Objective

2

To identify

Dendrobium flexicaule

and its related species， and analyze the differences in polysaccharide composition and

D

-mannose content， so as to provide theoretical basis for the accurate identification and quality control of

Dendrobium

medicinal materials.

Method

2

Nine samples of

Dendrobium

（S1-S9） were identified by DNA barcoding and infrared spectroscopy， and the contents of polysaccharides and

D

-mannose were determined by ultraviolet spectrophotometry （UV） and high performance liquid chromatography （HPLC）， respectively. UV detection condition was 488 nm， HPLC detection conditions were the mobile phase of 20 mmol·L

-1

ammonium acetate solution-acetonitrile （81.5∶18.5） and the detection wavelength at 250 nm.

Result

2

DNA barcoding results showed that samples S1-S3 were

D. nobil

e， samples S4-S5 were

D. officinale

， sample S6 was

D. huoshanense

， and S7-S9 were

D. flexicaule

. One-dimensional infrared spectroscopy showed that only

D. nobile

had stable characteristics at the wavenumber of 1 570-1 467 cm

-1

， showing a "W" shape， while no absorption peak was found at the wavenumber of 842-740 cm

-1

， but the other

Dendrobium

samples had stable absorption peaks at the wavenumber of 842-740 cm

-1

. In the first derivative spectrum， at the wavenumber of 785 cm

-1

，

D. huoshanense

presented a "V" shape， while the rest of

Dendrobium

presented a "W" shape. At the wavenumber of 1 110 cm

-1

，

D. flexicaule

had a stable characteristic peak. In the second derivative spectrum， at the wavenumber of 1 125 cm

-1

，

D. officinale

presented an "M" shape， and the rest of

Dendrobium

was approximately "W" shape. The results of determination showed that the contents of polysaccharides in samples S1-S9 were 9.35%， 9.12%， 32.78%， 49.38%， 48.97%， 32.48%， 32.95%， 39.41% and 25.32%， and their contents of

D

-mannose were 1.39%， 0.47%， 13.57%， 3.04%， 33.85%， 23.57%， 16.64%， 17.47% and 19.49%， respectively. Among them，

D. flexicaule

had high polysaccharide and

D

-mannose contents.

Conclusion

2

Both DNA barcoding and infrared spectroscopy can be used to identify

D. flexicaule

and its related species， and infrared spectroscopy is cost-effective and easy to operate. At the same time，

D. flexicaule

has high contents of polysaccharides and

D

-mannose， which can provide a scientific basis for rapid identification of

D. flexicaule

and its relatives， and provides a reference for its quality control， and resource development and utilization.