Patent Application: US-91936009-A

Abstract:
disclosed is the use of hypericum tip extracts containing hypericin , of hypericin , to prepare medicinal products and / or food supplements for the treatment of neuropathic pain .

Description:
freeze - dried extracts of hypericum ( hypericum perforatum ) flowering stems and one of its components , hypericin , have proved effective in reducing the symptoms of neuropathic pain in various experimental models , following oral administration . the studies were conducted on rodents , which have always constituted a good animal model to reproduce the characteristics of human pain symptoms and predict possible remedies . the freeze - dried extracts can derive from freeze - drying of either the whole plant material extracted with water - ethanol solvent , or of the most hydrophilic component of the plant . the active doses of freeze - dried hypericum extracts range from 10 mg / kg to 100 mg / kg . the freeze - dried extracts preferably derive from extraction of the whole plant with water - alcohol solvents ( 0 - 100 % ethanol , methanol , isopropanol , etc .) or water - acetone solvents ( 0 - 100 %) and separation and freeze - drying of a more hydrophilic component from the plant . freeze - dried hypericum extracts preferably have a content of naphthodianthrone derivatives ( hypericin + pseudohypericin ) amounting to not less than 0 . 25 %, evaluated by the hplc method ( minimum 0 . 025 mg per kg of body weight ). one of the naphthodianthrone derivatives , hypericin , has proved active at a dose corresponding to its concentration in freeze - dried extracts . the phloroglucinol derivatives isolated ( hyperforin and adihyperforin ) have proved unable to reduce neuropathic pain . up to the dose of 3000 mg / kg per os the freeze - dried extract does not change the animal &# 39 ; s behaviour , as demonstrated by the fact that the number of falls from the rotating rod consecutively declines as the sessions are repeated , demonstrating that the animals &# 39 ; motor coordination is wholly comparable to that of the controls ( ref . 29 rota rod test ). when analyzed in terms of numerous parameters ( behaviour , movement , muscle tone , autonomic signs ), the extracts did not cause any alteration . the scores of the treated animals did not differ from those of the controls ( ref . 28 irwin test ). the invention is described in greater detail in the examples and preparations below . the freeze - dried hypericum ( hypericum perforatum ) flowering stem extract is prepared from hypericum flowering stems . after drying and selection of the tips , extraction is performed with a water - ethanol solution containing 50 - 80 % alcohol , with a plant : solvent ratio of 1 : 13 . the solution is concentrated under reduced pressure to remove the ethanol , and dried by a freeze - drying process in suitable freeze - dryers . the freeze - dried extract of the hydrophilic fraction of hypericum , containing polar water - soluble substances , was prepared by a process of physical separation of the non - hydrophilic substances , and centrifugation with a decanter . the two fractions were then freeze - dried separately . the freeze - dried extract was chemically characterised by hplc analysis , which showed a total hypericin concentration ( hypericin + pseudohypericin ) of 0 . 27 to 0 . 37 %. a reduction in the pain threshold was induced by administering oxaliplatin 2 . 4 mg / kg for 5 consecutive days for a total of 3 weeks . by the end of the treatment period , the pain perception threshold of the rats was statistically lower than that of the controls ( ref . 23 ). the total freeze - dried extract at the dose of 30 and 60 mg / kg of body weight proved to be active to a statistically significant extent . oxaliplatin 2 . 4 mg / kg − 1 for 5 consecutive days a week ( 15 i . p . injections - cumulative dose 36 mg / kg ) the freeze - dried extract of the hydrophilic fraction at the dose of 30 mg / kg of body weight proved active to a statistically significant extent in the oxaliplatin - induced neuropathy pain test . neuropathic pain is characterised by the development of an altered perception of pain , which is manifested as continuous spontaneous pain and hyperalgesia . in this model , the rats were anaesthetised with chloral hydrate 400 mg / kg i . p . or sodium pentobarbital 40 mg / kg i . p .. the sciatic nerve was then exposed at thigh level by retracting the femoral biceps . proximally to the trifurcation of the sciatic nerve , approx . 7 mm of nerve was released from the membranes and 4 loose ligatures were tied round the nerve , approx . 1 mm apart . in another group of animals an identical incision was made , but without the nerve ligature ( sham operation ). neuropathy developed in 14 days . the tests with the potentially analgesic substances were performed on the 14th and 21st days after the operation using the paw pressure test ( ref . 24 ). the total freeze - dried extract at the dose of 10 , 30 , 60 and 100 mg / kg of body weight proved to be active to a statistically significant extent . the freeze - dried extract of the hydrophilic fraction at the doses of 10 , 30 , 60 and 100 mg / kg of body weight proved active to a statistically significant extent , as shown in table 2b below . the total freeze - dried extract at the doses of 30 and 100 mg / kg of body weight and the extract of the hydrophilic fraction at the dose of 30 mg / kg proved active to a statistically significant extent in the paclitaxel - induced neuropathic pain test ( ref . 25 ). treatment : paclitaxel 0 . 5 mg / kg − 1 was injected i . p . for four days ( days 1 , 3 , 5 and 8 ). the cumulative dose of paclitaxel was 2 . 0 mg / kg − 1 . the test was performed 14 - 15 days after the last injection of paclitaxel . vehicle : saline : ethylene oxide 9 : 1 8 rats per group ( two experiments ). { circumflex over ( )} p & lt ; 0 . 05 ; versus rats treated with paclitaxel . a reduction in the pain threshold was obtained in the rat by i . v . administration of vincristine ( 150 gamma / kg i . v . every 2 days for 5 days until the cumulative dose of 750 gamma / kg was reached ); the test ( paw - pressure ) was conducted 4 days after the last injection ( ref . 26 ). alternatively , the vincristine was applied ( brushed ) directly onto the sciatic nerve . the total freeze - dried extract at the doses of 30 and 100 mg / kg of body weight and the freeze - dried extract of the hydrophilic fraction at the dose of 30 mg / kg proved active to a statistically significant extent . treatment with vincristine : five i . v . injections of 150 μg / kg − 1 performed every 2 days up to a cumulative dose of 750 μg / kg − 1 i . v . the test was performed 4 days after the last injection of vincristine . 7 - 8 rats per group ( two experiments ). * p & lt ; 0 . 01 versus rats treated with vincristine 14 rats per group ( two experiments ). using the same method as in example 1 , the following results were obtained by administering hypericin at the doses indicated in table 5 . treatment : monosodium iodoacetate ( mia ) 2 mg in a volume of 25 μl was injected into the antechamber of the left knee of non - anaesthetised rats . each value represents the mean of 2 experiments ( 11 rats ). 1 . nanna b et al “ an evidence - based algorithm for the treatment of neuropathic pain ” medscape general medicine 2007 ; 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