Spiroaspertrione A, a Bridged Spirocyclic Meroterpenoid, as a Potent Potentiator of Oxacillin against Methicillin-Resistant Staphylococcus aureus from Aspergillus sp. TJ23

Abstract

Bioassay-guided isolation of cultures of Aspergillus sp. TJ23 yielded a novel terpene-polyketide hybrid spiromeroterpenoid, spiroaspertrione A (1), bearing a unique spiro[bicyclo[3.2.2]nonane-2,1'-cyclohexane] carbocyclic skeleton, and a new biointermediate, andiconin B (2). Their structures and absolute configurations were elucidated by spectroscopic analyses, single-crystal X-ray diffraction, and electronic circular dichroism calculations. Compound 1 demonstrated potent resensitization of oxacillin against methicillin-resistant Staphylococcus aureus by lowering the oxacillin minimal inhibitory concentration up to 32-fold from 32 to 1 μg/mL.

Three New Indole Diketopiperazine Alkaloids from Aspergillus ochraceus

“…Analyses of the 1 8), H-C(5) to C(7) and C(9), H-C(1) to C(3) and C(9) established the presence of the indole ring. HMBCs from H-C(14) to C (12), H-C(11) to C(3), C (12), H-C(16) to C (18), H-C (17) to C(16) and C(18) revealed the presence of diketopiperazine with a proline moiety. [24] In addition, HMBCs from Me(23)/Me(24) to C(3) revealed the presence of another prenyl unit that contained a terminal double bond at C(3).…”

“…The 13 C-NMR and HSQC spectra indicated 26 carbon signals ascribed to three carbonyls (d(C) 181.9 (C(2)), 164.8 (C(12)), and 169.4 (C(18))), ten olefinic or aromatic carbons, two sp 3 quaternary carbons, two sp 3 methines, five sp 3 methylenes, and four methyl groups (d(C) 25.6, 22.2, 21.4, and 17.8). Analyses of the 1 H, 1 H-COSY spectrum revealed five spin systems of H-C(4)/H-C(5), H-C(25)/H-C (26), H-C(20)/H-C (21), H-C(10)/H-C(11), and H-C(14)/H-C(15)/H-C(16)/H-C (17). HMBCs from H-C(4) to C(3), C(6), C(8), H-C(5) to C(7) and C(9), H-C(1) to C(3) and C(9) established the presence of the indole ring.…”

“…[24] In addition, HMBCs from Me(23)/Me(24) to C(3) revealed the presence of another prenyl unit that contained a terminal double bond at C(3). HMBCs from H-C(14) to C(12), H-C(11) to C(3), C(12), H-C(16) to C(18), H-C (17) to C(16) and C (18) revealed the presence of diketopiperazine with a proline moiety. Two structural fragments were connected according to the key HMBCs from H-C(10) to C(2), C(9), and C (12).…”

Polyketide and Prenylxanthone Derivatives from the Endophytic Fungus Aspergillus sp. TJ23

“…TJ23, an endophytic fungus belong to the Aspergillus family, was isolated from the medicinal plant Hypericum perforatum L. Our previous studies on the secondary metabolites of this strain under different cultural conditions had led to the isolation of several novel and bioactive compounds. For example, two terpene-polyketide hybrid meroterpenoids, spiroaspertrione A [4] and aspermerodione [5] were found to be potential inhibitors of methicillin-resistant Staphylococcus aureus (MRSA).…”

“…TJ23 was chemically re-investigated. This work gave rise to the isolation and characterization of two new compounds, asperetide (1) and asperanthone (4), and six known compounds, (S)-3butyl-7-methoxyphthalide (2), [10] ruguloxanthone C (3), [11] tajixanthone hydrate (5), [12] tajixanthone methanoate (6), [13] salimyxin B (7), [14] and ergosterol (8; Figure 1). [15] Herein, we described the isolation, structural determination, and biological activity evaluation of the isolates.…”