Loquat (Eriobotrya japonica (Thunb) Lindl.): Evaluation of nutritional value, polyphenol composition, antidiabetic effect, and toxicity of leaf aqueous extract

Effects of Loquat Juice Addition on Sensory Characteristics and Volatile Organic Compounds of Loquat Beer

Beer, as an ancient and widely consumed alcoholic beverage, holds a rich cultural heritage and history. In recent years, fruit beer has gained significant attention as a distinct beer type produced by incorporating fruit juice into traditional beer ingredients. This study employed headspace solid-phase microextraction-gas chromatography-mass spectrometry techniques, redundancy analysis, and orthogonal projections to latent structures discriminant analysis to analyze the sensory evaluation, physicochemical properties, organic acids, and volatile organic compounds (VOCs) of loquat beer with different proportions of loquat juice. The results shown that the addition of an appropriate amount of loquat juice (40%) enhanced the overall sensory quality of the beer; as the proportion of loquat juice increased, the contents of malic acid and tartaric acid significantly increased (p < 0.05). A total of 100 VOCs were identified, among which 23 key VOCs (VIP > 1, p < 0.05) represented the most important characteristic flavor components in loquat beer based on their odor activity value (OAV). This study holds significant importance for the value-added processing and economic development of loquat.

Inhibitive Mechanism of Loquat Flower Isolate on Tyrosinase Activity and Melanin Synthesis in Mouse Melanoma B16 Cells

Melanin naturally exists in organisms and is synthetized by tyrosinase (TYR); however, its over-production may lead to aberrant pigmentation and skin conditions. Loquat (Eriobotrya japonica (Thunb.) Lindl.) flowers contain a variety of bioactive compounds, while studies on their suppressive capabilities against melanin synthesis are limited. Loquat flower isolate product (LFP) was obtained by ethanol extraction and resin purification, and its inhibitory efficiency against TYR activity was investigated by enzyme kinetics and multiple spectroscopy analyses. In addition, the impact of LFP on melanin synthesis-related proteins' expression in mouse melanoma B16 cells was analyzed using Western blotting. HPLC-MS/MS analysis indicated that LFP was composed of 137 compounds, of which 12 compounds, including flavonoids (quercetin, isorhamnoin, p-coumaric acid, etc.) and cinnamic acid and its derivatives, as well as benzene and its derivatives, might have TYR inhibitory activities. LFP inhibited TYR activity in a concentration-dependent manner with its IC50 value being 2.8 mg/mL. The inhibition was an anti-competitive one through altering the enzyme's conformation rather than chelating copper ions at the active center. LFP reduced the expression of TYR, tyrosinase-related protein (TRP) 1, and TRP2 in melanoma B16 cells, hence inhibiting the synthesis of melanin. The research suggested that LFP had the potential to reduce the risks of hyperpigmentation caused by tyrosinase and provided a foundation for the utilization of loquat flower as a natural resource in the development of beauty and aging-related functional products.

Phytochemical analysis, antioxidant, and antihyperlipidemic activities of Teucriumtakoumitense

Objective

The main purpose of the present work was to determine the chemical composition, safety, and antioxidant and antihyperlipidemic activities of an aqueous extract of Teucrium takoumitense.

Methods

Phytochemical analysis (total phenolic, total flavonoid, and total hydroxycinnamic acid contents), antioxidant activity (ferric-reducing antioxidant power, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid, 2,2-diphenyl-1-picrylhydrazil, and total antioxidant capacity tests), acute toxicity, and antihyperlipidemic activity were evaluated according to established models. In addition, the phytochemical profile was determined by methylation followed by gas chromatography-mass spectrometry (GC/MS).

