The West African Sorghum Bicolor Leaf Sheath Extract Jobelyn® and its Diverse Therapeutic Potentials

Sorghum bicolor is an ancient plant that has been cultivated in North-eastern Africa for over 5000 years [1]. This is a cane like grass, up to 6 meters tall with large branched clusters of grains. The individual grains are around 3-4 mm in diameter and vary in colour from white, red, brown, yellow, purple, to black. The leaves resemble those of maize and grow rapidly. Sorghum grains of different cultivars are a rich source of phenolic compounds. These are natural bioactive compounds found in plants, which offer potential health benefits. Examples include secondary metabolites and antioxidants. As plants absorb the sunlight they produce high levels of oxygen and secondary metabolites by photosynthesis, which results in medicinal components being produced and stored in plant leaves. Flavonoids and phenolic acids are the most important group of secondary metabolites and bioactive compounds in plant [2]. In planta, antioxidant polyphenols have a range of roles including protection against herbivores and microbial infection, as allelopathic agents and UV protectants [3]. In humans, there is now increasing evidence on the role of phenolic compounds as protective dietary agents [4]. They are also considered to be natural and antioxidant substances capable of scavenging free superoxide radicals, supporting anti-aging mechanisms and reducing the risk of cancer. The Sorghum grain is a rich and diverse source of phenolic compounds, particularly phenolic acids and flavonoids. Similar to other cereals like maize and wheat, most of the phenols in the Sorghum grain are located in the bran, but differ in that Sorghum grain contains higher levels of phenolic compounds compared to most cereals and even fruits and vegetables depending on their variety [5]. Anthocyanidins are the primary flavonoids found in Sorghum grain and include apigeninidin, apigeninidin 5-glucoside, luteolinidin, luteolinidin 5-glucoside and 3-deoxyanthocyanidins, which is the most common [6]. The biosynthetic pathway that is responsible for the accumulation of 3-deoxyanthocyanins flavonoid compounds is controlled by the yellow seed1 (ys1) gene present in most varieties of Sorghum grains [7]. The uncommonly high levels of flavonoid accumulation in the Sorghum grain differentiates Sorghum from other grains and certainly makes it an interesting grain for healthy dietary applications or a source of bioactive compounds. More intriguing is the fact that the West African variety of Sorghum synthesizes exceptionally high amounts of 3-deoxyanthocyanins pigments in their non-grain tissue [8]. Compared to the Sorghum grain, the leaf sheath and glumes contribute to a greater biomass and may provide an easier and more cost-effective approach to obtain large quantities of stable 3-deoxyanthocyanins pigments.