Naringin, neohesperidin and their corresponding dihydrochalcones as bioactive substances: a symphony of bitter-sweet

Abstract Bitter is generally undesirable, although it is an important part of flavor. Bitter substances exhibit diverse health-promoting activities, which is in line with the famous Chinese saying ‘a good medicine tastes bitter’. Naringin (NAG) and neohesperidin (NHP), two important flavanones that give bitterness to citrus fruits, show various pharmacological activities. Interestingly, their hydrogenation products, i.e. naringin dihydrochalcone (NDC) and neohesperidin dihydrochalcone (NHDC), undergo a dramatic taste shift from bitter to intensely sweet, which can be 300 and 1000 times sweeter than sucrose, respectively. Such sweeteners not only provide a sweet taste without the burden of increased calorie intake and glycemia, but also may exert multiple bioactivities. This review summarizes common dietary bitter and sweet compounds with sensory scores. Taste conversions induced by structural changes from bitter NAG and NHP to sweet NDC and NHDC are particularly discussed. In addition, the taste-sensing mechanisms, pharmacological characteristics, dietary distribution, synthesis, and food industry applications of these bitter–sweet interchangeable compounds are outlined. In conclusion, the bitter NAG and NHP are promising therapeutic candidates for management of diverse etiologically complex diseases while their corresponding dihydrochalcones NDC and NHDC are promising sweeteners, which might be a blessing for those who need to control sugar intake.