Heme synthesis - note that some reactions occur in the cytoplasm and some in the mitochondrion (yellow)
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Porphyria

The porphyrias are inherited or acquired disorders of certain enzymes in the heme biosynthetic pathway (also called porphyrin pathway). They are broadly classified as hepatic porphyrias or erythropoietic porphyrias, based on the site of the overproduction and mainly accumulation of the porphyrins (or their chemical precursors). more...

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Overview

In humans, porphyrins are the main precursors of heme, an essential constituent of hemoglobin, myoglobin, and cytochrome.

Deficiency in the enzymes of the porphyrin pathway leads to insufficient production of heme. This is, however, not the main problem; most enzymes—even when less functional—have enough residual activity to assist in heme biosynthesis. The largest problem in these deficiencies is the accumulation of porphyrins, the heme precursors, which are toxic to tissue in high concentrations. The chemical properties of these intermediates determine in which tissue they accumulate, whether they are photosensitive, and how the compound is excreted (in the urine or feces).

Subtypes

There are eight enzymes in the heme biosynthetic pathway: the first and the last three are in the mitochondria, while the other four are in the cytosol.

  1. δ-aminolevulinate (ALA) synthase
  2. δ-aminolevulinate (ALA) dehydratase
  3. hydroxymethylbilane (HMB) synthase
  4. uroporphyrinogen (URO) synthase
  5. uroporphyrinogen (URO) decarboxylase
  6. coproporphyrinogen (COPRO) oxidase
  7. protoporphyrinogen (PROTO) oxidase
  8. ferrochelastase

Hepatic porphyrias

The hepatic porphyrias include:

  • ALA dehydratase deficiency
  • acute intermittent porphyria (AIP): a deficiency in HMB synthase
  • hereditary coproporphyria (HCP): a deficiency in COPRO oxidase
  • variegate porphyria (VP): a deficiency in PROTO oxidase
  • porphyria cutanea tarda (PCT): a deficiency in URO decarboxylase

Erythropoietic porphyria

The erythropoietic porphyrias include:

  • X-linked sideroblastic anemia (XLSA): a deficiency in ALA synthase
  • congenital erythropoietic porphyria (CEP): a deficiency in URO synthase
  • erythropoietic protoporphyria (EPP): a deficiency in ferrochelatase

Porphyria variegata

Variegate porphyria (also porphyria variegata or mixed porphyria) results from a partial deficiency in PROTO oxidase, manifesting itself with skin lesions similar to those of porphyria cutanea tarda combined with acute neurologic attacks. It may first occur in the second decade of life; there is a cohort of sufferers living in South Africa descended from a single person from the Netherlands, Berrit Janisz, who emigrated in the 17th century.

Signs and symptoms

The hepatic porphyrias primarily affect the nervous system, resulting in abdominal pain, vomiting, acute neuropathy, seizures, and mental disturbances, including hallucinations, depression, anxiety, and paranoia. Cardiac arrhythmias and tachycardia (fast heart rate) may develop as the autonomic nervous system is affected. Pain can be severe and can, in some cases, be both acute and chronic in nature. Constipation is frequently present, as the nervous system of the gut is affected.

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Aromatic Plants of Yungas. Part II. Chemical Composition of the Essential Oil of Phoebe porphyria (Griseb.) Mez. (Lauraceae)
From Journal of Essential Oil Research: JEOR, 3/1/04 by Lopez, Maria L

Abstract

The essential oil of Phoebe porphyria (Griseb.) Mez. (Lauraceae) collected from northwestern Argentina (Yungas area) was analyzed by GC/MS. Twenty-five components were characterized, representing 87.0% of the total components detected. 1,8-Cineole (10.5%), [beta]-caryophyllene (19.3%) and spathulenol (17.1%) were the major constituents of the oil, which was obtained in 0.15% yield.

Key Word Index

Phoebe porphyria, Lauraceae, essential oil composition, 1,8-cineole, [beta]-caryophyllene, spathulenol.

