Plicatic acid

This highly hydroxylated phenyl-tetralin-type lignan acid is available from Thuja plicata. It is recovered in about 2% yield from the heartwood. Because it is one of the strongest known natural acids, plicatic acid (6) is readily separable from 

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Respiratory hypersensitivity is an adverse reaction in the respiratory tract driven by immune mechanisms such as IgE antibody mediated allergic responses. Other less well understood mechanisms that have an immune component are also involved in respiratory hypersensitivity. OA is one outcome of respiratory hypersensitivity. Respiratory hypersensitivity and OA to proteins are primarily mediated by IgE antibody with subsequent inflammatory cell infiltrates. This same mechanism is responsible for OA to specific LMW chemicals such as the acid anhydrides and platinum salts. However, the role for IgE mediated responses in OA to other LMW chemicals such as the isocyanates and plicatic acid is poorly defined and other mechanisms may be responsible. 

Certain LMW agents will cause OA via a poorly defined mechanism. Only about 20% of workers with OA to toluene diisocyanate (TDI) have IgE detectable to TDI indicating that IgE antibody may be more an indicator of exposure rather than a mediator of the disease [10], Similar data exist for workers with asthma caused by plicatic acid from western red cedar [11], The inability to detect IgE antibody in the majority of these workers may be based in technical issues such as the nature of the chemical-protein... 

Chan-Yeung, M., Giclas, PC., and Henson, P.M., Activation of complement by plicatic acid, the chemical compound responsible for asthma due to western red cedar (Thuja plicata), J. Allergy Clin Immunol., 65, 333, 1980. 

Extensive studies have been done on a clearly defined asthma syndrome produced by exposure to western red cedar. ° Plicatic acid has been identified as the etiologic agent. The western red cedar asthma syndrome includes rhinitis, conjunctivitis, wheezing, cough, and nocturnal attacks of breathlessness characterized by a precipitous decline in FEVi. There is no apparent relation between skin sensitivity and respiratory changes. No precipitating IgG antibodies are found in the serum of sensitized individuals, and circulating IgE antibodies are present in about one-third of affected individuals. 

Coupling of such radicals yields a great variety of products. One type of dimerization gives the stable ether linked pinoresorcinol (Eq. 25-11). Through a complex sequence of reactions, it can be converted into other plant compounds including the phytoalexin plicatic acid, a major component of western... 

The term lignan typically refers to dimers of monolignols that are linked via an 8-8 (P-P ) bond, whereas the term neolignan refers to dimers and oligomers that contain bonds other than the 8-8 bond. Most lignans are optically active, and typically only one enantiomer is found in a given species. Examples of lignans include (+)-pinoresinol (1.72), (+)-sesamin (1.73), and (-)-plicatic acid (1.74). 

Fig. 5-8. Examples of phenolic extractives and related constituents. 1, Gallic acid 2, ellagic acid 3, chrysin 4, taxifolin 5, catechin 6, genistein 7, plicatic acid 8, pinoresinol 9, conidendrin 10, pinosylvin 11, /3-thujaplicin.

CARTIER, A., CHAN, H MALO, J-L., PINEAU, L TSE, K.S. CHAN-YEUNG, M. (1986) Occupational asthma caused by eastern white cedar (Thuja occidentalis) with demonstration that plicatic acid is present in this wood dust and is the causal agent. Journal of Allergy and Clinical Immunology, 77, 639-645. 

It is puzzling that this risk from smoking is not seen in all chemical exposures that cause occupational asthma. For example, a large series of 232 patients with asthma caused by western red cedar wood (in which the causal agent is believed to be plicatic acid) contained only 5 per cent of current smokers (Chan-Yeung et al., 1987). This is similar to isocyanate-induced... 

Oxodihydroinumakilactone 15-acetate, T38.il Olivin, Y16.4 Cervicarcin, Y18.6 C20H22O10 Plicatic acid, Y7.13 Q2oH22Si... 

Sun BE, Hong R, Kang YB, Deng L (2009) Asymmetric Total Synthesis of (-)-Plicatic Acid via a Highly Enantioselective and Diastereoselective Nucleophilic Epoxidation of Acyclic Trisubstitued Olefins. J Am Chem Soc 131 10384... 

Gardner JAF, Barton GM, Maclean H (1959) The Polyoxyphenols of Western Red Cedar Thuja plicata Donn.) 1. Isolation and Preliminary Characterization of Plicatic Acid. Can J Chem 37 1703... 

Vedal S, Chanyeung M, Enarson DA, Chan H, Dorken E, Tse KS (1986) Plicatic Acid Specific Ige and Nonspecific Bronchial Hyperresponsiveness in Western Red-Cedar Workers. J Allergy Clin Immunol 78 1103... 

Frew A, Chang JH, Chan H, Quirce S, Noertjojo K, Keown P, Chan-Yeung M (1998) T-Lymphocyte Responses to Plicatic Acid Human Semm Albumin Conjugate in Occupational Asthma Caused by Western Red Cedar. J Allergy Clin Immunol 101 841... 

Total Synthesis of (-)-Plicatic Acid The enantioselective synthesis of (-)-plicatie acid, which has been identified as the causative agent of occupational asthma, features an interesting FC... 

Plicatic acid (87) SCHEME 2.11 Enantioselective synthesis of (-)-plicatic add. 

Plicatic acid (41), a lignan isolated from the heartwood of Western red cedar Thuja plicata D. Don) (Coniferae) was found to activate the classical pathway of complement. The mechanism by which this activation occurred was not completely defined at the molecular level, but appeared to involve interference with the control of active Cls in serum by Cl-In. By virtue of its ability to interfere with Cl-In in its inactivation of active Cl, plicatic acid might act as a protector of active Cl [26]. 

Giclas PC (1982) Effect of plicatic acid on human serum complement includes interference with Cl inhibitor function. J Immunol 129 168-172... 

Piperinic acid, T1 Piperitenone oxide, T4 Piperitols, T4 Piperitone, T2 Piperitone oxide, T4 Pipitzols, T1 Pisatin, Y3 Piscidic acid, A30 Plathyterpol, T39 Platicodigenin, T45 Platydesmine, K31 Platynecine, K22 Plicatic acid, Y7 Plinols, T3 Plumericin, T16 Plumieride, T16 Pluviine, K6 Podocarpic acid, T33 Podolactones, T38 Polyether antibiotics, Yll Polyporenic acid A, T50 Ponasterone, T48 Porantherine, K29 Porphyrins, Y23 Portentol, Y15 Portulal T40 Preisocalamendiol, T22 Pretoxin, T31 Pristimerin, T45 Pristimerol, T45 Proaporphine alkaloids, K3 Proline, All Prolinol, A17 Pronuciferine, K3 19-propylthevinol, K4 Prostaglandins, Y16 Protoaphins, YIO Protoemetine, K2 Protostanes, T50... 

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