Ultrasound-assisted intensified aqueous extraction of phenolics from waste Syzygium cumini leaves: Kinetic studies and evaluation of antioxidant, antidiabetic and anticancer potential

Latest Advances in Green Extraction of Polyphenols from Plants, Foods and Food By-Products

Phenolic compounds present in plants and foods are receiving increasing attention for their bioactive and sensory properties, accompanied by consumers' interest in products with health benefits derived from natural rather than artificial sources. This, together with the sustainable development goals for the 21st century, has driven the development of green extraction techniques that allow obtaining these compounds with the safety and quality required to be applied in the food, cosmetic and pharmaceutical industries. Green extraction of natural products involves practices aiming at reducing the environmental impact of the preparation processes, based on using natural or less-polluting solvents, lower energetic requirements and shorter extraction times, while providing greater efficiency in the recovery of target compounds. In this article, the principles of sustainable extraction techniques and the advances produced in recent years regarding green isolation of polyphenols from plants, food and food waste are reviewed.

Ultrasound-Assisted Extraction of Squalene and 2-Acetyl-1-Pyrroline from Pandan Leaf: The Effects of Drying Methods and Extraction Conditions

Pandan, a tropical crop, is rich in squalene (SQ), known for its antioxidant and hypoglycemic properties, and 2-acetyl-1-pyrroline (2-AP), which imparts a characteristic aroma. This study focuses on the extraction of the two bioactive compounds from Pandan leaves and investigates the effects of drying methods, extraction solvents, and conditions on the yield of SQ and 2-AP. Results show that hot air-dried Pandan leaves when extracted using the binary solvent system of ethanol and n-hexane (EH), yield higher SQ content while maintaining an adequate content of 2-AP. To further optimize the extraction process, a single-factor experiment was followed by optimization using Box-Behnken design (BBD) and response surface methodology (RSM). The optimal extraction conditions were determined as follows: ultrasound time of 60 min, a temperature of 50 °C, power of 300 W, and a solid-to-liquid ratio of 1:5 g/mL. Under these conditions, an SQ yield of 1229.98 ± 13.09 μg/DW 1 g Pandan leaves and a 2-AP yield of 80.72 ± 0.88 μg/DW 1 g Pandan leaves were achieved, representing increases of 3.30% and 9.82% compared to pre-optimization values. Additionally, the antioxidant activities of EH extracts were evaluated through various in vitro assays. The extracts demonstrated significant DPPH and ABTS free radical scavenging activity (12.46 μmol TE/g DW and 22.14 μmol TE/g DW, respectively), along with ferric and cupric ion reducing power (10.629 μmol TE/g DW and 14.275 μmol TE/g DW, respectively). The extracts also exhibited notable inhibitory effects on α-amylase and α-glucosidase. The findings suggest that these extracts are a promising natural source of antioxidants with potential applications in health and nutrition.

Exploring the therapeutic potential of Caralluma fimbriata for antioxidant and diabetes management: a 28-day rat model study

This study evaluated the anti-oxidant and anti-diabetic potential of Caralluma fimbriata (CF) in 28-days rat modelling trial. Diabetes is a chronic disorder characterized by elevated blood glucose levels and insulin resistance and cause microvascular and macrovascular issues. Caralluma fimbriata was evaluated for its nutritional composition along with anti-oxidant potential of CF powder (CFP) and CF extract (CFE) using total phenolic contents (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric ion reducing antioxidant power (FRAP) assays. Furthermore, anti-diabetic potential was computed by dividing rats into four groups of 5 individuals each. Rats of Group I was non-diabetic and no supplementation was given while rats of group II were diabetic and no supplementation was given. While group III and group IV rats were diabetic and received CFP and CFE supplementation respectively. CF powder's TPC, and DPPH and FRAP activity were observed maximum at 44.17 ± 0.006 (μgFe/g) in water, 68.75 ± 0.49 (μgFe/g) in acetone and 800.81 ± 0.99 (μgFe/g) in hexane. Supplementation of CFP and CFE reduced blood glucose effectively i.e. (125.00 ± 4.04 and 121.00 ± 4.49 mg/dL, respectively). Moreover, the consumption of C. fimbriata can be helpful in the management of diabetes mellitus due to its glucose lowering potential, anorexic effects, anti-oxidant potential and α-amylase inhibition.

Extraction optimization and constituent analysis of total flavonoid from Hosta plantaginea (Lam.) Aschers flowers and its ameliorative effect on chronic prostatitis via inhibition of multiple inflammatory pathways in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Hosta plantaginea (Lam.) Aschers flowers (HPF) are well-known for their high flavonoid content, which contribute to their widely as traditional Chinese medicine for alleviating inflammation. Despite their recognized potential, information regarding the total flavonoid (TF) of HPF and its therapeutic application in treating chronic prostatitis (CP) remains unknown.

AIM OF THE STUDY

We aimed to investigate the extraction optimization, constituent analysis, and alleviating effect of TF on CP as well as its potential mechanism.

MATERIALS AND METHODS

The optimized extraction of TF from HPF was explored using response surface methodology with a Box-Behnken design model. The major flavonoids in TF were identified based on UHPLC-MS approach. Efficacy of TF (25 and 100 mg/kg, p.o.) on CP was evaluated in prostate antigen emulsion-induced autoimmune CP rat model by measuring prostatic index, the levels of leukocytes and lecithin bodies, as well as histopathological examination. The protein expression contents were detected by western blotting. Additionally, the antioxidant (DPPH and ABTS) and anti-inflammatory (cyclooxygenase 2, COX-2 inhibitory) effects of TF were also evaluated in vitro.

