Influence of sulfur fumigation on volatile oil constituents of Codonopsis radix (Dangshen) by GC-MS method

Background: Sulfur fumigation is one of the processing methods of Chinese medicinal herbs. This method can be used in bleaching herbs and controlling microorganisms, parasites and insects. Codonopsis Radix (Dangshen in Chinese), dried roots of Codonopsis pilosula, is one of the herbs commonly processed by sulfur fumigation. This study reports the influence of sulfur fumigation on the chemical constituents of the volatile oil of Dangshen.

Materials and Methods: The volatile oil of air-dried or sulfur fumigated Dangshen was extracted by water-steam distillation and separated by GC capillary column chromatography. The components in the individual volatile oil were identified and quantitatively determined by GC-MS.

Results: The results showed that 45 compounds were separated and identified from the volatile oil of Dangshen samples. Among them, the contents of 23 compounds in sulfur-fumigated Dangshen were much lower than that in air-dried Dangshen, such as 4-bromo-1-cyclohexene (6), 3,5-dimethylcyclopentene (7), phenylethyl alcohol (11), 2,3 diazabicyclo[2.2.1]hepy-2-ene,4-methyl-1-(pent-4-en-1-yl)- (22) and cedren-13-ol, 8- (35). On the contrary, the contents of 12 compounds were increased after sulfur fumigation, such as (+)-sativene (25), thujopsene (27), chamigren (30), a-guaiene (32) and 3- buten-2-one, 3-methyl-4-[(1R,2R,6S)-1,3,3-trimethyl-7-oxabicyclo[4.1.0]hept-2-yl] , (3E)-rel- (43). Furthermore, two peaks [bicyclo[3.2.0]heptan-2-one,6 hydroxy-5-methyl-6-vinyl- (17) and bornyl bromide (20)] disappeared and four peaks [3-(decyloxy)-2-hydroxy-1-propanesulfonic acid (18), α-lonone (19) tetradecanoic acid (42) and methyl cis-9,10 epoxystearate (45)] newly appeared in the chromatogram of the volatile oil of sulfur-fumigated Dangshen.

Conclusions: Sulfur fumigation caused significant variations in the constituents of volatile oil of Dangshen. Further explorations are needed to investigate how these chemical variations occurred and whether these variations would affect the clinical efficacy and safety of Dangshen in human use.