Results

The aqueous extract of T. takoumitense had a high content of total polyphenols (87.01 ± 0.31 mg gallic acid equivalent (GAE)/g extract) and hydroxycinnamic acid (2.28 ± 0.1 g/100 g Powdered Material) and a low content of total flavonoids (2.99 ± 0.16 mg GAE/g extract). In addition, the extract demonstrated remarkable antioxidant activity (DPPH IC50 = 76.67 ± 0.56 μg/mL, ABTS IC50 = 89.65 ± 0.27 μg/mL, FRAP EC50 = 296.32 ± 0.86 μg/mL, TAC value = 43 ± 0.27 mg EAA/g extract). The main compounds were identified as benzene, (hexyloxy)- (19.32%), 2,6a-methano-6aH-indeno[4,5-b]oxirene, octahedro-(1a.alpha., 2.beta., 3a.alpha., 6a.beta., 6b.alpha.)- (32.42%), d-fucose (5.47%), 5-hydroxymethylfurfural (5.47%) and guaiacol (3.19%). The LD50 was estimated to be between 500 and 2000 mg/kg. Furthermore, at 500 and 250 mg/kg, the aqueous extract of T. takoumitense exhibited good antihyperlipidemic activity in vivo.

Conclusion

T. takoumitense extract has significant pharmacological potential and a varied chemical composition.

Loquat fruit peel extract regulates lipid metabolism and liver oxidative stress in mice: In vivo and in silico approaches

ETHNOPHARMACOLOGICAL RELEVANCE

In Moroccan traditional medicine, fresh or dried loquat (Eriobotrya japonica (Thunb.) Lindl.) fruit peels infused in water and taken for 45 days are used as natural remedies against hypercholesterolemia, hyperglycemia and cardiovascular diseases. This is the first experimental study approving the folk medicinal use of loquat fruit peels originated from eastern Morocco.

AIM OF THE STUDY

The study aims to investigate the effect of loquat fruit peel extract on lipid metabolism and liver oxidative status in mice as well as to predict the possible mechanisms.

MATERIALS AND METHODS

The study was carried out using high fat/fructose diet-induced hyperlipidemic mice model treated with the loquat peel extract for 45 days at two doses (100 and 200 mg/kg/day) in comparison to fenofibrate drug. The plasma, tissue, fecal and biliary lipids and blood glucose were analyzed using enzymatic methods. The liver oxidative status was evaluated and the polyphenol profiling was conducted using the HPLC-DAD method. Possible mechanisms involved in the observed pharmacological effects were predicted by in silico method.

RESULTS

The extract at a dose of 200 mg/kg possessed higher effect than at 100 mg/kg. It significantly reduced plasma total cholesterol (TC), triglycerides (TG), LDL-cholesterol, atherogenic index, LDL-C/HDL-C ratio and plasma glucose (-36%, -45%, -45%, -82%, -87%, 58%, respectively), while the HDL-cholesterol was increased (+172%). Moreover, the extract reduced TC and TG in the liver and adipose tissue by increasing their excretion in bile and fecal matter. It prevented the liver oxidative stress and decreased body weight and organ relative mass. The extract appears to be nontoxic (LD₅₀ > 5000 mg/kg) and contains five polyphenols including ferulic acid (32.74 ± 0.71 mg/g), caffeic acid (21.48 ± 0.32 mg/g), 5-O-Caffeoylquinic acid (112.15 ± 1.86 mg/g), chlorogenic acid (42.05 ± 0.92 mg/g) and quercetin (32.69 ± 0.68 mg/g). These phenolics and/or their circulating metabolites presented differential interaction capacities with the potential enzymes and transcription factors implicated in lipid homeostasis such as HMG-CoA reductase, lipoprotein lipase, fatty acid synthase, Cyp7a1, ABCG, PPARs, RXR, FXR and RAR.

CONCLUSION

Our findings justify the traditional use of loquat fruit peels and suggest that their aqueous extract could be used as substrate to produce phytotherapeutic drugs or dietary supplements to prevent hyperlipidemia, hyperglycemia and related cardiovascular diseases.

Chemical Characterization and In Vitro Gas Production Kinetics of Alternative Feed Resources for Small Ruminants in the Maltese Islands

The ever-increasing human population, the problem associated with climate change and recent crises-COVID-19 disease and trade conflicts-all impacted on the availability and cost of animal feed raw materials. This is clearly visible in realities which heavily rely on importation such as islands and small states, where producers involved in the agricultural sector were strongly affected by the sharp increase in prices. To deal with these global issues, alternative resources are perceived to replace conventional ingredients. This work aimed at assessing the nutritive value of different resources (sheep feed, mature carob, Maltese bread, wild asparagus, prickly lettuce, and loquat) for small ruminants present in the Maltese Islands, analyzing their chemical composition, gas production kinetics and antioxidant properties. In general, the variation in chemical composition resulted in different rumen fermentation kinetics (p < 0.007). The ratio between GP-24 h and GP-48 h was higher in Maltese bread than other substrates; loquat, prickly lettuce and wild asparagus showed lower fermentation kinetics in accordance with their high NDF and ADF contents. The antioxidant activity may be partially related to the polyphenolic content that was higher in wild asparagus, prickly lettuce and loquat. All feed characteristic confirmed their potential to be included as ingredients in ruminant diets and as a source of fiber.

