The traditional plant treatment, Sambucus nigra (elder), exhibits insulin-like and insulin-releasing actions in vitro

Sambucus nigra (elder) has been documented as a traditional treatment of di abetes. In the present study, an aqueous extract of elder (AEE, 1 g/L) sign ificantly increased 2-deoxy-glucose transport, glucose oxidation and glycog enesis of mouse abdominal muscle in the absence of added insulin (2 x 2 fac torial design). in acute 20-min tests, 0.25-1 g/L AEE evoked a stepwise sti mulation of insulin secretion from clonal pancreatic beta-cells. The insuli n releasing effect of AEE (0.5 g/L) was significantly potentiated by 16.7 m mol/L of glucose and significantly reduced by 0.5 mmol/L of diazoxide. AEE did not further enhance insulin secretion in cells stimulated by 10 mmol/L of L-alanine, 1 mmol/L of 3-isobutyl-1-methylxanthine or a depolarizing con centration of KCI (25 mmol/L). Prior exposure of clonal pancreatic beta-cel ls to AEE did not alter subsequent stimulation of insulin secretion induced by 10 mmol/L of L-alanine, thereby precluding a detrimental effect on cell viability. The insulinotropic action of AEE was partially dependent upon u se of heat during extract preparation. Activity of AEE was heat-stable, ace tone-insoluble and unaltered by prolonged exposure to acid/alkali (0.1 mol/ L of HCl and NaOH). However, activity was significantly decreased 41% by di alysis to remove components with molecular mass <2000 Da. Sequential extrac tion with solvents revealed activity in both methanol and water fractions, indicating a cumulative effect of more than one extract constituent. Known constituents of elder, including lectin, rutin and the lipophilic triterpen oid (lupeol) and sterol (beta-sitosterol), did not stimulate insulin secret ion. The results demonstrate the presence of insulin-releasing and insulin- like activity in the traditional antidiabetic plant, Sambucus nigra.