Tailored Functionalization of Natural Phenols to Improve Biological Activity

Phenols are widespread in nature, being the major components of several plants and essential oils. Natural phenols’ anti-microbial, anti-bacterial, anti-oxidant, pharmacological and nutritional properties are, nowadays, well established. Hence, given their peculiar biological role, numerous studies are currently ongoing to overcome their limitations, as well as to enhance their activity. In this review, the functionalization of selected natural phenols is critically examined, mainly highlighting their improved bioactivity after the proper chemical transformations. In particular, functionalization of the most abundant naturally occurring monophenols, diphenols, lipidic phenols, phenolic acids, polyphenols and curcumin derivatives is explored.

Effects of different drying conditions on curcumin concentration in turmeric

Turmeric (Curcuma longa), belongs to Zingiberaceae family. The rhizomes contain bioactive compounds of the curcuminoids group (natural phenols). They are used in food and pharmaceutical industry. The aim of this research was to acquire dried turmeric with high total curcumin content. In this study, optimum turmeric drying conditions and new extraction techniques were explored. Fresh turmeric samples were subjected to constant vs changing drying air temperatures and pre-treatment (blanching). Changing drying air temperature and use of non-blanched turmeric slices resulted in the highest concentration of curcumin. Ultrasonic extraction instead of soxhlet extraction improved the extraction efficiency and decreased extraction time. Keywords: Turmeric, Curcumin; Drying; Blanching; Extraction

Molecular Docking Evaluation of Some Natural Phenolic Compounds as Aldose Reductase Inhibitors for Diabetic Complications

The enzyme aldose reductase (AR) is a member of aldoketoreductase super-family which catalyzes the formation of sorbitol from glucose through polyol pathway of glucose catabolism. Reduced sorbitol production via polyol pathway due to AR inhibition is a target of choice for controlling major complications of diabetes. Epalrestat is the only commercially available inhibitor of AR till date,thus, there is a great need to search for more economical, nontoxic and safer inhibitors of AR enzyme. Flavonoids,the polyphenol compounds in plants have been reported for inhibitory effects against AR. The objective of this study is to explore the binding modes of naturalphenolic compounds with AR to design safer natural drugs as alternatives to synthetic drugs. We conducted a molecular docking study on some naturalphenolic compounds with AR enzyme in complex with the synthetic inhibitor. The overlay of the docked pose of the selected natural phenols with the ARreference inhibitor complex showed that the selected natural compounds have the similar binding pattern with the active site residues of the enzyme as that of co-crystallized inhibitor. The results of docking study showed the best binding affinity of AR with that of 2-(4-hydroxy-3-methoxyphenyl) ethanoic acid and butein, having the lowest binding free energy of –9.8 kcal/mol and–9.7 kcal/mol, respectively. This information can be utilized to design potent, economical and non-toxic natural AR inhibitors from natural phenols for the therapeutics of diabetic complications.