Antiallergic Activity

In both in vitro and animal models of allergy, perilla preparations have demonstrated anti-allergic effects. Luteolin and rosmarinic and caffeic acids are chiefly responsible for this activity.

Seed extract The defatted seed extract has been shown to inhibit chemically induced type IV allergy and inflammation in vivo, with the luteolin constituent exhibiting the most potent activity.

Perilla seed extract has also been shown to inhibit histamine release from mast cells in a dose-dependent manner. The effect is more potent than for isolated flavonoids including catechin, quercetin and caffeic acid. Additionally, in a case report of perilla seed extract, 1 50 mg/day for 2 weeks selectively inhibited the production of serum IgE in two human subjects suffering allergic symptoms including sneezing, nasal obstruction and itchy eyes (Oryza Co. 2003).

Leaf Perilla leaf extract is thought to downregulate Th2-type cytokine production and prevent the Th1/Th2 balance from shifting toward Th2-type immune responses. A study on the effects of perilla leaf extract on cytokine production in allergic reaction in mice found that it suppressed IgE and IgG antibodies as well as IL-4, IL-5 and IL-10 (Ishihara et al 1999).

An aqueous extract of perilla leaf was shown in vitro and in vivo to inhibit local and systemic reactions in a mast cell-mediated immediate-type allergic reaction. Plasma histamine levels and cyclic AMP were reduced in a dose-dependent manner. Perilla also inhibited IgE-induced TNF-alpha production (Shin et al 2000). Oral administration of a hot water extract of perilla leaf was also shown to inhibit histamine release from mast cells and reduce scratching in an animal model of dermatitis (Wakame et al 2000).

Oral administration of a perilla leaf extract inhibited the inflammatory response in an induced allergic reaction in animals. Luteolin, rosmarinic and caffeic acids were isolated and identified as active constituents. Luteolin has been shown in vivo to © 2007 Elsevier Australia

inhibit TNF-alpha and arachidonic acid and reduce oedema (Ueda et al 2002). In another inflammatory model, perilla dose-dependently reduced the allergic response in mice by over 40%. Rosmarinic acid was identified as the main active constituent (Makino et al 2001) and has been shown to decrease the inflammatory response and increase superoxide radical scavenging in vivo (Osakabe et al 2004a). An extract of perilla leaf with high levels of rosmarinic acid decreased cytokine activity in asthma-induced rats (Sanbongi et al 2004). A perilla leaf decoction was found to suppress IgA nephropathy in genetically predisposed rats, possibly through modulation of the intestinal mucosal immune system. Perilla suppressed proteinuria, proliferation of glomerular cells, serum levels of IgA, glomerular IgA and IgG depositions in the mice. Rosmarinic acid seems to produce this effect synergistically with other constituents (Makino etal 2003b).

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