Chilean “chaura” berries (Gaultheria phillyreifolia and G. poeppigii): isolation of secondary metabolites and antioxidant activity

Berries from the Gaultheria genus (Ericaceae) are used worldwide as food and in traditional medicine [1]. Most studies have been carried out with Asian [2], North American and European species [3], [4]. Five edible Gaultheria species occurs in Chile [5] and little is known on their secondary metabolite chemistry. The aims of the present work were to isolate the main secondary metabolites from Gaultheria phillyreifolia and G. poeppigii berries, and to evaluate their antioxidant activity. A combination of membrane chromatography (MC) and counter-current chromatography (CCC) was used to isolate the main compounds. The products were characterized by spectroscopic and spectrometric means. The antioxidant activity was measured by different spectrophotometric assays. The fruit extracts were submitted to MC to separate anthocyanins from copigments. Four anthocyanins were isolated by CCC and identified as galactoside and arabinoside of cyanidin and delphinidin. From the copigment fraction, CCC allowed the isolation of quercetin-3-arabinoside, 3-rutinoside and 3-rhamnoside, 3-caffeoylquinic acid and the iridoids monotropein-10-trans-coumarate, monotropein-10-trans-cinnamate and 6α-hydroxy-dihydromonotropein-10-trans-cinnamate. The latter two compounds are new natural products. Other 34 compounds were tentatively identified by HPLC-DAD-ESI-MSⁿ. The G. phillyreifolia samples showed better antioxidant activity in the FRAP, TEAC and CUPRAC assays. On the other hand, the G. poeppigii samples showed better results in the DPPH and ORAC assays. The observed differences between both species were validated by a Partial Least Square Discriminant Analysis (PLS-DA). This is the first report on the isolation and characterization of secondary metabolites from Chilean Gaultheria phillyreifolia and G. poeppigii berries.

Fig. 1

• References

• 1 Luo B, Gu R, Kennelly EJ, Long C. Gaultheria ethnobotany and bioactivity: blueberry relatives with anti-inflammatory, antioxidant, and anticancer constituents. Curr Med Chem 2018; 25: 5168-5176
• 2 Zhang B, He XL, Ding Y, Du GH. Gaultherin, a natural salicylate derivative from Gaultheria yunnanensis, towards a better non-steroidal anti-inflammatory drug. Eur J Pharmacol 2006; 530: 166-171
• 3 McDougall GJ, Austin C, Van Schayk E, Martin P. Salal (Gaultheria shallon) and aronia (Aronia melanocarpa) fruits from Orkney: phenolic content, composition and effect of wine making. Food Chem 2016; 205: 239-247
• 4 Ferguson A, Carvalho E, Gourlay G, Walker V, Martens S, Salminen JP. et al. Phytochemical analysis of salal berry (Gaultheria shallon Pursh.), a traditionally-consumed fruit from western North America with exceptionally high proanthocyanidin content. Phytochemistry 2018; 147: 203-210
• 5 Teillier S, Escobar F. Revision of the genus of Gaultheria L. (Ericaceae) in Chile. Gayana Bot 2013; 70: 136-153