Senna

Botanical Profile

Senna alexandrina is a tropical to subtropical Fabaceae species and the principal botanical source of classical senna leaves and senna fruits. From a raw-material perspective, leaf and fruit preparations must be considered separately because of their hydroxyanthracene-derivative profiles.

Senna alexandrina Mill. is a shrub to subshrub with paripinnate leaves, yellow flowers and flat legumes. The species is native to, or historically cultivated in, dry to semi-dry regions of northeastern Africa and Arabia and is grown for medicinally characterised leaf and fruit raw materials. The formerly common trade names Alexandrian senna and Tinnevelly senna reflect historical origins and trade routes. Botanically, leaves and fruits are central; they differ in form, content and tradition of use. Clear species and plant-part identity is essential because senna raw materials can yield strongly active anthranoid-containing preparations.

Phytochemistry

Senna leaves and fruits contain hydroxyanthracene derivatives, particularly sennosides A and B and related dianthrone glycosides. Flavonoids, mucilage, naphthalene derivatives, resin components and other phenolic accompanying substances also occur. Sennosides are typical analytical marker compounds and are used in quality assessment of anthranoid-containing senna raw materials. Leaf and fruit raw materials differ in composition, content and accompanying-substance spectrum. Drying, storage, origin, particle size and extraction solvent influence stability and content. Unlike mild herbal or food raw materials, senna preparations require separate assessment because of their anthranoid fraction.

Traditional Uses

Senna is among the historically important plant raw materials of Arab, North African, Indian and European medicinal-plant traditions. Senna leaves and fruits were distributed via trade routes from North Africa, the Red Sea region and India and entered pharmacies, herbals and pharmaceutical raw-material traditions. Traditional use referred to defined leaf or fruit preparations and, because of their strong action, was clearly distinguished from ordinary herbal beverages. Historical information reflects documented medicinal-raw-material traditions and must not be understood as general food statements.

Current Research

Research on senna focuses on anthranoid chemistry, sennosides, metabolism by intestinal flora, quality testing, stability, dosage and safety. European and international monographs address defined leaf and fruit drugs and their preparations. Modern investigations also consider differentiation of Senna species, chromatographic authenticity testing, content determination and contaminant control. Safety topics include in particular long-term use, sensitive target groups, electrolyte balance and the clear distinction between short-term use of defined preparations and non-specific use of anthranoid-containing plant extracts.

Sources

• Plants of the World Online: Senna alexandrina Mill.; Royal Botanic Gardens, Kew.
• EMA/HMPC documents on Sennae folium and Sennae fructus.
• European assessments of hydroxyanthracene derivatives in foods.