Emodin - A natural anthraquinone derivative with diverse pharmacological activities.

Emodin (1,3,8-trihydroxy-6-methyl-anthraquinone) is a natural anthraquinone derivative that is present in numerous globally renowned herbal medicines. It is recognised as a protein tyrosine kinase inhibitor and as an anticancer drug, active against various tumour cells, including lung, breast, liver, and ovarian cancer cells. Recently, its role in combination chemotherapy with various allopathic medicines, to minimize their toxicity and to enhance their efficacy, has been studied. The use of emodin in these therapies is gaining popularity, due to fewer associated side effects compared with standard anticancer drugs. Emodin has a broad therapeutic window, and in addition to its antineoplastic activity, it displays anti-ulcer, anti-inflammatory, hepatoprotective, neuroprotective, antimicrobial, muscle relaxant, immunosuppressive and antifibrotic activities, in both in vitro and in vivo models. Although reviews on the anticancer activity of emodin have been published, none coherently unite all the pharmacological properties of emodin, particularly the anti-oxidant, antimicrobial, antidiabetic, immunosuppressive and hepatoprotective activities of the compound. Hence, in this review, all of the available data regarding the pharmacological properties of emodin are explored, with particular emphasis on the modes of action of the molecule. In addition, the manuscript details the occurrence, biosynthesis and chemical synthesis of the compound, as well as its toxic effects on biotic systems.

Single-step isolation of embelin using high-performance countercurrent chromatography and determination of the fatty acid composition of seeds of Embelia schimperi.

Embelin (2,5-dihydroxy-3-undecyl-p-benzoquinone) is known for its potent anthelmintic activity, but also for wound-healing, antidiabetic, anticonvulsant, antitumour, anti-inflammatory, analgesic, hepatoprotective, antioxidant, antibacterial and antispermatogenic activities. A high-performance countercurrent chromatography method was developed for the purification of embelin from an extract of the seeds of Embelia schimperi fruit. The optimized solvent system (n-hexane-ethylacetate-ethanol-water, 7:3:7:3) resulted in the isolation of 13.9 mg of embelin, directly from 100 mg of crude extract, in a single step within a short time (40 min). Although the compound appeared to be completely pure when analysed by ultra-performance liquid chromatography (UPLC) with photo diode array detection, the purity was established as ~90% by UPLC-mass spectrometry. Furthermore, we report the fatty acid composition of the seeds of E. schimperi fruit. Nine fatty acids were quantified from the fruit seed extract by gas chromatography-mass spectrometry, with linoleic (46.4%), palmitic (21.5%) and oleic (19.6%) acids making up the largest proportions.

Myricetin: A Dietary Molecule with Diverse Biological Activities.

Myricetin is a common plant-derived flavonoid and is well recognised for its nutraceuticals value. It is one of the key ingredients of various foods and beverages. The compound exhibits a wide range of activities that include strong anti-oxidant, anticancer, antidiabetic and anti-inflammatory activities. It displays several activities that are related to the central nervous system and numerous studies have suggested that the compound may be beneficial to protect against diseases such as Parkinson's and Alzheimer's. The use of myricetin as a preserving agent to extend the shelf life of foods containing oils and fats is attributed to the compound's ability to protect lipids against oxidation. A detailed search of existing literature revealed that there is currently no comprehensive review available on this important molecule. Hence, the present work includes the history, synthesis, pharmaceutical applications and toxicity studies of myricetin. This report also highlights structure-activity relationships and mechanisms of action for various biological activities.

Gingerols and shogaols: Important nutraceutical principles from ginger.

Gingerols are the major pungent compounds present in the rhizomes of ginger (Zingiber officinale Roscoe) and are renowned for their contribution to human health and nutrition. Medicinal properties of ginger, including the alleviation of nausea, arthritis and pain, have been associated with the gingerols. Gingerol analogues are thermally labile and easily undergo dehydration reactions to form the corresponding shogaols, which impart the characteristic pungent taste to dried ginger. Both gingerols and shogaols exhibit a host of biological activities, ranging from anticancer, anti-oxidant, antimicrobial, anti-inflammatory and anti-allergic to various central nervous system activities. Shogaols are important biomarkers used for the quality control of many ginger-containing products, due to their diverse biological activities. In this review, a large body of available knowledge on the biosynthesis, chemical synthesis and pharmacological activities, as well as on the structure-activity relationships of various gingerols and shogaols, have been collated, coherently summarised and discussed. The manuscript highlights convincing evidence indicating that these phenolic compounds could serve as important lead molecules for the development of therapeutic agents to treat various life-threatening human diseases, particularly cancer. Inclusion of ginger or ginger extracts in nutraceutical formulations could provide valuable protection against diabetes, cardiac and hepatic disorders.