Document Type : Review Article


1 Department of Biological Sciences, Faculty of Science, University of Kurdistan, Kurdistan, Sanandaj, Iran

2 Nanobiotechnology Department, Faculty of Innovative Science and Technology, Razi University, Kermanshah, Iran

3 Laser Research Centre, Faculty of Health Science, University of Johannesburg, Doornfontein, 2028, South Africa

4 Wellman Centre for Photomedicine, Massachusetts General Hospital, Boston, MA 02114, USA

5 Department of Dermatology, Harvard, California, USA

6 High Performance Powertrain Materials Laboratory, School of Engineering, University of British Columbia – Okanagan, Kelowna, V1V 1V7, Canada

7 Department of Neuroscience, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037; Howard Hughes Medical Institute, The Scripps Research Institute, La Jolla, CA 92037, USA

8 Department of Drug and Food Control, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran



There are up to one million secondary metabolites found in plant species, some of which may have desirable therapeutic activities. Among these secondary metabolites, catechin, gallic acid, and epigallocatechin-3-gallate are natural phenolic compounds with promising antioxidant and antibacterial activity. However, these compounds have disadvantages of poor solubility and low bioavailability in physiological conditions, along with side effects in patients. Therefore new strategies could rely on formulations with other synthetic and natural materials. Nanoformulations of secondary metabolites could be new efficient strategies to treat many chronic bacterial infections. Combinations and conjugates of catechin, gallic acid, and epigallocatechin-3-gallate with various antibiotics could reduce the dose of these compounds, increase their antibacterial activity, and decrease cytotoxicity against healthy cells. For instance, a smart combination of two or more secondary metabolites may improve therapeutic applications in physiological conditions. In this regard, the growth of antibiotic-resistant bacteria, specifically multidrug-resistant bacteria with overexpression of efflux pumps and expression of the penicillinase enzyme, has been inhibited significantly. According to recent investigations, this review will discuss the advances and challenges of new micro and nanoformulations of these natural products.


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