Novel Antimicrobial Indolepyrazines A and B from the Marine-Associated Acinetobacter sp. ZZ1275.

Komal Anjum,Wenwen Yi,Sidra Kaleem,Xiaoyuan Lian,Guowan Zheng,Zhizhen Zhang

doi:10.3390/md17020089

Abstract

Two new alkaloids indolepyrazines A (1) and B (2) were isolated from the marine-derived Acinetobacter sp. ZZ1275. Their structures were elucidated through extensive nuclear magnetic resonance (NMR) spectroscopic analyses, high resolution electrospray ionization mass spectroscopy (HRESIMS) data, and electronic circular dichroism (ECD) calculation. Indolepyrazine A represents the first example of alkaloids with an indole-pyrazine-oxindole skeleton. Both 1 and 2 showed antimicrobial activities against methicillin-resistant Staphylococcus aureus, Escherichia coli, and Candida albicans with minimum inhibitory concentration (MIC) values of 12 μg/mL, 8–10 μg/mL, and 12–14 μg/mL, respectively.

Highlights

IntroductionSpecies of the genus Acinetobacter are Gram-negative bacteria and important soil organisms
Species of the genus Acinetobacter are Gram-negative bacteria and important soil organisms.They are found in hospital environments as a major source of infection in debilitated patients.The species Acinetobacter baumannii, in particular, is known to cause nosocomial infections, such as endocarditis, meningitis, pneumonia, septicaemia, and tract infection [1]
ZZ1275 was isolated from a sample of coastal muds during the process of our ongoing research to discover novel bioactive compounds from marine-associated microorganisms [10,11,12,13,14]

Summary

Introduction

Species of the genus Acinetobacter are Gram-negative bacteria and important soil organisms. They are found in hospital environments as a major source of infection in debilitated patients. It is our understanding that no natural product has yet been reported from marine-derived Acinetobacter species. ZZ1275 showed activities against the growth of methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, and Candida albicans. Chemical investigation of this antimicrobial extract resulted in the isolation and identification of two new alkaloids, named indolepyrazines A (1) and B (2). We have reported the isolation and culture of the strain ZZ1275 as well as the isolation, structural elucidation, and antimicrobial evaluation of the two compounds.

Results and Discussion

General Experimental Procedures

Isolation and Identification of Strain ZZ1275

Large Scale Culture of Strain ZZ1275

ECD Calculation

Conclusions