Phenolic acids of borage (Borago officinalis L.) and evening primrose (Oenothera biennis L.)

Abstract

The composition of phenolic acids, both free and liberated from esters and glycosides, was determined in evening primrose and borage seeds by GC and MS. The free phenolic acid fraction was predominant in these seeds. Protocatechuic acid was the principal phenolic acid of the free and esterified phenolic acids in evening primrose seeds. Ferulic acid represented a high proportion of the free phenolic acids, but hydroxycaffeic acid was the major constituent of phenolic acids liberated from esters of borage seeds.There is a growing interest in substituting synthetic food antioxidants such as BHA, BHT, propyl gallate (PG), and TBHQ with natural alternatives. Fruits, vegetables, leaves, seeds, roots, and barks have been targeted as potential sources of natural antioxidants (1,2).The seeds of borage (Borago officinalis L.) and evening primrose (Oenothera biennis L.) plants are good sources of the EFA γ-linolenic acid (18:3n-6). Evening primrose seeds contain from 10 to 17% oil, and γ-linolenic acid may constitute up to 10% of the FA (3). On the other hand, the content of oil in borage seeds, containing up to 25% γ-linolenic acid, ranges from 17 to 25% (4). Although this FA is quite prone to oxidation, the oil in these seeds resists oxidation. This suggests that these oleaginous seeds must contain some potent antioxidants (5). Lu and Foo (6) and Shahidi et al. (7) demonstrated that the antioxidative activity in evening primrose may be due to the presence of phenolic compounds. Balasinska and Troszynska (8) reported that phenolics extracted from evening primrose seeds may protect lipids from oxidation caused by free radicals. Therefore, the meals after extraction of oils may be potential sources of natural food antioxidants.The available information on phenolic compounds of evening primrose and borage seeds is diverse and fragmentary. Lu and Foo (6) reported the presence of a procyanidin gallate oligomer in evening primrose seeds. Later, Shahidi et al. (7) demonstrated that evening primrose seeds contain catechins as well as dimers and trimers of proanthocyanidins. Subsequently, Balasinska and Troszynska (8) reported the presence of a phenolic acid in an acetone/water extract of evening primrose seeds. However, the authors did not attempt to identify the phenolic acid. Recently, Wettasinghe et al. (9) identified rosmarinic, syringic, and sinapic acids in ethanolic extracts of borage meals.In this study we shall report the composition of free, soluble ester and soluble glycoside phenolic acids present in defatted borage and primrose seeds. MATERIALS AND METHODSMaterials. Seeds of borage (B. officinalis L.) and evening primrose (O. biennis L.), obtained from the Institute of Horticulture of the University of Warmia and Mazury (Olsztyn, Poland) were ground, extracted with hexane for 12 h using a Soxhlet apparatus, and then dried at room temperature.Preparation of crude phenolic extract. Soluble phenolics were extracted six times from defatted ground seed into aqueous 80% (vol/vol) methanol (at a ratio of 1:1, wt/vol) at room...

Composition of phenolic acids in sea buckthorn (Hippophae rhamnoides L.) berries

“…The total contents of free phenolics found in berries were similar to those reported by Zadernowski et al (18) for defatted borage and evening primrose seeds, but over 10 times lower than those found in defatted rapeseed meals (24). Eleven free phenolic acids were tentatively identified in this fraction ( Table 2).…”

“…(Table 1). These values are up to 30 times higher than those reported for defatted evening primrose and borage seeds (18), as well as sesame and cottonseed flours …”

“…The total content of phenolic acids liberated from glycosides was over 100 times higher than that reported for defatted evening primrose and borage seeds (18). Fourteen phenolic acids were tentatively identified in this fraction (Table 4).…”

Phenolics and polyphenolics in foods, beverages and spices: Antioxidant activity and health effects – A review

“…More recent studies have suggested that the antioxidant properties of evening primrose may arise from phenolic acids such as gallic, caffeic, p-hydroxybenzoic, vanillic, ferulic and salicylic acids, as well as proanthocyanidins and flavanols (Zadernowski, Nowak-Polakowska, & Konopka, 1996), catechin and epicatechin derivatives or protocatechuic and gallic acids and esters (Peschel, Dieckmann, Sonnenschein, & Plescher, 2007;Schmidt, Niklová, Pokorný, Farkaš, & Sekretár, 2003). Salicylic,vanillic,gallic, ferulic and caffeic acids are found in smaller quantities in evening primrose seeds (Zadernowski, Naczk, & Nowak-Polakowska, 2002).…”

Quantitative Analysis of Biologicaly Active Polyphenols in Evening Primrose (Oenothera Paradoxa) Seeds Aqueous Extracts

“…A large number of flavonoids have been found in Oenothera sp., including myricetin, quercetin and kaempferol glycosides, as well as a biflavonoid of mirycetin, namely speciin [Howard et al, 1972;Zinsmeister et al, 1977;Marzouk et al, 2009]. The phenolic acids present in these species are mainly gallic acid together with ethyl-and metyl-esters, protocatechuic, caffeic and ellagic [Zinsmeister & Bartl, 1971;Zadernowski et al, 2002;Schmidt et al, 2003]. Fractionation of the seed extracts, obtained from defatted pulp, showed the presence of hydrolysable and condensed tannins.…”