LA VIA BIOGENETICA DELL’ACETATO ACIDI GRASSI E POLICHETIDI

I POLICHETIDI Costituiscono una cospicua classe di composti naturali raggruppati sulla base della loro comune biogenesi Tutti derivano da b-polichetoni formatisi per condensazione di molecole di acido acetico (C2): nCH3CO2H [ [CH2CO]n I metaboliti che appartengono a questa classe sono gli acidi grassi, i composti poliacetilenici e le prostaglandine, molti antibiotici macrolidici, e molti composti aromatici (antrachinoni e tetracicline)

ACIDI GRASSI E POLICHETIDI Acidi grassi saturi, insaturi, ramificati e acetilenici Sostanze di riserva energetica degli organismi; prodotti per uso commerciale utilizzati negli alimenti, nei cosmetici Prostaglandine, Trombosani e Leucotrieni Attività farmacologica Polichetidi aromatici Polifenoli e flavanoidi di diversa natura: Aflatossine (micotossine da Aspergillus spp.), Antracicline (da Spreptomyces spp. Farmaci antitumorali), Antibiotici macrolidi

GLI ACIDI GRASSI

Figure Number: 26-00-02T01 Title: Table 26.1 common naturally occurring fatty acids Caption: Notes:

Acidi grassi

Figure Number: 26-00CO 26-00CO Title: Stearic and Linoleic Acids Caption: Stick models embedded in electrostatic potential maps of stearic acid and linoleic acid. Notes: Stearic acid is a saturated fatty acid (found in saturated fats). Linoleic acid is an unsaturated fatty acid (found in unsaturated fats). Saturated fatty acids have no carbon–carbon double bonds in their hydrocarbon "tails." They generally take up extended conformations and stack together efficiently, producing solids. Unsaturated fats have one or more C–C double bonds in their hydrocarbon tails. The double bond(s) cause the tails to fold over rather than take up an extended conformation. Unsaturated fatty-acid molecules do not stack together efficiently, and unsaturated fatty acids are generally liquid oils at room temperature. Diacylglycerol fats and oils are called lipids.

Figure Number: 26-00-03UN Title: Fatty Acids Caption: Space-filling models of stearic, oleic, linolenic, and linoleic acids. Notes: Stearic acid is a saturated fatty acid which is a solid at room temperature. The others are unsaturated fatty acids which are oils at room temperature. Note that only stearic acid has an extended conformation.

Figure Number: 26-00-04UN Title: Fatty Acids Caption: Space-filling models of stearic, oleic, linolenic, and linoleic acids. Notes: Stearic acid is a saturated fatty acid which is a solid at room temperature. The others are unsaturated fatty acids which are oils at room temperature. Note that only stearic acid has an extended conformation.

Figure Number: 26-00-05UN Title: Fatty Acids Caption: Space-filling models of stearic, oleic, linolenic, and linoleic acids. Notes: Stearic acid is a saturated fatty acid which is a solid at room temperature. The others are unsaturated fatty acids which are oils at room temperature. Note that only stearic acid has an extended conformation.

Figure Number: 26-00-06UN Title: Fatty Acids Caption: Space-filling models of stearic, oleic, linolenic, and linoleic acids. Notes: Stearic acid is a saturated fatty acid which is a solid at room temperature. The others are unsaturated fatty acids which are oils at room temperature. Note that only stearic acid has an extended conformation.

I TRIGLICERIDI I principali grassi naturali sono i trigliceridi: esteri del glicerolo con gli acidi grassi Grassi: a temperatura ambiente sono solidi Oli: a temperatura ambiente sono liquidi Trigliceridi semplici: contengono il medesimo acido grasso Trigliceridi misti: contengono acidi grassi diversi

STRUTTURA E FUNZIONE DEI TRIGLICERIDI Grassi Animali:contengono una elevata percentuale di acidi grassi saturi Grassi Vegetali (Oli): contengono una elevata percentuale di acidi grassi insaturi; le stesse caratteristiche si ritrovano ne grassi dei pesci Ruolo Fisiologico: grassi ed oli rappresentano una riserva energetica a lungo termine; possono essere soggetti, se necessario, al metabolismo ossidativo Uso Commerciale degli Oli: alimenti, cosmetici e farmaci

