Fruits, immunity and COVID

The natural products are known to be loaded with an immense variety of secondary metabolites, named phytochemicals (PhC), with significant redox-modulating properties and inflammatory response modulating properties. 

Earlier they were only considered ‘health promoting’ due to their radical-scavenging activity and/or direct antioxidant effects on cellular biomolecules but now they are believed to interfere with cell functions by intercepting reactive species at the level of critical cell signaling pathways. Additionally, these products have also demonstrated interactions with enzymes, receptors, and transcription factors.

Fraxinus angustifolia Vahl, the so-called manna, has shown effectiveness in scavenging several reactive radicals and antioxidant protection in a complex environment, such as human red blood cells. Its extract has also demonstrated anti-inflammatory effects in an in vitro model of intestinal bowel disease.

Licorice extracts have also displayed relevant and interesting radical-scavenging, antioxidant, and anti-inflammatory effects. These activities, when combined with the tyrosinase and elastase inhibitory activities, make highly active components for cosmeceuticals products with anti-ageing properties.

Nigella sativa oil obtained from a cultivar produced in the region Marche is been found rich in thymoquinone content. Thymoquinone content is well known to impart anti-inflammatory and antioxidant effects to the oil, along with, the other oil components may exert synergistic effects.

The health-promoting effects of green tea are mainly studied on catechins. Green tea flavonols also possess antioxidative, anti-inflammatory, and antiproliferative effects. flavonol glycoside (FLG)- and flavonol aglycone (FLA)-enriched fractions isolated from green tea extract showed radical-scavenging activity in a study. They both attenuated intracellular oxidative stress in neuron-like PC-12 cells, significantly reduced inflammatory genes in murine macrophages and inhibited proliferation of both the colon adenoma cell line DLD-1 and the breast cancer cell line E0771. Moreover, treatment with FLG or FLA combined with paclitaxel showed synergistic anticancer effects on the DLD-1 cell line. 

Mastiha, a natural product of the Mediterranean area, is found as a dried resinous exudate from the stems and branches of the tree, Pistacia lentiscus has also demonstrated antioxidant and anti-inflammatory properties. Its antioxidant potential may be correlated to the inhibition of protein kinase C, while its anti-inflammatory capacity is correlated to the inhibition of NF-κB activation.

Source: Allegra M. Antioxidant and Anti-Inflammatory Properties of Plants Extract. Antioxidants (Basel). 2019;8(11):549. Published 2019 Nov 14. doi:10.3390/antiox8110549