Comparisons between conventional, ultrasound-assisted and microwave-assisted methods for extraction of anthraquinones from Heterophyllaea pustulata Hook f. (Rubiaceae)

• Published in: Ultrasonics sonochemistry Vol. 21; no. 2; pp. 478 - 484
• Main Authors: Barrera Vázquez, M.F., Comini, L.R., Martini, R.E., Núñez Montoya, S.C., Bottini, S., Cabrera, J.L.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01.03.2014; Elsevier
• Subjects: Anthraquinones; Anthraquinones - isolation & purification; Chemical Fractionation - methods; Chemistry; Exact sciences and technology; General and physical chemistry; Microwave assisted extraction; Microwaves; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Rubiaceae - chemistry; Solvents - chemistry; Time Factors; Ultrasonic chemistry; Ultrasonics; Ultrasound-assisted extraction; MAE; AQs; O2; 1O2; Anthraquinones; UAE; Microwave assisted extraction; AUP; Ultrasound-assisted extraction; HPLC; tR; Anthraquinone; Sonochemistry; Microwave; Extraction; Ultrasound; area under each peak; retention times; singlet molecular oxygen; High-performance liquid chromatography; Emicrowave-assisted extraction; superoxide anion; t(R)
• ISSN: 1350-4177; 1873-2828
• DOI: 10.1016/j.ultsonch.2013.08.023

•UAE and UAE+MAE is an attractive alternative to the extraction of natural AQs.•The combination UAE+MAE exhibited the highest efficiency to the extraction of AQs.•Optimal conditions were: UAE/benzene/50°C/60 minplus MAE/ethyl acetate/900W/15min. This work reports a comparative study about extraction methods used to obtain anthraquinones (AQs) from stems and leaves of Heterophyllae pustulata Hook (Rubiáceae). One of the conventional procedures used to extract these metabolites from a vegetable matrix is by successive Soxhlet extractions with solvents of increasing polarity: starting with hexane to eliminate chlorophylls and fatty components, following by benzene and finally ethyl acetate. However, this technique shows a low extraction yield of total AQs, and consumes large quantities of solvent and time. Ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) have been investigated as alternative methods to extract these compounds, using the same sequence of solvents. It was found that UAE increases the extraction yield of total AQs and reduces the time and amount of solvent used. Nevertheless, the combination UAE with benzene, plus MAE with ethyl acetate at a constant power of 900W showed the best results. A higher yield of total AQs was obtained in less time and using the same amount of solvent that UAE. The optimal conditions for this latter procedure were UAE with benzene at 50°C during 60min, followed by MAE at 900W during 15min using ethyl acetate as extraction solvent.