# Isolation of Three New Diketopiperazine Alkaloids from Penicillium sp. SCH3-Sd2

## TL;DR

Researchers isolated three new alkaloids from a marine-derived Penicillium fungus and tested their antibacterial activity.

## Contribution

The discovery and structural characterization of three new diketopiperazine alkaloids from Penicillium sp. SCH3-Sd2.

## Key findings

- Three new diketopiperazine alkaloids were isolated from Penicillium sp. SCH3-Sd2.
- The compounds showed weak and selective antibacterial activity against Kocuria rhizophila KCTC 1915.
- Structures were confirmed using spectroscopic and advanced analytical methods.

## Abstract

Intensive analysis of the culture broth of the marine-derived Penicillium sp. strain SCH3-Sd2 led to the isolation of one spirocyclic diketopiperazine alkaloid, spirotryprostatin H (1), as well as two indolyl diketopiperazines, fumitremorgins O and P (2 and 3). The planar structures of 1–3 were elucidated by comprehensive spectroscopic analyses, while their absolute configurations were determined by combined NOESY and ECD analyses, and the configuration of the proline moiety was further confirmed using the advanced Marfey’s method. The evaluation of the antibacterial activity of compounds 1–3 against six bacterial strains revealed weak and selective activity only against Kocuria rhizophila KCTC 1915, with minimum inhibitory concentration (MIC) values of 64, 128, and 64 μg/mL, respectively.