Newly isolated compounds from West African Sorghum bicolor leaf sheaths Jobelyn® show potential in cancer immunosurveillance

Jobelyn, a West African pharmaceutical product derived from Sorghum bicolor leaf sheaths has been shown to possess strong antitumour and anti-inflammatory properties. This study aims to evaluate the expression of cell surface markers CD69 on activated natural killer (NK) cells; natural killer T (NKT) cells; and T cells from human peripheral blood mononuclear cells (PBMC) upon treatment with Jobelyn fractions using flow cytometry. Blood was collected from 3 donors, PBMC were isolated and plated with each specific fraction: crude extracts (J); ethyl acetate (JE); n-butanol (JB); secondary compounds from JE (JE5; JE6); purified and semi-purified compounds from JE5 (P8 and P9) at specific concentrations (2.5-500 g/ml). For the crude extracts, JE was the most active showing significant expression of CD69 on NK-(P  0.001), T(P  0.0001), and NKTtreated cells (P  0.0001). Secondary compound, JE5, of JE also showed significant CD69 expression on NK(P  0.018) and T-treated cells (P  0.027), but not on NKT-treated cells (P  0.084). Similarly, the semi-purified compound P8, from JE5 showed increased expression of CD69 on NK(P0.023); T(P  0.001), and NKT-treated cells (P0.007). Evidence of innate effector cells activation by ethanolic extracts of Jobelyn suggests that this variety of Sorghum may be able to mediate direct cell cytotoxicity supporting the control and clearance of a number of tumour cells.