Medicinal Plants Classification Biosynthesis and ... - Index of

Pharmacologic Study of Some Plant Species from The Brazilian Northeast
Monocrotaline (MCT) (Figure 3) is the main PA found in plants of Crotalaria genus.
Although it is a hepatotoxic alkaloid, pneumotoxic, nefrotoxic, cardiotoxic, teratogenic and
carcinogenic effects were also related (Mattocks, 1986; Thomas et al., 1996; Ribeiro et al.,
1993; Cheecke, 1998; Medeiros et al., 2000; Kosogof et al., 2001).
The main alteration observed in lungs are edema and congestion, with consolidated areas
in parenchyma, causing interstitial and arteriolar lesion, inflammation, hemorrhage and
fibrosis (Gardiner et al., 1965; Newberne, et al., 1974; Nobre et al., 1994; Baybutt, Molteni,
1999; Baybutt et al., 2002; Copple et al., 2002).
Figure 3. MCT molecule.
Schraufnagel (1990) studied lungs of rats treated with monocrotaline. He observed
formation of new blood vessels, which occurs on pleural surface and on bronchovascular tree,
but not in alveolar capillaries, suggesting that these capillaries answer in different ways to
these angiogenic stimuli.
Deaths can occur due to damage on kidneys (Jubb et al., 1993). The main alterations are
tubular damage and glomerulonephritis (Hayashi, Lalich, 1967; Carstens, Allen, 1970;
McGrath et al., 1975; Figueredo et al., 1987).
Hepatocytes show citoplasmatic and nuclear gigantism (megalocytosis) (Bull, 1955;
Cheeke, Shull, 1985; Mattocks, 1986; Thomson, 1990; Jubb et al., 1993). Other lesions are
progressive fibrosis, bile ducts proliferation (Cheeke, Shull, 1985; Mattocks, 1986; Thomson,
1990) and occlusion of veins (Cheeke, Shull, 1985; Mattocks, 1986). There is impairment of
metabolic liver functions. The levels of serum proteins are diminished due to the reduction in
protein synthesis (Miranda et al., 1980), causing ascites and edema (Cheeke, Garman, 1974).
In liver, MCT is first activated to an electrophilic compound named monocrotaline
pirrole (MCTP). It can also be named dehydromocrotaline (DHM), which have characteristics
of a bifunctional agent of crossed linkage and has half-life period of 3s in aqueous with pH
next to neutral. Stabilization of MCTP by red blood cells makes the transport to the liver
easier. The evidences of the involvement of pulmonary endothelium in MCT intoxication is
supported by the similarity between hepatic and pulmonary endothelium, evidence of
thymidine increase (or deoxythymidine) and reduction of 5-hydroxitriptamine removed by
endothelial cells and outflow of macromolecules. In primary pulmonary hypertension,
disturbs on endothelial cell surface are suspects of being the initial factor to the formation of
platelet aggregation and cause thrombosis in situ (Lamé et al., 2000).
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