Structural and Bioactivity Characterization of Filipin Derivatives from Engineered Streptomyces filipinensis Strains Reveals Clues for Reduced Haemolytic Action

Abstract

The rise in the number of immunocompromised patients has led to an increased incidence of fungal infections, with high rates of morbidity and mortality. Furthermore, misuse of antifungals has boosted the number of resistant strains to these agents; thus, there is urgent need for new drugs against these infections. Here, the in vitro antifungal activity of filipin III metabolic intermediates has been characterized against a battery of opportunistic pathogenic fungi—Candida albicans, Candida glabrata, Candida krusei, Cryptococcus neoformans, Trichosporon cutaneum, Trichosporon asahii, Aspergillus nidulans, Aspergillus niger, and Aspergillus fumigatus—using the Clinical and Laboratory Standards Institute broth microdilution method. Structural characterization of these compounds was undertaken by mass spectrometry (MS) and nuclear magnetic resonance (NMR) following HPLC purification. Complete NMR assignments were obtained for the first time for filipins I and II. In vitro haemolytic assays revealed that the haemolytic action of these compounds relies largely on the presence of a hydroxyl function at C26, since derivatives lacking such moiety show remarkably reduced activity. Two of these derivatives, 1′-hydroxyfilipin I and filipin I, show decreased toxicity towards cholesterol-containing membranes while retaining potent antifungal activity, and could constitute excellent leads for the development of efficient pharmaceuticals, particularly against Cryptococcosis.

Comparative Genomic and Metabolic Analysis of Streptomyces sp. RB110 Morphotypes Illuminates Genomic Rearrangements and Formation of a New 46-Membered Antimicrobial Macrolide

“…Despite the intrinsic instability and often high toxicity of polyene macrolactams, several derivatives are world-leading drugs in clinical use, such as nystatin (tetraenes), filipins (pentaenes), , and amphotericin B (heptaene). , As the numbers of conjugated double bonds within the polyene macrolides have been presumed to correlate with higher fungicidal activity, we anticipated a similar degree of antibiotic activity of termidomycin A ( 1 ). Indeed, activity studies revealed moderate to good antimicrobial activity against Gram-positive and Gram-negative bacteria and fungi ( Bacillus subtilis , Escherichia coli , Pseudomonas aeruginosa , Mycobacterium vaccae , Sporobolomyces salmonicolor , and Penicillium notatum (Table S5)) in comparison to that of the positive controls ciprofloxacin and amphotericin B.…”

“…First, the acquired metabolic data of strain RB110−1 was searched for the absence/presence of the proposed longer-chain termidomycin congener E (5; Figure 2C, Figures S20−S23 Bioactivity Studies. Despite the intrinsic instability and often high toxicity of polyene macrolactams, several derivatives are world-leading drugs in clinical use, such as nystatin (tetraenes), 42 filipins (pentaenes), 43,44 and amphotericin B (heptaene). 44,45 As the numbers of conjugated double bonds within the polyene macrolides have been presumed to correlate with higher fungicidal activity, we anticipated a similar degree of antibiotic activity of termidomycin A (1).…”

“…RB110, a phenomenon that has been proposed to allow for the division of labor among the bacterial population. The altered metabolic productivity is believed to influence the population-wide fitness as well as interaction mechanisms with co-occurring microbes. − While the parental morphotype RB110–1 is more prolific in terms of spore formation, its emerging morphotype RB110–2 unleashes the production of additional antifungal metabolites, including the increased production of several griseorhodin derivatives and a novel 46-member glycosylated macrolide named termidomycin A. Thus, it is hypothesized that the coproduction of both antibiotics potentially offers a growth benefit or protection for the emerging genetically heterogeneous bacterial colony and/or the spore-forming parental phenotype. , …”

Polyene Antibiotics Physical Chemistry and Their Effect on Lipid Membranes; Impacting Biological Processes and Medical Applications

“…It has also been used to detect Niemann–Pick type C disease [ 13 ] which is an autosomal recessive lysosomal storage disorder due to mutations in the NPC1 or NPC2 gene that can lead to a fatal disease in neonatal infants or chronic neurodegeneration in adults [ 87 ]. Filipin, similar to other polyenes, has been used to construct semi-synthetic derivatives searching to increase safety [ 88 ].…”

The Discovery of Actinospene, a New Polyene Macrolide with Broad Activity against Plant Fungal Pathogens and Pathogenic Yeasts

“…the presence three vinyl methyls, eight olefinic protons, fourteen oxymethine, and an aminosugar moiety. The The geometry of the three double bonds of the tetraene chromophore has been assigned as 16E, 18E, and 22E-configuraiton based on the large vicinal coupling constants between H-16 and H-17 (J = 14.9 Hz), H-18 and H-19 (J = 15.0 Hz), H-22 and H-23 (J = 13.7 Hz) [21]. The vicinal coupling constant J20,21 could not be detected due to the absence of proton on C-20.…”