Natural Product Chemistry (Tsutomu HATANO)

Natural Product Chemistry Tsutomu HATANO, PhD

Major Areas of Research

1. Searching New Natural Substances Effective on Drug-resistant Bacteria
2. Analyses of Tannin-Protein Complexes

Current Research Interests

Recent investigations on the pharmacologically active natural compounds revealed that tannins, flavonoids, and related polyphenols have anti-tumor and various antimicrobial effects, in addition to the antioxidant effects. We have found that several flavonoid compounds isolated from licorice, which is one of the most frequently used natural medicines in Asian countries, had noticeable suppressive effects on the beta-lactam resistance of methicillin-resistant Staphylococcus aureus (MRSA). We also found some hydrolysable tannins isolated from Psidium guajava leaves showed antibacterial effects on Vibrio and Aeromonas species, which are known to be food-poisoning bacteria. On the other hand, our studies showed oligomeric hydrolysable tannins isolated from Tamarix plant species have potent antitumor effects. Tannins are regarded to be polyphenols with potent biding effects on proteins. Although the participation of electrostatic interaction, hydrogen bonding, hydrophobic interaction, and also covalent binding in the tannin-protein association have been reported, details for each of the tannin-protein combinations have not yet been characterized well. Our studies clarified some polyphenolic compounds, which are also known as metabolites of tannins, bind human serum albumin at Site I and Site II, depending on their structures. Formation of large hypermolecules of tannin-protein complexes has been reported, too.

Selected Recent Publications

1. Bao L.-M., Eerdunbayaer, Nozaki A., Takahashi E., Okamoto K., Ito H., Hatano T. (2012) Hydrolysable tannins isolated from Syzygium aromaticum: Structure of a new C-glucosidic ellagitannin and spectral features of tannins with a tergalloyl group, Heterocycles, 85 (2), 365-381.
2. Orabi M. A. A., Taniguchi S., Terabayashi S., Hatano T. (2011) Hydrolyzable tannins of tamaricaceous plants. IV: Micropropagation and ellagitannin production in shoot cultures of Tamarix tetrandra, Phytochemistry, 72 (16), 1978-89.
3. Nozaki A., Kimura T., Ito H., Hatano T. (2009) Interaction of polyphenolic metabolites with human serum albumin: A circular dichroism study, Chem. Pharm. Bull., 57 (9), 1019-1023.