Angiotensin-converting enzyme inhibitory and antioxidant activities of enzymatically synthesized phenolic and vitamin glycosides.

Amyloglucosidase from Rhizopus mould and beta-glucosidase from sweet almond were employed for the preparation of phenolic and vitamin glycosides of vanillin, N-vanillylnonanamide, DL-dopa, dopamine, curcumin, alpha-tocopherol (vitamin E), pyridoxine (vitamin B(6)), ergocalciferol (vitamin D(2)), thiamin (vitamin B(1)) and riboflavin (vitamin B(2)). Approx. 20 enzymatically prepared phenolic and vitamin glycosides were subjected to ACE (angiotensin-converting enzyme) inhibition activity measurements, and 14 glycosides were tested for antioxidant activities. Both phenolic and vitamin glycosides exhibited IC(50) values for ACE inhibition in the 0.52+/-0.03-3.33+/-0.17 mM range and antioxidant activities ranging from 0.8+/-0.04 to 1.18+/-0.06 mM. Comparable ACE inhibition values were observed between free phenols and vitamin glycosides. However, antioxidant activities of glycosides were, in general, lesser than those of free phenols. Best IC(50) value for ACE inhibition were observed for 11-O-(D-fructofuranosyl)thiamin (0.52+/-0.03 mM), 3-hydroxy-4-O-(6-D-sorbitol)phenylalanine (0.56+/-0.03 mM), 4-O-(beta-D-glucopyranosyl)vanillin (0.61+/-0.03 mM), 4-O-(D-galactopyranosyl)vanillin (0.61+/-0.03 mM) and pyridoxine-D-glucoside (0.84+/-0.04 mM). Similarly, best IC(50) values for antioxidant activity were observed for 1,7-O-(bis-beta-D-glucopyranosyl)curcumin (0.8+/-0.04 mM), 4-O-(beta-D-glucopyranosyl)vanillin (0.9+/-0.05 mM), 3-hydroxy-4-O-(beta-D-galactopyranosyl-(1'-->4)beta-D-glucopyranosyl)phenylalanine (0.9+/-0.05 mM), 20-O-(D-glucopyranosyl)ergocalciferol (0.9+/-0.05 mM) and dopamine-D-galactoside (0.93+/-0.05 mM).

Syntheses of dopa glycosides using glucosidases.

Syntheses of L: -dopa 1a glucoside 10a,b and DL: -dopa 1b glycosides 10-18 with D: -glucose 2, D: -galactose 3, D: -mannose 4, D: -fructose 5, D: -arabinose 6, lactose 7, D: -sorbitol 8 and D: -mannitol 9 were carried out using amyloglucosidase from Rhizopus mold, beta-glucosidase isolated from sweet almond and immobilized beta-glucosidase. Invariably, L: -dopa and DL: -dopa gave low to good yields of glycosides 10-18 at 12-49% range and only mono glycosylated products were detected through glycosylation/arylation at the third or fourth OH positions of L: -dopa 1a and DL: -dopa 1b. Amyloglucosidase showed selectivity with D: -mannose 4 to give 4-O-C1beta and D: -sorbitol 8 to give 4-O-C6-O-arylated product. beta-Glucosidase exhibited selectivity with D: -mannose 4 to give 4-O-C1beta and lactose 7 to give 4-O-C1beta product. Immobilized beta-glucosidase did not show any selectivity. Antioxidant and angiotensin converting enzyme inhibition (ACE) activities of the glycosides were evaluated glycosides, out of which L: -3-hydroxy-4-O-(beta-D: -galactopyranosyl-(1'-->4)beta-D: -glucopyranosyl) phenylalanine 16 at 0.9 +/- 0.05 mM and DL: -3-hydroxy-4-O-(beta-D: -glucopyranosyl) phenylalanine 11b,c at 0.98 +/- 0.05 mM showed the best IC(50) values for antioxidant activity and DL: -3-hydroxy-4-O-(6-D: -sorbitol)phenylalanine 17 at 0.56 +/- 0.03 mM, L: -dopa-D: -glucoside 10a,b at 1.1 +/- 0.06 mM and DL: -3-hydroxy-4-O-(D: -glucopyranosyl)phenylalanine 11a-d at 1.2 +/- 0.06 mM exhibited the best IC(50) values for ACE inhibition.

