Potent inhibition of monoamine oxidase b by a piloquinone from marine-derived streptomyces sp. CNQ-027

Hyun Woo Lee, Hansol Choi, Sang Jip Nam, William Fenical, Hoon Kim

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26 Scopus citations


Two piloquinone derivatives isolated from Streptomyces sp. CNQ-027 were tested for the inhibitory activities of two isoforms of monoamine oxidase (MAO), which catalyzes monoamine neurotransmitters. The piloquinone 4,7-dihydroxy-3-methyl-2-(4-methyl-1-oxopentyl)-6H-dibenzo[b,d]pyran-6-one (1) was found to be a highly potent inhibitor of human MAO-B, with an IC value of 1.21 µM; in addition, it was found to be highly effective against MAO-A, with an IC value of 6.47 µM. Compound 1 was selective, but not extremely50 so, for MAO-B compared with50 MAO-A, with a selectivity index value of 5.35. Compound 1,8-dihydroxy-2-methyl-3-(4-methyl-1-oxopentyl)-9,10-phenanthrenedione (2) was moderately effective for the inhibition of MAO-B (IC = 14.50 µM) but not for MAO-A (IC > 80 µM). There was no time-dependency in inhibition50 of MAO-A or -B by compound 1, and50the MAO-A and -B activities were almost completely recovered in the dilution experiments with an excess amount of compound 1. Compound 1 showed competitive inhibition for MAO-A and -B, with K values of 0.573 and 0.248 µM, respectively. These results suggest that piloquinones from a microbial source could be potent reversible MAO inhibitors and may be useful leadi compounds for developing MAO enzyme inhibitors to treat related disorders, such as depression, Parkinson’s disease, and Alzheimer’s disease.

Original languageEnglish
Pages (from-to)785-790
Number of pages6
JournalJournal of Microbiology and Biotechnology
Issue number4
StatePublished - Apr 2017

Bibliographical note

Publisher Copyright:
© 2017 by The Korean Society for Microbiology and Biotechnology.


  • Competitive inhibitor
  • Monoamine oxidase
  • Piloquinone
  • Potent selective inhibitor
  • Streptomyces sp. CNQ-027


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