In vitro investigations of biological activities of Thymus willdenowii and Thymus atlanticus polyphenol-rich extracts

Thyme species produce a wide variety of phenolic compounds including tannins, phenolic acids, and flavonoids. Thymus atlanticus (T. atlanticus) and Thymus willdenowii (T. willdenowii) are important thyme species in the southeast of Morocco, with numerous biological properties. The polyphenolic extracts of these two thyme species were obtained using ethanol through Soxhlet apparatus. Antioxidant (DPPH, FRAP, and TAC methods), antihemolytic (2,2'-Azobis(2-amidinopropane) dihydrochloride (AAPH) induced hemolysis test), hypolipidemic (3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase activity inhibition test), and anti-inflammatory (protein denaturation inhibition) effects of extracts were carried out using in vitro methods. The results showed that the polyphenolic extracts of these two species revealed important amounts of phenolic compounds. The contents of flavonoids were significant in the two species, while the contents of tannins and anthocyanin were very low. T. atlanticus showed an important antioxidant activity and a considerable antihemolytic effect in AAPH-induced hemolysis test (IC50 = 0.29 mg/mL), while T. willdenowii showed an important anti-inflammatory activity in heat-induced protein denaturation test (IC50 = 1.61 mg/mL). Moreover, both extracts at a dose of 20 µg/mL showed an important in vitro hypolipidemic activity by inhibiting HMG-CoA reductase activity (T. willdenowii: 51.16 %; T. atlanticus: 62.83 %). In conclusion, T. willdenowii and T. atlanticus extracts have considerable antioxidant, antihemolytic, hypolipidemic, and anti-inflammatory effects. The richness of these species in polyphenols gives them a large specter of biological properties, making them a valuable source of natural bioactive compounds that could prevent or treat various diseases.

Bacterial cellulose production by a strain of Komagataeibacter rhaeticus isolated from residual loquat

In this study, loquat extract was selected as a promising substrate for bacterial cellulose (BC) production. A new BC-producing bacterial strain was isolated from residual loquat and identified as Komagataeibacter rhaeticus. BC production with different carbon sources and with loquat extract was investigated. Among all tested carbon sources, glucose was demonstrated to be the best substrate for BC production by K. rhaeticus, with up to 7.89 g/L dry BC obtained under the optimal initial pH (5.5) and temperature (28 °C) with 10 days of fermentation. The total sugar and individual sugars were investigated in different loquat extracts, in which fructose, glucose, and sucrose were the three main sugars. When loquat extract was prepared with a solid‒liquid (S-L) ratio of 2:1, the concentrations of glucose, fructose, and sucrose were 7.91 g/L, 9.31 g/L, and 2.84 g/L, respectively. The BC production obtained from loquat extract was higher than that of other carbon sources except glucose, and 6.69 g/L dry BC was obtained from loquat extract with an S-L ratio of 2:1. After BC production, all sugars substantially decreased, with the utilization of glucose, fructose, and sucrose reaching 93.9%, 87.9%, and 100%, respectively. These results suggested that the different sugars in loquat extract were all carbon sources participating in BC production by K. rhaeticus. Structural and physicochemical properties were investigated by SEM, TGA, XRD, and FT-IR spectroscopy. The results showed that the structural, chemical group, and water holding capacity of BC obtained from loquat extract were similar to those of BC obtained from glucose, but the crystallinity and thermal stability of BC were higher than those of BC from mannose and lactose but lower than those of BC from glucose and fructose. KEY POINTS: • A new BC-producing strain was isolated and identified as Komagataeibacter rhaeticus. • Loquat extract is an alternative substrate for BC production. • The BC obtained from loquat extract owns advanced physicochemical properties.