Determination of obestatin-like immunoreactive subtances in some commonly consumed plants affecting appetite

Obestatin is a newly identified hormone composed of 23 amino acids, which has recently been defined as a product of the ghrelin gene. Obestatin and ghrelin, two peptide hormones that have opposite effects on body weight control, are both derived from the same ghrelin gene. Obestatin has effects such as reducing food intake, promoting weight loss, decreasing gastric emptying, reducing thirst and anxiety, improving memory, regulating sleep, and increasing the secretion of pancreatic enzymes. Obestatin is mainly produced in the X/A-like cells of the oxyntic mucosa and also in pancreatic cells. With its anorexigenic effects, obestatin antagonizes the effects of ghrelin when both hormones are applied together. Additionally, obestatin has been identified in various animal groups such as mammals, birds, and amphibians, and the ghrelin sequence has been evolutionarily well conserved. In this study, the presence of obestatin-like immunoreactive substances in commonly consumed plants thought to affect appetite was investigated. These plants include Opuntia ficus-indica, Asparagus officinalis, Anethum graveolens, Brassica oleracea var. capitata, Camellia sinensis [L.] O. Kuntze, Zea mays, Brassica oleracea L. var. acephala, Morus spp, Vitis vinifera, and Allium cepa. Protein isolation from the plants was performed using QB buffer, and plant extracts were screened for obestatin-like immunoreactive substances using the sandwich ELISA method. As a result, different levels of obestatin immunoreactivity were detected in all the plants (0.86-3.78 ng/mg protein). Among the studied plants, Brassica oleracea L. var. acephala exhibited the highest obestatin immunoreactivity (3.78 ng/mg protein). In conclusion, this study observed that ghrelin or obestatin-like immunoreactive substances are present not only in the animal kingdom but also in plants. This supports the idea that obestatin is a universal hormone. Moreover, plants containing obestatin-like substances at varying levels may have an effect on weight control in both humans and animals.