Identification of geographical origin of Lignosus samples using Fourier transform infrared and two-dimensional infrared correlation spectroscopy

• A good example in analysing incomplete sample using 2DIR spectroscopy.
• Sample (M26/08) origin determined by comparing with authenticated sample (M49/07, M23/08).
• Spectrum of M26/08 at 1260–950 cm−1 was 99.4% similar to M23/08.
• M26/08 and M23/08 were more closely related than M49/07.
• 2DIR correlation technique increases resolution and simplifies overlapping bands.

Lignosus spp. is a medicinal mushroom that has been used as a folk remedy for ‘clearing heat’, eliminating phlegm, ‘moistening the lungs’ and as an anti-breast cancer agent. The objective of this study was to identify the active chemical constituents of the mushroom limited number of sample by using Fourier transform infrared (FTIR) and two-dimensional correlation Fourier transform infrared spectroscopy (2DIR). The sample M26/08 was purchased from a Chinese medicine shop in Kuala Lumpur, while M49/07 and M23/08 were collected from Semenyih and Kuala Lipis respectively. The three samples have strong absorption peaks corresponding to the stretching vibration of conjugated carbonyl CO group. Both fresh sample M49/07 and M23/08 showed an identical peak of 1655 cm−1, whereby M26/08 contained stretching vibration of 1648 cm−1. The peaks from 1260 cm−1 onwards were assignation of carbohydrate content including saccharides. Spectrum of M26/08 showed region from 1260 cm−1 to 950 cm−1 which was 99.4% similar to M23/08. The chemical constitutes of M26/08 and M23/08 were closely correlated (r = 0.97), whereas the correlation coefficient of M26/08 and M49/07 was 0.94. The use of second derivative and 2DIR spectroscopy enhanced the distinct differences to a more significant level. Although the geographical origin of M26/08 was unknown, its origin was determined by comparing with M49/07 and M23/08. The visual and colorful 2DIR spectra provided dynamic structural information of the chemical components analyzed and demonstrated a powerful and useful approach using the spectroscopy of different samples.

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