the present invention relates to the use of abnormal cannabidiols and homologues and derivatives thereof as neuroprotective agents . these therapeutic agents are represented by compounds having the formula i as defined above . the preferred compounds used in accordance with the present invention are encompassed by the following structural formula ii in all of the above formulae , as well as in those provided hereinafter , the straight lines represent bonds . where there is no symbol for the atoms between the bonds , the appropriate carbon - containing radical is to be inferred . for example in formula ii , the radical extending from the phenyl ring is a polymethylene ( ch 2 ) radical terminated with a methyl radical , i . e . a butylenylmethyl radical . pharmaceutical compositions may be prepared by combining a therapeutically effective amount of at least one compound according to the present invention , or a pharmaceutically acceptable salt thereof , as an active ingredient , with conventional ophthalmically acceptable pharmaceutical excipients , and by preparation of unit dosage forms suitable for topical ocular use . the therapeutically efficient amount typically is between about 0 . 0001 and about 5 % ( w / v ), preferably about 0 . 001 to about 1 . 0 % ( w / v ) in liquid formulations . for ophthalmic application , preferably solutions are prepared using a physiological saline solution as a major vehicle . the ph of such ophthalmic solutions should preferably be maintained between 4 . 5 and 8 . 0 with an appropriate buffer system , a neutral ph being preferred but not essential . the formulations may also contain conventional , pharmaceutically acceptable preservatives , stabilizers and surfactants . preferred preservatives that may be used in the pharmaceutical compositions of the present invention include , but are not limited to , benzalkonium chloride , chlorobutanol , thimerosal , phenylmercuric acetate and phenylmercuric nitrate . a preferred surfactant is , for example , tween 80 . likewise , various preferred vehicles may be used in the ophthalmic preparations of the present invention . these vehicles include , but are not limited to , polyvinyl alcohol , povidone , hydroxypropyl methyl cellulose , poloxamers , carboxymethyl cellulose , hydroxyethyl cellulose cyclodextrin and purified water . tonicity adjustors may be added as needed or convenient . they include , but are not limited to , salts , particularly sodium chloride , potassium chloride , mannitol and glycerin , or any other suitable ophthalmically acceptable tonicity adjustor . various buffers and means for adjusting ph may be used so long as the resulting preparation is ophthalmically acceptable . accordingly , buffers include acetate buffers , citrate buffers , phosphate buffers and borate buffers . acids or bases may be used to adjust the ph of these formulations as needed . in a similar vein , an ophthalmically acceptable antioxidant for use in the present invention includes , but is not limited to , sodium metabisulfite , sodium thiosulfate , acetylcysteine , butylated hydroxyanisole and butylated hydroxytoluene . other excipient components which may be included in the ophthalmic preparations are chelating agents . the preferred chelating agent is edentate disodium , although other chelating agents may also be used in place of or in conjunction with it . ingredient amount (% w / v ) active ingredient about 0 . 001 - 5 preservative 0 - 0 . 10 vehicle 0 - 40 tonicity adjustor 0 - 10 buffer 0 . 01 - 10 ph adjustor q . s . ph 4 . 5 - 8 . 0 antioxidant as needed surfactant as needed purified water as needed to make 100 % the actual dose of the active compounds of the present invention depends on the specific compound , and on the condition to be treated ; the selection of the appropriate dose is well within the knowledge of the skilled artisan . the ophthalmic formulations for use in the method of the present invention are conveniently packaged in forms suitable for metered application , such as in containers equipped with a dropper , to facilitate application to the eye . containers suitable for dropwise application are usually made of suitable inert , non - toxic plastic material , and generally contain between about 0 . 