Occurrence And Quantification Of Isopaynantheine

This subarticle summarizes occurrence (qualitative and quantitative, where available) and quantification methods for isopaynantheine in Mitragyna speciosa leaves, extracts, and finished products. Focus is limited to analytical chemistry (no pharmacology). Primary sources are method papers and plant/product surveys with explicit method parameters; occurrence values are reported conservatively, only where directly supported by data[1].

Data Sources And Inclusion Criteria

Included sources:
  • Validated LC–MS/MS or LC–HRMS methods with stated calibration ranges, LLOQs, and matrix descriptions[2].
  • Plant and product surveys (chemotype work, market validation studies) that report isopaynantheine as part of an indole/oxindole alkaloid panel[3].
  • Metabolism/PK methods where parent isopaynantheine is a quantified analyte in biological matrices[4].
Excluded:
  • Non-validated or qualitative-only reports without analyte-specific parameters.
  • Reviews that summarize ranges without traceable primary data.

Occurrence In Leaves And Extracts

Fresh Malaysian leaves (isolation-focused work)

Chear et al. and Flores-Bocanegra et al. confirm the presence of isopaynantheine in fresh Malaysian M. speciosa leaves, isolating it alongside paynantheine, mitragynine, speciociliatine, speciogynine, and mitraciliatine. These studies emphasize structure elucidation; concentrations are typically discussed qualitatively (e.g., “major” vs. “minor” within the indole class)[5].

LC–ESI–TOF–MS/metabolomics datasets

LC–ESI–TOF–MS metabolomics work on kratom leaf identifies “3-Isopaynantheine” with specific retention time and accurate mass in leaf extracts, confirming its repeated detection among endogenous alkaloids[6].

Indole/oxindole-focused method development

Flores-Bocanegra 2020 describes multiple chromatographic strategies for kratom indole and oxindole alkaloids, including isopaynantheine as part of an expanded panel, with quantitative analysis applied to leaf samples and reference preparations[7].

In these plant-level studies, isopaynantheine is consistently reported as a lower-abundance component relative to mitragynine but grouped with other “major” indole alkaloids (paynantheine, speciogynine, mitraciliatine, speciociliatine) on an absolute mg/g basis[8].

Occurrence In Commercial Products (Capsules, Powders, Extracts)

Kratom validation and chemotype analysis (Manwill et al. 2022)

  • UPLC-HRMS quantification of indole and oxindole alkaloids in multiple commercial products (powders, capsules, and US-grown plants) reports isopaynantheine as quantifiable in most tested samples, with levels varying by chemotype[9].
  • While the focus is broader chemotype classification, the data show that isopaynantheine is present at mg/g or sub-mg/g levels, generally lower than mitragynine but comparable to other secondary indoles.

Market surveys and intake assessments

Recent US market analyses and intake studies (Sharma et al., Chear et al., related work summarized in Manwill 2022 and Tanna 2022) incorporate isopaynantheine in their broader alkaloid panels. The compound is treated as one of several structural analogues that contribute to total alkaloid burden and potential exposure[10].

Comparative metabolomics/chemotype context

PLOS ONE chemotype analyses show that isopaynantheine is part of a subset of indole alkaloids whose relative abundances vary by plant strain, environment, and cultivation conditions[11].

Applied Matrices (Tea, Extracts) and Detection in Biological Samples

  • Metabolism and urine studies: Philipp et al. (2011) administered pure isopaynantheine (ISO-PAY) and mitraciliatine to rats and monitored both parent alkaloids and metabolites in urine using LC–linear ion trap MS. In rat and human urine (kratom users), ISO-PAY and/or metabolites were detectable, confirming systemic exposure despite low abundance of the parent compound [12].
  • Clinical PK panel: In clinical kratom pharmacokinetic studies, isopaynantheine appears among purified reference standards enabling simultaneous measurement of multiple kratom alkaloids in human plasma, though ISO-PAY plasma concentration–time curves remain less developed than those for mitragynine [13].
  • Human plasma LC–MS/MS panels (11-alkaloid methods): Recent LC–MS/MS assays quantify 11 kratom alkaloids simultaneously, including isopaynantheine; variable recovery and signal intensity across analytes result from compound-specific physicochemical properties [14].

Quantification Methods (Plant/Products and Bioanalysis)

  • A. Plant / Product QC (Indole/Oxindole Panels): Analytical profiling of kratom product matrices consistently uses UPLC–HRMS or UPLC–MS/MS (ESI+, MRM or accurate-mass detection) to quantify isopaynantheine alongside related indole/oxindole alkaloids. Typical parameters include C18 reverse-phase chromatography (e.g., ACQUITY BEH C18), 15–25 min run times, and calibration curves spanning low-ng/mL to several hundred ng/mL. These assays support batch comparison, chemotype classification, and multi-alkaloid quantification across powders, extracts, and commercial products [15], [16].
  • B. Bioanalytical Methods (PK / Metabolism): Detection of isopaynantheine in biological systems is performed using LC–MS/MS platforms optimized for parent compound and metabolite identification.
  • 1. LC–MS/MS with triple quadrupole or ion trap: Philipp et al. employed LC–linear ion trap MS to measure parent isopaynantheine and metabolites in rat and human urine, confirming its metabolic detectability [17].
  • 2. Human plasma LC–MS/MS (11-alkaloid clinical panels): Newer validated UPLC–MS/MS assays quantify 11 kratom alkaloids—including isopaynantheine—using MRM transitions tailored for each analyte [18].
  • Typical validation parameters: Linearity across relevant ng/mL ranges, LLOQ adequate for post-dose plasma/urine detection, and full accuracy/precision, recovery, and stability testing following FDA bioanalytical method validation guidelines [19].

Reporting Guidance for Batch-Level Occurrence

  • Matrix and Sample Preparation: Reporting must clearly distinguish leaf, extract, or finished-product matrices, including extraction parameters such as solvent system, extraction time, and temperature [20].
  • Analytical Method Details: Required method descriptors include platform (UPLC–HRMS or UPLC–MS/MS), column chemistry, chromatographic gradient, and ionization mode. MRM transitions or exact mass values for isopaynantheine should be explicitly reported [21].
  • Validation-Related Parameters: Essential QC metrics—calibration range, LLOQ, and accuracy/precision results—should be presented to support analytical validity [22].
  • Quantitative Results with Units: Data must follow field standards: mg/g dry weight for plant materials, and either % w/w or mg per serving for commercial products. These formats align with conventions used across analytical kratom literature [23].

Summary

  • Across leaves, extracts, and commercial kratom products, isopaynantheine is consistently detected as a lower-abundance indole alkaloid relative to mitragynine, yet it is frequently grouped among structurally related “major” indoles such as paynantheine, speciogynine, mitraciliatine, and speciociliatine [24].
  • Validated UPLC–MS(/MS) and UPLC–HRMS analytical platforms enable quantitative determination of isopaynantheine in plant materials, finished products, and biological samples. Although numerical values vary by chemotype and study design, converging evidence demonstrates that isopaynantheine is:
    • Readily quantifiable in many kratom samples.
    • Present at mg/g or sub-mg/g levels in plant materials, and at proportionally lower levels in some processed extracts depending on manufacturing parameters [25].
    • Detectable in rat and human urine following kratom consumption or pure-compound administration, confirming systemic exposure [26].
  • These analytical findings provide a reproducible and coherent framework for batch-level occurrence reporting of isopaynantheine and allow meaningful cross-study comparisons of kratom alkaloid compositions.