'Bioflavonoids' are a class of nutrients found in plants that share one of three similar structural backbones; a simple disambiguation of their structures and subcategories can be found here.
They are broken down into Flavones, Isoflavonoids, and Neoflavonoids initially. Each of these categories can be broken down further, but this page encompasses them all.
There are some properties that these compounds possess that is common to their structure, and some differences exist between compounds because of their structure. For example, due to their structure Isoflavonoids are more potent at interacting with estrogen when compared to Flavones.
The effects of bioflavonoids can sort of be grouped together into a 'General Overview' when getting them from foods.
They tend to be anti-carcinogenic, regulate hormonal status (although not too potently) and can confer long term benefits to bone and fat metabolism (stronger bones with lesser risk of osteopenia, less fat in the future although its a hard to place causation on bioflavonoids for this).
When supplemented, and taken away from foods, it is best to treat each molecule on an individual basis. A simple change can mean a world of a difference, and especially for this class dose is important.
(Common misspellings for Bioflavonoids include bioflavinoids, bioflavanoids, flavinoids, flavanoids, falvanoids, falvinoids, bioflavonoid, bioflavanoid)