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Russula subnigricans
General Details, Taxonomy and Biology, Clinical Effects, First Aid
Phylum: Basidiomycota
Class: Basidiomycetes
Order: Russulales
Family: Russulaceae
Genus: Russula
Species: subnigricans
Clinical Group: GROUP 3 - Myotoxic mushroom poisoning
Common Names: Rank Russula
Solitary, scattered or gregarious mostly under live oak. Fruiting fro late summer to early winter.
PILEUS (cap) 9-20 cm in diameter, broadly convex becoming plane to depressed. Surface smooth, viscid when wet. Whitish, turning brownish to dirty reddish brown or dull dirty orange-yellow or a mixture of these shades. Margin in-rolled, not striate.

LAMELLAE (gills) adnate to slightly decurrent, moderately distant, alternating with long and short. Dirty whitish, soon staining dark reddish.

STIPE (stem) 7-13 cm in height, 3-7 cm thick, equal or tapering towards base, hard, solid. Whitish, staining reddish to greyish brown when handled or with age.

FLESH thick, crisp, whitish bruising slowly to reddish brown to greyish brown. Taste mild to slightly bitter.


Spores 6-10 μm, nearly round with low amyloid warts and ridges.
First Aid
Description: First aid for poisoning by plants or mushrooms where no agreed first aid method is currently available.
In the absence of research or clinical data about first aid for poisoning caused by this species, no first aid method can currently be recommended. Seek Medical Advice without delay.
Clinical Effects & Treatment
Deadly poisonous
Clinical Classification
Group 3A - Rapid onset myotoxicity
The known toxic compounds are myotoxin,gastrointestinal toxin, cadmium, mycotoxin russuphelins.

A small, highly strained carboxylic acid, cycloprop-2-ene carboxylic acid was isolated from R. subnigricans. This compound is responsible for fatal rhabdomyolysis; the LD100 value in mice was 2.5 mg/kg.

A chlorinated triphenylether named as russuphelin A (1). It takes the form of colorless needles.
Molecular formula is C20H14O6Cl4.
Melting point is 293-294 C.
The structure of russuphelin A is 2,6-bis(2,6-dichloro-4-hydroxyphenyloxy)-1,4-dimethoxybenzene (1).
This compound showed in vitro cytotoxic activity against tumor cells.

Russuphelin B (2)
Appear as colorless needles.
Molecular formula is C19H12Cl4O6.
Structure of russuphelin B is 2,6,-bis(2,6-dichloro-4-hydroxyphenyloxy-4-hydroxy-1-methoxybenzene.
Cytotoxic activity was observed in vitro against P388 leukemia cells.
IC50 15.4 μg/ml

Russuphelin C (3)
Appear as a pale brown amorphous solid.
Molecular formula is C18H10Cl4O6
Strucutre of russuphelin C is 2,6-bis(2,6-dichloro-4-hydroxyphenyloxy)-1,4-dihydroxybenzene.
Cytotoxic activity was observed in vitro against P388 leukemia cells.
IC50 0.94 μg/ml

Russuphelin D (4)
Appear as colorless needles.
Molecular formula is C14H11Cl3O4.
Structure of russuphelin D is 2-(2,6-dichloro-4-hydroxyphenyloxy)-6-chloro-1,4-dimethoxybenzene.
Cytotoxic activity was observed in vitro against P388 leukemia cells.
IC50 12.1 μg/ml

Russuphelin E (5)
Appear as amorphous solids.
Structure of russuphelin E is 2-(2,6-dichloro-4-methoxyphenyloxy)-6-chloro-4-hydroxy-1-methoxybenzene.

Russuphelin F (6)
Appear as amorphous solids.
Structure of russuphelin F is 2-(2,6-dichloro-4-methoxyphenyloxy)-6-chloro-1-hydroxy-4-methoxybenzene.
Clinical Effects Overview
Symptoms from ingesting this potentially myotoxic mushroom most often start with onset of GIT effects within 2hr (nausea, vomiting, diarrhoea, abdominal pain) but many cases resolve over 24hr. In some cases the GIT effects are more severe and are followed by rhabdomyolysis, myalgias, hypertension, dehydration, renal failure, hyperkalaemia, arrhythmias, myocarditis and cardiovascular collapse.

Chest tightness, dyspnea, generalized muscle pain can occur after 6-12 hr. In severe cases patients present with "haematuria" or "haemoglobinuria" (may actually be myoglobinuria) and significantly elevated creatine kinase levels, indicative of development of acute rhabdomyolysis and this may be associated with secondary acute renal failure, with death in fatal cases occurring within 12-24 hr post-ingestion.

Death in severely poisoned patients may be delayed more than 72hr in the setting of intensive support measures including haemodialysis.
Primary Clinical Effect
The primary effect is acute gastrointestinal irritation, followed by rhabdomyolysis.
Treatment Overview
Most cases of gastrointestinal irritant mushroom ingestion will develop a self limited illness and recover over a period of hours, with no more than simple supportive care, notably fluid replacement.

Only a minority of cases will have severe GIT fluid loss requiring full resuscitation with IV fluids and, on occasion, pressors. A further small subset will develop hypovolaemic shock and complications thereof, requiring more substantial intervention.

The major risk is acute renal failure secondary to rhabdomyolysis and the potential for this to progress to hyperkalaemia and consequent potentially lethal cardiac effects.
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