Determination of D-Pinitol in a decoction of Desmodium Adscendens by means of a newly developed GC-method

A decoction of the leaves and stems of Desmodium adscendens (Fabaceae), a herb occurring in Africa and South America, is used in traditional medicine for the treatment of asthma, hepatitis, muscle spasms, pain, fever, and seizures. Previous phytochemical research revealed that flavonoids, soyasaponins, β-phenylethylamines, and an indol-3-alkylamine were present in D. adscendens. Our investigations have led to the identification of D-pinitol, a low molecular weight carbohydrate with antihyperglycemic, hepatoprotective and anti-inflammatory effects, as a potentially active compound. In order to prepare a quantified extract of D. adscendens with a known level of D-pinitol to be used in in vivo experiments, an analytical GC-method was developed. Several parameters were studied, i.e. the derivatisation reagent, the internal standard and sample preparation. The final method was validated and shown to be linear, specific, precise (RSD% <1.3%) and accurate (recovery of 103.4% –105.8%). The amount of pinitol in lyophilized decoctions from D. adscendens used in in vivo experiments was about 5%. Also different food supplements were analyzed in which the amount ranged from 1.8mg/capsule to 30mg/capsule and was 2.0mg/ml solution.