Helenalin

262.3

262.30

4GUY9L896T

85236

DTXSID50217868

STERNUTATIVE CRYSTALS FROM BENZENE

63.6

1.24630

1.25g/cm3

167-168 °C

473ºC at 760 mmHg

179.9ºC

1.565

SLIGHTLY SOL IN WATER; SOL IN ALCOHOL, CHLOROFORM, HOT BENZENE

LD50 in mice, rats (mg/kg): 150, 125 orally (Witzel)

D25 -102.8° (c = 3.64 in 95% ethanol)

BITTER

III

6.1(b)

2811

HELENIUM MICROCEPHALUM (SMALLHEAD SNEEZEWEED) IS...VERY TOXIC, PARTICULARLY IN THE FLOWERING STAGE. THE TOXIC PRINCIPLE IS NOW BELIEVED TO BE A SESQUITERPENE, HELENALIN.

Agents obtained from higher plants that have demonstrable cytostatic or antineoplastic activity. (See all compounds classified as Antineoplastic Agents, Phytogenic.)|Drugs or agents which antagonize or impair any mechanism leading to blood platelet aggregation, whether during the phases of activation and shape change or following the dense-granule release reaction and stimulation of the prostaglandin-thromboxane system. (See all compounds classified as Platelet Aggregation Inhibitors.)|Anti-inflammatory agents that are non-steroidal in nature. In addition to anti-inflammatory actions, they have analgesic, antipyretic, and platelet-inhibitory actions.They act by blocking the synthesis of prostaglandins by inhibiting cyclooxygenase, which converts arachidonic acid to cyclic endoperoxides, precursors of prostaglandins. Inhibition of prostaglandin synthesis accounts for their analgesic, antipyretic, and platelet-inhibitory actions; other mechanisms may contribute to their anti-inflammatory effects. (See all compounds classified as Anti-Inflammatory Agents, Non-Steroidal.)|Agents that have a strengthening effect on the heart or that can increase cardiac output. They may be CARDIAC GLYCOSIDES; SYMPATHOMIMETICS; or other drugs. They are used after MYOCARDIAL INFARCT; CARDIAC SURGICAL PROCEDURES; in SHOCK; or in congestive heart failure (HEART FAILURE). (See all compounds classified as Cardiotonic Agents.)

DOGS TOLERATED RAPID IV INJECTIONS OF 0.3% HELENALIN OR CRUDE 50% ETHANOL EXTRACT OF HELENIUM MICROCEPHALUM AT A MAXIMUM CUMULATIVE DOSE OF 90 MG HELENALIN/KG OR A MAXIMUM OF 10 G PLANT/KG. THE PHARMACODYNAMIC RESPONSES WERE AN INITIAL CHOLINERGIC EFFECT, A NICOTINIC EFFECT, STIMULATION OF THE RESPIRATORY & CENTRAL NERVOUS SYSTEMS, & PROGRESSIVE CARDIAC FAILURE.|THE MODE OF ACTION OF HELENALIN AS A PROTEIN SYNTHESIS INHIBITOR IN P-388 LYMPHOCYTIC LEUKEMIA CELLS WAS INVESTIGATED IN CRUDE LYSATES OF THE CELLS. THERE WAS A 4-MIN LAG AFTER THE ADDITION OF DRUG BEFORE INHIBITION OF PROTEIN SYNTHESIS OCCURRED. BOTH DRUGS ALLOWED RUN-OFF OF PREFORMED POLYSOMES BUT DID INHIBIT THE FORMATION OF 80 S INITIATION COMPLEX, SUGGESTING A PREFERENTIAL INHIBITION OF GREATER THAN OR EQUAL TO INITIATION REACTIONS.|HELENALIN WAS CAPABLE OF ALKYLATING THE THIOL GROUP OF REDUCED GLUTATHIONE & L-CYSTEINE IN VITRO. HELENALIN WAS ACTIVE AGAINST EHRLICH ASCITES & WALDER 256 ASCITES CARCINOSARCOMA IN VIVO & HAD CYTOTOXIC ACTIVITY AGAINST H.EP-2 TUMOR CELLS IN VITRO.

INTENSELY POISONOUS, CAPABLE OF CAUSING PARALYSIS OF VOLUNTARY & CARDIAC MUSCULATURE & FATAL GASTROENTERITIS.|HELENIUM MICROCEPHALUM (SMALLHEAD SNEEZEWEED) IS...VERY TOXIC, PARTICULARLY IN THE FLOWERING STAGE. THE TOXIC PRINCIPLE IS NOW BELIEVED TO BE A SESQUITERPENE, HELENALIN.

dihydrohelenalin