Isolation, Characterization and Bioactivity of 18 Microbial Metabolites of 4'-hydroxyflavanone

Flavonoids, an important part of the human diet, are associated with many beneficial biological activities. Although most flavonoids are considered to be safe, their potential toxicities as well as their drug interactions have not been well studied. This underlines the importance of determining the metabolic pathways of flavonoids that are being consumed in measurable amounts by man. Microorganisms can be utilized as models of drug metabolism to establish the fate of flavonoids in mammalian systems[1]. This procedure gives significant quantities of metabolites for complete structure elucidations and for further pharmacological evaluations. Fermentation of 4'-hydroxyflavanone (1) with fungal cultures, Beauveria bassiana (ATCC 13144 and ATCC 7159) yielded (2–5) and (7). B. bassiana (ATCC 13144) and B. bassiana (ATCC 7159) in addition, gave one more metabolite each, namely, (6) and (8) respectively. Cunninghamella echinulata (ATCC 9244) transformed 1 to (8–12). Mucor ramannianus (ATCC 9628) metabolized 1 to (13–19). Structures of the metabolites were elucidated by means of spectroscopic data. None of the metabolites tested showed antibacterial, antifungal and antiprotozoal activities against selected organisms.

1

2

3

4

5

6

7

8

9

10

11

12

R1

H

OH

GlcMe

H

OH

H

GlcMe

OH

H

H

H

H

R2

OH

OH

OH

OH

OH

GlcMe

OH

OH

Glc

OSO3H

OH

OH

R3

H

OH

OH

OSO3H

OSO3H

H

H

H

H

OH

OH

Glc

	13	14	15	16	17	18	19
R1	H	H	H	H	H	H	H
R2	H	H	OH	OH	OH	H	H
R3	OH	OH	OH	OH	OMe	deoxyallose	deoxyallose
R4	βOH	αOH	βOH	αOH	βOH	O	αOH

Acknowledgements: This work was supported, in part, by the United States Department of Agriculture, Agricultural Research Specific Cooperative Agreement no. 58–6408–2-00009.

References: [1] Rosazza PN, Duffel MW, Alkaloids: Chemistry and Pharmacology, Vol. 27, Chap. 4, ed. by Brossi A., Academic Press, New York, 1986, pp. 391–392.