Background: Flavonoids are an important group of natural products because they possess a variety of biological
activities such as antioxidant, anti-inflammatory and anti-cancer; the modification of their structure could improve their
biological activities. The nitro group is included in diverse pharmaceuticals with a variety of biological activities, such as
anti-cancer and anti-inflammatory agents.
Objective: The study aimed at introducing a nitro group into the structure of flavonoids in order to observe how their antiproliferative, antioxidant and anti-inflammatory activities change.
Methods: In this investigation, we established diverse conditions of aromatic nitration of chrysin (1), quercetin (2) and
naringin (3) flavonoids using bismuth (III) nitrate, acetic acid or Silica gel and NOx gases. The antiproliferative activity in
CaSki, MDA and SK-LU-1 cancer cell lines, and the anti-inflammatory activity and antioxidant activity of flavonoids and
nitro derivatives were evaluated as well.
Results: As a result, mild nitration conditions were established, and 8-nitrochrysin, 5’nitroquercetin and 3’nitronaringin
were obtained. The number and hydroxyl group position in the flavonoid are important to carry out the nitration reaction.
Although chrysin showed a higher antiproliferative activity than quercetin and naringin, the introduction of the nitro group
at C-8 did not improve its antiproliferative, antioxidant and anti-inflammatory activities. On the other hand, the introduction
of the nitro group at C-5̍ in quercetin structure was important to improve its antioxidant and antiproliferative activities on
cancer cell lines. The introduction of the nitro group at C-3’ in naringin improved its anti-inflammatory activity, but not its
antioxidant and antiproliferative activities. Chrysin, 8-nitrochrysin, quercetin and 5’-nitroquercetin did not show necrotic
Conclusion: The introduction of a nitro group into flavonoids structure improved their antiproliferative, antioxidant and
anti-inflammatory activities, and these results promote future investigations of structural modification on 2-
phenylbenzopyran skeleton to optimize their biological activity.