We have already reported (1971) that Syrian sumach (Rhus coriaria) leaves (23.35% tannins) contain (1966, 1971), beside the main polyphenolic component gallotannin the flavonols myricetin, quercetin and kaempferol, together with ellagic acid, m-digallic acid and gallic acid. All were isolated and identified after acid hydrolysis of both the ethyl acetate (E) and methanol (M) extracts. It is noteworthy to point out that the flavonols already mentioned could not be identified in either extracts (E or M) prior to acid hydrolysis. P e r k i n and A 11 e n (1896) were able to isolate gallic acid and its derivatives, together with myricetin from R. coriaria leaves. Also the flavonol fisetin was later isolated from the wood of R. szrccedanea (0 y a m a d a , 1939) and from the stem of R. rhodunthema ( P e r k i n , 1897). However, these flavonoid aglycones were similarly isolated only after acid hydrolysis of the plant extracts.Trials were then made to isolate and identify glycosidic flavonoids probably present in the investigated Rhus coriaria leaves.As already pointed out, ethyl gallate (CeHlo05) was isolated from the acetate extract (E) of the leaf material.The methyl ester of gallic acid (CBHBOS), isolated from the same extract (E) through adsorption chromatography could also be separated from a n acetonet water extract of the leaves; thus showing that this ester, also isolated from this extract during elution with methanol is originally contained in the investigated plant material, but not formed as a result of methanolysis of the gallic acid present in the same extract during elution with waterlmethanol mixtures.In addition, the identified flavonoid glycosides, namely quercetin-3-glucoside (isoquercitrin, C2iH2001a) and myricetin-3-rhamnoside (myricitrin, C21H20012) were isolated from the ethyl acetate extract (E).Beside reference paper chromatography with authentic materials, the identification of both flavonoid glycosides given above was confirmed by both physical as well as chemical methods of analysis including acid hydrolysis and preparation of some of the corresponding derivatives.
ExperimentalThe ethyl acetate extract (E) of Syrian Rhus coriaria leaves, containing 12 components of polyphenolic nature was applied on a polyamide (Ultramid BM2, BASF, Germany) colurnn. Elution with water, followed by waterlmethanol mixtures gave rise to 10 fractions, whereby UV light as well as specific colour reagents were engaged. El Sissi et al., Polyphenolic Components of Rhus Bd. 21, Heft 1Fraction I proved to contain mainly sugars. These were purified, then paper chromatographically identified as already given ( E l S i s s i et al., 1966).