Syntheses of alpha-tocopheryl glycosides by glucosidases.

Enzymatic syntheses of water-soluble alpha-tocopheryl glycosides were carried out in di-isopropyl ether using amyloglucosidase from Rhizopus mold or beta-glucosidase isolated from sweet almond. Optimum conditions for the amyloglucosidase were: alpha-tocopherol 0.5 mmol, D-glucose 0.5 mmol, 400 activity unit (AU) amyloglucosidase, 0.2 mM pH 7 phosphate buffer and 72 h; and for the beta-glucosidase: alpha-tocopherol 0.5 mmol, D: -glucose 0.5 mmol, 110 AU beta-glucosidase, 0.1 mM pH 6 phosphate buffer and 72 h. Out of 11 carbohydrates employed, amyloglucosidase reacted only with D-glucose to give 50% of 6-O-(alpha-D-glucopyranosyl)alpha-tocopherol. However, the beta-glucosidase gave 6-O-(beta-D-glucopyranosyl)alpha-tocopherol, 6-O-(alpha-D-galactopyranosyl)alpha-tocopherol, 6-O-(beta-D-galactopyranosyl)alpha-tocopherol, 6-O-(alpha-D-mannopyranosyl)alpha-tocopherol and 6-O-(beta-D-mannopyranosyl)alpha-tocopherol in yields ranging from 10-25%. Water solubility of 6-O-(alpha-D-glucopyranosyl)alpha-tocopherol was 26 g/l at 25 degrees C. alpha-Tocopheryl glycosides showed antioxidant activities with IC(50) values from 0.5 to 1 mM and angiotensin-converting enzyme (ACE) inhibitory activity with IC(50) values from 1.3 to 2.6 mM.

Syntheses of N-vanillyl-nonanamide glycosides using amyloglucosidase from Rhizopus and beta-glucosidase from sweet almond.

Enzymatic syntheses of N-vanillyl-nonanamide, 1, glycosides with D-glucose, 2, D-galactose, 3, D-mannose, 4, D-ribose, 5, maltose, 6, and lactose, 7, were carried out using amyloglucosidase from Rhizopus and beta-glucosidase from sweet almond. The latter catalysed the syntheses of N-vanillyl-nonanamide glycosides (8-13) and exclusively yielded beta-glycosides with carbohydrates 2, 3, 4, 6 and 7, while amyloglucosidase yielded C1-alpha- and beta-glycosides and 6-O-aryl derivatives (8, 9, 11 and 12).

Synthesis, anticonvulsant and antihypertensive activities of 8-substituted quinoline derivatives.

A series of 8-substituted quinolines were synthesized and tested against seizures induced by maximal electro shock (MES), pentylenetetrazole (scMet) and antihypertensive activities. Neurologic deficit was evaluated by the rotarod test. Among the newly synthesized derivatives, several compounds with a 2-hydroxypropyloxyquinoline moiety displayed excellent anticonvulsant and antihypertensive activities. Compound 20 (8-(3'-(4''-phenylpiperazino)-2'-hydroxypropyloxy)quinoline) was potent in both series as an anticonvulsive agent. 13 (8-(3'-piperazino)-2'-hydroxypropyloxyquinoline) and 14 (8-(3'-imidazolo)-2'-hydroxypropyloxyquinoline) showed very good anticonvulsant activities in the propanol series of compound, whereas in the ethane series, 1 (8-(2'-piperazino-ethanoxy)quinoline) and 2 (8-(2'-imidazolo-ethanoxy)quinoline) were the most active as anticonvulsive agents. Compounds 20 (8-(3'-(4''-phenylpiperazino)-2'-hydroxypropyloxy)quinoline), 13 (8-(3'-piperazino)-2'-hydroxypropyloxyquinoline) and 19 (8-(3'-(4''-ethylpiperazino)-2'-hydroxypropyloxy)quinoline) have shown excellent antihypertensive activity. They have significantly antagonized the pressor response elicited by adrenaline. These pharmacological results suggest that their anticonvulsant and antihypertensive effects may be correlated to the presence of beta-blocking properties, and that those properties depend on the presence of aryloxypropanolamine.

