Toxicity Assessment of Common Beans (Phaseolus vulgaris L.) Widely Consumed by Tunisian Population

Abstract

This research aimed at assessing the content and the functional properties of phytohemagglutinin (PHA) in different varieties of beans widely consumed in Tunisia through soaking, cooking, autoclaving, germination, and their combinations. This study was carried out on three varieties of white beans grown in different localities of Tunisia, namely Twila, Coco, and Beldia, as well as on imported and local canned beans. All bean samples underwent biochemical and immunological evaluation by employing several techniques such as indirect competitive enzyme-linked immunosorbent assay (ELISA), hemagglutinating assay, Ouchterlony double immunodiffusion, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Biochemical and immunological analyses indicated that raw dry beans contained a considerable amount of proteins and PHAs. ELISA demonstrated that soaking, either in plain water or in alkaline solution, caused an increase in the concentration of PHA. A slight increase of PHA was produced equally by germination during 4 days in all bean varieties. Cooking or autoclaving of presoaked beans resulted in a complete disappearance of PHA. ELISA test also proved that both imported and local canned beans contained fingerprints of PHA. Hemagglutination assays showed that not only cooked and autoclaved presoaked beans lacked the ability to agglutinate red blood cells but also autoclaved unsoaked beans did. In agar gel immunodiffusion using rabbit anti-PHA serum, raw, soaked, cooked unsoaked, and sprouted beans gave precipitin arc reactions, indicating that PHA existed in immunoreactive form in the tested seeds. SDS-PAGE electrophoretograms showed protein isolates of Twila and Beldia beans to have different profiles through soaking, cooking, and autoclaving processes. This work revealed that the combination of soaking and cooking/autoclaving was the best way in reducing PHA content and its activity in all bean varieties when compared with germination.

Oral Administration of Raw White Kidney Beans (Phaseolus Vulgaris L. Var. Beldia) Induces Overgrowth of Fecal Coliforms and Lactobacilli in Wistar Rats

“…The general suggestion is that the bacterial populations and changes in microbial community are dependent on the dose of PHA fed to animals. Hence, it seems reasonable to assume that 300 mg Beldia flour beans (~2.76 mg PHA/day) [41] employed in this research were sufficient enough to evoke a bacteriological response in the rat small intestine.…”

Is There Such a Thing as “Anti-Nutrients”? A Narrative Review of Perceived Problematic Plant Compounds

“…Adeparusi et al found that autoclaving lima beans for 20 min eliminated all anti-nutrients except tannins [ 23 ]. Boiling of red and white kidney beans, notoriously rich in phytohemoggluttinin (PHA), also resulted in complete elimination of lectins [ 24 ]. Microwave ovens on the other hand, are not an effective method for lectin deactivation.…”

New research highlights: Impact of chronic ingestion of white kidney beans (Phaseolus vulgaris L. var. Beldia) on small-intestinal disaccharidase activity in Wistar rats

“…In a preliminary study, the phytohemagglutinin present in white kidney beans ( Phaseolus vulgaris L.) variety Beldia, frequently consumed by Tunisian population (INRAT, Tunis, Tunisia), was characterized and some of its properties were described [ 28 ]. Biochemical and immunological evidence indicated that raw Beldia seeds contain elevated levels of bioactive lectins, approximately 9.20 g/kg [ 28 ].…”

“…In a preliminary study, the phytohemagglutinin present in white kidney beans ( Phaseolus vulgaris L.) variety Beldia, frequently consumed by Tunisian population (INRAT, Tunis, Tunisia), was characterized and some of its properties were described [ 28 ]. Biochemical and immunological evidence indicated that raw Beldia seeds contain elevated levels of bioactive lectins, approximately 9.20 g/kg [ 28 ]. The raw Beldia beans demonstrated when orally administered to growing rats for 10 days at dose of 300 mg induced substantial modification of the morphology and physiological functions of the small intestine (i.e., disruption of absorption process) [ 29 ].…”