From by-products to new application opportunities: the enhancement of the leaves deriving from the fruit plants for new potential healthy products

In the last decades, the world population and demand for any kind of product have grown exponentially. The rhythm of production to satisfy the request of the population has become unsustainable and the concept of the linear economy, introduced after the Industrial Revolution, has been replaced by a new economic approach, the circular economy. In this new economic model, the concept of "the end of life" is substituted by the concept of restoration, providing a new life to many industrial wastes. Leaves are a by-product of several agricultural cultivations. In recent years, the scientific interest regarding leaf biochemical composition grew, recording that plant leaves may be considered an alternative source of bioactive substances. Plant leaves' main bioactive compounds are similar to those in fruits, i.e., phenolic acids and esters, flavonols, anthocyanins, and procyanidins. Bioactive compounds can positively influence human health; in fact, it is no coincidence that the leaves were used by our ancestors as a natural remedy for various pathological conditions. Therefore, leaves can be exploited to manufacture many products in food (e.g., being incorporated in food formulations as natural antioxidants, or used to create edible coatings or films for food packaging), cosmetic and pharmaceutical industries (e.g., promising ingredients in anti-aging cosmetics such as oils, serums, dermatological creams, bath gels, and other products). This review focuses on the leaves' main bioactive compounds and their beneficial health effects, indicating their applications until today to enhance them as a harvesting by-product and highlight their possible reuse for new potential healthy products.

Daraesoon (shoot of hardy kiwi) mitigates hyperglycemia in db/db mice by alleviating insulin resistance and inflammation

BACKGROUND/OBJECTIVES

Mitigating insulin resistance and hyperglycemia is associated with a decreased risk of diabetic complications. The effect of Daraesoon (shoot of hardy kiwi, Actinidia arguta) on hyperglycemia was investigated using a type 2 diabetes animal model.

MATERIALS/METHODS

Seven-week-old db/db mice were fed either an AIN-93G diet or a diet containing 0.4% of a 70% ethanol extract of Daraesoon, whereas db/+ mice were fed the AIN-93G diet for 7 weeks.

RESULTS

Consumption of Daraesoon significantly reduced serum glucose and blood glycated hemoglobin levels, along with homeostasis model assessment for insulin resistance in db/db mice. Conversely, Daraesoon elevated the serum adiponectin levels compared to the db/db control group. Furthermore, Daraesoon significantly decreased both serum and hepatic triglyceride levels, as well as serum total cholesterol levels. Additionally, consumption of Daraesoon resulted in decreased hepatic tumor necrosis factor-α and monocyte chemoattractant protein-1 expression.

CONCLUSIONS

These results suggest that hypoglycemic effect of Daraesoon is mediated through the improvement of insulin resistance and the downregulation of pro-inflammatory cytokine expression in db/db mice.

Antioxidant Activity Analysis of Native Actinidia arguta Cultivars

Kiwiberry (Actinidia arguta) is a perennial fruit tree belonging to the family Actinidiaceae. Kiwiberries are known to have an extremely high concentration of sugars, phenolics, flavonoids, and vitamin C, and possess delicious taste and health-promoting properties. Numerous studies have focused on kiwiberry fruits, demonstrating that they possess a higher phytochemical content and greater antioxidant activities than other berry fruits. The purpose of this study was to compare the phytochemical content and antioxidant potential of leaf, stem, root, and fruit extracts from twelve kiwiberry cultivars grown in Wonju, Korea, characterized by a Dwa climate (Köppen climate classification). In most kiwiberry cultivars, the total phenolic (TPC) and total flavonoid (TFC) phytochemical content was significantly higher in leaf and stem tissues, while the roots exhibited higher antioxidant activity. In fruit tissues, the TPC and TFC were higher in unripe and ripe kiwiberry fruits, respectively, and antioxidant activity was generally higher in unripe than ripe fruit across most of the cultivars. Based on our results, among the 12 kiwiberry cultivars, cv. Daebo and cv. Saehan have a significantly higher phytochemical content and antioxidant activity in all of the tissue types, thus having potential as a functional food and natural antioxidant.

