Sphinx Journal of Pharmaceutical and Medical Sciences, Vol. 2, Issue 1, 2021, pp. 1-8. Sphinx Journal of Pharmaceutical and Medical Sciences e-mail: sjpms@sphinx.edu.eg ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ Received in 12/9/2021 & Accepted in 11/10/2021 *Corresponding author: A. S. Ahmed, E-mail: amany.mohamed4@pharm.aun.edu.eg CHEMICAL INVESTIGATION OF GREVILLEA ROBUSTA A. CUNN FLOWERS A. S. Ahmed 1,2* and M. A. Makhboul 1 1 Department of Pharmacognosy, Faculty of Pharmacy, Assiut University, Assiut 71526, Egypt 2 Department of Pharmacognosy, Faculty of Pharmacy, Sphinx University, New Assiut 10, Egypt The ethyl acetate soluble fraction of the air-dried flowers of Grevillea robusta was fractionated and separated to obtain eight compounds by different chromatographic techniques. Structures of the isolated compounds were determined on the basis of the extensive spectroscopic analysis, including 1D and 2D NMR and compared with the literature data. These compounds were identified as 3,5-dihydroxy cinnamate, 6-hydroxy coumarin, p-hydroxy benzeldahyde, methyl gallate, ethyl gallate arbutin 6”-O-3,5- dihydroxycinnamic acid ester, robustaside D, together with cyanogenic glycoside named dhurin (s). This study aims to further phytochemical investigation of G. robusta' flower to discover more secondary metabolites with wide range of therapeutic values. Keywords: Grevillea robusta, Proteaceae, phenolic compounds, cyanogenic glycoside. INTRODUCTION Silk-oak (Grevillea robusta), also often called silver-oak, is a medium to large tree commonly planted as an ornamental in many warm-temperate and semitropical climates. It is a flowering plant in the family Proteaceae. It is a tree, the largest species in its genus but is not closely related to the true oaks, Quercus 1 . Previous work has shown the presence of several 5-/7-alkyl resorcinol and arbutin derivatives in the wood and leaves of Grevillea robusta 2-5 . Kaempferol-5-O-β-glucoside a rare flavonol glycoside has been isolated from the fresh flowers of Grevillea robusta 6 . The alcoholic extracts of the leaves and bark of Grevillea robusta A. Cunn showed a significant anti-inflammatory activity using carrageenan-induced edema 7 . Grevillea flowers were used as a food source by Australian Aborigines. The flowers were sucked for their sweet nectar or used to make sweet drinks. They were also used by Australian Aborigines as traditional bush medicines to treat wounds and sores, skin diseases, diarrhea and dysentery and as bactericidal preparations 8 . MATERIALS AND METHODS General experimental procedure I H NMR (500 MHz, CDCl3 and CD3OD), 13 C NMR (150 MHz) Varian JMNGX 500 MHz spectrometer, with tetramethylsilane (TMS) as an internal standard. Mass analyses were recorded on a JEOL JMS-DX 200L and FAB-MS mass spectrometer. Column chromatography was carried out on silica gel 60 (Merck; 230-400 mesh) and octadecylsilyl (ODS) (Pharmacia Co. Tokyo, Japan). TLC was performed on silica gel 60 F254 plates (0.25 mm, Merck Co.) and on Rp -18 plates (40-63 µm, Merck Co.), and spots were detected under UV light and colored by spraying with 10% H2SO4 solution followed by heating. Plant material