Natural Blue Pigments from Kusagi Fruit: Trichotomine Derivatives for Food, Beverage, Textile, and Cosmetic Colorants
Researchers are characterizing trichotomine derivatives from Clerodendron trichotomum (kusagi) fruit as stable, natural blue pigments. The work isolates and identifies novel trichotomine analogs, elucidates their structures, and evaluates color stability across pH, temperature, and light exposure. Candidate pigments are assessed for use as natural blue colorants in food, beverages, textiles, and cosmetics, with glycosylated derivatives showing enhanced stability relative to trichotomine.
Overview
This research focuses on identifying and characterizing novel natural blue pigments derived from the fruit of the kusagi tree (Clerodendron trichotomum Thunb.). The fruit contains trichotomine, a bis-indole alkaloid responsible for an intense blue color historically used as a textile dye, along with trichotomine glycosides that may offer improved stability. Preliminary work suggests that at least five additional trichotomine analogs exist in kusagi fruit extracts and that glycosylated forms are more stable in solution than trichotomine alone. The goal is to fully characterize these derivatives and evaluate their suitability as natural blue colorants for applications in food, beverages, cosmetics, and textiles.
Technical specifications
Research approach:
- Analytical profiling of kusagi fruit extract using HPLC with UV/vis detection, high-resolution mass spectrometry, and tandem MS
- Solvent partitioning followed by semi-preparative HPLC isolation of individual trichotomine derivatives
- Structure elucidation of analogs using high-resolution MS, MS/MS, and 2D-NMR
- Color stability testing of each analog across aqueous buffers from pH 1 to pH 10, under varying temperatures and light conditions
Key findings to date:
- Trichotomine confirmed in extract by comparison with a synthetic standard
- Multiple trichotomine O-glycosides identified beyond the two previously known
- Glycosylated trichotomine derivatives show enhanced stability relative to trichotomine itself
- Extract inventory available from 500 kg of kusagi fruit for continued analysis
Potential applications:
- Natural blue food and beverage colorants
- Alternatives to synthetic blue dyes such as FD&C Blue No. 1 and No. 2
- Textile dyes and cosmetic colorants
Technology readiness level
This project is at an early-to-mid stage of analytical research. Trichotomine and several glycoside derivatives have been identified in kusagi fruit extracts, but full structural characterization and systematic stability evaluation of additional analogs are still in progress. The work is intended to advance toward a well-characterized library of candidate natural blue pigments suitable for further development and evaluation for natural colorant use cases.
About Oregon State University
Oregon State University is a comprehensive public research university and Oregon’s land‑grant institution, with a main campus in Corvallis and a statewide footprint. Industry partners tap a statewide Extension network and county offices to pilot and scale solutions with communities and companies across Oregon. A coastal marine science campus in Newport anchors ocean research and provides access to open‑ocean wave‑energy test ranges and grid‑connected infrastructure under development nearby, enabling sea‑to‑shore prototyping. Field stations and university‑managed research forests support long‑term trials and product validation in real‑world environments. A dedicated technology transfer office and the OSU Advantage programs—including the Advantage Accelerator—streamline IP, licensing, startup formation, and industry agreements.
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