Figure Number: Title: Table 26.2 Approximate Percentage of Fatty Acids in Some Common Fats and Oils Caption: Notes:

Figure Number: 26-00-13UN Title: Fats and Oils Caption: Space-filling models of a triacylglycerol fat and a triacylglycerol oil. Notes: Saturated fatty acid chains pack together well in triacylglycerol molecules as well as they do in single fatty acid molecules. Furthermore, saturated fat (triacylglycerol) molecules also pack together well, so saturated fats are solids at room temperature. Triacylglycerols composed of unsaturated fatty acids do not pack together well, so unsaturated fats are generally oils at room temperature. The term "fats" is often used to refer to solid (mostly saturated) fats and the term "oils" is often used to refer to liquid (unsaturated) fats.

Figure Number: 26-00-14UN Title: Fats and Oils Caption: Space-filling models of a triacylglycerol fat and a triacylglycerol oil. Notes: Saturated fatty acid chains pack together well in triacylglycerol molecules as well as they do in single fatty acid molecules. Furthermore, saturated fat (triacylglycerol) molecules also pack together well, so saturated fats are solids at room temperature. Triacylglycerols composed of unsaturated fatty acids do not pack together well, so unsaturated fats are generally oils at room temperature. The term "fats" is often used to refer to solid (mostly saturated) fats and the term "oils" is often used to refer to liquid (unsaturated) fats.

I fosfolipidi Fosfogliceridi: componente lipidico principale delle membrane cellulari (40%): Lecitine (colina); Cefaline (etanolammina) Sfingolipidi: presenti nei tessuti delle cellule cerebrali e nervosi

Figure Number: 26-00-23UN Title: Distearylphosphatidylserine Caption: Space-filling model of distearylphosphatidylserine. Notes: Distearylphosphatidylserine is a phosphatidylserine. A phosphatidylserine is built from a molecule of serine (an amino acid) and a phospholipid molecule. A phospholipid molecule is built from a molecule of glycerol, two fatty acid molecules, and a molecule of phosphoric acid. Phospholipids and phosphatidylserines are found in cell membranes. Also found in cell membranes are phosphatidylethanolamines (similar to phosphatidylserines except that ethanolamine is used in place of serine) and phosphatidylcholines (choline used in place of serine).

Proprietà tensioattive

Saponi

LE PROSTAGLANDINE E LE AFLATOSSINE Le prostaglandine sono un gruppo di acidi grassi a venti atomi di carbonio che mostrano molteplici attività farmacologiche, regolazione: della pressione sanguigna, della concentrazione muscolare liscia, della secrezione gastrica e regolazione dell’aggregazione piastrinica Le aflatossine sono potenti micotossine prodotte dai funghi Aspergillus flavus ed A. parasiticus. Le aflatossine sono principalmente dannose per il fegato, causando ingrossamento epatico, accumulo di grassi e necrosi. Contemporaneamente stimolano la proliferazione delle cellule del dotto biliare e la morte sopraggiunge per perdita delle funzionalità epatiche

LA BIOSINTESI DEI POLI-b-CHETOESTERI

LA BIOSINTESI DEGLI ACIDI GRASSI

Acidi grassi insaturi

Acidi grassi poliisaturi (non mammiferi) La posizione dei doppi legami successivi dipende dall'organismo interessato

Acidi grassi poliisaturi (mammiferi)

Acido ricinoleico Acidi grassi acetilenici

BIOSINTESI DEI TRIGLICERIDI

BIOSINTESI DEI FOSFOLIPIDI

DIVERSI TIPI DI ACIDI GRASSI Gli acidi grassi insaturi sono biosintetizzati nella maggior parte degli organismi per deidrogenazione degli acidi grassi saturi Gli acidi grassi acetilenici sono prodotti mediante deidrogenazione di acidi grassi insaturi Gli acidi grassi ramificati (ritrovati nei mammiferi e nella membrana di alcuni batteri) si possono formare attraverso vari meccanismi: metilmalonil-CoA

Fenoli semplici

Antrachinoni

AFLATOSSINE