Prediction of Potential Geographical Distribution Patterns of Actinidia arguta under Different Climate Scenarios

Actinidia arguta (Siebold and Zucc.) Planch.ex Miq, called “hardy kiwifruit”, “baby kiwi” or “kiwi berry”, has a unique taste, is rich in nutrients and has high economic value and broad market prospects. Active research on the potential geographic distribution of A. arguta in China aims to provide a reference basis for its resource investigation, conservation, development and utilization and introduction of cultivation. In this study, the Maxent model was used to combine climatic factors, soil factors and geographical factors (elevation, slope and aspect) to predict the current and future (2041–2060 and 2081–2100) potential distribution of A. arguta and to analyze the impact of climate change on it. The results showed that the suitable distribution range of A. arguta in China was 23–43 N and 100–125 E, with a total area of about 3.4451 × 106 km2. The highly suitable area of A. arguta was mainly concentrated in the middle and low mountain areas of the south of Shaanxi, the east of Sichuan, the middle and west of Guizhou and the west of Yunnan, presenting a circular distribution. The Jackknife test was used to calculate the main environmental factors affecting the distribution of A. arguta. The first four main factors were annual mean temperature (bio_1), precipitation of the warmest quarter (bio_18), elevation (ELE) and mean temperature of the warmest quarter (bio_10), which provided a contribution up to 81.7%. Under the scenarios of three representative concentrations (SSP1_2.6, SSP2_4.5 and SSP5_8.5) in the future, the area of low and moderate suitable habitat decreased, while the area of highly suitable habitat increased. The migration direction of the centroid in the highly suitable habitat moved to the southwest in the future scenario period.

Effect of the Oral Administration of Common Evening Primrose Sprout (Oenothera biennis L.) Extract on Skin Function Improvement in UVB-irradiated Hairless Mice

Most of the studies on common evening primrose (Oenothera biennis L.) are focused on its oils (isolated from seed, root, and stem tissues). We aimed to investigate the effect of the oral administration of OBS-E on the improvement of skin function in skin-damaged hairless mice exposed to excessive ultraviolet B (UVB) radiation owing to the preliminary in vitro findings regarding the antioxidant, anti-wrinkle, and skin moisturizing activities of OBS-E. OBS-E administration for 14 weeks did not significantly affect the body weight or clinical signs. Significant reductions were observed in wrinkle parameters (area, number, length, and depth, and metalloproteinase levels) in OBS-E-administered mice compared with those in UVB-irradiated control mice. OBS-E significantly increased skin elasticity and hyaluronic acid content, but it significantly decreased transepidermal water loss. Histomorphometrical analysis revealed that OBS-E significantly reduced the epidermal thickness, area of the collagen-occupied region, and number of microfolds and inflammatory and mast cells. These results demonstrate that OBS-E can effectively enhance skin functions in terms of ameliorating wrinkle formation, promoting skin-moisturization, enhancing skin barrier function, and inhibiting inflammatory reactions. The obtained results provide good starting point for the continuation in the process of developing new inner beauty products based on OBS-E.

Antioxidant Activity of Sprouts Extracts Is Correlated with Their Anti-Obesity and Anti-Inflammatory Effects in High-Fat Diet-Fed Mice

Obesity is closely associated with oxidative stress and chronic inflammation leading to related metabolic diseases. Some natural extracts or polyphenols reportedly possess anti-obesity and anti-inflammatory effects as well as antioxidant activity. In this study, we assessed the correlations between the antioxidant, anti-obesity, and anti-inflammatory activities of plant extracts with potent antioxidant activity in diet-induced obese mice. Sprouts of Cedrela sinensis (CS) and Oenothera biennis L. (OB) were selected as the most potent antioxidant plant based on analysis of in vitro antioxidant activity of the extracts of ten different edible plants. C57BL/6 mice were fed with a high-fat diet (HFD) and orally treated with 50% ethanol extract of CS or OB at 50 or 100 mg/kg body weight 5 days a week for 14 weeks. Body weight gain, weight of adipose tissue, adipocyte size, and levels of lipid metabolism, inflammation, and oxidative stress markers were investigated. The CS or OB extract reduced body weight gain, visceral adipose tissue weight, adipocyte size, and plasma leptin levels, and expressions of adipogenic genes (PPARγ and fatty acid synthase) in the adipose tissue and liver of HFD-fed mice. Both extracts also reduced mRNA levels of pro-inflammatory cytokines (IL-6 and TNF-α) and oxidative stress-related genes (heme oxygenase- (HO-) 1 and p40^phox). Body weight gain of mice was significantly correlated with visceral adipose tissue weight and adipocyte size. Body weight gain and adipocyte size were significantly correlated with plasma total cholesterol and 8-epi PGF2α levels, mRNA levels of leptin, HO-1, p40^phox, and CD-11 in the adipose tissue, and mRNA levels of TNF-α in the adipose tissue and liver. These results suggest that the CS and OB extracts with potent antioxidant activity may inhibit fat deposition in adipose tissue and subsequent inflammation.

