Elders (Sambucus spp.) are widely distributed throughout the world. In central Europe, the most common species are black elder (Sambucus nigra L.), red elder (Sambucus racemosa L.), and dwarf elder (Sambucus ebulus L.). Black elder is the most widespread, being found across Europe, central and western Asia, and northern Africa . Black elder is a deciduous
shrub that grows to a height of 4-6 m. From spring until summer the corymbs are in flower. The berries are dark violet-black drupes which grow in clusters and are only edible when fully ripe. Other parts of the plant, such as the green stems and branches, are not edible and not recommended for human consumption.
In 400 BCE, Hippocrates referred to the elder tree as his "medicine chest." Other noted classical healers, including Theophrastus, Dioscorides and Galen, regarded the elder as one of nature's greatest healing plants. The herbalist Hildegard von Bingen in the 12th century, and the physician and author, Dr. Martin Blochwich in the 17th century, continued to extol its virtues . In the early 20th century, British herbalist Maud Grieves provided a comprehensive review of the historical uses of black elder as a traditional medicine . Prior to antibiotics, elderberry was found as one of the main ingredients in many preparations used by herbalists , pharmacists, and physicians. Today, elderberry is employed as an alternative to conventional medicines and mainly in the form of an extract for treating the common cold, influenza and Herpes virus infections [5–9]. Elderberry is often recommended for use as a complementary therapy together with the classic antioxidant nutrients, vitamin C and zinc, to support the natural process of recuperation .
The European black elderberries are rich dietary sources of plant pigments and phenolic compounds. They contain the flavonols, quercetin-3-glucoside and quercetin-3-rutinoside, and a number of anthocyanins: a group of phenolic compounds responsible for the attractive red, purple, and violet colours of many fruits, flowers, vegetables, and also elderberries. The anthocyanins of elderberries were identified as cyanidin-3-sambubioside-5-glucoside, cyanidin-3,5-diglucoside, cyanidin-3-sambubioside, cyanidin-3-glucoside, cyanidin-3-rutinoside, pelargonidin-3-glucoside, and pelargonidin-3-sambubioside. The anthocyanins of elderberries are bioactive; for example, able to enhance the postprandial plasma antioxidant status of healthy humans [10–13]. Animal and in vitro studies have shown that anthocyanins decrease necrotic and apoptotic cell death and lower infarct risks through anti-inflammatory and relaxant effects on coronary arteries .
Influenza virus (IV) infections cause seasonal epidemics and have the potential to become pandemic. Only a few medications are approved for use in the treatment of influenza A and B virus infections while they act directly and specifically against influenza viruses, the problem with these medications is that drug-resistance can develop relatively quickly [15, 16]. Thus, there is an urgent need for new and more broadly based anti-influenza medications that do not allow resistance. Active substances with an unspecific inhibitory action against IV propagation--regardless of the viral subtype--would probably not lead to resistance, if such IVs do not evade inhibition by changes in their viral properties . Moreover, bacterial super-infection during an ongoing IV infection can lead to severe pneumonia , and therefore substances with dual action against both types of pathogens--bacteria and IV--would be of further interest.
We have shown that a standardized elderberry liquid extract displays antimicrobial effects against the Gram-positive bacteria Streptococcus pyogenes and group C and G Streptococci, and the Gram-negative bacterium Branhamella catarrhalis, which often cause infections of the upper respiratory tract. As it was already known that elderberry extract can display activity against IV, we investigated the ability of a specific standardized extract of black elderberries to impair the propagation of human pathogenic influenza A and B virus strains, A/Thailand/KAN-1/2004 (KAN-1, H5N1) and B/Massachusetts/71 (Mass), in cell culture at non-toxic concentrations.