Ultrasound-assisted extraction of flavonoids and phenolic compounds from Ocimum tenuiflorum leaves

Application progress of ultrasound in the production and processing of traditional Chinese herbal medicines

The quality of Chinese herbal medicines is the key to the quality of traditional Chinese medicine. The processing of Chinese herbal medicines is an important part of the production and quality formation of medicinal materials. Traditional processing methods have low productivity and cannot guarantee the quality of Chinese herbal medicines. Among various non-thermal processing methods, ultrasonic technology has been proved to be a very valuable green processing technology. This paper will discuss the application of ultrasonic technology in the production and processing of Chinese herbal medicines in recent years, including the extraction, cleaning, drying and sterilization of effective components of Chinese herbal medicines. This review summarizes its principle, characteristics and application progress in recent years, and discusses its existing problems. The effects of ultrasound on the chemical structure and biological activity of bioactive compounds extracted from Chinese herbal medicines are mainly introduced. In addition, this paper discusses the effects of different ultrasonic conditions such as frequency, power, time and temperature on the chemical properties and processing of Chinese herbal medicines. In general, the use of ultrasound in the production and processing of Chinese herbal medicines has great application potential.

Design of Experiments for Optimizing Ultrasound-Assisted Extraction of Bioactive Compounds from Plant-Based Sources

Plant-based materials are an important source of bioactive compounds (BC) with interesting industrial applications. Therefore, adequate experimental strategies for maximizing their recovery yield are required. Among all procedures for extracting BC (maceration, Soxhlet, hydro-distillation, pulsed-electric field, enzyme, microwave, high hydrostatic pressure, and supercritical fluids), the ultrasound-assisted extraction (UAE) highlighted as an advanced, cost-efficient, eco-friendly, and sustainable alternative for recovering BC (polyphenols, flavonoids, anthocyanins, and carotenoids) from plant sources with higher yields. However, the UAE efficiency is influenced by several factors, including operational variables and extraction process (frequency, amplitude, ultrasonic power, pulse cycle, type of solvent, extraction time, solvent-to-solid ratio, pH, particle size, and temperature) that exert an impact on the molecular structures of targeted molecules, leading to variations in their biological properties. In this context, a diverse design of experiments (DOEs), including full or fractional factorial, Plackett-Burman, Box-Behnken, Central composite, Taguchi, Mixture, D-optimal, and Doehlert have been investigated alone and in combination to optimize the UAE of BC from plant-based materials, using the response surface methodology and mathematical models in a simple or multi-factorial/multi-response approach. The present review summarizes the advantages and limitations of the most common DOEs investigated to optimize the UAE of bioactive compounds from plant-based materials.

Extraction of phenol compound from Mentha piperita by ultrasonic waves based on a response surface methodology

In this study, optimization of the extraction of phenol compounds from Mentha piperita using ultrasonic waves with response surface methodology (RSM) was assessed. In this regard, a central composite design with three independent variables of time (5, 27.5, and 50 min), temperature (25, 45, and 65°C), and concentrations of ethanol in the water-ethanol solution (0%, 50%, and 100%) was used. Besides, the antioxidant activity tests (DPPH radical scavenging assay, ferric reducing antioxidant power [FRAP], and oxidative stability indexes [OSI]) were examined. Significant effects of independent variables on the extraction of phenol compound, DPPH radical scavenging power, and OSI of M. piperita extract, with the regression coefficients of 0.89, 0.92, and 0.94, respectively, were noted. However, no significant difference in terms of the FRAP among different treatments was noted. Also, the best antioxidant activity of M. piperita was obtained by using the ultrasonic wave for 50 min at 65°C and 59.6% v/v ethanol/water solution. While the findings of RSM confirmed the experimental results, due to the favored properties of M. piperita extract by the proposed method, further research to investigate possible applications in the food industry is recommended.

Bioactive Properties of Extracts from Plectranthus barbatus (Coleus forskohlii) Roots Received Using Various Extraction Methods

The aim of this study was to verify various extraction methods: shaking water bath extraction (SWA), ultrasound-assisted extraction (UAE) and microwave assisted extraction (MAE), and their parameters to optimize the extraction yield as well as maximize the concentration of polyphenols in Plectranthus barbatus extracts. Extracts were obtained from dried roots of P. barbatus in various degrees of fragmentation and analyzed for content of polyphenols, antioxidant capacity and flavonoids. Additionally, phenolic compounds in extracts were analyzed using the UHPLC-DAD-ESI-MS/MS method. The conducted research showed that roots of P. barbatus are rich in polyphenolic compounds. A total of 15 phenolic compounds, belonging to the group of phenolic acids and their derivatives, were identified. The extraction yield was similar for all extraction methods and averaged 31%. Irrespective of the extraction method, the yield was the lowest in the case of using 80% ethanol as the solvent. The extracts obtained from the finer fraction were characterized by a higher antioxidant capacity as well as a higher concentration of polyphenolic compounds including flavonoids. UAE seems to be the most effective method for extraction of polyphenols from P. barbatus roots. Regardless of the extraction method, ethanol was a better extractant than distilled water. All ethanolic extracts were characterized by a high antioxidant capacity. The 80% ethanol solution was considered the best solvent for the extraction of flavonoids, while the 40% and 60% ethanol solutions were sufficient for the effective extraction of polyphenolic compounds in general.

