Results: 4

1.

Figure 2. From: Diarylheptanoids from Dioscorea villosa (Wild Yam).

The ΔδS-R values of MTPA esters of 1, 4, 6 and 8 used for the determination of absolute condiguration.

Shi-Hui Dong, et al. J Nat Prod. ;75(12):2168-2177.
2.

Figure. From: Diarylheptanoids from Dioscorea villosa (Wild Yam).

Figure 4. Chiral separation of three pairs of enantiomers (2/3, 4/5 and 6/7) by HPLC (2/3 and 6/7: Chiralcel® OJ, 10 μm, 250 × 4.6 mm; 4/5: Chiralpak® IA, 5 μm, 250 × 4.6 mm)

Shi-Hui Dong, et al. J Nat Prod. ;75(12):2168-2177.
3.
Figure 3

Figure 3. From: Diarylheptanoids from Dioscorea villosa (Wild Yam).

Comparison of the 1H NMR spectra of the MTPA esters of the enantiomeric mixture of 2 and 3 (δH 4.5 to 5.8). The resonances of H-1 and H-3 could be readily assigned based on their chemical shifts and splitting patterns. However, the four resonances of H-1 revealed a small but significant difference in their integrals (47.6:52.4, and vice versa), providing evidence for the fact that the isolate was an enantiomeric mixture of 2 and 3 rather than a pure single enantiomer.

Shi-Hui Dong, et al. J Nat Prod. ;75(12):2168-2177.
4.

Figure 1. From: Diarylheptanoids from Dioscorea villosa (Wild Yam).

Representation of the concept of 1H NMR-guided fractionation for the metabolomic mining of Dioscorea phytoconstituents. A 30 mg aliquot of crude MeOH extract of wild yam was carefully dried in vacuo, dissolved in 600 μL of DMSO-d6, and a high S/N 1H NMR spectrum collected (400 MHz, 5 mm broadband probe with ATM, NS = 5 K). Under these conditions, signals in the aromatic region between δH 6.0 and 8.5 (2.47%) were readily detected and some of them could even be recognized as diagnostic AA′XX′ resonances of the subsequently isolated diarylheptanoids.

Shi-Hui Dong, et al. J Nat Prod. ;75(12):2168-2177.

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