Bioactive compounds in flowers and fruits of Sambucus nigra L

• Main Author: Ho, Giang Thanh Thi
• Format: Dissertation
• Language: English

Sambucus nigra L. or black elder has a long history of use in traditional European medicine for treatment of inflammations, infections, diabetes and for boosting the immune system. The aim of this thesis was to investigate the potential health benefits of elderberries and elderflowers with main focus on the immunomodulatory effects and the anti-diabetic potential of pectic polysaccharides and phenolic constituents. Pectic polysaccharides isolated from the 50% EtOH, 50 °C and 100 °C water extracts from the elderberries and the elderflowers were shown to contain homogalacturonan (HG), rhamnogalacturonan-I (RG-I), arabinogalactan-I (AG-I) and arabinogalactan-II (AG-II), in addition to arabinans. Rhamnogalacturonan-II (RG-II) was only present in some of the elderflower fractions. The distribution of sugar residues, molecular weight, and their linkages varied between the fractions. Weak acid hydrolysis was performed on the most active acidic fractions from the elderberries and the elderflowers. An almost complete loss of Ara was observed, the amount of some linkages to Rha and Gal were also decreased. A negative Yariv test after weak acid hydrolysis indicated a degradation of AG-II. Ester groups in the polysaccharide fractions from the elderflowers were reduced after treatment with NaOH. The de-esterified polysaccharides showed the same distribution of linkages as their respective native polysaccharides. In order to isolate the hairy regions, one acidic fraction from elderberries (SnBe50-I-S3) and four acidic fractions from elderflowers (SnFl-50-I-S2, 50WSnFl-I-S2, 100WSnFl-I-S2, 100WSnFl-I-S3) were treated with endo-polygalacturonase. This led to the isolation of five sub-fractions from the elderberry fraction and two sub-fractions from each of the elderflower fractions. RG-I like structure and side chains of AG-I and AG-II were the predominant part in the isolated sub-fraction-I and sub-fraction-II from the elderberries and in the sub-fractions-I from the elderflowers. These fractions showed high degree of branch points compared to the native fractions. Sub-fractions-II from the elderflowers consisted of RG-I and also small amounts of RG-II structures. Complement and macrophages are both part of the innate and adaptive immune system. All the acidic polysaccharide fractions from elderberries and elderflowers showed dose-dependent complement fixating activity and stimulated nitric oxide (NO) production in RAW 264.7 macrophages, with elderflower fractions being