Antioxidant Activity: The Presence and Impact of Hydroxyl Groups in Small Molecules of Natural and Synthetic Origin

Abstract

Polyhydroxylated natural phenolic compounds, especially those with low molecular weights, are characterized by their ability to eliminate free radicals as they act as strong antioxidants. The various types of phenolic compounds represent the most important natural antioxidants in addition to some vitamins. The chemical structures of these compounds is discussed in details with their action mechanisms to remove free radicals and prevent many incurable and malignant diseases. In addition to these natural compounds, the last two decades have witnessed increased attempts by many scientific groups and research centers to synthesize chemical compounds in large quantities to mimic these natural compounds, but at a lower cost and greater biological effectiveness. Herein, we conduct a chemical survey of relevant synthetic compounds containing the hydroxyl groups prepared in chemical laboratories and studied for their biological efficacies, such as their effectiveness as antioxidants, as well as the mechanism of elimination of free radicals.

Characterization and Biological Activity of Fiber-Type Cannabis sativa L. Aerial Parts at Different Growth Stages

“…Among the flavonoids, luteolin-7- O -glucuronide presented the highest interaction with both radicals (peak area reduction >95%), which is probably related to its abundance and to the presence of an additional free hydroxylic group, compared to the other compounds of the same class. According to literature, the ortho position of the two OH groups on the benzene ring facilitates radical delocalization by resonance, justifying the major scavenging activity of this compound [ 44 ]. Cannabinoids showed a clear percentage reduction in the acetone extract, where flavonoids were not present, confirming that, although to a lower extent, they contributed to the total antioxidant power of the plant.…”

X-ray Structure Determination, Antioxidant Voltammetry Studies of Butein and 2′,4′-Dihydroxy-3,4-dimethoxychalcone. Computational Studies of 4 Structurally Related 2′,4′-diOH Chalcones to Examine Their Antimalarial Activity by Binding to Falcipain-2

“…Specifically, an increase in the number of hydroxyl groups at the ortho position in a phenol compound denotes an increase in antioxidant activity [42]. Hence, phenol compounds with two hydroxyl groups at the ortho position (catechols), have been suggested to be the most active antioxidants [43]. Thus, the catechol nature of Butein coupled with its two additional hydroxyl groups may explain its higher collection efficiency and better antioxidant capacity.…”

Nitrostilbenes: Synthesis and Biological Evaluation as Potential Anti-Influenza Virus Agents

“…In our ongoing study on the structural optimization of RSV, we focused on the R 2 and R 4 groups in the new scaffold and maintained the 4 -OH group on ring B (Figure 1) due to its well-documented role in antioxidant activity [33,34]. We started from the evidence that the introduction of a substituent with different electronic and lipophilic properties at the 4-position on the aromatic ring A (R 3 ) (Figure 1) improved the anticancer, antibacterial, and antioxidant activities [35][36][37][38].…”