Hypoglycemic Constituents Isolated from Trapa natans L. Pericarps

Abstract

Trapa natans L., called water chestnut or water caltrop, is a floating aquarium plant. Its fruits are widely used as food. Two new tannins, 1 and 2, one new neolignan, 14, one new norlignan, 17, and 20 known compounds, 3-13, 15, 16, and 18-24 were isolated from T. natans pericarps in this study. The 1, 2, 14, and 17 structures were elucidated using a chemical method and extensive spectral evidence. A series of hydrolyzable tannins, 1-8, a lignin, 13, a flavonoid, 16, a norlignan, 17, and phenolic compounds, 18, 20, 21, and 24 resulted in the enhanced glucose uptake activity in C2C12 myotubes. Compounds 4 and 5 significantly increased GLUT4 protein expression in C2C12 myotubes. In addition, 4 and 5 improved the phosphorylation of AMPK, AKT(S473), and AKT(T308). The involvement of AMPK and PI3K in the mechanism of action of compounds 4 and 5 was confirmed by use of AMPK and PI3K inhibitors, which completely suppressed the 4- and 5-mediated activities of glucose uptake in C2C12 myotubes. We also demonstrated that 4 and 5 could increase GLUT4 protein levels in plasma membranes.

Peer Review #1 of "Polyphenol-rich Trapa quadrispinosa pericarp extract ameliorates high-fat diet induced non-alcoholic fatty liver disease by regulating lipid metabolism and insulin resistance in mice (v0.2)"

“…Eight phenolic compounds (R t = 9. 45, 23.07, 24.15, 24.76, 30.72, 35.58, 36.52 and 47.65 min) were tentatively identified according to previous studies (Hatano et al 1990;Huang et al 2016). Their structures were shown in Figure 1B.…”

“…But the pericarps of T. quadrispinosa were usually discarded in large quantities after the seeds had been harvested. Interestingly, recent researches have demonstrated that the pericarps of water caltrop also displayed multiple biological activities, including hypoglycemic (Huang et al 2016), anti-tumor (Lin et al 2013), anti-inflammatory (Kim et al 2015), antioxidant effects and hepatprotective activity (Kim et al 2014). To our knowledge, the therapeutic effect of Trapa quadrispinosa pericarps extract (TQPE) in high-fat diet (HFD) induced NAFLD, remains unknown.…”

Anti-Influenza Virus Activity and Chemical Components from the Parasitic Plant Cuscuta japonica Choisy on Dimocarpus longans Lour.

“…The correlation between H-1 to H-6 [δ H 5.05 (H-1), 3.46 (H-2), 3.48 (H-3), 3.37 (H-4), 3.77 (H-5), 4.23 and 4.55 (H 2 -6)] showed a coupling network in the 1 H- 1 H COSY spectrum, which proved the presence of the sugar unit to be a glucospyranoside ( Figure 4 ). The β-configuration of glucopyranose was determined through NOESY correlations and coupling constant [ 12 ]. HMBC correlations between the H-6 and carbonyl carbon (δ C 169.1, C-9″) indicated the presence of p -coumaroyl moiety at glucose methylene signal (δ C 64.7, C-6).…”

Utilization of Trapa natans

“…Its husk have higher bioactivity properties (anti-cancer, anti-atherogenic, antimicrobial, antioxidant, hepatoprotective, immune enhancing, anti-imflammatory, anti-hyperglycemic, anti-skin photoaging) than fruits (Zhu, 2016). After harvesting period, pink colored TN husks change its color to dark brown in time (Huang et al, 2016). These husks contain dietary fibres and polyphenols (such as hydrolysable tannins) (Yasuda et al, 2014;Kim et al, 2014;Huang et al, 2016).…”

“…After harvesting period, pink colored TN husks change its color to dark brown in time (Huang et al, 2016). These husks contain dietary fibres and polyphenols (such as hydrolysable tannins) (Yasuda et al, 2014;Kim et al, 2014;Huang et al, 2016). The total phenolic, flavonoid and tannin amounts in TN husk extract were: 63.81% mg/g gallic acid equivalents, 21.34% mg/g of rutin equivalents and 17.11% mg/g of total tannin equivalents respectively (Malviya et al, 2010;Zhu, 2016).…”