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Antifungal anthracycline antibiotics, spartanamicins A and B from Micromonospora spp
M G Nair1, S K Mishra, A R Putnam
1Department of Horticulture, Michigan State University, East Lansing 48824.
Abstract:
Spartanamicins A and B, two antifungal antibiotics, were produced by a culture of Micromonospora spp. strain No. MSU-43097 (ATCC 53803), isolated from a potted soil containing asparagus (Asparagus officinalis L.) plants. The antibiotics were isolated from the mycelial cake using organic solvents. The structures of spartanamicins A and B were determined by spectral and chemical means. Spartanamicin B is more active as an antifungal compound than it's analogue, A. The minimum inhibitory concentration for spartanamicin B on Candida albicans and Aspergillus, Cladosporium, Cryptococcus, Rhodotorula and Staphylococcus spp. ranged from 0.2 to 1 microgram/ml. It was not active against Staphylococcus aureus, Escherichia coli and Citrobacter spp. but some strains of S. aureus were sensitive.
Insights
Two novel antifungal antibiotics, spartanamicins A and B, were discovered from Micromonospora spp. Spartanamicin B exhibits potent activity against various fungi, with a minimum inhibitory concentration of 0.2-1 µg/ml.
Area of Science:
- Microbiology
- Natural Product Chemistry
- Antimicrobial Research
Background:
- Micromonospora species are known producers of bioactive secondary metabolites.
- Soil microorganisms are a rich source of novel antimicrobial compounds.
- The emergence of antifungal resistance necessitates the discovery of new therapeutic agents.
Purpose of the Study:
- To isolate and characterize novel antifungal antibiotics from Micromonospora spp.
- To evaluate the antifungal activity and spectrum of the isolated compounds.
- To elucidate the chemical structures of the identified antibiotics.
Main Methods:
- Isolation of Micromonospora spp. strain No. MSU-43097 from asparagus plant soil.
- Extraction and purification of antibiotics using organic solvents from mycelial cake.
- Structure elucidation of spartanamicins A and B via spectral and chemical analyses.
- Determination of minimum inhibitory concentrations (MICs) against various microbial species.
Main Results:
- Two antifungal antibiotics, spartanamicins A and B, were successfully isolated.
- Spartanamicin B demonstrated significant antifungal activity against Candida albicans, Aspergillus, Cladosporium, Cryptococcus, and Rhodotorula spp. with MICs ranging from 0.2 to 1 µg/ml.
- Spartanamicin B showed limited activity against Gram-negative bacteria like Escherichia coli and Citrobacter spp., and some strains of Staphylococcus aureus.
Conclusions:
- Spartanamicins A and B represent a new class of antifungal antibiotics produced by Micromonospora.
- Spartanamicin B is a promising candidate for further investigation as a therapeutic antifungal agent.
- The study highlights the potential of soil-derived actinomycetes for novel drug discovery.