Synthesis and anticonvulsant activity of novel 1-substituted-1,2-dihydro-pyridazine-3,6-diones.

The synthesis and pharmacological evaluation of novel 1-substituted-1,2-dihydro-pyridazine-3,6-diones (4a--l, 5a--j) as potential anticonvulsant agents are described. The compounds were tested in vivo for the anticonvulsant activity. The compound which have maximum protection against MES induced seizures is 1-[3-(2-aminophenylamino)-2-hydroxypropyl)-1,2-dihydro-pyridazine-3,6-dione 4h (ED(50)=44.7 mg x kg(-1) i.p.) 1-[2-hydroxy-3-piperazin1-yl-propyl)-1,2-dihydro-pyridazine-3,6-dione 4c (ED(50)=72 mg x kg(-1) i.p.) and 1-[2-hydroxy-3-imidazol-1-yl-propyl)-1,2-dihydro-pyridazine-3,6-dione 4d (ED(50)=79 mg x kg(-1) i.p.) were also found to have maximum protection against MES induced seizures. Whereas all these compounds failed to protect the animals from subcutaneous pentylenetetrazole (Metrozol) seizure threshold test (sc-Met).

Pharmacological evaluation of some new 6-amino/methyl pyridine derivatives.

In the present study, a series of 2-substituted-pyridines were synthesized and characterized by IR, (1)H-NMR and Elemental Analysis. The compounds were assayed against seizures induced by maximal electro shock (MES) and pentylenetetrazole (scMet). Neurologic deficit was evaluated by the rotarod test. The decrease in the elevated motor activity by introceptive chemical stimuli (amphetamine antagonistic activity) was studied at the dose level of 25 and 50 mg/kg, antihistaminic and cardiac activity were also studied. All the compounds exhibited significant anticonvulsant activity. Compounds 2-(2-hydroxy-3-piperazinopropylamino)-6-aminopyridine, 2-[2-hydroxy-3-(1-imidazolyl)propylamino]-6-aminopyridine, 2-[2-(1-imidazolyl)ethylamino]-6-methylpyridine and 2-[2-(methylamino)ethylamino]-6-methylpyridine were most active of the series against MES-induced seizures. Compounds 2-[2-(phenylamino)ethylamino]-6-aminopyridine, 2-[2-[bis(2-hydroxyethyl)amino]ethylamino]-6-aminopyridine, 2-[2-(diethylamino)ethylamino]-6-methylpyridine and 2-[2-hydroxy-3-(1-imidazolyl)propylamino]-6-methylpyridine exhibited significant decrease in the elevated motor activity at the dose of 50 mg/kg. Remarkable sympathetic blocking activity was observed with 2-(2-hydroxy-3-piperazinopropylamino)-6-aminopyridine, 2-(2-hydroxy-3-morpholinopropylamino)-6-methylpyridine and 2-(2-hydroxy-3-piperazinopropylamino)-6-methylpyridine only. Compounds 2-[2-(diethylamino)ethylamino]-6-aminopyridine, 2-[2-[bis(2-hydroxyethyl)amino]ethylamino]-6-aminopyridine, and 2-[2-(diethylamino)ethylamino]-6-methylpyridine exhibited significant blocking of histamine induced contraction on guinea pig ileum.