Anti-proliferative and computational studies of two new pregnane glycosides from Desmidorchis flava.

Two new pregnane glycosides named desmiflavasides C (1) and D (2) were isolated from the sap of Desmidorchis flava (N.E.Br.) Meve & Liede and have had their structures confirmed from 1D and 2D NMR spectroscopic techniques and mass spectrometry (ESIMS). Further, the effects of desmiflavasides C (1) and D (2) on the proliferation of breast and ovarian cancer cells as well as normal breast epithelial cells in culture were examined. Interestingly, desmiflavasides C (1) and D (2) were able to cause a substantial decline in the viability of cancer cells in a concentration-dependent manner. Moreover, treatment of normal cells with compound 2 resulted in no significant growth inhibition, indicating that its cytotoxicity was selective towards cancer cells. Furthermore, the activity of compound 2 against cancer as well as normal epithelial cells was found to be similar to that of a previously reported pregnane glycoside, nizwaside (3). Molecular docking studies of desmiflavasides C (1) and D (2) and nizwaside (3) were carried out to ascertain if it was possible to predict any important binding orientations required of small molecule drug candidates with suggested protein target molecules for the purposes of being able to predict the affinity and activity to an acceptable degree by such compounds. Desmiflavaside D (2) showed a relatively good binding affinity (-22.4449kcal/mol) as compared to the other two compounds viz., nizwaside (3) (-20.0319kcal/mol), and desmiflavaside C (1) (-19.4042kcal/mol). Docking results of the three pregnane glycosides viz., 1-3 revealed that these ligand molecules can accurately interact with the target protein.

Nizwaside: a new anticancer pregnane glycoside from the sap of Desmidorchis flava.

The sap from the succulent Desmidorchis flava (N.E.Br) Meve and Liede yielded a new pregnane glycoside, named nizwaside whose structure was established using 1D and 2D NMR techniques as well as mass spectrometry (ESIMS). Nizwaside was tested for anticancer, DPPH antioxidant, urease enzyme inhibition, α-glucosidase enzyme inhibition and acetylcholinesterase inhibition activities. Interestingly, nizwaside showed significant anti-proliferative effects on MDA MB231 breast cancer cells with an IC(50) of 23.5 µg/ml. Moreover, nizwaside was more effective than Doxorubicin, a well-known clinical anticancer drug, in suppressing MDA MB231 cell proliferation even at concentrations lower than that of Doxorubicin (75 µg/ml nizwaside vs. 100 µg/ml Doxorubicin). On the other hand, nizwaside showed relatively weak antioxidant activity with 15 % inhibition.