Solanum aculeatissimum Jacq. () is a perennial undershrub (30 to 90 cm in height) and tropical America is its place of origin. It grows wild throughout the world, and is used to treat bronchitis and rheumatism in China.
Three alkaloids, solanine (), solasonine (), and β-solamardine () have been isolated from the acid methanolic extracts of the fruits (). The fruit, Kikania lei (Hawaii), is cooked and eaten. Solanum aculeatissimum also contains two new steroidal glycosides, aculeatisides A () and B () in the roots (). The yields of solasodine and aculeatiside B are surprisingly high (3.8 and 3.0% dry weight, respectively). Solasodine (), an aglycon of solasonine and β-solamargine and nuatigenin (), an aglycon of aculeatiside A and B are potentially useful precursors for the manufacture of steroidal hormones and pharmaceuticals, since nuatigenin and solasodine can be converted to the pregnane derivatives () as well as diosgenin (). Thus the potential utilization of the sapogenin nuatigenin has stimulated investigations on the biosynthesis, as well as the potential economic production, of the steroidal saponins by tissue culture.
Solasodine and its glycosides, solasonine and β-solamardine, have been isolated from cell and tissue cultures of a number of Solanaceae plants (). The ability to produce steroid glycoalkaloids was retained by non-permealized cells of Solanum aviculare ().
Callus cultures were induced from the germinating seedlings of S. aculeatissimum. Solanidine, solasodine, and solamardine were detected in the callus tissues (). Solanum aculeatissimum leaf disks displayed poor morphogenetic responses. Excised shoots, however, were rooted on a hormone-free medium and grown to maturity in the greenhouse (). To our knowledge, the production of aculeatisides has not yet been reported by tissue culture of this plant.
Solanum aculeatissimum Jacq. is a rich source of solanidine and nuatigenin glyco-sides, potentially valuable starting materials to produce steroid hormones. In vitro cell cultures and propagation of Solanum aculeatissimum Jacq. have been established by several workers.
Callus tissues from germinated seeds accumulated solasodine derivatives. In comparison, undifferentiated callus tissues induced from mature leaves did not possess the ability to form solasodine or nuatigenin glycosides. However, callus from the mature leaves can produce the steroidal ketones, stigmast-3-one (or its isomer) and stigmast-4-en-one, and the saturated sterols of A5-sterols, such as campestanol and stigmastanol. Thus callus culture could transform sterols to the corresponding saturated sterols via oxidation of the hydroxy group and hydrogen-ation of the resulting α, β-unsaturated ketones.
Studies on steroid glycosides in the roots regenerated from undifferentiated callus indicate that regenerated roots can accumulate the nuatigenin glycosides, aculeatiside A and B, in quantities comparable to the intact roots.
Selections from the book: “Medicinal and Aromatic Plants V”, 1993.