What it is
Silymarin is not a single molecule but a defined complex of flavonolignans extracted from milk thistle seed. Silybin, present as two diastereomers, is usually the largest single contributor, sitting alongside silychristin, silydianin and isosilybin. Manufacture concentrates this group from the seed through solvent extraction and purification, and the 80% figure that dominates the trade refers to the complex as a whole rather than to any one of its members.
Formulation considerations
Two numbers, two methods. A buyer who specifies “80% silymarin” and a buyer who specifies “30% silybin” may be describing the same drum, and the only way to avoid confusion at goods-in is to state both the percentage and the analytical method on the specification. Certificates from different manufacturers vary in which they lead with.
Solubility shapes the format choice. Water insolubility means that straightforward aqueous dosing is not available, and this is the reason phospholipid-complexed and otherwise solubilised grades exist in the market. In solid dose the native powder behaves conventionally: it flows well at 80 mesh, compresses with standard excipients and shows no unusual incompatibilities. Bitterness is pronounced enough that unencapsulated formats need careful thought.
Applications
Capsules and film-coated tablets take most of the volume. Oil suspensions and softgels are used where a lipid carrier suits the dose form, and phospholipid complexes serve formulators who need a more dispersible material. Available in bulk quantities, with pricing on application.
Applications
- Capsules and tablets
- Softgels and oil suspensions
- Phospholipid complexes
- Powder blends
Handling and storage
Hold in sealed containers below 25 degrees Celsius, protected from light and moisture. The flavonolignan complex is reasonably stable at ambient temperature but discolours with prolonged light exposure and will darken under sustained heat. Typical shelf life is 36 months from manufacture in unopened packaging. Keep the liner closed between withdrawals, since moisture pickup reduces flow and promotes lump formation in an otherwise free-flowing powder.
Common questions
What does 80% silymarin actually measure?
Eighty percent silymarin is a group assay determined by UV spectrophotometry, covering the full flavonolignan complex rather than a single compound. If you need a defined silybin figure, specify it separately by HPLC, since the two methods give materially different numbers on the same lot.
Is milk thistle extract water soluble?
It is practically insoluble in water and soluble in ethanol and acetone. Aqueous formats therefore need either a solubilised or phospholipid-complexed grade, or a format where dissolution is not required.
How bitter is the powder in an open format?
Noticeably bitter, with a lingering character that is difficult to mask at higher inclusion. Most formulators place it in capsules or film-coated tablets rather than loose powders or chewables.
What documentation is supplied with each lot?
A lot-specific Certificate of Analysis accompanies every delivery, together with the Technical Data Sheet, Safety Data Sheet, specification sheet and allergen declaration.