Photodynamic chlorophyllametabolites, including phytoporphyrin (phylloerythrin), in the blood of photosensitive livestock: Overview and measurement

Abstract

A spectrofluorometric method for the quantification of phytoporphyrin in the blood of photosensitive animals has been validated, and can be applied to the measurement of other chlorophyll a metabolites in blood. This will be a useful tool in the further investigation of the cause and pathogenesis of idiopathic photosensitivities of farm animals.

Secondary Plant Products Causing Photosensitization in Grazing Herbivores: Their Structure, Activity and Regulation

“…Secondary hepatogenic (also referred to as Type 3) photosensitization results from the accumulation of the photodynamic compound phytoporphyrin through the circulatory system of the herbivore. Phytoporphyrin is a microbially-produced metabolite of chlorophyll and is normally cleared from the herbivore’s circulatory system by hepatic metabolism, however, secondary photosensitization may occur as a result of either acute or chronic liver damage in the affected animal when porphyrin and derivatives are not cleared by the damaged liver (Figure 3) [15,36,37]. …”

“…Normal plasma concentrations in sheep have been shown to be less than 0.01 mM/L, with photosensitization occurring at concentrations >0.03 mM/L in affected animals [85]. If hepatic function is impaired, phytoporphyrin levels increase in the systemic circulation [36] and subsequently accumulate in the skin, where activation by sunlight results in damage to the sensitive dermal layers. Although the mode of action of phytoporphyrin is unknown, studies have shown binding of phytoporphyrin to Golgi apparatus and mitochondria, indicating that these organelles may be the primary target of this photocytotoxic compound [36,86].…”

Chronic sporidesmin toxicosis and photosensitisation in an alpaca (Vicugna pacos) in New Zealand

“…As with facial eczema in ruminants, elevated activities of liver enzymes in serum, especially γ-glutamyl transferase (GGT),and bilirubin concentrations were helpful in the diagnosis (Coulton et al 1997). Raised concentrations of phytoporphyrin (phylloerythrin) in serum confirmed that the pathogenesis of the photosensitisation was secondary to liver disease (Campbell et al 2010). …”

Review of genetic studies of susceptibility to facial eczema in sheep and dairy cattle

“…Thus, high phylloerythrin and clinical cases of FE were not good indicators of liver damage from FE on an animal-to-animal basis. Likewise, measuring phylloerythrin concentration in blood (Campbell et al 2010) will not assist in determining the extent of FE-induced liver damage. Phylloerythrin concentration was lowly inherited in cattle, with a value of 0.1990.07 (Morris et al 2009).…”