Alkaloids PDF

ALKALOIDS AP. DR KHAIRANA HUSAIN NFNF1813 INTRODUCTION ❑Derived from Arabic “al kaly” (i.e. soda or basic) ❑Define: Natural organic nitrogenous bases, found mainly in plants (also occur in microorganisms and animal), containing at least one nitrogen atom in a heterocyclic ring and p...

ALKALOIDS AP. DR KHAIRANA HUSAIN NFNF1813 INTRODUCTION ❑Derived from Arabic “al kaly” (i.e. soda or basic) ❑Define: Natural organic nitrogenous bases, found mainly in plants (also occur in microorganisms and animal), containing at least one nitrogen atom in a heterocyclic ring and physiologically active. INTRODUCTION ❑nitrogen atom present: secondary, tertiary or quaternary amines (rare in primary amine) ❑Classified according to the nature of the basic nitrogen-containing structures from which they are derived (e.g: piperidine, quinoline, indole etc.) DISTRIBUTION AND OCCURRENCE ❑ Dicots are more rich in alkaloids than Monocots. ❑ Families rich in Alkaloids: Apocynaceae, Rubiaceae, Solanaceae and Papaveracea. ❑ Families free from Alkaloids: Rosaceae, Labiatae FUNCTIONS ❑ Defence mechanism ❑ Nitrogenous source or waste ❑ Most have pharmacological activities ❑ CNS : depressant (morphine), stimulant (caffeine) ❑ Autonomic NS : sympathomimetic (ephedrine), sympatholytic (yohimbine), parasympathomimetic (pilocarpine), anticholinergic (atropine), ganglioplegic (nicotine) ❑ Anaesthesia (cocaine), treat fibrilation (quinidine), antitumor (vinblastine), antimalaria (quinine), antibacteria (berberine), amebicide (emetine) ❑ Starting materials for drug synthesis CLASSIFICATION OF ALKALOIDS ❑Biogenetic Based on the biogenetic pathway that form the alkaloids : acetate pathway or shikamate pathway ❑Botanical Source According to the plant source of alkaloids. ❑Type of Amines Primary, Secondary, Tertiary alkaloids. Basic alkaloids skeleton Isoquinoline Pyridine piperidine TROPANE ALKALOIDS TROPANE ALKALOIDS anticholinergic activity Local anaesthetic antispasmodic & prevent motion sickness TROPANE ALKALOIDS ❑ Local anaesthetic ❑ Mostly used as drug of abuse to generate stimulation & euphoria but cause depression & dependence PIPERIDINE ALKALOIDS O O OH O N N Lobelin CH3 O Piperine Lobelia inflata Indian-tobacco PYRROLIZIDINE ALKALOIDS O OH O O O H OH N Acetyl-lycopsamine ❑ inflammatory, rheumatic & GI disorders QUINOLIZIDINE ALKALOID N O N N N N HN O Lupinine ❑Potentially toxic to humans INDOLIZIDINE ALKALOIDS ❑Active against AIDS virus HIV OH OH OH H H OH HO OH N N HO Swainsonine Castanospermine PYRIDINE ALKALOIDS N CH3 N Nicotine ❑ Respiratory stimulant/depressant ❑ Nicotine patch to assist stopping smoking habit Tobacco TETRAHYDROISOQUINOLINE ALKALOIDS H3CO H3CO N NH HO CH3 H3CO OR1 R2 Anhalamine (R1=H, R2=H) Lophocerine Anhalonidine (R1=H, R2=Me) Anhalomine (R1=Me, R2=Me) BENZYLTETRAHYDROISOQUINOLINE ALKALOIDS H3CO N H3CO H3CO H3CO opium poppy Papaverine ❑ Used in expectorant & male impotence MODIFIED BENZYLTETRAHYDRO-ISOQUINOLINE ALKALOIDS Thebaine or Paramorphine morphine Codeine ❑powerful analgesic & narcotic INDOLE ALKALOIDS N H Basic skeleton for indole alkaloid ERGOT ALKALOIDS IMIDAZOLE ALKALOIDS N N Pilocarpine ❑Used as miotic eyedrop & treatment of glaucoma  PURINE ALKALOIDS 6 H 7 1 N 5 N 8 2 N 4 N 9 3 Purine Caffeine Theobromine Theophylline CNS stimulant Diuretic & smooth Smooth muscle relaxant & weak muscle for relief of bronchospasm diuretic relaxant & diuretic