Caffeine:
Sources: Coffee, tea, cola nuts, mate, guarana.
Effects: Stimulant of central nervous system, cardiac muscle, and
respiratory system, diuretic Delays fatigue.

Theophylline:
Sources: Tea
Effects: Cariac stimulant, smooth muscle relaxant, diuretic, vasodilator
 

Theobromine:
Sources: Principle alkaloid of the cocoa bean (1.5-3%) Cola nuts and tea
Effects: Diuretic, smooth muscle relaxant, cardiac stimulant, vasodilator.
 

(Info from Merck Index)

The presence of the other alkaloids in colas and tea may explain why these sometimes have a stronger kick than coffee. Colas, which have lower caffeine contents than coffee are, reportedly, sometimes more active. Tea seems the strongest for some. Coffee seems more lasting for mental alertness and offers fewer jitters than the others.

A search in CAS and produced these names and synonyms:

RN   58-08-2  REGISTRY
CN   1H-Purine-2,6-dione, 3,7-dihydro-1,3,7-trimethyl- (9CI)  (CA INDEX NAME) OTHER CA INDEX NAMES: CN   Caffeine (8CI) OTHER NAMES:
CN   1,3,7-Trimethyl-2,6-dioxopurine
CN   1,3,7-Trimethylxanthine
CN   7-Methyltheophylline
CN   Alert-Pep
CN   Cafeina
CN   Caffein
CN   Cafipel
CN   Guaranine
CN   Koffein
CN   Mateina
CN   Methyltheobromine
CN   No-Doz
CN   Refresh'n
CN   Stim
CN   Thein
CN   Theine
CN   Tri-Aqua
MF   C8 H10 N4 O2

The correct name is the first one, 1H-Purine-2,6-diione,3,7-dihydro-1,3,7-trimethyl- (This is the "inverted name") The "uninverted name" is 3,7-Dihydro-1,3,7-trimethyl-1H-purine-2,6-dione

Merck Index excerpt...Caffeine: 3,7-dihydro- 1,3,7-trimethyl- 1H-purine- 2,6-dione; 1,3,7-trimethylxanthine; 1,3,7-trimethyl- 2,6-dioxopurine; coffeine; thein; guaranine; methyltheobromine; No-Doz.

C8H10N4O2; mol wt 194.19. C 49.48%, H 5.19%, N 28.85%, O 16.48%.

Occurs in tea, coffee, mate leaves; also in guarana paste and cola nuts: Shuman, U.S. pat. 2,508,545 (1950 to General Foods). Obtained as a by-product from the manuf of caffeine-free coffee: Barch, U.S. pat. 2,817,588 (1957 to Standard Brands); Nutting, U.S. pat. 2,802,739 (1957 to Hill Bros. Coffee); Adler, Earle, U.S. pat. 2,933,395 (1960 to General Foods).

Crystal structure: Sutor, Acta Cryst. 11, 453, (1958). Synthesis: Fischer, Ach, Ber. 28, 2473, 3135 (1895); Gepner, Kreps, J. Gen. Chem. USSR 16, 179 (1946); Bredereck et al., Ber. 83, 201 (1950); Crippa, Crippa, Farmaco Ed. Sci. 10, 616 (1955); Swidinsky, Baizer, U.S. pats. 2,785,162 and 2,785,163 (1957 to Quinine Chem. Works); Bredereck, Gotsmann, Ber. 95, 1902 (1962).

Hexagonal prisms by sublimation, mp 238 C. Sublimes 178 C. Fast sublimation is obtained at 160-165 C under 1mm press. at 5 mm distance. d 1.23. Kb at 19 C: 0.7 x 10^(-14). Ka at 25 C:

Monohydrate, felted needles, contg 8.5% H2O. Efflorescent in air; complete dehydration takes place at 80 C. LD50 orally in rats: 200 mg/kg.

Acetate, C8H10N4O2.(CH3COOH)2, granules or powder; acetic acid odor; acid reaction. Loses acetic acid on exposure to air. Soluble in water or alcohol with hydrolysis into caffeine and acetic acid. Keep well stoppered.

Hydrochloride dihydrate, C8H10N4O2.HCl.2H2O, crystals, dec 80-100 C with loss of water and HCl. Sol in water and in alcohol with dec.

Therap Cat: Central stimulant.

Therap Cat (Vet): Has been used as a cardiac and respiratory stimulant and as a diuretic.