Lindsey Ellis

Sarah Tucker

Two Novel Anti-Inflammatory 21-Nordammarane Saponins from Tetraploid Jiaogulan (Gynostemma pentaphyllum)[1]

Gynostemma pentaphyllum (G. pentaphyllum) is a perennial creeping plant and is often an ingredient found in tea. Its common name in China, Japan, and Southeast Asian countries is Jiaogulan. Previous chemical investigations have detected saponins in G. pentaphyllum, which are responsible for many of the health benefits associated with the plant. The saponins are responsible for anti-inflammatory properties of the plant, and can be extracted. To date, more than 170 saponins with diverse carbon skeletons have been isolated from G. pentaphyllum. Two novel 21-nordammarane saponins, 20-oxo-21-nordammar-22, 24-diene saponins, 21-norgypenosides (Scheme 1) were characterized from the tetraploid Jiaogulan and investigated for potential anti-inflammatory effects (reduction of inflammation of various tissues). The past few decades have shown increased interest in these compounds because most diseases are linked to inflammation (heart disease, diabetes, cancer, etc.), and anti-inflammatory products can reduce heart disease risk, lower blood pressure, and can help soothe the pain associated with arthritis.

Electron circular dichroism spectroscopy (ECD) was used to determine the absolute stereochemistry of the natural nordammarane products. The structures were established by comparison of their experimental and calculated ECD spectra. Theoretical calculations of ECD were performed with a Gaussian program package using a time-dependent density functional theory (TD-DFT). The model for 1a (Figure 1) was calculated by using the TD-DFT method. The calculated result of 1a produced a mirror image ECD curve of the experimental ECD spectra of 1 and 2 and the calculated ECD spectrum of 1a (Figure 2).

Lindsey Ellis

Sarah Tucker

Scheme 1. Structures of Norammaranes 1, 1a, and 2

Figure 1. Electron Circular Dichroism Spectrum of 1a

fλ, 1a=i=1i=2fiλ, where fiλ=hn12πσ2e-λ-λmax22σ2

Function 1: Function 2:

Position: λmax,1 = 310 nm Position: λmax,2 = 250 nm

Width: s1 = 20 nm Width: s2 = 30 nm

Height: h1 = -3.5 Height: h2 = 0.8

Normation: n1 = 1.995E-2 Normation: n2 = 1.330E-2

Figure 2. Electronic Circular Dichroism (ECD) Spectra of Compounds 1, 1a, and 2

fλ, N=i=1i=mfiλ, where fiλ=hn12πσ2e-λ-λmax22σ2

For N = 1a (λmax,m [nm], sm [nm], hm, nm): 310, 20, -3.5, 0.01995 (m = 1); 250, 30, 0.8, 0.0133 (m = 2). For N = 2: 200, 1, -10, 0.3989 (m = 1); 210, 5, 3, 0.07979 (m = 2); 225, 7, 2.5, 0.05699 (m = 3); 270, 55, -1, 0.007523 (m = 4); 270, 10, 1, 0.03989 (m = 5); 285, 15, 4, 0.02660 (m = 6); 300, 10, 4, 0.03989 (m = 7); 320, 15, 5, 0.02660 (m = 8); 350, 20, -0.5, 0.01995 (m = 9).

For N = 1: 200, 3, 7, 0.1330 (m = 1); 220, 9, 3, 0.04433 (m = 2); 270, 60, -1, 0.006649 (m = 3); 275, 7, 1.5, 0.05699 (m = 4); 285, 15, 6, 0.02660 (m = 5); 300, 9, 3.5, 0.04433 (m = 6); 320, 20, 7, 0.01995 (m = 7); 350, 20, -1, 0.01995 (m=8).

[1]() Yang, F.; Shi, H.; Zhang, X.; Yu, Y. Two Novel Anti-Inflammatory 21-Nordammarane Saponins from Tetraploid Jiaogulan (Gynostemma pentaphyllum. (dx.doi.org/ 10.1021/jf404726z) J. Agric. Food Chem. 2013, 61, 12646−12652.