Monoterpenes: Novel insights into their biological effects and roles on glucose uptake and lipid metabolism in 3T3-L1 adipocytes

Antidiabetic, hypolipidemic, and antioxidative properties of aqueous and ethanolic extracts of Sage (Salvia officinalis L.) against streptozotocin-induced diabetes and oxidative stress in Wistar albino male rats

Background and Aim

Diabetes mellitus (DM) is a chronic disease characterized by insulin insufficiency and hyperglycemia, often leading to complications such as oxidative stress, dyslipidemia, and organs damage. Sage (Salvia officinalis L.), a medicinal plant with rich antioxidant and bioactive compounds, has shown promise in managing diabetes and related complications. This study investigates the antidiabetic, hypolipidemic, and antioxidative effects of aqueous (AE) and ethanolic (EE) extracts of S. officinalis leaves at doses of 400 and 800 mg/kg body weight in Wister albino male rats with streptozotocin (STZ)-induced type 2 diabetes and oxidative stress.

Materials and Methods

Wistar albino male rats (n = 49) were divided into seven groups: Normal control, diabetes-induced control (STZ), metformin-treated (50 mg/kg/day), and groups treated with AE (400 and 800 mg/kg/day) and EE (400 and 800 mg/kg/day). Parameters assessed included weight gain percentage, random blood glucose (RBG), fasting blood glucose (FBG), lipid profiles, liver and kidney function markers, oxidative stress biomarkers (glutathione [GSH], catalase [CAT], superoxide dismutase [SOD], malonaldehyde [MDA]), and histopathological examination of the pancreas.

Results

AE and EE significantly reduced RBG and FBG and improved weight gain recovery. At 800 mg/kg, AE and EE effectively reduced triglycerides, total cholesterol, low-density lipoproteins cholesterol (LDL-C), and very LDL-C (VLDL-C) while increasing high-density lipoproteins cholesterol more than 400 mg/kg doses or metformin. Liver and kidney functions were restored with high-dose AE and EE showing superior efficacy. Antioxidant biomarkers (GSH, CAT, and SOD) were significantly enhanced, while MDA levels were reduced. Histopathological analysis confirmed restoration of islets of Langerhans and acinar cells to near-normal conditions in treated groups.

Conclusion

The AE and EE of S. officinalis demonstrated potent antidiabetic, hypolipidemic, and antioxidative properties, offering significant potential as a natural therapeutic option for managing diabetes and oxidative stress-related complications.

A review of sarcopenia pathogenesis and therapeutic approaches: resistance exercise, nutrition, and monoterpenes

PURPOSE

Sarcopenia, characterized by the age-related loss of muscle mass and function, is a multifactorial condition influenced by oxidative stress, hormonal changes, and chronic inflammation. This study investigated the effects of resistance exercise and nutritional interventions, including antioxidants, such as monoterpenes, on sarcopenia prevention and treatment.

METHODS

To identify relevant studies, a comprehensive literature search was conducted using electronic databases including PubMed and Google Scholar. Keywords such as "sarcopenia," "resistance exercise," "antioxidants," "nutrition," "muscle regeneration," and related terms were utilized to gather evidence on the prevention and management of sarcopenia.

RESULTS

This review focuses on the etiological factors of sarcopenia, particularly the decline in muscle function and acceleration of muscle protein degradation. This highlights the critical importance of the combined effects of exercise and nutrition in overcoming these challenges, with special emphasis on the potential of antioxidant intake as a promising solution for managing this condition.

CONCLUSION

An integrated approach combining periodic resistance exercise with antioxidant-rich nutritional strategies is essential for the management of sarcopenia. By promoting muscle development and inhibiting protein breakdown, this dual strategy provides an effective framework for preventing and treating sarcopenia, and improving quality of life of the aging population. Further studies are warranted to explore the clinical potential of monoterpenes in the treatment of sarcopenia.

