Pressurized Hot Liquid Extraction with 15% v/v Glycerol-Water as An Effective Environment-Friendly Process to Obtain Durvillaea incurvata and Lessonia spicata Phlorotannin Extracts with Antioxidant and Antihyperglycemic Potential

Abstract

Brown seaweed phlorotannins have shown the potential to promote several health benefits. Durvillaea incurvata and Lessonia spicata—species that are widely distributed in central and southern Chile—were investigated to obtain phlorotannin extracts with antioxidant and antihyperglycemic potential. The use of an environmentally friendly and food-grade glycerol-based pressurized hot liquid extraction (PHLE) process (15% v/v glycerol water) was assessed for the first time to obtain phlorotannins. Multiple effects were analyzed, including the effect of the species, harvesting area (Las Cruces and Niebla), and anatomical part (holdfast, stipe, and frond) on the extracts’ polyphenol content (TPC), antioxidant capacity (AC), and carbohydrate-hydrolyzing enzyme—α-glucosidase and α-amylase—inhibitory activity. Contaminants, such as mannitol, heavy metals (As, Cd, Pb, Hg, and Sn), and 5-hydroxymethylfurfural (HMF), were also determined. The anatomical part used demonstrated a significant impact on the extracts’ TPC and AC, with holdfasts showing the highest values (TPC: 95 ± 24 mg phloroglucinol equivalents/g dry extract; DPPH: 400 ± 140 μmol Trolox equivalents/g dry extract; ORAC: 560 ± 130 μmol TE/g dry extract). Accordingly, holdfast extracts presented the most potent α-glucosidase inhibition, with D. incurvata from Niebla showing an activity equivalent to fifteen times that of acarbose. Only one frond and stipe extract showed significant α-glucosidase inhibitory capacity. No α-amylase inhibition was found in any extract. Although no HMF was detected, potentially hazardous cadmium levels (over the French limit) and substantial mannitol concentrations—reaching up to 50% of the extract dry weight—were found in most seaweed samples and extracts. Therefore, further purification steps are suggested if food or pharmaceutical applications are intended for the seaweed PHLE extracts obtained in this study.

The Potential of Using Cochayuyo (Durvillaea incurvata) Extract Obtained by Ultrasound-Assisted Extraction to Fight against Aging-Related Diseases

“…The results obtained are consistent with those described in previous investigations. Regarding algae's capacities to inhibit the activity of the enzymes α-glucosidase and α-amylase, Erpel et al (2021) showed that an extract of phlorotannins obtained from Durvillaea incurvata from Niebla at a concentration of 500 µg/mL inhibited the activity of the…”

“…The results obtained are consistent with those described in previous investigations. Regarding algae's capacities to inhibit the activity of the enzymes α-glucosidase and α-amylase, Erpel et al (2021) showed that an extract of phlorotannins obtained from Durvillaea incurvata from Niebla at a concentration of 500 µg/mL inhibited the activity of the α-glucosidase enzyme by approximately 80% with an IC 50 of 245.1 ± 5.3 µg/mL and the activity of acarbose around 40% with an IC 50 of 659.5 ± 36.7 µg/mL. Regarding α-glucosidase inhibition, the present study's extracts showed a slightly higher percentage inhibition (at same concentration) and IC 50 values lower than the extract described by Erpal et al (2021), thus indicating that they have a relatively higher inhibitory capacity.…”

Concise review of genus Lessonia Bory

“…Numerous seaweeds have been reported as sources of natural antioxidants (Zimmermann et al 2005;Hurd et al 2014;Araújo et al 2020), including Lessonia. For example, dry tissue and extracts of L. spicata showed high antioxidant activity in aqueous extracts from its holdfast, 100% α-glucosidase inhibitory activity with ~ 170 µg mL −1 and were an effective and safe antihyperglycemic and antitubercular agent for human consumption (Erpel et al 2021). L. nigrescens methanolic extract (100 µg mL −1 ) inhibited 99% of Mycobacterium.…”

Potential of Cochayuyo (<em>Durvillaea incurvata</em>) Extract Obtained by Ultrasound Assisted Extraction Against Aging Related Diseases.

“…The results obtained are consistent with those described in previous investigations. Regarding the inhibition capacity of the algae on the enzymes α-glucosidase and α-amylase, Erpel et al (2021) showed that an extract of phlorotannins obtained from Durvillaea incurvata from Niebla at a concentration of 500 µg/mL inhibited the activity of the α-glucosidase enzyme by approximately 80%, with an IC50 of 245.1 ± 5.3 µg/mL and acarbose around 40%, with an IC50 of 659.5 ± 36.7 µg/mL. Regarding α-glucosidase inhibition, the present extracts show a slightly higher percentage inhibition (at same concentration), and an IC50 lower than that extract described by Erpal et al (2021), so they would be presenting a relatively higher inhibitory capacity.…”

“…On the other hand, regarding α-amylase inhibition, authors reported no effect on the enzyme activity, while our extracts do demonstrate inhibition capacity. This may be since different extraction methods were used (pressurized hot liquid vs ultrasonic assisted), which may generate a different profile of bioactive compounds, having different inhibition capacities [16]. Another study reported that ethanolic and acetone extracts of cochayuyo, at a concentration of 1000 µg/mL, inhibited α-glucosidase by 96.9 ± 0.4 and 99.3 ± 0.3%, showing an IC50 of 473.4 ± 0.9 and 466.0 ± 1.3 µg/mL, respectively (acarbose 797.85 ± 1.1 µg/mL) [8].…”