Enzymic synthesis of loganin by carboxyl group methylation of loganic acid

Loganic Acid Methyltransferase: Insights into the Specificity of Methylation on an Iridoid Glycoside

“…In contrast to other characterized SABATH methyltransferases that demonstrate broad substrate tolerance, CrLAMT has been shown to be remarkably specific for only its physiological iridoid substrate . Specifically, CrLAMT only methylates the glycosylated and hydroxylated iridoid ring rather than the aglycone (loganetic acid) or deoxyloganic acid . The enzyme also demonstrates strict stereospecificity for loganic acid (6 S ,7 R ) as a substrate and fails to methylate either 7‐epiloganic acid (6 S ,7 S ) or the oxidized 7‐keto dehydrologanic acid.…”

“…The conversion of loganic acid into loganin is catalyzed by loganic acid methyltransferase (LAMT) through the transfer of a methyl group from S‐adenosyl‐methionine (SAM) to the carboxylate of loganic acid . Random sequencing of a C. roseus leaf epidermis‐enriched cDNA library identified multiple genes encoding putative SAM‐dependent O ‐methyltransferases, and biochemical characterization of a heterologously expressed candidate LAMT from C. roseus (CrLAMT) confirmed its function as a loganic acid methyltransferase .…”

Biosynthesis of monoterpenes

“…In other investigations, -terpineol was converted into terpinen-4-ol (6%) and thujone (2%), and terpinen-4-ol was converted into ct-terpineol (10%) in different fractions from homogenates of Tanacetum vulgare;614 and a system from Vinca rosea esterified loganic acid to yield loganin. 253 Considerable work has been carried out on the interconversion of monoterpenes in orange juice vesicles. [3-14C]-Linalool was converted into A2,8-p-menthadien-l-ol in 25% yield,513 and this reinforces the view that LPP is the immediate precursor of cyclic terpenes in this tissue.…”

Phytochemistry, synthesis, analytical methods, pharmacological activity, and pharmacokinetics of loganin: A comprehensive review

“…Loganin (Figure 1), a monoterpene IG, is named because it was first discovered in the fruit of Strychnos nux‐vomica . It is a key intermediate in indole alkaloid biosynthesis (Madyastha, Guarnaccia, & Coscia, 1971), so it is very important to confirm the structure and stereochemistry of loganin. So far, the absolute configuration of loganin has been studied by Nuclear Magnetic Resonance, Infrared Absorption Spectroscopy, and Circular Dichroism methods.…”