Resveratrol decreases MSU-induced recurrent attacks of gouty arthritis. Despite
its demonstrated anti-inflammatory effects, the mechanisms underlying resveratrolmediated repression of IL-1b production in MSU-activated monocytes remain
poorly understood. Resveratrol suppresses the secretion of active IL-1b by human
primary monocytes stimulated with MSU crystals through suppression of Syk
activation (Chung et al. 2019). Antioxidant or cytotoxic properties, of resveratrol,
able to alter the process of differentiation of naive T lymphocytes into Th17 lymphocytes through activation in particular of sirtuin-1, and to reduce the production
of pro-inflammatory substances such as interleukins. This action on the cells of the
immune system thus highlights a new property of resveratrol as an immunomodulator that could counteract the occurrence or progression of inflammation in various pathological processes (Delmas et al. 2019).
6.2.1.3 Epigallocatechin-3-Gallate
Polyphenols are a big family of phytochemicals that includes a wide range of
natural substances with various biological activities. Amongst these activities, the
immunomodulatory property has significant importance due to the central and vital
roles of the immune system in the human body (Pan et al. 2019; Sobhani et al.
2020). It is abundant in phenolic composition of green tea, Camellia sinensis (Fm:
Theaceae). Epigallocatechin-3-gallate (EGCG) is the ester of epigallocatechin and
gallic acid. It has a broad range of reported in-vivo and in-vitro anti-inflammatory,
anti-proliferative, chemopreventive, anti-invasive, and anti-oxidant anti-angiogenic
activity (Singh et al. 2011; Yang et al. 2011). It blocks the stimulation of NF-jB by
blocking the degeneration of inhibitor of nuclear factor kappa B (Muraoka et al.
2002) and also blocks the MAPK pathways. The downregulation of iNOS transcription and NO release in macrophages depend on blocking of NF-jB. EGCG
increases the production of NO to block endothelial exocytosis and to leukocyte
adherence ECs (Yamakuchi et al. 2008). Furthermore, that EGCG blocks NF-jB
stimulation in HECs and therefore it inhibits the expression of MCP-1 (Hong
et al. 2007).
6.2.1.4 Quercetin
The plant flavonol, quercetin, is a polyphenol, describing very broadly spreading
secondary plant metabolites. Food like grapevines, apples, broccoli, red onions,
berries, and tea, capers are a rich source of quercetin. It shows anti-mutagenic,
neuroprotective, anti-oxidative, anti-inflammatory, anticancer/chemopreventive,
antihypertensive activities. It also helps to lower blood-glucose-level. It activates
several kinase enzymes that phosphorylate elF 2, hence blocking cell translation.
The underlying mechanisms behind these activities are broad and extensively
categorized. Quercetin scavenges nitrogen and ROS, targets notable proinflammatory signaling pathways including NF-jB, MAPK and STAT1, and block
6 Natural Compounds Extracted from Medicinal Plants …
217
its demonstrated anti-inflammatory effects, the mechanisms underlying resveratrolmediated repression of IL-1b production in MSU-activated monocytes remain
poorly understood. Resveratrol suppresses the secretion of active IL-1b by human
primary monocytes stimulated with MSU crystals through suppression of Syk
activation (Chung et al. 2019). Antioxidant or cytotoxic properties, of resveratrol,
able to alter the process of differentiation of naive T lymphocytes into Th17 lymphocytes through activation in particular of sirtuin-1, and to reduce the production
of pro-inflammatory substances such as interleukins. This action on the cells of the
immune system thus highlights a new property of resveratrol as an immunomodulator that could counteract the occurrence or progression of inflammation in various pathological processes (Delmas et al. 2019).
6.2.1.3 Epigallocatechin-3-Gallate
Polyphenols are a big family of phytochemicals that includes a wide range of
natural substances with various biological activities. Amongst these activities, the
immunomodulatory property has significant importance due to the central and vital
roles of the immune system in the human body (Pan et al. 2019; Sobhani et al.
2020). It is abundant in phenolic composition of green tea, Camellia sinensis (Fm:
Theaceae). Epigallocatechin-3-gallate (EGCG) is the ester of epigallocatechin and
gallic acid. It has a broad range of reported in-vivo and in-vitro anti-inflammatory,
anti-proliferative, chemopreventive, anti-invasive, and anti-oxidant anti-angiogenic
activity (Singh et al. 2011; Yang et al. 2011). It blocks the stimulation of NF-jB by
blocking the degeneration of inhibitor of nuclear factor kappa B (Muraoka et al.
2002) and also blocks the MAPK pathways. The downregulation of iNOS transcription and NO release in macrophages depend on blocking of NF-jB. EGCG
increases the production of NO to block endothelial exocytosis and to leukocyte
adherence ECs (Yamakuchi et al. 2008). Furthermore, that EGCG blocks NF-jB
stimulation in HECs and therefore it inhibits the expression of MCP-1 (Hong
et al. 2007).
6.2.1.4 Quercetin
The plant flavonol, quercetin, is a polyphenol, describing very broadly spreading
secondary plant metabolites. Food like grapevines, apples, broccoli, red onions,
berries, and tea, capers are a rich source of quercetin. It shows anti-mutagenic,
neuroprotective, anti-oxidative, anti-inflammatory, anticancer/chemopreventive,
antihypertensive activities. It also helps to lower blood-glucose-level. It activates
several kinase enzymes that phosphorylate elF 2, hence blocking cell translation.
The underlying mechanisms behind these activities are broad and extensively
categorized. Quercetin scavenges nitrogen and ROS, targets notable proinflammatory signaling pathways including NF-jB, MAPK and STAT1, and block
6 Natural Compounds Extracted from Medicinal Plants …
217