Table 3.

In vitro effect of plant extracts, isolated compounds, and dietary antioxidants on the effector functions of neutrophils specifically stimulated via Fcγ and complement receptors.

Therapy	Source	Effect	Reference
Areca catechu  (aqueous extract of dried ripe nuts)		↓ expression of FcγRs and CRs in human neutrophils. ↓ neutrophil phagocytic ability towards complement- and IgG-opsonized microspheres.	[148]
Chrysoeriola Eriodictyolb Isorhamnetinc 4′-Methoxyeriodictyold	Lychnophora granmongolense	↓ production of ROS in rabbit neutrophils stimulated via FcγRs and/or CRs.	[149]
Quercetin (3,5,7,3′,4′-pentahydroxyflavone)	Lychnophora ericoides	↓ oxidative metabolism in rabbit and human neutrophils specifically stimulated via FcγRs and CRs, either alone or in combination, without affecting the phagocytic and microbial killing capacity.	[149–151]
	Commercial	↓ human neutrophil degranulation, ↓ the activity of elastase, myeloperoxidase, and NADPH oxidase.	[151–153]
		Scavenges O2 •−, H2O2, HOCl, and chloramines.	[151, 154]
		↓ FcγR-stimulated ROS generation in neutrophils from RA patients with active disease who do not respond to anti-TNF-α drug therapy.	[151]
Galangin (3,5,7-trihydroxyflavone)	Commercial	Strongly inhibits oxidative metabolism in rabbit and human neutrophils specifically stimulated via FcγRs and CRs, either alone or in combination.	[150, 151]
		↓ myeloperoxidase and horseradish peroxidase activity.	[150, 151]
		↓ activity of NADPH oxidase in FcγR- and/or CR-stimulated human and rabbit neutrophils.	[153]
		Scavenges H2O2, HOCl, and chloramines.	[151]
		↓ FcγR-stimulated ROS generation in neutrophils from RA patients with active disease who are refractory to anti-TNF-α drug therapy.	[151]
Kaempferol (3,5,7,4′-tetrahydroxyflavone)	Commercial	↓ oxidative metabolism in rabbit and human neutrophils specifically stimulated via FcγRs and/or CRs.	[150, 151]
		↓ NADPH oxidase activity in human and rabbit neutrophils stimulated via FcγRs and/or CRs.	[153]
		↓ myeloperoxidase and horseradish peroxidase activity.	[150, 151]
		Scavenges H2O2, HOCl, and chloramines.	[151]
Myricetin (3,5,7,3′,4′,5′-hexahydroxyflavone)	Commercial	Slightly ↓ oxidative metabolism in rabbit and human neutrophils specifically stimulated via FcγRs and/or CRs.	[150, 151]
		↓ human neutrophil degranulation.	[152]
		↓ activity of elastase, myeloperoxidase, NADPH oxidase, and horseradish peroxidase.	[150–153]
		Scavenges O2 •−, H2O2, HOCl, and chloramines.	[151, 154]
Hydroxylated phenylcoumarins Acetoxylated phenylcoumarins	Laboratory synthesis	↓ oxidative metabolism in rabbit and human neutrophils specifically stimulated via FcγRs.	[155, 156]
		Scavenges HOCl.	[156]
		↓ activity of myeloperoxidase, NADPH oxidase, and horseradish peroxidase.	[156, 157]
Vitamin C plus vitamin E	Commercial	↓ ROS generation by human neutrophils stimulated via FcγRs.	[158]

CR: complement receptor; FcγR: Fcγ receptor; IgG: immunoglobulin G; RA: rheumatoid arthritis; ROS: reactive oxygen species; TNF-α: tumor necrosis factor-α.

^a5, 7, 4′-trihydroxy-3′-methoxyflavone.

^b5, 7, 3′, 4′-tetrahydroxyflavanone.

^c3, 5, 7, 3′-tetrahydroxy-4′-methoxyflavone.

^d5, 7, 3′-trihydroxy-4′-methoxyflavanone.