential for driving plasticity during development, but is an unintentional behaviour of cells during cancer progression. The EMT-associated reprogramming of cells not only suggests that fundamental changes may occur to several regulatory networks but also that an intimate interplay exists between them. Disturbance of a controlled epithelial balance is triggered by altering several layers of regulation, including the transcriptional and translational machinery, expression of non-coding RNAs, alternative splicing and protein stability.

Regulatory networks defining EMT during cancer initiation and progression

Epithelial–mesenchymal transition (EMT) is a cellular programme that is known to be crucial for embryogenesis, wound healing and malignant progression. During EMT, cell–cell and cell–extracellular matrix interactions are remodelled, which leads to the detachment of epithelial cells from each other and the underlying basement membrane, and a new transcriptional programme is activated to promote the mesenchymal fate. In the context of neoplasias, EMT confers on cancer cells increased tumour-initiating and metastatic potential and a greater resistance to elimination by several therapeutic regimens. In this Review, we discuss recent findings on the mechanisms and roles of EMT in normal and neoplastic tissues, and the cell-intrinsic signals that sustain expression of this programme. We also highlight how EMT gives rise to a variety of intermediate cell states between the epithelial and the mesenchymal state, which could function as cancer stem cells. In addition, we describe the contributions of the tumour microenvironment in inducing EMT and the effects of EMT on the immunobiology of carcinomas. Epithelial–mesenchymal transition (EMT) is crucial for embryogenesis, wound healing and cancer development, and confers greater resistance to cancer therapies. This Review discusses the mechanisms of EMT and its roles in normal and neoplastic tissues, the contribution of cell-intrinsic signals and the microenvironment to inducing EMT, and its effects on the immunobiology of carcinomas.

New insights into the mechanisms of epithelial–mesenchymal transition and implications for cancer

Emerging Biological Principles of Metastasis

Eating five servings of fruits and vegetables per day! This is what is highly recommended and heavily advertised nowadays to the general public to stay fit and healthy! Drinking green tea on a regular basis, eating chocolate from time to time, as well as savoring a couple of glasses of red wine per day have been claimed to increase life expectancy even further! Why? The answer is in fact still under scientific scrutiny, but a particular class of compounds naturally occurring in fruits and vegetables is considered to be crucial for the expression of such human health benefits: the polyphenols! What are these plant products really? What are their physicochemical properties? How do they express their biological activity? Are they really valuable for disease prevention? Can they be used to develop new pharmaceutical drugs? What recent progress has been made toward their preparation by organic synthesis? This Review gives answers from a chemical perspective, summarizes the state of the art, and highlights the most significant advances in the field of polyphenol research.

Plant Polyphenols: Chemical Properties, Biological Activities, and Synthesis

Plumbagin is one of the simplest plant secondary metabolite of three major phylogenic families viz. Plumbaginaceae, Droseraceae, and Ebenceae, and exhibits highly potent biological activ- ities, including antioxidant, antiinflammatory, anticancer, antibacterial, and antifungal activities. Recent investigations indicate that these activities arise mainly out of its ability to undergo redox cycling, generating reactive oxygen species and chelating trace metals in biological system. The com- pound is endowed with a property to inhibit the drug efflux mechanism in drug-resistant bacteria, thereby allowing intracellular accumulation of the potent drug molecules. An interesting bioactivity exhibited by this compound is the elimination of stringent, conjugative, multidrug-resistant plasmids from several bacterial strains including opportunistic bacteria, such as Acinetobacter baumannii. Moreover, plumbagin effectively induces apoptosis and causes cell cycle arrest, which is, in part, due to the inactivation of NF-kB in cancer cells. Therefore, it has been suggested that designing ''hybrid drug molecules'' of plumbagin by combining it with other appropriate anticancer agents may lead to the generation of novel and potent anticancer drugs with pleiotropic action against human cancers. This comprehensive review is an attempt to understand the chemistry of plumbagin and catalog its biological

Perspectives on medicinal properties of plumbagin and its analogs

Several plant-derived polyphenolic compounds are considered to possess anticancer and apoptosis-inducing properties in cancer cells. Such compounds are recognized as naturally occurring antioxidants but also exhibit prooxidant properties under appropriate conditions. Evidence in the literature suggests that the antioxidant properties of polyphenolics such as gallotannins, curcumin, and resveratrol may not fully account for their chemopreventive effects. We propose a mechanism for the cytotoxic action of these compounds against cancer cells that involves mobilization of endogenous copper and the consequent prooxidant action.

https://iubmb.onlinelibrary.wiley.com/doi/pdf/10.1080/152165400300001471

Putative mechanism for anticancer and apoptosis-inducing properties of plant-derived polyphenolic compounds.

Summary Over many centuries humans have been mining the bounties of nature for discovering substances that have been used for the treatment of all human diseases; many such remedies are useful even today as modern day medicine. Emerging evidence also suggests that the search is still continuing for harnessing active compounds from nature in combating human illnesses although pharmaceutical industries are equally active for synthesizing small molecule compounds as novel therapeutics. The lesson learned over many centuries clearly suggests that further sophisticated search for finding compounds from natural resources together with robust characterization and chemical synthesis will lead to the discovery of novel drugs that may have high therapeutic efficacy against all human diseases including cancer. Black cumin seed (Nigella sativa) oil extracts have been used for many centuries for the treatment of many human illnesses, and more recently the active compound found in black seed oil, viz. thymoquinone (TQ) has been tested for its efficacy against several diseases including cancer. However, further research is needed in order to assess the full potential of TQ as a chemopreventive and/or therapeutic agent against cancers. Here, we have summarized what is known regarding the value of black seed oil and its active compound TQ, and how this knowledge will help us to advance further research in this field by creating awareness among scientists and health professionals in order to appreciate the medicinal value of TQ and beyond.

From here to eternity - the secret of Pharaohs: Therapeutic potential of black cumin seeds and beyond.

The identification of small subpopulations of cancer stem cells (CSCs) from blood mononuclear cells in human acute myeloid leukemia (AML) in 1997 was a landmark observation that recognized the potential role of CSCs in tumor aggressiveness. Two critical properties contribute to the functional role of CSCs in the establishment and recurrence of cancerous tumors: their capacity for self-renewal and their potential to differentiate into unlimited heterogeneous populations of cancer cells. These findings suggest that CSCs may represent novel therapeutic targets for the treatment and/or prevention of tumor progression, since they appear to be involved in cell migration, invasion, metastasis, and treatment resistance-all of which lead to poor clinical outcomes. The identification of CSC-specific markers, the isolation and characterization of CSCs from malignant tissues, and targeting strategies for the destruction of CSCs provide a novel opportunity for cancer research. This overview describes the potential implications of several common CSC markers in the identification of CSC subpopulations that are restricted to common malignant diseases, e.g., leukemia, and breast, prostate, pancreatic, and lung cancers. The role of microRNAs (miRNAs) in the regulation of CSC function is also discussed, as are several methods commonly used in CSC research. The potential role of the antidiabetic drug metformin- which has been shown to have effects on CSCs, and is known to function as an antitumor agent-is discussed as an example of this new class of chemotherapeutics.

Aamir Ahmad

Papers

Perspectives on medicinal properties of plumbagin and its analogs

Putative mechanism for anticancer and apoptosis-inducing properties of plant-derived polyphenolic compounds.

From here to eternity - the secret of Pharaohs: Therapeutic potential of black cumin seeds and beyond.

Overview of cancer stem cells (CSCs) and mechanisms of their regulation: implications for cancer therapy.

Anti-oxidant, pro-oxidant properties of tannic acid and its binding to DNA