5 and about 15 ml solution . one package may contain one or more unit doses . especially preservative - free solutions are often formulated in non - resealable containers containing up to about ten , preferably up to about five units doses , where a typical unit dose is from one to about 8 drops , preferably one to about 3 drops . the volume of one drop usually is about 20 - 35 μl . abnormal cannabidiol , also named as abn - cbd ( 4 -[( 1r , 6r )- 3 - methyl - 6 -( 1 - methylenthenyl )- 2 - cyclohexen - 1 - yl ]- 5 - pentyl - 1 , 3 - benzenediol , m . w . 314 . 47 , may be purchased from tocris cookson inc ., ellisville , mo ., usa . the above compound is well known and may be purchased or synthesized by methods known in the art . the dissection and dissociation of the rat hippocampal neuron cell cultures is carried out . briefly , whole cerebral neocortices are removed from fetal rats , gestation age 15 - 19 days and kept in calcium free and magnesium free hanks &# 39 ; balanced salt solution . the hippocampi are removed under a dissecting microscope and the meninges are stripped away . when all the hippocampi are removed , the tissues are incubated in 0 . 05 % trypsin solution for 30 minutes at 37 ° c . at the end of 340 minutes , the trypsin solution is replaced with plating medium ( minimal essential medium supplemented with 2 % hyclone horse serum , 1 % fetal calf serum , 25 mm glucose , 1 % glutamine and 1 % penicillin / streptomycin and n 2 supplement ). then the tissues are triturated with a pasteur pipette 10 times and then again with a pipette whose tip has been fire polished to about half the normal diameter . the dissociated neuronal cells then are plated on poly d - lysine coated , 15 mm 24 well plates ( 2 × 10 5 cells / well ) in plating medium . the cell cultures are kept at 37 ° c . in a humidified , 5 % co 2 containing atmosphere . after 1 - 2 days , the horse serum level in the plating media is increased to 8 %. after 4 - 7 days , the non - neuronal cell division is halted by 24 hours exposure to 10 − 6 m cytosine arabinoside ( ara - c ), and the cells are then placed into growing medium with 4 % horse serum , 1 % fetal calf serum , 25 mm glucose , 1 % glutamine and 1 % penicillin / streptomycin and n 2 supplement . subsequent medium replacement is carried out every other day until the neuronal cells mature ( 15 - 20 days ). only matured cell cultures are selected for study . exposure of the excitatory amino acids is performed in minimal essential medium ( mem ). extreme care is taken to wash out the growing medium from cultures before the addition of the excitatory amino acid since the neurons are very sensitive to disturbance . matured cell cultures are exposed to either glutamate , α - amino - 3 - hydroxy - 5 - methyl - 4 - isoxazole propionic acid ( ampa ), n - methyl - d - aspartate ( nmda ), or kainic acid . cytotoxicity or cell injury is scored by light microscopy examination with trypan blue . in most experiments , the overall neuronal cell injury is quantitated by the amount of lactate dehydrogenase ( ldh ) released by the damaged cells into the media 24 hours after drug exposure . ldh is measured at room temperature using promega non - radioactive cytotoxicity assay kit . the absorbance of the reaction mixture is measured at 490 nm . the effect of the abnormal cannabidiol of example 1 on nmda - induced neurotoxicity shows that the compound of example 1 has a neuroprotective effect . abnormal cannabidiol receptor activity may be measured in accordance with the procedure disclosed in ( wagner j a et al ., hypertension 33 [ part ii ], 429 ( 1999 ); járai z et al ., pnas 96 , 14136 ( 1999 ), which is hereby incorporated by reference in its entirety . the experiment of example 2 is repeated with other abnormal cannabidiols and the results are essentially as shown for the compound of example 1 . the foregoing description details specific methods and compositions that can be employed to practice the present invention , and represents the best mode contemplated . however , it is apparent from one of ordinary skill in the art that different pharmaceutical compositions may be prepared and used with substantially the same results . that is , other abnormal cannabidiols , will effectively provide neuroprotection in animals and are within the broad scope of the present invention .
the invention relates to the use of abnormal cannabidiols as neuroprotective agents . in particular said compounds are represented by the formula i wherein r is selected from the group consisting of x wherein x is 0 or an integer of from 1 to 7 .