Authors: Nongnuch Klinpikul | Somchye Dittapohn | Wongnapa Nakyai | Wannisa Keawbankrud
Source: Trends in Sciences (article, 2025-07-05)
Field: Chemistry — Analytical Chemistry

Optimization of Eco-Friendly Mordant-Assisted Extraction and Stability of Natural Pigments from Six Plant Species for Pressed Paint Development This study aimed to optimize the decoction extraction efficiency of natural pigments from 6 plant species-Clitoria ternatea L., Scleropyrum pentandrum, Vitex pinnata L., Oroxylum indicum L., Xylia xylocarpa, and Careya sphaerica-by systematically varying extraction temperature (60 and 80 °C), time (30 - 90 min), and extraction conditions (normal and mordant-assisted). The main objective was to improve pigment yield and stability for potential use in sustainable natural dye and colorant applications. Results indicated that higher extraction temperatures (80 °C) and extended extraction times (90 min) significantly increased pigment yields, with Clitoria ternatea L. achieving the highest yield (12.92 % ± 0.03) under standard conditions. In contrast, the condition at 60 °C has a % yield of 11.47 ± 0.02. Mordant-assisted extractions increased overall yields (3.16 - 4.57 %) but required careful parameter optimization to avoid degradation of thermolabile compounds. UV-vis spectroscopy revealed that both extraction conditions and sodium chloride addition as a mordant significantly enhanced pigment absorption, particularly in Oroxylum indicum L., which showed optimal light absorption at 60 °C for 60 min (4.16 ± 0.09). Cytotoxicity assays demonstrated that most extracts exhibited minimal toxicity at low concentrations (&lt; 0.1 mg/mL), with Oroxylum indicum L. showing the highest cell viability (95.65 ± 1.32 %). Pressed paint products formulated with sodium chloride-mordanted pigments displayed good stability under various conditions. The optimal extraction conditions identified in this experiment are as follows: the best temperature is 80 °C, the optimal extraction time is 90 min, and the use of a mordant is necessary for all plant species tested. Among the plants studied, Clitoria ternatea L. yielded the most intense color with a dark blue shade and the lowest L* value (38.14), indicating the highest color intensity under these conditions. HIGHLIGHTS Optimized Extraction Conditions: The study identified optimal decoction extraction conditions for Clitoria ternatea L. at 80 °C for 90 min, yielding the highest crude extract output (12.92 %), emphasizing the importance of temperature and duration in maximizing efficiency. Temperature and Duration Effects: Elevated temperatures (80 °C) and prolonged durations (90 min) enhanced solubility and mass transfer rates, improving extraction yields while maintaining compound stability under controlled conditions. Impact of Mordant-Assisted Extraction: Mordant-assisted extractions significantly reduced crude extract yields (3.16 - 4.57 %) compared to standard methods, highlighting a trade-off between dye fixation and bioactive compound recovery. UV-Vis Spectroscopy Insights: UV-Visible spectroscopy revealed that temperature, duration, and sodium chloride addition significantly influenced pigment solubility and light absorption, with maximum absorption bands aligning with chlorophyll and carotenoid profiles. Eco-Friendly Applications: The findings support sustainable practices by demonstrating the potential of plant-based extracts for natural dyeing and cosmetic applications, offering eco-friendly alternatives to synthetic dyes. GRAPHICAL ABSTRACT Mordant ; Environmentally friendly ; Extraction (chemistry) ; Natural (archaeology) ; Pulp and paper industry ; Biochemical engineering ; Materials science ; Polymer science ; Engineering ; Chemistry ; Biology ; Chromatography ; Composite material ; Dyeing ; Ecology Dye analysis and toxicity ; Dyeing and Modifying Textile Fibers