Deoxyloganic acid

Further work on secoiridoid biosynthesis has now shown, using [7,8- H2]-7-deoxyloganic acid, that the C-8 proton as well as the C-7 proton is retained in the sequence loganin secologanin (126)— morroniside (129) (cf. Vol. 3, p. 28) in Lonicera morrowii, Cornus officinalis, and Gentiana thunbergii ... 

Pentacyclic oxindole alkaloids. From the same laboratories at the University of Mississippi still later in 2001, a study of the 7-deoxyloganic acid and a series of pentacyclic oxindole alkaloids from the Peruvian plant Una de Gato or Cat s Claw was reported. This plant is indigenous to the Peruvian rainforest and used in traditional medicine by native people for a variety of ailments. 

It is interesting in connection with the above incorporation of deoxyloganic acid into loganin that loganic acid [acid corresponding to (10)] has been isolated... 

It has been shown that 7-deoxyloganic acid (81) is a precursor of various iridoglucosidesFeeding experiments on the plants Gardinia jasminoides and Paederia scandens have shown that the acid is incorporated into the irido-glucosides of these plants and a biogenetic scheme is proposed. ... 

The first of these proposals (Scheme 2) is based on feeding experiments [25] in Forsythia viridissima and Forsythia europea. The C-10 site of deoxyloganic acid is oxidised to alcohol to give adoxosidic acid, and further oxidation at the same position result in forsythide which, in turn, must be the common origin to a series of derivatives found in Forsythia. This route may be exclusive for this tribe. 

Rigane, G., Ben Salem, R., Sayadi, S., and Bouaziz, M. (2011). Phenolic composition, isolation and structure of a new deoxyloganic acid derivative from Dhokar and Gemri-Dhokar olive cultivars. Journal of Food Science, 76(7), 965-973. 

Antirrhinoside 269 is the main iridoid glucoside in Antirrhinum majus. Early biosynthetic studies on this secondary metabolite, based on feeding experiments of deuterium-labeled hypotetical intermediates, established that 8-epi-deoxyloganic acid 286 and deoxygeniposidic acid 288 are the precursors for 269 (Figure 3.81) [287]. 

Formation of Deoxyloganic Acid from Geraniol Formation of 8-e/ i-Deoxyloganin and Related Iridoids Iridoids Derived from 10-Hydroxycitronellol Conversion of Loganin to Secologanin Secologanin as a Precursor for Indole Alkaloids Distribution of Iridoid Monoterpenes Biological Activity... 

Route 1 derives from 10-hydroxygeraniol (3), via iridodial (2) and iridotrial (4), and culminates in deoxyloganic acid (5) (Fig. 20.2). Scrambling of label between positions 3 and 11 occurs. Deoxyloganic acid is converted to loganin (6) and, finally, to secoiridoids (Jensen, 1991). 

Fig. 20.2. Biosynthesis of deoxyloganic acid (Jensen, 1991 modified and used with permission of the copyright owner, Oxford University Press, Oxford).

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