Ferroverdin
{{Short description|Green pigment produced in the mycelium of Streptomyces}}
Ferroverdin refers to three different coordination compounds that were first isolated in 1955 by Chain, Tonolo, and Carilli.{{cite journal | journal = Nature | doi = 10.1038/224589a0 | title = Structure of ferroverdin | year = 1969 | last1 = Candeloro | first1 = Sofia | last2 = Grdenić | first2 = D. | last3 = Taylor | first3 = Noel | last4 = Thompson | first4 = B. | last5 = Viswamitra | first5 = M. | last6 = Hodgkin | first6 = Dorothy Crowfoot | volume = 224 | issue = 5219 | pages = 589–591| pmid = 5346597 |bibcode = 1969Natur.224..589C | s2cid = 4288012 }} It consists of three p-vinylphenyl-3-nitroso-4-hydroxybenzoate ligands complexed with a ferrous ion. Ferroverdin is a green pigment produced in the mycelium of species of Streptomyces. It is claimed to be the “first stable ferrous compound to be found in nature.”{{cite book | doi = 10.1007/BFb0119549 | chapter = Naturally occurring non-porphyrin iron compounds | year = 1966 | last1 = Neilands | first1 = J. B. | title = Structure and Bonding | volume = 1 | pages = 59–108| isbn = 978-3-540-03675-3 }} There are three types of ferroverdin: A, B, and C. In ferroverdin A, both R groups are hydrogens.{{cite journal | doi = 10.1016/0040-4020(95)00071-F | title = 4-Hydroxy-3-nitrosobenzamide and its ferrous chelate from Streptomyces murayamaensis | year = 1995 | last1 = Cone | first1 = M | journal = Tetrahedron | volume = 51 | issue = 11 | pages = 3095–3102}}
In ferroverdin B, R1 is a hydroxyl group (OH) and R2 is a hydrogen (according to a diagram in the paper, the R-groups are on the vinyl group, on the carbon opposite the phenyl; they are respectively trans and cis relative to the phenyl group).{{cite journal |author1=Tomoda, H |author2=Tabata, N |author3=Shinose, M |author4=Takahashi, Y |author5= Woodruff, H. |name-list-style=amp | year = 1999 | title = Ferroverdins, inhibitors of cholesteryl ester transfer protein produced by streptomyces sp. wk-5344. i. production, isolation and biological properties | journal = The Journal of Antibiotics | volume = 52 | issue = 12 | pages = 1101–1107 | pmid = 10695673 | doi=10.7164/antibiotics.52.1101| doi-access=free }} In ferroverdin C, R1 is a hydrogen while R2 is a carboxyl group (COOH). Ferroverdin is immune to chelating and oxidizing agents due to the strong interaction between the ligands and ferrous ion. However, it can be broken down by reductive processes.1{{Citation needed|reason=Orphan number (1) not linking to any reference. Question: Does it correspond to the orphan reference numbered 6, now isolated in the section "Further reading"?|date=March 2024}} The presence of ferroverdin peaks when there are four to eight μg/mL of Fe2+ in the media usually in the form of a salt.
Biological role
Ferroverdin has no antimicrobial or insecticidal activity, and may in fact be a siderophore. Siderophores are responsible for transporting iron (usually as Fe3+) from the medium into the cell to meet the metabolic needs of the organism. The significance of ferroverdin in the transfer pathway of iron remains unknown. Ferroverdin A, B, and C have also been found to inhibit cholesteryl ester transfer protein (CETP) which contributes to high blood pressure in humans.
Structure
The nitrosophenolate chelating group in the three ferroverdins is unusual. Simple synthetic analogues have been made containing 2-nitrosophenol itself. These complexes adopt a facial geometry owing to the binding of alkali metals to the three oxygen centers. Natural ferroverdin has thermodynamic specificity for fac geometry where the ligands have cis arrangements around the bivalent iron atom in low spin. The geometry was determined by 1H NMR which showed the same peak for the three ligands. Even though mer geometry is more sterically favorable, ferroverdin has fac geometry theoretically due to better π stabilization in its d6 orbitals, but further research is being done to provide evidence.{{cite journal | doi = 10.1007/BF02841933 | title = Ferroverdin: Cation variation and recognition of isomerictris chelate geometries by iron oxidation states|author1=Surajit Chattopadhyay |author2=Partha Basu |author3=Debashis Ray |author4=Samudranil Pal |author5=Animesh Chakravorty | journal = Journal of Chemical Sciences| year = 1990| volume = 102| issue = 3| pages = 195–202| s2cid = 92660666| doi-access = free}}
See also
- {{Annotated link|Streptomyces lunaelactis}}
References
{{Reflist}}
Further reading
- {{cite journal | doi = 10.1128/MMBR.00006-10 | title = Nitroaromatic compounds, from synthesis to biodegradation | year = 2010 | last1 = Ju | first1 = K.-S. | last2 = Parales | first2 = R. E. | journal = Microbiology and Molecular Biology Reviews | volume = 74 | issue = 2 | pages = 250–272 | pmid = 20508249 | pmc = 2884413}}