Cryptolepine, the major alkaloid of Cryptolepis sanguinolenta (Lindl.) Schlechter (Apocynaceae), attenuates early and late-phase symptoms of asthma

Aqueous root extract of Cryptolepis sanguinolenta has been used traditionally to treat many upper respiratory tract disorders. Besides its well-known broad spectrum antimicrobial activity, we had reasoned that cryptolepine can directly attenuate the symptoms of asthma. Therefore, this study evaluates cryptolepine, the main compound of the aqueous extract of Cryptolepis sanguinolenta, on early and late-phase symptoms of asthma attack. In the early phase study, isolated cryptolepine was evaluated on its ability to reverse histamine-induced bronchoconstriction and reduce histamine release from mast cells and bronchial mucus secretion. In the late phase study, cryptolepine was evaluated on its ability to affect airway inflammation and hypersensitivity as well as its ability to attenuate airway remodeling induced by ovalbumin. In the early asthma phase study, Cryptolepine (10-100 mg/kg) significantly and dose dependently inhibited Histamine-induced bronchoconstriction in guinea pigs. The protection lasted beyond 24 h. It also decreased the volume and optical density of bronchial secretions in mice. Cryptolepine (10-100 mu g/mL) stabilized mesentery mast cells in vitro against Compound 48/80 -induced degranulation. In the late phase study, cryptolepine (10-100 mg/kg) prevented ovalbumin-induced airway obstruction and basal membrane smooth muscle hypertrophy. It significantly reduced systemic leukocytosis and inflammatory cell infiltration into airways in antigen-sensitized animals. Using the skin prick test, cryptolepine reduced the hypersensitivity to allergen challenge in antigen-sensitized animals. Cryptolepine's effects in the late phase was similar to dexamethasone (1 mg/kg) used as standard drug. Cryptolepine attenuates both early and late phase symptoms of asthma. It reduces bronchospasms, bronchial secretions, airway remodeling and hypersensitivity. This gives scientific credence to the traditional usage of cryptolepis extracts in upper respiratory tract disorders. (C) 2020 The Author(s). Published by Elsevier B.V. on behalf of African Institute of Mathematical Sciences / Next Einstein Initiative.