molecular formula: g19h23no4 . molecular weight: 329.38 . cas no: 115-53-7 . appearance: white powder . test method: hplc . action and uses:which is now known to be effective in neuralgia and rheumatic diseases. sinomenine is a unique plant alkaloid, as it potently releases histamine in association with degranulation of mast cells in connective tissue, preferentially in the skin and joint capsules. the released histamine is responsible for the pharmacological actions of sinomenine, such as vasodilation, increased vascular permeability, acceleration of the thoracic and peripheral lymph flow, contraction of smooth muscles, increased peristalsis of the intestines, and stimulation of gastric acid secretion