Enrichment in Antioxidant Flavonoids of Stamen Extracts from Nymphaea lotus L. Using Ultrasonic-Assisted Extraction and Macroporous Resin Adsorption

Abstract

<jats:p>Nymphaea lotus L. is the medicinal plant that has long been used for food, cosmetics and traditional medicines in Africa and Asia since ancient times. Its flavonoids and other interesting phytochemical compounds from rhizome, leaf and the whole flowers have been reported in the previous published research. However, stamens, which are essential for reproductive functions, may also represent new alternative sources of potential antioxidant flavonoids, as investigated in this study. The innovative green chemistry methods, i.e., ultrasound-assisted extraction (UAE) as well as a macroporous resin (MPR) purification procedure, were employed in this current research. Using a full factorial design coupled to three-dimensional (3D) surface plot methodology, the influence of three variables, namely aqEtOH concentration (ranging from 50 to 100% (v/v), US frequency (ranging from 0 (no US applied) to 45 kHz), and the extraction duration (ranging from 20 to 60 min), were evaluated. Five MPRs with different surface areas, average pore diameters, matrix types and polarities were also investigated for the purification of total flavonoids. The optimal UAE condition is 90% (v/v) aqEtOH with 34.65 khz ultrasonic frequency and 46 min of extraction duration. Compared with the conventional heat reflux extraction (HRE) method, a significant 1.35-fold increase in total flavonoids content was obtained using optimized UAE conditions (169.64 for HRE vs. 235.45 mg/g dry weight for UAE), causing a 2.80-fold increase when this UAE associated with MPR purification (475.42 mg/g dry weight). In vitro cell free antioxidant activity of N. lotus stamen extracts and in cellulo antioxidant investigation using yeast model showed the same trend, indicating that the best antioxidant flavonoid can be found in UAE coupled with MPR purification. Moreover, in the yeast model, the expression of key antioxidant genes such as SIR2 and SOD2 were expressed at the highest level in yeast cells treated with the extract from UAE together with MPR purification. Consequently, it can be seen that the UAE combined with MPR purification can help enhance the flavonoid antioxidant potential of the stamens extract from this medicinal species.</jats:p>

Callus Culture of Thai Basil Is an Effective Biological System for the Production of Antioxidants

“…The cellular antioxidant assay confirmed the interest of natural antioxidant from plant extracts [ 18 , 48 , 49 ]. In the past decade, natural antioxidants have generated increasing interest due to their possible use as an alternative to potentially hazardous synthetic antioxidants such as butylated hydroxyanisole (BHA) or butylated hydroxytoluene (BHT) in various food preparations and their possible use as nutraceuticals [ 50 ].…”

Ultrasonic-Assisted Ionic Liquid Extraction of Two Biflavonoids from Selaginella tamariscina

“…Obtaining biflavonoids from medicinal plants is one of the main ways. Currently, there are many traditional methods for extracting biflavonoids, including diafiltration, 17 soxhlet extraction, 18 heating reflux extraction, 19 and alkali-soluble acid precipitation. 20 But these extraction methods have the disadvantages of being environmentally unfriendly and time-consuming, as well as having low extraction efficiency.…”

A Critical Cross-Species Comparison of Pollen from Nelumbo nucifera Gaertn. vs. Nymphaea lotus L. for Authentication of Thai Medicinal Herbal Tea

“…Flavonoids were successfully used to interpret evolutionary relationships in a number of angiosperm groups as well as for botanical authentication [ 22 , 23 ]. Both N. nucifera [ 9 , 24 , 25 , 26 ] and N. lotus [ 27 , 28 , 29 ] were reported to accumulate large amounts of a wide variety of different flavonoids, and some of them were proposed as chemotaxonomic markers that might be used for authentication purposes. A representative high-performance liquid chromatography (HPLC) reference pattern was established for each species using an optimized extraction method designed for flavonoid extraction from lotus stamens [ 29 ].…”

“…A stamen sample (100 mg), placed in 5 mL quartz tubes equipped with a vapor condenser, was extracted by ultrasound-assisted extraction in 1 mL 90% ( v / v ) aqEtOH in USC1200TH ultrasonic bath (Prolabo, Fontenay-sous-Bois, France) using optimized extraction conditions of 30 kHz frequency for 45 min at 45 °C [ 29 ]. The extract was then centrifuged 15 min at 5000× g (Heraeus Biofuge Stratos, Thermo Scientific, Illkirch, France), and the obtained supernatant was filtered through 0.45 μm of nylon syringe membranes (Merck Millipore, Saint-Quentin Fallavier, France).…”

“…The extract was then centrifuged 15 min at 5000× g (Heraeus Biofuge Stratos, Thermo Scientific, Illkirch, France), and the obtained supernatant was filtered through 0.45 μm of nylon syringe membranes (Merck Millipore, Saint-Quentin Fallavier, France). Flavonoid enrichment was obtained through an additional DAX-8 (Merck Millipore, Saint-Quentin Fallavier, France) macroporous resin purification step as previously described [ 29 ].…”