This work is part of the search in native food matrices from arid regions of Argentina of interest to improve human health. Prosopis species are ethnic food resources in South America capable of growing in arid and semi-arid environments. This work was focused to determine the nutritional and phytochemical composition of Prosopis nigra fine flour and to evaluate its biological properties. Flour showed a high level of sucrose (30.35 g/100 mu g flour), fiber (6.34 g/100 g flour), polyphenols (0.45 g GAE/100 g flour), and minerals (potassium, calcium, and magnesium). Apigenin C glycosides and phenylpropanoid acids were identified in free and bound phenolic enriched extracts, respectively. Polyphenols (especially free polyphenols) were able to inhibit enzymes associated with the metabolic syndrome, including alpha-amylase (IC50 30.1 mu g GAE/mL), alpha-glucosidase (IC50 22.5 mu g GAE/mL), while bound phenolics may control lipase activity (IC50 33.5 mu g GAE/mL) and exhibit antioxidant activity by different action mechanisms (SC50 between 16 and 93 mu g GAE/mL). Both extracts were more effective to inhibit cyclooxygenase-2 than phospholipase A(2) and lipoxygenase, proinflammatory enzymes. Polyphenolic extracts did not show any mutagenic effect. Our studies add value to this non-conventional flour as a promising food resource that could be used as a functional food or functional ingredient in formulations to reduce the risk of the development of obesity. These studies revalue our native resources by promoting their conservation, their use and their propagation.