Neoaustin: a meroterpene produced by Penicillium sp

Julio Zukerman-Schpector; Stella H Maganhi; Taicia Pacheco Fill; Edson Rodrigues-Fo; Ignez Caracelli

doi:10.1107/S1600536809006618

. 2009 Feb 25;65(Pt 3):o612. doi: 10.1107/S1600536809006618

Neoaustin: a meroterpene produced by Penicillium sp.

Julio Zukerman-Schpector ^a,^*, Stella H Maganhi ^a, Taicia Pacheco Fill ^a, Edson Rodrigues-Fo ^a, Ignez Caracelli ^b

PMCID: PMC2968484 PMID: 21582264

Abstract

The title meroterpene neoaustin {systematic name: (1′S,2′R,3S,7′R,9′S,11′S,12′R)-11′-hydroxy-2,2,2′,9′,12′-pentamethyl-6′,15′-dimethylene-2,6-dihydro-13′-oxaspiro[pyran-3,5′-tetracyclo[7.5.1.0^1,11.0^2,7]pentadecane]-6,10′,14′-trione}, C₂₅H₃₀O₆, comprises five rings, three six-membered and two five-membered. The absolute configuration was established based on [α_D] = +166.91° (c 1.21, CH₂Cl₂). In the crystal, the molecules are connected into a supramolecular helical chain via O—H⋯O hydrogen bonds reinforced by C—H⋯O contacts.

Related literature

For related literature, see: dos Santos & Rodrigues-Fo (2002 ▶, 2003 ▶); Maganhi et al. 2009 ▶. For ring conformation analysis, see: Cremer & Pople (1975 ▶); Iulek & Zukerman-Schpector (1997 ▶).

Experimental

Crystal data

C₂₅H₃₀O₆
M _r = 426.49
Orthorhombic,
a = 11.2152 (4) Å
b = 13.2870 (5) Å
c = 14.3914 (7) Å
V = 2144.55 (15) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 290 K
0.49 × 0.39 × 0.21 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: none
18157 measured reflections
2622 independent reflections
2453 reflections with I > 2σ(I)
R _int = 0.048

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.106
S = 1.07
2622 reflections
286 parameters
H-atom parameters constrained
Δρ_max = 0.17 e Å⁻³
Δρ_min = −0.13 e Å⁻³

Data collection: APEX2, COSMO and BIS (Bruker, 2006 ▶); cell refinement: SAINT (Bruker, 2006 ▶); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶) and PARST (Nardelli, 1995 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809006618/tk2374sup1.cif

e-65-0o612-sup1.cif^{(26.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809006618/tk2374Isup2.hkl

e-65-0o612-Isup2.hkl^{(126.2KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O4—H1O4⋯O2ⁱ	0.82	2.06	2.852 (3)	162
C5—H5⋯O3ⁱⁱ	0.93	2.63	3.386 (3)	139

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

We thank FAPESP, CNPq and CAPES for financial support. Publication costs were met by FAPESP (Proc. 2008/02531–5). Professor R. A. Burrow of the Federal University of Santa Maria is gratefully acknowledged for helping with the collection of the intensity data.

supplementary crystallographic information

Comment

Endophytic fungi live in very intimate association with plant tissue and can produce compounds similar and sometimes identical to those produced by the host plant. Thus, fungi have been a rich source of important biologically active secondary metabolites, such as meroterpenoids, a class of complex metabolites derived from a mixed terpenoid-polyketide biosynthetic pathway. During an on-going study of substances produced by endophytic fungi, the title compound (I) was isolated and its structure postulated based on APCIMS (Atmospheric Pressure Chemical Ionization Mass Spectrometry) and a variety of NMR studies (dos Santos and Rodrigues-Fo, 2003). As suitable crystals were subsequently obtained, a crystal structure determination of (I) was undertaken, Fig. 1. The three six-membered rings are in different distorted conformations. Referring to the labels in Scheme 1, ring A is in a highly distorted half-boat conformation, ring B in a slightly distorted chair, and ring C is in a chair distorted towards a half-chair conformation. The five membered rings, D and E, are in a highly distorted envelope and a distorted twist conformation, respectively. The ring-puckering parameters (Cremer & Pople, 1975; Iulek & Zukerman-Schpector, 1997) in the order for A, B, C, D and E (when applicable) are: q₂ = 0.434 (2), 0.044 (2), 0.161 (2), 0.562 (2), 0.284 (2) Å, q₃ = 0.241 (2), 0.552 (2), -0.650 (2) Å, Q = 0.496 (2), 0.554 (2), 0.669 (2)°, φ₂ =-73.0 (3), -36 (3), 146.7 (7), -154.3 (3), 25.1 (5)°, and θ₂ = 60.9 (3), 4.5 (2), 166.1 (2)°. The absolute configuration was established based on the [α_D] = +166.914.97° (c 1.21, CH₂Cl₂) and the results reported in dos Santos and Rodrigues-Fo (2003). The molecules are linked via O-H···O hydrogen bonds, Fig. 2. which extend into a supramolecular helical chain which is reinforced via C-H···O contacts (Table 1).

Experimental

Compound (I), Neoaustin, was produced during cultivation of the fungus Penicillum sp over sterilized rice, and isolated from the methanol extract of the culture. Suitable crystals were obtained, by slow evaporation, from a mixture of dichloromethane, methanol and water.