211
13
The over 20 different alkylamides of Echinacea have attracted attention due to their pharmacological activities such as immunostimulatory activity, and they have been used for
the treatment of cold, flu, respiratory infections and inflammations, but they also act as
cannabinomimetics (Raduner et al. 2006; Woelkart et al. 2008). Their amine group is
usually an isobutylamine or 2-methylbutylamine, and the acyl moiety has between 11and 16-carbon atoms with a trans-double bond situated at the 2-position and additional
double bonds or acetylenic bonds (Raduner et al. 2006; Rizhsky et al. 2016). Alkamides
have been reported to be present in other plants, for instance, affinin in Heliopsis longipes
(Compositae). Affinin stimulates GABA release from brain cells and can be used as analgesic for toothache (Rios et al. 2007).
The amide capsaicin is the hot component in chilli peppers (Capsicum annuum,
Solanaceae) (. Fig. 13.2). The initial burning effect of capsaicin is found to affect the
pain receptors (TRPV1), making them less sensitive. The aromatic portion of capsaicin
is derived from phenylalanine through ferulic acid and vanillin, this aldehyde being the
substrate for transamination to yield vanillylamine. The acid portion of the amide structure is a branched-chain fatty acyl-CoA being produced by chain extension with three
malonyl residues from isobutyryl-CoA (derived from valine)(Aza-Gonzalez et al. 2011).
Capsaicin starts accumulating in fruits of Capsicum upon ripening. Its biosynthesis occurs
in the epidermis cells of the placenta in the fruit and they accumulate on the interlobular
septum (Stewart et al. 2007).
13.3.4 Conium Alkaloids (Pseudoalkaloids, e.g. Coniine)
The hemlock poisons are toxic to animals and can be found in seeds, vegetative or flowering parts of some plants. The precursor for coniine is a fatty acid, capric (octanoic)
acid, which is transformed into the ketoaldehyde by successive oxidation and reduction
steps. L-alanine is used for the transamination reaction, leading to 7-amino-octanone.
Cyclization leads to the N-containing heterocyclic ring of γ-coniceine and then reduction to coniine. γ-coniceine is even more toxic than coniine. Other biosynthesis pathways
(malonyl and butyryl CoA, which are cyclized or a lysine precursor) have been discussed
but seem unlikely (Panter and Keeler 1989). Coniine is found in poison hemlock (Conium
maculatum, Apiaceae), in seeds of Cicuta maculata (Apiaceae, therefore also called cicutine) and in Sarracenia (Sarraceniaceae) (Reynolds 2005; Green et al. 2013). Other derivatives are methylconiine, N,N-dimethylconiine, conhydrinone, pseudoconhydrine and
N-methyl pseudoconhydrine.
13.4 Non-protein Amino Acids
Besides the 20 amino acids used for protein biosynthesis additionally many nonproteinogenic amino acids exist. One of them is willardiine derived from uracil, naturally found often in Fabaceae such as Acacia willardiana, Mimosa asperata, and pea
(Pisum sativum). Willardiine acts as an AMPA-type glutamate receptor agonist, while
5- iodowillardiine is a selective kainite-type glutamate receptor agonist.
Also the γ-aminobutyric acid (GABA) neurotransmitter is a non-protein amino acid.
Others mimic the function of neurotransmitters. Quisqualic acid, for instance, mimics
L-glutamic acid. It can be isolated from seeds of Quisqualis species (Combretaceae) and
13.4 · Non-protein Amino Acids
13
The over 20 different alkylamides of Echinacea have attracted attention due to their pharmacological activities such as immunostimulatory activity, and they have been used for
the treatment of cold, flu, respiratory infections and inflammations, but they also act as
cannabinomimetics (Raduner et al. 2006; Woelkart et al. 2008). Their amine group is
usually an isobutylamine or 2-methylbutylamine, and the acyl moiety has between 11and 16-carbon atoms with a trans-double bond situated at the 2-position and additional
double bonds or acetylenic bonds (Raduner et al. 2006; Rizhsky et al. 2016). Alkamides
have been reported to be present in other plants, for instance, affinin in Heliopsis longipes
(Compositae). Affinin stimulates GABA release from brain cells and can be used as analgesic for toothache (Rios et al. 2007).
The amide capsaicin is the hot component in chilli peppers (Capsicum annuum,
Solanaceae) (. Fig. 13.2). The initial burning effect of capsaicin is found to affect the
pain receptors (TRPV1), making them less sensitive. The aromatic portion of capsaicin
is derived from phenylalanine through ferulic acid and vanillin, this aldehyde being the
substrate for transamination to yield vanillylamine. The acid portion of the amide structure is a branched-chain fatty acyl-CoA being produced by chain extension with three
malonyl residues from isobutyryl-CoA (derived from valine)(Aza-Gonzalez et al. 2011).
Capsaicin starts accumulating in fruits of Capsicum upon ripening. Its biosynthesis occurs
in the epidermis cells of the placenta in the fruit and they accumulate on the interlobular
septum (Stewart et al. 2007).
13.3.4 Conium Alkaloids (Pseudoalkaloids, e.g. Coniine)
The hemlock poisons are toxic to animals and can be found in seeds, vegetative or flowering parts of some plants. The precursor for coniine is a fatty acid, capric (octanoic)
acid, which is transformed into the ketoaldehyde by successive oxidation and reduction
steps. L-alanine is used for the transamination reaction, leading to 7-amino-octanone.
Cyclization leads to the N-containing heterocyclic ring of γ-coniceine and then reduction to coniine. γ-coniceine is even more toxic than coniine. Other biosynthesis pathways
(malonyl and butyryl CoA, which are cyclized or a lysine precursor) have been discussed
but seem unlikely (Panter and Keeler 1989). Coniine is found in poison hemlock (Conium
maculatum, Apiaceae), in seeds of Cicuta maculata (Apiaceae, therefore also called cicutine) and in Sarracenia (Sarraceniaceae) (Reynolds 2005; Green et al. 2013). Other derivatives are methylconiine, N,N-dimethylconiine, conhydrinone, pseudoconhydrine and
N-methyl pseudoconhydrine.
13.4 Non-protein Amino Acids
Besides the 20 amino acids used for protein biosynthesis additionally many nonproteinogenic amino acids exist. One of them is willardiine derived from uracil, naturally found often in Fabaceae such as Acacia willardiana, Mimosa asperata, and pea
(Pisum sativum). Willardiine acts as an AMPA-type glutamate receptor agonist, while
5- iodowillardiine is a selective kainite-type glutamate receptor agonist.
Also the γ-aminobutyric acid (GABA) neurotransmitter is a non-protein amino acid.
Others mimic the function of neurotransmitters. Quisqualic acid, for instance, mimics
L-glutamic acid. It can be isolated from seeds of Quisqualis species (Combretaceae) and
13.4 · Non-protein Amino Acids