Following is the structure: 
 
Molecular Formula: C₇H₁₅NO₃ 
Molecular Weight: 161.199 g/mol
IUPAC Name: (3R)-3-hydroxy-4-(trimethylazaniumyl)butanoate
Synonyms  of L-Carnitine (CAS NO.541-15-1): (R)-(3-Carboxy-2-hydroxypropyl)trimethylammonium hydroxide ; 1-Propanaminium, 3-carboxy-2-hydroxy-N,N,N-trimethyl-, hydroxide, inner salt, (R)- ; 1-Propanaminium, 3-carboxy-2-hydroxy-N,N,N-trimethyl-, inner salt, (R)- ; Ammonium, (3-carboxy-2-hydroxypropyl)trimethyl-, hydroxide, inner salt, L- ; Carnitine
CAS number: 541-15-1
refractive index: -32 ° (C=1, H₂O)
Merck: 14,1849
BRN: 4292315 
Storage temp.: 2-8 °C
Melting point: 208-212 °C
alpha -31 º (c=10, H2O)
Water solubility of  L-Carnitine (CAS NO.541-15-1): 2500 g/L (20 °C)
Appearance of L-Carnitine (CAS NO.541-15-1): White crystalline
Canonical SMILES: C[N+](C)(C)CC(CC(=O)[O-])O
Isomeric SMILES: C[N+](C)(C)C[C@@H](CC(=O)[O-])O
InChI: InChI=1S/C7H15NO3/c1-8(2,3)5-6(9)4-7(10)11/h6,9H,4-5H2,1-3H3/t6-/m1/s1
InChIKey: PHIQHXFUZVPYII-ZCFIWIBFSA-N

  L-Carnitine (CAS NO.541-15-1) was originally found as a growth factor for mealworms and labeled vitamin Bt.

  The use of L-Carnitine (CAS NO.541-15-1) showed some promise in a controlled trial in selected cases of male infertility improving sperm quality.L-Carnitine improved glucose disposal among 15 patients with type II diabetes and 20 healthy volunteers.It is essential cofactor of fatty acid metabolism, and it is required for the transport of fatty acids through the inner mitochondrial membrane. It is synthetized primarily in the liver and kidney, and it highest concentrations found in heart and skeletal muscle.

Organism	Test Type	Route	Reported Dose (Normalized Dose)	Effect	Source
dog	LD50	unreported	7gm/kg (7000mg/kg)		Cancer Treatment Reports. Vol. 63, Pg. 558, 1979.
mouse	LD50	intraperitoneal	750mg/kg (750mg/kg)		Gekkan Yakuji. Pharmaceuticals Monthly. Vol. 9, Pg. 759, 1967.
mouse	LD50	subcutaneous	9gm/kg (9000mg/kg)	SENSE ORGANS AND SPECIAL SENSES: LACRIMATION: EYE BEHAVIORAL: CONVULSIONS OR EFFECT ON SEIZURE THRESHOLD GASTROINTESTINAL: CHANGES IN STRUCTURE OR FUNCTION OF SALIVARY GLANDS	Acta Biologica et Medica Germanica. Vol. 35, Pg. 645, 1976.

 L-Carnitine (CAS NO.541-15-1) hasn't been listed as a carcinogen by ACGIH, IARC, NTP, or CA Prop 65. And the toxicological properties have not been fully investigated. You can see actual entry in RTECS for complete information.

Hazard Codes: Xi
Risk Statements: 36/37/38 
R36/37/38: Irritating to eyes, respiratory system and skin.
Safety Statements: 26-36-37/39 
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. 
S36: Wear suitable protective clothing. 
S37/39: Wear suitable gloves and eye/face protection.
WGK Germany: 3
RTECS: BP2980000
F: 3-10
Hazard Note: Irritant
HS Code: 29239000 

In animals, carnitine is biosynthesized primarily in the liver and kidneys from the amino acids lysine or methionine.Carnitine transports long-chain acyl groups from fatty acids into the mitochondrial matrix. L-Carnitine (CAS NO.541-15-1) products and supplements are not allowed to be imported into Canada (Health Canada). It is stable under normal temperatures and pressures, and it absorbs moisture or water from the air. It should avoid the condition like incompatible materials, exposure to moist air or water. while, it is incompatibilities with other materials strong oxidizing agents. Its hazardous decomposition products are carbon monoxide, oxides of nitrogen oxides, carbon monoxide, carbon dioxide. And its hazardous polymerization will not occur.