Sustainable Recovery of Phlorotannins from Durvillaea incurvata: Integrated Extraction and Purification with Advanced Characterization

Abstract

The rising demand for bioactive compounds from marine resources highlights the need for sustainable separation technologies. This study introduces an integrated process combining ultrasound-assisted extraction (USAE) and resin purification (RP) to isolate phlorotannins from Durvillaea incurvata, a brown seaweed with significant biomedical potential. Using a 32.5% ethanol-water solvent system for USAE followed by RP on Diaion HP-20 resin, phlorotannins were enriched 2.4-fold, with simultaneous removal of interfering compounds such as mannitol (~100%), which was demonstrated by FTIR and HPLC-IR analysis. Advanced characterization using UHPLC-QToF-MS/MS identified five novel phlorotannins with polymerization degrees of 3 to 8 phloroglucinol units in both USAE extracts and post-RP. Mass balance based on spectrophotometric measurements indicated a purification factor of ~2, confirming process effectiveness. RP streams showed distinct phlorotannin profiles, with one phlorotannin exceeding 70% relative abundance. However, MS/MS results showed significantly lower recoveries than spectrophotometric data, revealing a novel insight into RP purification. These findings highlight the critical role of comprehensive chemical characterization in optimizing sustainable phlorotannin extraction from seaweed. They propose a framework for scalable, eco-efficient technologies for achieving high-purity phlorotannin recovery. This approach facilitates the development of phlorotannin-based applications in the nutraceutical and pharmaceutical industries.

Keywords: UHPLC-QToF MS/MS; brown seaweed; integrated extraction–purification processes; mass balance; spectrophotometric.

Figure 1

(A) TPC and TPhC, and (B) antioxidant capacity (DPPH and ORAC assays) of RE, CE, and RP streams (CS, WS, and ES) from Durvillaea incurvata frond. ^{(A–D; a–d)} Values that do not share a letter are significantly different.

Figure 2

(a) FTIR spectra of mannitol, phloroglucinol, CE, and RP streams. (b) Characteristic bands of each FTIR spectrum associated with specific types of vibrations.

Figure 3

Proposed structures of the five identified phlorotannins in the extracts of Durvillaea incurvata frond.

Figure 4

Distribution of the five proposed phlorotannins identified in the process streams (CE, CS, WS, and ES) from Durvillaea incurvata frond.

Figure 5

Relative mass balance of the integrated process of USAR-RP from Durvillaea incurvata frond. Relative abundances correspond to the ratio of the relative area of phlorotannin and ExS of the stream.

Figure 6

Percentage distribution of ExS, TP, TPh, Mannitol, and specific phlorotannins of CE in the RP streams.