Bioactivity, phytochemical profile and pro-healthy properties of Actinidia arguta: A review

Hardy kiwi (Actinidia arguta) is a climbing, perennial and dioecious vine from Actinidiaceae family, native from Asia and valued as ornamental and traditional medicine. In the last decade, the growing interest as fruit-bearing plant encourage the expanding cultivation of A. arguta mainly to fruits production, particularly in Europe and North America. A. arguta plants have an extensive range ofbioactive compoundsthat can be obtained from different botanical structures, such as fruits, leaves, flowers and stems. These bioactive molecules, with well-recognized health-promoting properties, include phenolic compounds, minerals, carbohydrates or even volatile substances, with a great potential to be used in several formulations of food products. Phytochemical studies on this plant reported hypoglycemic effects as well as antioxidant and anti-inflammatory activities, among others. The traditional uses ofA. arguta have been experimentally proved byin vitroandin vivostudies, in which its bioactivities were associated to its phytochemical composition. This review aims to assess and summarize the phytochemical and healthy properties ofthe different botanical parts of A. arguta, describing their bioactive composition and exploring it potential functional properties on foodstuffs.

Antioxidant and anti-inflammatory effects of Lilium lancifolium bulbs extract

Lilium lancifolium is native to Northeast Asia and its bulbs have been used for medicinal treatment. Moreover, Japan has been using L. lancifolium bulbs more actively as food ingredients than Korea. Therefore, this study was to investigate the characteristics of Korean L. lancifolium bulbs, with respect to food component and functionality. As a result of proximate composition analysis, L. lancifolium bulbs have an abundant carbohydrate content. HPLC analysis indicated p-coumaric acid and ferulic acid contents of Korean L. lancifolium extract were 1.14 ± 0.01, 1.46 ± 0.00 mg/g, but only p-coumaric acid was less detected in Japanese extract. Also, Korean L. lancifolium bulbs extract exhibited significant antioxidant effects, as evaluated with antioxidant activity and compound, than Japanese extract. Furthermore, Korean L. lancifolium bulbs extract significantly inhibited pro-inflammatory protein expressions through MyD88 dependent pathway. Therefore, these results suggested Korean L. lancifolium bulbs have the potential to being functional food ingredients. PRACTICAL APPLICATIONS: Lilium lancifolium is a perennial plant belonging to the Liliaceae family. The storage organ of L. lancifolium is surrounded by several fleshy nodes at the base of the stem, called the bulb, which has been used as food or medicine to treat pneumonia and bronchitis. L. lancifolium is widely found in countries of Northeast Asia, such as Korea, Japan, and China, and its bulbs have been studied for presence of bioactive compounds that have important functional activities. The bioactive compounds in the L. lancifolium bulbs may vary from region to region. In this study, the difference observed in the contents of different bioactive compounds and the efficacy of anti-inflammatory effects of L. lancifolium bulbs from different regions were consistent in this regard. As a comparative study of food materials by region, these L. lancifolium bulbs have the potential to be used as a food material for preventing inflammatory diseases.

Metabolomic Screening of Anti-Inflammatory Compounds from the Leaves of Actinidia arguta (Hardy Kiwi)

The metabolomic screening of potential anti-inflammatory compounds in the leaves of Actinidia arguta was performed by using LC-MS/MS. Ethanol extracts were prepared, and the anti-inflammatory effects were investigated based on nitric oxide (NO) synthesis and inducible nitric oxide synthase expression in lipopolysaccharide-induced RAW 264.7 macrophages. The 75% ethanol extract showed the highest inhibitory effect on nitric oxide (NO) production, and it was further separated by in vitro bioassay-guided fractionation using preparative LC with reversed-phase column separation. Through multiple steps of fractionation, sub-fraction 1-3 was finally purified, and caffeic acid derivatives, such as caffeoylthreonic acid and danshensu (salvianic acid A), were successfully identified as key anti-inflammatory compounds by LC-MS/MS and metabolomics analyses. This is the first study identifying anti-inflammatory compounds in A. arguta (Actinidia arguta) leaves through bioassay-guided fractionation and metabolomics screening. Results of this study would be useful for the application of A. arguta leaves as a nutraceutical.

Actinidia arguta extract attenuates inflammasome activation: Potential involvement in NLRP3 ubiquitination

ETHNOPHARMACOLOGICAL RELEVANCE

Actinidia arguta (A. arguta) has been widely used in Asian countries as a traditional medicinal herb to treat inflammation-related diseases, such as gastritis, bronchitis, and arthritis.

AIM OF THE STUDY

The inhibitory effect of A. arguta leaves' extract (AA) on inflammasome activation was investigated to verify its traditional use in treating inflammation-related diseases.

MATERIALS AND METHODS

Bone marrow-derived macrophages (BMDMs) primed by lipopolysaccharide (LPS) were activated by selective inflammasome stimulators, and the effect of AA on inflammasome activation was investigated. A monosodium urate crystal (MSU)-induced peritonitis mouse model was used to study the in vivo efficacy of AA on inflammasome activation.

RESULTS

In the in vitro study, AA regulated NLRP3 ubiquitination and apoptosis-associated speck-like protein containing a CARD (ASC) oligomerization, leading to the inhibition of NLRP3 inflammasome-mediated interleukin (IL)-1β secretion. The inhibitory effect of AA on inflammasome activation in vitro was further confirmed in vivo using an MSU-induced peritonitis mouse model.

CONCLUSION

AA provided scientific evidence, substantiating the traditional claims for its use in the treatment of inflammation and inflammation-mediated metabolic disorders, including gout.

Hypoglycemic and antioxidant effects of Daraesoon (Actinidia arguta shoot) in animal models of diabetes mellitus

BACKGROUND/OBJECTIVES

The primary objective of the treatment of diabetes mellitus is the attainment of glycemic control. Hyperglycemia increases oxidative stress which contributes to the progression of diabetic complications. Thus, the purpose of this study was to investigate the hypoglycemic and antioxidant effects of Daraesoon (Actinidia arguta shoot) in animal models of diabetes mellitus.

MATERIALS/METHODS

Rats with streptozotocin-induced diabetes received an oral administration of a starch solution (1 g/kg) either with or without a 70% ethanol extract of Daraesoon (400 mg/kg) or acarbose (40 mg/kg) after an overnight fast and their postprandial blood glucose levels were measured. Five-week-old C57BL/6J mice were fed either a basal or high-fat/high-sucrose (HFHS) diet with or without Daraesoon extract (0.4%) or acarbose (0.04%) for 12 weeks after 1 week of adaptation to determine the effects of the chronic consumption of Daraesoon on fasting hyperglycemia and antioxidant status.

RESULTS

Compared to the control group, rats that received Daraesoon extract (400 mg/kg) or acarbose (40 mg/kg) exhibited a significant reduction in the area under the postprandial glucose response curve after the oral ingestion of starch. Additionally, the long-term consumption of Daraesoon extract or acarbose significantly decreased serum glucose and insulin levels as well as small intestinal maltase activity in HFHS-fed mice. Furthermore, the consumption of Daraesoon extract significantly reduced thiobarbituric acid reactive substances and increased glutathione levels in the livers of HFHS-fed mice compared to HFHS-fed mice that did not ingest Daraesoon.

CONCLUSIONS

Daraesoon effectively suppressed postprandial hyperglycemia via the inhibition of α-glucosidase in STZ-induced diabetic rats. Chronic consumption of Daraesoon alleviated fasting hyperglycemia and oxidative stress in mice fed a HFHS diet.