Plant Name

Phoebe porphyria (Griseb.) Mez., Lauraceae. Common name 'laurel de la falda' (1).

Source

The plant was collected from Tartagal, province of Salta, in October 2000. Voucher specimens have been deposited in the Herbarium of the Museo Botanico de Cordoba (CORD).

Plant Part

Air-dried aerial parts were subjected to hydrodistillation for 3 h using a Clevenger-type apparatus to produce oil in 0.15% yield.

Previous Work

To the best of our knowledge, nothing is known about the chemical composition of P. porphyria oil. However, ocoteine has been identified in this species (2). In addition, an analysis of P. porosa oil has boon published (3).

Present Work

Gas chromatography: The oil was analyzed with a Shirnadzu GC-RIA gas Chromatograph equipped with a fused silica column (30 m x 0.25 mm) coated with DB-5. The temperature of the column was programmed from 60°-240°C at 4°C/min. The injector and detector temperatures were at 250°C. The gas earner was He, at a flow rate of 1 mL/min. Peak areas were measured by electronic integration. The relative amounts of the individual components are based on the peak areas obtained, without FID response factor correction. Programmed temperature retention indices of the compounds were determined relative to n-alkanes. GC analysis was still performed using a column Supelcowax-10 with the same conditions as described above. Gas chmmatography/mass spectrometry analyses were performed on a Perkin Elmer Q-910 using a 30 m x 0.25 mm capillary column coated with DB-5. The temperature of the column and the injector were the same as those of GC. The carrier gas was He, at a flow rate of mL/min. Mass spectra were recorded at 70 eV The oil components were identified by comparison of their retention indices, mass spectra with those of authentic samples, by peak enrichment, mass spectra library of National Institute of Standards and Technology (NIST 3.0), Adams's library (4), and our mass spectra library, which contains references mass spectra and retention indices of volatile compounds. GC/MS analysis was still performed using a column Supelcowax 10 with the same conditions as describe above. The chemical components identified in P. porphyria oil are listed in Table I. The oil was found to be rich in the sesquiterpenoid compounds spathulenol and [beta]-caryophyllene as well as 1,8-cineole.

Acknowledgments

The authors thank CONICOR, SECyT-UNC and PROYUNGAS (LIEY) for financial support. We also thank Biol. N. von Muller for technical assistance.

References

1. L. Parodi and M. Dimitri, Enciclopedia Argentina de Agricultura y Jardineria. p. 398. Bs. As. Acme. (1959).

2. F. Baralle, A. Busch, MJ Vernengo and AM Kuck, Isolation of ocoteine from Nectandra saligna and Phoebe porfiria. Lloydia, 35, 300-302 (1972).

3. T. Reynolds and G. Kite, Volatile constituents of Phoebe porosa Mez. J. Essent. Oil Res. 7, 415-418 (1995).

4. R.P. Adams, Identification of essential oil components by Gas Chromatography/Mass Spectroscopy. Allured Publ. Corp. Carol Stream, IL. USA (1995).

Maria L. Lopez, Maria P. Zunino and Julio A. Zygadlo*

Institulo Multidisciplinario de Biologia Vegetal, Facultad de Ciencias Exactas, Fisicas y Naturales, Universidad Nacional de Cordoba, Avenida Velez Sarsfield 1600, 5000 Cordoba, Argentina

Abel G. Lopez, Enrique I. Lucini and Silvina M. Faillaci

Inslituto de Ciencia y Tecnologia de los Alimentos, Facultad de Ciencias Exactas, Fisicas y Naturelles, Universidad National de Cordoba, Avenida Velez Sarsfield 1600, 5000 Cordoba, Argentina

"Address for correspondence Received: January 2001

Revised: February 2001

1041-2905/04/0002-0129S6.00/0-© 2003 Allured Publishing Corp. Accepted: May 2001

Copyright Allured Publishing Corporation Mar/Apr 2004
Provided by ProQuest Information and Learning Company. All rights Reserved

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