Extraction Processes Affect the Composition and Bioavailability of Flavones from Lamiaceae Plants: A Comprehensive Review

Lamiaceae plants are a widespread family of herbaceous plants with around 245 plant genera and nearly 22,576 species distributed in the world. Some of the most representative and widely studied Lamiaceae plants belong to the Ocimum, Origanum, Salvia, and Thymus genera. These plants are a rich source of bioactive molecules such as terpenes, flavonoids, and phenolic acids. In this sense, there is a subgroup of flavonoids classified as flavones. Flavones have antioxidant, anti-inflammatory, anti-cancer, and anti-diabetic potential; thus, efficient extraction techniques from their original plant matrixes have been developed. Currently, conventional extraction methods involving organic solvents are no longer recommended due to their environmental consequences, and new environmentally friendly techniques have been developed. Moreover, once extracted, the bioactivity of flavones is highly linked to their bioavailability, which is often neglected. This review aims to comprehensively gather recent information (2011–2021) regarding extraction techniques and their important relationship with the bioavailability of flavones from Lamiaceae plants including Salvia, Ocimum, Thymus, and Origanum.

Extraction of Flavonoids From Natural Sources Using Modern Techniques

Flavonoids are one of the main groups of polyphenols found in natural products. Traditional flavonoid extraction techniques are being replaced by advanced techniques to reduce energy and solvent consumption, increase efficiency and selectivity, to meet increased market demand and environmental regulations. Advanced technologies, such as microwaves, ultrasound, pressurized liquids, supercritical fluids, and electric fields, are alternatives currently being used. These modern techniques are generally faster, more environmentally friendly, and with higher automation levels compared to conventional extraction techniques. This review will discuss the different methods available for flavonoid extraction from natural sources and the main parameters involved (temperature, solvent, sample quantity, extraction time, among others). Recent trends and their industrial importance are also discussed in detail, providing insight into their potential. Thus, this paper seeks to review the innovations of compound extraction techniques, presenting in each of them their advantages and disadvantages, trying to offer a broader scope in the understanding of flavonoid extraction from different plant matrices.

Ultrasonication-assisted extraction of a phytomelatonin-rich, erucic acid-lean nutraceutical supplement from mustard seeds: an antioxidant synergy in the extract by reductionism

Phytomelatonin-rich (194.02 ± 2.45-205.80 ± 1.67 ng/g of dry mustard seeds) and erucic acid-lean (below 2%) extracts from an oilseed crop, (yellow and black mustard seeds) have been successfully obtained by ultrasonication-assisted-extraction in ethanol-water. Fourier-transform infrared spectroscopy and liquid chromatography-mass spectrum analyses have confirmed the presence of phytomelatonin along with tocopherol, ascorbic acid, limonene and linalool in the extract. Field emission scanning electron micrographs confirmed the cavitational effects of sonication on mustard seed matrices. Electron paramagnetic resonance spectroscopy established the strong antioxidant activities (72.25-75.49%) of the extracts foregoing erroneous spectrophotometric result of pan assay interference compounds. A synergistic effect value of 1.13 (greater than unity) confirmed synergistic co-existence of the antioxidants in the extract. This study interestingly revealed that an antioxidant synergy could be obtained by classical reductionism. Acute oral toxicity of the extracts were found to be greater than 5000 mg/kg body weight of rats. The extracts are perfectly safe to be utilized as antioxidative food supplements.

Optimization of Ultrasound-Assisted Extraction of Total Flavonoids from Dendranthema indicum var. aromaticum by Response Surface Methodology

Dendranthema indicum var. aromaticum is a new species with strong fragrance and is used as a herbal medicine by Chinese folks. The abundant flavonoids play important roles in its pharmacological activities. In this study, an ultrasound-assisted method was used to extract total flavonoids (TF) from D. indicum var. aromaticum by response surface methodology. A quadratic model was developed to optimize the extraction conditions, whose accuracy was verified by statistic analysis. Ethanol and acetic acid at the volume ratio of 70% : 2% were selected as the extract solvent. The optimized extraction conditions were as follows: extraction time, 40 min; solid/liquid ratio, 1 : 23 g/mL; and temperature, 60°C. This is the first report of an efficient and easy-operating method for TF extraction from D. indicum var. aromaticum. Besides, this study provides reference for future pharmacological research on D. indicum var. aromaticum and extraction of bioactive components from other herbs.

