M. hyalina produces the sulfur-containing volatile
tris(methylthio)methane (TMTM)
To identify the volatiles from M. hyalina which are responsible
for the garlic-like smell, the GC-MS chromatograms of SPME volatile
collections of the headspace of slant cultures of M. hyalina were
compared with the collections from the headspace of the growth medium.
Three major constituents could be identified (Figure 1) of which the
HR-MS of the molecular ions M+ and
[M+2]+ (for the 34S
isotopologue) revealed the molecular formulas
C3H8S2 (m/z measured
108.0062, 110.0020 calc. 108.0062, 110.0020; RI 894; 2% rel.),
C3H8S3 (m/z measured
137.9626, 139.9585 calc. 137.9626, 139.9584; RI 1197; 2% rel.), and
C4H10S3 (m/z measured
153.9942, 155.9910 calc. 153.9939, 155.9897, RI 1217; 96% rel.).
C3H8S2 and
C3H8S3 could be
identified as bis(methylthio)methane (RIlit. 889) and
dimethyl trithiocarbonate (RIlit. 1196), respectively by
comparison of their mass spectra and RI with the datasets of the NIST
library and additionally with mass spectra and RI of authentic samples
recorded under the same conditions.
For C4H10S3, the major
compound of the headspace of M. hyalina , library searches in NIST
and Wiley mass spectra databases revealed no hit in combination with the
RI. Therefore M. hyalina was extracted by hydro distillation. The
obtained essential oil consisted mainly of three compounds (by GC-MS):
Octenol-3-ol (22.4%) 3-octenone (21.7%) and
C4H10S3 (27,3%). NMR
analysis of the mixture could reduce the structure motive of
C4H10S3 to
(CH3-X)n-CH (X = S, O, etc. )
which in combination with the empirical formula
C4H10S3 from HR-MS led
to the structure of tris(thiomethyl)methane. Comparison with an
authentic sample of tris(methylthio)methane (Aldrich) showed to be
identical with respect to NMR and mass spectra, and
RI
(Figure 1 and Table 1).