Chikao Nishino

Antibacterial activity and mode of action of plant flavonoids against Proteus vulgaris and Staphylococcus aureus

(−)-Epigallocatechin, an antibiotic found in Elaeagnus glabra, and 28 other related plant flavonoids were tested for their antibacterial activity against Proteus vulgaris and Staphylococcus aureus. A free 3′,4′,5′-trihydroxy B-ring and a free 3-OH were necessary for antibacterial activity. DNA synthesis was predominantly inhibited by the active flavonoids in P. vulgaris, whereas RNA synthesis was inhibited in S. aureus.

Cytotoxicity of plant flavonoids against HeLa cells

Abstract (-)-Epigallocatechin and 28 other plant flavonoids were tested for cytotoxic activity against HeLa cells. Flavones and flavanones were active and several compounds with planar and non-planar ring systems showed high cytotoxic activities. Although no clear structure activity relationship was deduced, hydroxyl groups on the A- and B- ring affected the cytotoxic potency positively or negatively, depending on the position of substitution. The uptake of thymidine was predominantly inhibited by myricetin, whereas the uptake of uridine was inhibited by (−)- epigallocatechin; the uptake of both thymidine and uridine were inhibited by 7,8-dihydroxyflavone.

Antibacterial Activity of Flavonoids againstStaphylococcus epidermidis, a Skin Bacterium

Alcaraz M. J., M. L. Ferrandiz, and A. Villar, Flavonoid Inhibition of Soybean Lipoxygenase, Pharmazie, vol. 41, pp. 299-300 (1986). Kimmich G. A. and J. Randles, Phloretin-like Action of Bioflavonoids on Sugar Accumulation Capability of isolated Intestinal Cells, Membrane Biochemistry, vol. 1, Nos. 3 & 4, pp. 221-237 (1978). Middleton E., Jr., G. Drzewiecki, and J. Tatum, “The Effects of Citrus Flavonoids on Human Basophil and Neutrophil Function, Planta Medica, vol.53, pp. 325–328 (1987). Nishino C., N. Enoki, S.Tawata, A. Mori, K. Kobayashi, and M. Fukushima, Antibacterial Activity of Flavonoids Against Staphylococcus Epidermis, a Skin Bacterium, Agric. Biol, Chem., vol. 51, pp. 139-143 (1987). Randles J. and G. Kimmich, Effects of Phloretin and Theophylline on 3-O-methylglucose Transport by Intestinal Epithelial Cells, American Physiological Society, pp. C64-C72 (1978). Welton A., L. Tobias, C. Fiedler-Nagy, W. Anderson, W. Hope, K. Meyers, and J. Coffey, Effect of Flavonoids on Arachiodonic Acid Metabolism, Plant Flavonoids in Biol ogy and Medicine: Biochemical Pharmacological, and Structure-Activity Relationships, pp. 231-242 (1986). Wilkinson D. I. and E. K. Orenberg, “Effects of Nordihy droguaiaretic Acid, Phloretin, and Phloridzin on the Activity of Adenylate Cyclase, Lipoxygenase and Hexose Transport and Growth of Cultured Keratinocytes, Pharmacology and Therapeutics, vol. 26, pp. 660-666 (1987).

Isolation and Structure of Maingayic Acid, a Piscicidal Constituent of Callicarpa maingayi

A piscicidal constituent (1), C20H28O3, (chloroform), which was named maingayic acid, was isolated from the leaf of Callicarpa maingayi. On the basis of the chemical spectral studies, the pKMCS evaluation and the octant rule on the ORD curves, we have and deduced that maingayic acid is a furanoid diterpene acid possessing a rearranged labdane skeleton shown as 1’a.