Optimization and multivariate accelerated shelf life testing (MASLT) of a low glycemic whole jamun (Syzygium cumini L.) confection with tailored quality and functional attributes

An optimization and multivariate accelerated shelf-life testing (MASLT) was demonstrated to develop a low glycemic (GI) whole jamun (Syzygium cumini L.) confection (WJC) with soft texture and fruity hedonics targeted for diabetic strata. The hydrocolloids viz., agar (1-3 g), pectin (1-3 g), and polydextrose (24-28 g) were optimized [mixture design (MD)] to obtain hydrocolloid mix (HM) with a soft texture. Next, whole jamun ingredients viz, jamun pulp (JP) (20-30 g), seed powder (JSP) (1-5 g), and HM (25-35 g) were optimized (MD + PCA) for satisfactory texture, total polyphenolic content (TPC), and fruity hedonics. The optimized WJC was assayed for GI and modelled by univariate kinetics and MASLT (10-45 °C/75% humidity/120 days). Using MASLT, the collated effects of quality attributes (anthocyanin content, TPC, moisture, hardness, and total color change) were extracted as principal components to estimate new stability parameters viz, multivariate rate constants (k _m), acceleration factors ( α m T ), activation energy (E _am), and cut-off criterion. The optimized WJC contains 2.3 g agar, 1.9 g pectin, 27.2 g polydextrose, 26.4 g JP, and 2 g JSP and had satisfactory hardness (1007 g), TPC (2.8 mg gallic acid equivalents/g), and low GI value (48.6). The zero-order kinetic fitting of univariate versus MASLT resulted in α ( 45 , 10 ) T , E _a, and shelf life (10 °C) of 7.8 versus 6.2, 43.81 versus 39.22 kJ/mol and 175 versus 186 days, respectively. MASLT simplified the kinetic interpretations to a single variable by collating the useful information from critical quality parameters and predicted shelf life precisely than univariate kinetics.

Optimization of ultrasonic-assisted extraction of phenolic compounds from Justicia spicigera leaves

A Box-Behnken design (Extraction-time, pulse-cycle, sonication-amplitude) was employed to extract phenolic compounds from Justicia spicigera leaves by ultrasonic-assisted extraction. The muicle leaves extracts were analyzed measuring total phenolic compounds and antioxidant capacity. According to response surface methodology the optimal conditions of ultrasonic-assisted extraction to obtain the highest soluble phenolic content were 2 min (extraction time) for 0.7 s (pulse cycle) at 55% of sonication amplitude. Under these optimal conditions, the total phenolic content was higher when was used ultrasonic-assisted extraction (54.02 mg/g) than stirring (46.46 mg/g) and thermal decoction (47.76 mg/g); however, the antioxidant capacity from J. spicigera extracts did not increase by ultrasonic-assisted extraction. The extracts or aqueous infusions from J. spicigera leaves are used for therapeutic proposes, therefore the ultrasonic-assisted extraction is a useful technology to improve the extraction of phytochemicals from J. spicigera leaves.

Extraction Process, Component Analysis, and In Vitro Antioxidant, Antibacterial, and Anti-Inflammatory Activities of Total Flavonoid Extracts from Abutilon theophrasti Medic. Leaves

The flavonoid fraction was extracted from the leaves of Abutilon theophrasti Medic., which are usually used as a traditional Chinese herbal medicine for the treatment of inflammation and joint pain. The current study focused on the extraction process, component analysis, and in vitro antioxidant, antibacterial, and anti-inflammatory activities of the flavonoid fraction as a part of ongoing research on bioactive substances from natural plant sources. This study evaluated the antioxidant activities via assays of DPPH radical scavenging capacity, ABTS radical scavenging capacity, and reducing power and investigated inhibitory activities against Escherichia coli, Salmonella, Staphylococcus aureus, and Streptococcus. Moreover, the inflammatory activity of the flavonoid fraction was estimated by measurement of the content of tumor necrosis factor alpha, interleukin-1-beta, interleukin-6, interleukin-10, nitric oxide, and cyclooxygenase-2 and the gene expression levels of several inflammation markers, such as inducible nitric oxide synthase and cyclooxygenase-2, in RAW 264.7 macrophages after LPS treatment. In addition, the underlying anti-inflammatory mechanisms, that is, the activation of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways, were also revealed from the gene and protein expression levels. Taken together, these results suggested that the flavonoid fraction might exert in vitro antioxidant, antibacterial, and anti-inflammatory effects on LPS-stimulated RAW 264.7 macrophages and will be potentially useful as an adjuvant treatment for oxidative stress and bacterial and inflammatory diseases.

Extraction, molecular weight distribution, and antioxidant activity of oligosaccharides from longan (Dimocarpus Longan Lour.) pulp

Ultrasonic-microwave synergistic extraction (UMSE) was optimized for the extraction of oligosaccharides from longan pulp (OLP). Box-Behnken design was used to evaluate the effects of temperature (35-55°C), ultrasonic time (5-25 min), and water to material ratio (10-30 mL/g) on the extraction efficiency of crude OLP. A regression model was developed and its validity was statistically demonstrated. Significant interaction between temperature and water to material ratio was observed. The following optimal conditions for the extraction yield of crude OLP were determined: extraction temperature 55°C, ultrasonic time 18.52 min, and water to material ratio 10 mL/g. The extracted OLP were purified for the determination of molecular weight distribution and antioxidant activity. Results of matrix-assisted laser desorption ionization time-of-flight mass spectrometry revealed that the molecular weight distribution of the purified OLP ranged from m/z 495.138 to 795.511. The purified OLP exhibited a dose-dependent behavior in 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity.