¹³C Fourier transform n.m.r.: XIII—reassignment of the ¹³C spectrum of ergosterol

Abstract

Abstract-The complete labeling pattern of ergosterol isolated from(Merck, Sharpe and Dohnie, Canada). The yeasts were incubated for 20 h at 30 "C with constant aeration. A 500 ml culture of yeast was harvested by centrifuging to a final wet weight of 14g. The procedure for the isolation and purification of ergosterol was modified from that followed by Fryberg et ~1 .~ The 13C n.m.r. spectrum was determined on twice chromatographed (t.1.c. silica gel G ) ergosterol acetate (18 mg). G.1.p.c.: (98% pure), 0.25 mm i.d. x 40m column, coated with 3 % Silar-IOC on Gas-Chrom Q 100/120; temperature, 220°C; flow rate, 40 ml/min He. Relative retention time 1.6, relative to cholestanol acetate; Amax: 261.5,271, 281.5,293.5; Amax (authentic): 262, 271.5, 282, 294, envelopes were identical; m/e 378 ( M -CH,COOH), 367, 334, 312, 252. The spectrum was identical with authentic ergosterol acetate except for isotope multiplets, e.g. m/e 378 + (1,2,3, . . . The n.m.r. system consists of a Varian XL-100-15 spectrometer fitted with a TTlOO FT attachment. Conditions were: data set = 8 K; digitizing rate = 10 KHz; pulse width = 25 ,us; pulse delay = 2 s. Figure 1 (A) displays the proton noise-decoupled I3C n.m.r. spectrum of ergosterol acetate in CDCI,. The assignment of the individual carbons are indicated on the spectrum and the chemical shifts are contained in Table 1. The assignments are essentially those of Reich et al. ,5 however (see below). carbons are substantially enhanced over natural abundance. The biosynthetically enriched carbons correspond with the well-established pathway to steroids from acetyl CoA viz. acetate + mevalonate + isopentenyl pyrophosphate + farnesyl pyrophosphate 4 squalene -+ Of particular importance in the assignments of the enriched carbons are the pair of AB doublets due to 13C-l I-13C-12 and l3C-8-I3C-14, created by the head to head condensation of two farnesyl moieties and the subsequent cyclization step of squalene by cyclase. The assignments are confirmed by the carbon-carbon coupling constants, J(I 1-12) = 33 = 45 Hz.The characteristic triplet for C-12 in the enriched spectrum [ Fig. 1 (B

13C and 1H nuclear magnetic resonance spectroscopy of C-19 and 6β-methyl substituted steroids: long-range shift effects in conformational analysis

“…The chemical shifts in Table I for these compounds agree with tlie literature values to 0.6 ppm or better, which is in the range expected for solvent and concentration effects. Our assignments for Brr, Bb, and I c agree L\ ith those originally reported (10-1 3) except for the reversal of the assignments of C-12 and C-16; as noted for cholesterol (14) and sorne cholestanes (15) and later confirmed for several related steroids (16)(17)(18)(19).…”

Neoplaether, a new cytotoxic and antifungal endophyte metabolite fromNeoplaconema napellumIFB-E016

“…The methanol extract derived from the solid‐substrate fermentation materials of the endophytic strain IFB‐E016 was chromatographed repeatedly on silica gel, Sephadex LH‐20 and reversed‐phase ODS column to yield a new diphenyl ether (neoplaether) in addition to five known metabolites, monomethylsulochrin (Ma et al , 2004), physcion (Xiang et al , 2001), helvolic acid (Cole & Cox, 1981), as well as ergosterol (Cushley & Filipenko, 1976) and its peroxide (Ma et al , 1994).…”

Anti-Helicobacter pylori substances from endophytic fungal cultures

“…Through a bioassay-guided fractionation of the ethyl acetate extract of the endophytic culture, four main anti-H. pylori secondary metabolites (1-4) were obtained. On the basis of spectral and physical data, compounds 1-4 were identified as helvolic acid (Oxley 1966;Okuda et al 1967), monomethylsulochrin (Turner 1965), ergosterol (Cushley & Filipenko 1976), 3b-hydroxy-5a,8a-epidioxy-ergosta-6,22-diene (Ma et al 1994), respectively (Figure 1). To exclude the possibility that any of the four isolated metabolites might have originated from the medium materials used in the study, an LC-MS examination was therefore conducted with the ethyl acetate extract of the blank sterile medium treated identically to with fungal cultures.…”