Issue 13, 2022

Discovery of varlaxins, new aeruginosin-type inhibitors of human trypsins


Low-molecular weight natural products display vast structural diversity and have played a key role in the development of novel therapeutics. Here we report the discovery of novel members of the aeruginosin family of natural products, which we named varlaxins. The chemical structures of varlaxins 1046A and 1022A were determined using a combination of mass spectrometry, analysis of one- and two-dimensional NMR spectra, and HPLC analysis of Marfey's derivatives. These analyses revealed that varlaxins 1046A and 1022A are composed of the following moieties: 2-O-methylglyceric acid 3-O-sulfate, isoleucine, 2-carboxy-6-hydroxyoctahydroindole (Choi), and a terminal arginine derivative. Varlaxins 1046A and 1022A differ in the cyclization of this arginine moiety. Interestingly, an unusual α-D-glucopyranose moiety derivatized with two 4-hydroxyphenylacetic acid residues was bound to Choi, a structure not previously reported for other members of the aeruginosin family. We sequenced the complete genome of Nostoc sp. UHCC 0870 and identified the putative 36 kb varlaxin biosynthetic gene cluster. Bioinformatics analysis confirmed that varlaxins belong to the aeruginosin family of natural products. Varlaxins 1046A and 1022A strongly inhibited the three human trypsin isoenzymes with IC50 of 0.62–3.6 nM and 97–230 nM, respectively, including a prometastatic trypsin-3, which is a therapeutically relevant target in several types of cancer. These results substantially broaden the genetic and chemical diversity of the aeruginosin family and provide evidence that the aeruginosin family is a source of strong inhibitors of human serine proteases.

Graphical abstract: Discovery of varlaxins, new aeruginosin-type inhibitors of human trypsins

Supplementary files

Article information

Article type
21 Dec 2021
03 Mar 2022
First published
09 Mar 2022
This article is Open Access
Creative Commons BY license

Org. Biomol. Chem., 2022,20, 2681-2692

Discovery of varlaxins, new aeruginosin-type inhibitors of human trypsins

L. M. P. Heinilä, J. Jokela, M. N. Ahmed, M. Wahlsten, S. Kumar, P. Hrouzek, P. Permi, H. Koistinen, D. P. Fewer and K. Sivonen, Org. Biomol. Chem., 2022, 20, 2681 DOI: 10.1039/D1OB02454J

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity