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Dielectric constant-based optimization for sustainable extraction of centellosides from Centella asiatica using bio-based solvents
(2026-08-01)
Pakaweerachat, Pattarabhorn
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Chysirichote, Teerin
This study systematically examined the influence of solvent polarity and extraction temperature on the recovery of four major centellosides: madecassoside (MAD), asiaticoside (ASI), madecassic acid (MDA), and asiatic acid (ASA) from Centella asiatica. Extractions were performed using ethanol-water, acetone-water, ethanol-ethyl acetate, and hexane-ethyl acetate mixtures at 30–70 °C, covering dielectric constants (ε = 2–70) that correspond to the polarity range of the selected solvent systems. Extraction yields (mg g⁻¹) are expressed on a dry-weight basis. Ethanol–water mixtures demonstrated the highest efficiency for polar glycosides, yielding 19.6 ± 0.3 mg g⁻¹ dry matter (mg g⁻¹ DM) for MAD and 17.2 ± 0.3 mg g⁻¹ DM for ASI at 70 °C, with temperature effects mainly attributed to enhanced mass transfer and no significant thermal degradation observed. In contrast, aglycones (MDA and ASA) achieved optimal yields (3.3–6.5 mg g⁻¹) in solvents with lower dielectric constants, where solvent composition predominated over temperature effects. Solvent polarity, expressed in terms of dielectric constant, provided a quantitative indicator linking solvent selection to centelloside recovery and solvent-temperature interactions. Ethanol-water systems are recommended for food and nutraceutical applications, while ethyl acetate-ethanol mixtures are suited for cosmetic formulations. This work establishes a polarity-temperature framework for enhancing extraction using bio-based solvents, contributing to more sustainable production of bioactive-rich extracts from C. asiatica for use in food, cosmetic, and pharmaceutical industries.
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Optimization of ethanolic extraction of asiaticoside and asiatic acid: A stability study and correlation of dielectric constant
(2025-06-01)
Chysirichote, Teerin
;
Wattanasiriwit, Waewwan
;
Uraipong, Chatchaporn
This study optimized the extraction of asiaticoside and asiatic acid from Centella asiatica using an ultrasonic-assisted extraction method. The research focused on ethanol concentration, extraction temperature, and extraction duration to maximize yield efficiency. In addition, the stability of the extracted compounds was assessed under different temperature and pH conditions for practical applications. The highest asiaticoside yield was achieved using 53.7 % ethanol at 50.0 °C for 35 min., whereas asiatic acid extraction was most efficient using 63.3 % ethanol at 64.3 °C for 28 min. A significant correlation was observed between the dielectric constant of the extraction conditions, which was affected by solvent concentration and temperature, and extraction efficiency. Stability tests showed that temperature had a more pronounced impact than pH, with degradation accelerating at higher temperatures. The findings emphasize the importance of maintaining processing conditions below 70 °C and within an acidic to neutral pH range. These results provide valuable insights for industrial applications in pharmaceutical, cosmetic, and nutraceutical sectors, underscoring the necessity of controlled conditions to preserve the bioactive properties of Centella asiatica extracts.
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Elucidation of antioxidant compounds recovery capacity from “Cẩm” purple rice bran by different sustainable extraction techniques
(2024-07-01)
Loan, Le Thi Kim
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Vinh, Bui The
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Tai, Ngo Van
“Cẩm” rice is a pigmented rice with the purple color that was well known as local cultivar in Tien Giang province (Vietnam). The bran of this rice is usually not properly used; however, it contains rich antioxidants that could be utilized for demanding healthy and nutritional foods. This study is aimed to study the different green and sustainable extraction methods for rice bran’s antioxidants, including microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), ultrasound followed by microwave (U+MAE), microwave followed by ultrasound (M+UAE), and conventional method as the control. The results showed that high extraction efficiency was found when Cẩm rice bran was extracted with the aid of sustainable extraction techniques such as sonication or microwave. The study also reported that dual synergistic-assisted extraction presented a higher content of bioactive compounds and their antioxidant activities compared with single-assisted extraction. In addition, U+MAE was shown to have a higher capacity to extract and maintain antioxidant activities than M+UAE. This study provides the fundamental information for further application and optimization process of extract of antioxidant compounds from Cẩm rice bran, as source of antioxidant and nutraceutical ingredient.
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Oxidative stability of Iresine herbstii extract-containing coconut oil during storage
(2023-01-01)
Sai-Ut, S.
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Senphan, T.
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Pongsetkul, J.
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Kaewthong, P.
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Tuntivisoottikul, K.
Virgin coconut oil was used as green solvent for the extraction of total phenolics from I. herbstii (I. herbstii: coconut oil, 1:10 (w/w)). I. herbstii extract-containing coconut oil (ECC) had dark red in color. Acid value (AV), peroxide value (PV), thiobarbituric acid-reactive substances (TBARS), ρ-anisidine value and volatile compounds were taken as parameters for evaluation of oxidative stability of EEC sample. All parameters of EEC sample were lowered, in comparison with the control sample during storage for 7 weeks. ECC sample produced less TBARS value than the control (p<0.05). Abundance of volatile compounds in all samples correlated well with the TBARS value. Results revealed the use of coconut oil as green solvent for extraction of bioactive compounds and natural red pigment from I. herbstii, where I. herbstii as antioxidant to prevent lipid oxidation in vegetable oil.

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