RESULTS

The optimized conditions for TF extraction were determined as 60% ethanol concentration, 30 mL/g liquid-to-solid ratio, 30 min extraction time, and 90 °C extraction temperature, and the extraction ratio is 65.98 ± 2.14%. A total of 15 major flavonoids in TF were characterized by comparison with reference standards. TF ameliorated the efficacy of CP in rats in a dose-independent manner, including reduced prostatic index and leukocytes levels, elevated lecithin body levels, ameliorated histopathological damage to prostate, and suppressed phosphorylated protein expressions of nuclear factor kappa-B (NF-κB) p65, inhibitor of NF-κB alpha (IκBα), c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (Erk), just another kinase 1 (JAK1), signal transducer and activator of transcription 3 (STAT3), phosphoinositide 3-kinase (PI3K) and protein kinase B (Akt). Simultaneously, the IC50 of TF to DPPH, ABTS radicals, and COX-2 were 2.02, 1.79, and 0.0838 mg/mL, respectively.

CONCLUSIONS

We first demonstrated that TF from HPF represents a promising candidate to alleviate CP through suppression of NF-κB, MAPKs, JAK-STAT, and PI3K-Akt signaling pathways.

Recovery and separation of glycyrrhizic acid from Natural Deep Eutectic Solvent (NADES) extract by macroporous resin: adsorption kinetics and isotherm studies

Natural Deep Eutectic Solvents (NADESs) have emerged as a green and sustainable alternative to conventional organic solvents to extract bioactive compounds. However, the recovery of bioactive compounds from the NADES extracts is challenging, restricting their large-scale applications. The present work investigated the recovery of glycyrrhizic acid (GA) from choline-chloride/lactic acid NADES extract using macroporous resins. GA possesses a wide spectrum of biological activities, and it is extracted from the well-known herb Glycyrrhiza glabra. During resin screening, DIAIONTM SP700 showed high adsorption and desorption capacities. The adsorption kinetics study demonstrated that the adsorption of GA on SP700 followed Pseudo First-order kinetic model. Moreover, the adsorption behaviors were elucidated by the Freundlich isotherm using a correlation coefficient based on a static adsorption study at different temperatures and pH. Furthermore, the thermodynamic parameters, for instance, the change of Gibbs free energy (ΔG*), entropy (ΔS*), and enthalpy (ΔH*), showed that the adsorption process was spontaneous, favorable and exothermic. In addition, the sample after macroporous resin treatment, which is enriched with GA exhibited good anticancer potential analyzed by SRB assay. The regenerated NADES solvent was recycled twice, keeping more than 90% extraction efficiency, indicating good reusability of NADES in the GA extraction process by using macroporous resin.

Green Solvents in the Extraction of Bioactive Compounds from Dried Apple Cultivars

New extraction protocols, gas-expanded liquid extraction (GXLE), and ultrasound extraction (UE) have been optimized with an emphasis on using green solvents and maximizing the extraction of 14 selected phenolic compounds, including flavonoid-based compounds and phenolic acids from dried apples. The design of the experiments' approach was applied to optimize the main extraction parameters. Fine tuning included optimization of the flow rate in GXLE and the extraction time for GXLE and UE. Optimized GXLE was carried out with CO₂-ethanol-water (34/53.8/12.2; v/v/v) at a flow rate of 3 mL/min at a temperature of 75 °C and pressure of 120 bar for 30 min. UE with ethanol-water 26/74 (v/v) lasted for 10 min at 70 °C. Both methods differed in solvent consumption and sample throughput, while providing a comparable total phenolic content of 2442 µg/g with an RSD < 10% and 2226 µg/g with RSD < 6%, for GXLE and UE, respectively. Both methods were used in determining the phenolic compounds in five apple cultivars, 'Angold', 'Artiga', 'Golden Delicious', 'Meteor', and 'Topaz'. Phenolic profiles were plotted with chlorogenic acid, catechin, epicatechin, hirsutrin, phloridzin, and guaiaverin as the main components. Statistical evaluation, including pair t-test, Bland-Altman test, and linear regression did not reveal any differences between UE and GXLE results.

Influence of Ultrasound-Assisted Vacuum Drying on Physicochemical Characteristics, Antioxidant Activity, and α-Glucosidase Inhibition Activity of Flos Sophorae Immaturus

Flos Sophorae Immaturus (FSI) contains a large number of bioactive substances with antioxidant and hypoglycaemic activity. However, a feasible drying process plays an important role in the retention of its biological activity. The present work investigated the effects of ultrasound-assisted vacuum drying (UAVD) on FSI samples in terms of drying time, colour, microstructure, and total flavonoid content (TFC). Meanwhile, the antioxidant activity and α-glucosidase inhibition activity were also evaluated. The results show that the drying time of UVAD samples was decreased by 40% compared to that of the single vacuum-dried (VD) samples (600 W for 10 min). The cellular porous structures of FSI tissue were formed by UAVD, which promoted the migration of water from the inside to the outside. Furthermore, samples treated by UAVD exhibited better antioxidant activities and α-glucosidase and α-amylase inhibition capacities, with DPPH (81.86%), ABTS (88.61%), FRAP (83.05%), α-glucosidase inhibition capacity (89%), α-amylase (85%), drying time (3 h), and total aberration (ΔE) (1.63) being the highest characteristic traits. In this condition, the highest levels of total flavonoid content (TFC), rutin, quercetin, kaempferol, isorhamnetin, and genistein were obtained with 266.94, 239.46, 35.56, 8.54, 10.37, and 5.64 mg/g DW, respectively. The results confirm that UAVD is a novel method that significantly reduced the VD time and promoted the release of the bioactive substances of FSI.