Crystal structure and anti‐inflammatory and anaphylactic effects of andrographlide sulphonate E in Xiyanping, a traditional Chinese medicine injection

Objectives Andrographlide sulphonate E, namely sodium 9‐dehydro‐17‐hydro‐andrographolide‐19‐yl sulphate, was one of the major ingredients of Xiyanping injection. The present study aimed to demonstrate its suitability as a reference standard for use of quality control of this traditional Chinese medicine preparation made from andrographlide that has been widely used to treat various infectious diseases. Methods The stable crystals were prepared for unambiguous elucidation of the chemical structure by comprehensive spectral and thermal analysis. The anti‐inflammatory effects were investigated using in vitro and in vivo methods, and the potential allergenic risk related with safety was evaluated by in silico molecular docking analysis. Key findings The dihydrated sulphonate derivative could be present as orthorhombic crystals with stable three‐dimensional supramolecular structure, providing it the favourable physico‐chemical stability as reference substance. It exhibited potent anti‐inflammatory activity both in vitro and in vivo, suggesting the potency responsible for clinic efficacy of Xiyanping. Molecular docking further demonstrated its low risk of allergic reaction, as well as the proposed mechanism of anaphylactic effect of andrographolide analogues. Conclusions Dihydrated sodium 9‐dehydro‐17‐hydro‐andrographolide‐19‐yl sulphate may be the ideal reference standard for use in quality control of Xiyanping.