Chemical content profile and antioxidant activity of Rhododendron ponticum L. (Ericaceae) extracts

Abstract

Rhododendron species (Ericaceae) is considered the most diverse group, with more than 1200 species famous for their colorful flowers. Rhododendron, also known as azalea, is a flowering tree in the Ericaceae family. Herein, in vitro antioxidant activities of acetone and methanol extracts of Rhododendron ponticum leaves were studied along with their phenolic contents using High-Performance Liquid Chromatography with a Diode-Array Detector (HPLC-DAD). Antioxidant activity was performed spectrophotometrically using ABTS·+, DPPH·, CUPRAC, and β-carotene/linoleic acid assays. Acetone extract showed better antioxidant activity than methanol extract in all tests. The HPLC-DAD analysis revealed fifteen phenolic compounds, of which seven were common for both extracts. Catechin (25.80 and 33.08 mg/g extract, respectively) and epicatechin (31.15 and 26.54 mg/g extract, respectively) were calculated as major phenolic components in acetone and methanol extracts.

Keywords

• Rhododendron ponticum
• HPLC-DAD
• Phenolic compound
• Antioxidant activity

References

1. Al-Mamary, M., Al-Meeri, A., & Al-Habori, M. (2002). Antioxidant activities and total phenolics of different types of honey. Nutrition Research, 22, 1041-1047.
2. Apak, R., Güçlü, K., Özyürek, M., & Karademir, S.E. (2004). Novel total antioxidant capacity index for dietary polyphenols and vitamins C and E, using their cupric ion reducing capability in the presence of neocuproine: CUPRAC Method. Journal of Agricultural and Food Chemistry, 52, 7970-7981.
3. Baytop, T. (1999). Therapy with Medicinal Plants in Turkey: Past and Present (Second edition). Nobel Tıp Kitabevleri.
4. Blois, M.S. (1958). Antioxidant determinations by the use of a stable free radical. Nature, 181, 1199-1200.
5. Caliskan, H., Argon, M., & Sabudak, T. (2022). The genus Isatis L.: A review on its flavonoid and phenolic compound profile. Records of Agricultural and Food Chemistry, 2(2), 75-83.
6. Chosson, E., Chaboud, A., Chulia, A.J., & Raynoud, J. (1998). Dihydroflavonol glycosides from Rhododendron ferrugineum. Phytochemistry, 49, 1431-1433.
7. Erdemoglu, N., Akkol, E. K., Yesilada, E., & Calış, I. (2008). Bioassay-guided isolation of anti-inflammatory and antinociceptive principles from a folk remedy, Rhododendron ponticum L. leaves. Journal of Ethnopharmacology, 119(1), 172-178.
8. Jing, X., Zhonghua, Z., Jianshe, L., & Yang, W. (2009). The effect of root of Rhododendron on the activation of NF-κ B in a chronic glomerulonephritis rat model. Journal of Nanjing Medical University, 23, 73.

9. Li, C.-J., Wang, L.-Q., Chen, S.-N., & Qin, G.-W. (2000). Diterpenoids from the fruits of Rhododendron molle. Journal of Natural Products, 63, 1214-1217.
10. Mahomoodally, M.F., Sieniawska, E., Sinan, K.I., Nancy, Picot-Allain, M.C., Yerlikaya, S., Cengiz Baloglu, M., & Zengin, G. (2019). Utilisation of Rhododendron luteum Sweet bioactive compounds as valuable source of enzymes inhibitors, antioxidant, and anticancer agents. Food and Chemical Toxicology, 111052.
11. Miller, H.M. (1971). A simplified method for the evaluation of antioxidants. Journal of the American Oil Chemists Society, 48, 91.
12. Oztasan, N., Altinkaynak, K., Akcay, F., Gocer, F., & Dane, S. (2005). Effect of mad honey on blood glucose and lipid levels in rats with streptozocin-induced diabetes. Turkish Journal of Veterinary and Animal Science, 29, 1093-1096.
13. Prakash, T.F., Snehal, D.S., Uday R.S., & Diyakar. (2008). Hepatoprotective activity of leaves of Rhododendron arboreum in CCl4 induced hepatotoxicity in rats. Journal of Medical Research, 2(11), 315-320.
14. Re, R., Pellegrini, N., Proteggente, A., Pannala, A., Yang, M., & Rice-Evans, C. (1999). Antioxidant activity applying an improved ABTS radical cation decolorization assay. Free Radical Biology and Medicine, 26, 1231-1237.
15. Robards, K., Prenzler, P.D., Tucker, G., Swatsitang, P., & Glover, W. (1999). Phenolic compounds and their role in oxidative processes in fruits. Food Chemistry, 66, 401-436.
16. Sales, F., & Milne, R. Güner, A., Özhatay, N., Ekim, T., & Başer, K.H.C. (Eds.) (2000). Rhododendron L. Flora of Turkey and the East Aegean Islands, University Press, Edinburgh, 11, 181-183.
17. Shrestha, A., Hakeem Said, I., Grimbs, A., Thielen, N., Lansing, L., Schepker, H., & Kuhnert, N. (2017). Determination of hydroxycinnamic acids present in Rhododendron species. Phytochemistry, 144, 216-225.
18. Silici, S., Sagdic O., & Ekici, L. (2010). Total phenolic content, antiradical, antioxidant, and antimicrobial activities of Rhododendron honeys. Food Chemistry, 121(1), 238-243.
19. Stevens, P., & Fernandez, J.W. (1978). Fang Architectonics. African Arts, 11(2), 90-92. https://doi.org/10.2307/3335466
20. Tokul Ölmez, Ö., Şahin, B., Çakır, C., & Öztürk, M. (2020). Rapid and easy method for simultaneous measurement of widespread 27 compounds in natural products and foods. Journal of Chemical Metrology, 14(1), 1-11.
21. Yarlioglues, M., Akpek, M., Ardic, I., Elcik, D., Sahin, O., & Kaya, M.G. (2011). Mad-honey sexual activity and acute interior myocardial infarctions in a married couple. Texas Heart Institute Journal, 38, 577-580.
22. Yeşil, T., & Akgül, Y. (2022). Major components of Rhododendron luteum leaves. Natural Product Research, 37(15), 2608-2612. https://doi.org/10.1080/14786419.2022.2055015