Phytochemical characterization and multifaceted bioactivity assessment of essential oil from Ptychotis verticillata Duby: Anti-diabetic, anti-tyrosinase, and anti-inflammatory activity

The aim of this study is to explore the pharmacological properties of the essential oil derived from Ptychotis verticillata Duby (PVEO), a medicinal plant native to Morocco, focusing on its antidiabetic, anti-tyrosinase, and anti-inflammatory effects. Additionally, the study aims to characterize the phytochemical composition of PVEO and evaluate its potential as a natural therapeutic alternative for various health conditions. To achieve this, phytochemical analysis was conducted using gas chromatography-mass spectrometry (GC-MS). Furthermore, in vitro assessments were conducted to investigate PVEO's antidiabetic activity by inhibiting α-amylase, xanthine oxidase, and α-glucosidase. Tests were also undertaken to evaluate the anti-inflammatory effect of PVEO on RAW 264.7 cells stimulated by lipopolysaccharide (LPS), as well as its efficacy as an anti-tyrosinase agent and its lipoxygenase inhibition activity. The results of the phytochemical analysis revealed that PVEO is rich in terpene compounds, with percentages of 40.35 % γ-terpinene, 22.40 % carvacrol, and 19.77 % β-cymene. Moreover, in vitro evaluations demonstrated that PVEO exhibits significant inhibitory activity against α-amylase, xanthine oxidase, and α-glucosidase, indicating promising antidiabetic, and anti-gout potential. Furthermore, PVEO showed significant anti-tyrosinase activity, with an IC50 of 27.39 ± 0.44 μg/mL, and remarkable lipoxygenase inhibition (87.33 ± 2.6 %), suggesting its candidacy for dermatoprotection. Additionally, PVEO displayed a dose-dependent capacity to attenuate the production of NO and PGE2, two inflammatory mediators implicated in various pathologies, without compromising cellular viability. The findings of this study provide a solid foundation for future research on natural therapies and the development of new drugs, highlighting the therapeutic potential of PVEO in the treatment of gout, diabetes, pigmentation disorders, and inflammation.

Insights into metabolic characteristics and biological activity changes in Zangju (Citrus reticulata cv. Manau Gan) peel at different maturity stages through UPLC-MS/MS-based metabolomics

In this study, comprehensive and systematic nontargeted metabolomics analysis was performed with the metabolites of Zangju peel (Citrus reticulata cv. Manau Gan, CRZP, which has been cultivated for over 400 years in Derong County, China.) at four different mature stages. A total of 1878 metabolites were identified, among which flavonoids were the most abundant (62.04 %), and identified 62 key differential metabolites significantly affected by maturity. Based on biological activity measurements, CRZP showed better antioxidant activity, lipase inhibition ability, inhibition of adipogenic differentiation in 3TT-L1 cells and promotion of lipid metabolism, with the biological activity of CRZP at different maturity stages being associated with key differential metabolite. Thus, CRZP is natural antioxidants and possess anti-obesity potential, and industrial production needs to consider the Maturity stage of its collection.

Effect of vitamin E, D-limonene, and their combination on nulliparous rabbit reproductive performance

Oxidative status is important in reproductive performance and using two natural antioxidants is more beneficial than one in nulliparous rabbits. The goal, effect of vitamin E (VitE), D-limonene (DL), and VitE+DL on maternal LBW (MLBW), conception (CR), pregnancy (PR), and kindling rates (KR), gestation length (GL), total litter size at birth (TLSB) and weaning (TLSW), live kits at birth (LKB) and weaning (LKW), dead kits at birth (DKB) and weaning (DKW), kits mortality rate at weaning (KMRW), Kit weight at birth (KWB) and weaning (KWW), total kit weight at birth (TKWB) and weaning (TKWW), and concentrations of progesterone (P4) and Malondialdehyde (MDA), during first two pregnancies. A total of 24 healthy female WNZ rabbits were randomly selected and assigned into four groups (6/each). Control (animals injected with 1.0 mL propylene glycol), VitE (60 mg IM injection/animal, 2X/week pre-mating and 3X post-mating until mid-pregnancy, DL (20 mg IM injection/animal, 2X/week pre-mating and 1X at mating, and VitE+DL (IM injection/animal with the same doses and times applied in VitE and DL groups. All animals were treated during 1st pregnancy only. The results confirmed that animals treated with VitE+DL gained significant maternal LBW in 1st pregnancy, reduced dead kit number at birth and kit mortality rate at weaning, increased live kits and total kit weight at birth and weaning in the two pregnancies, and also increased significantly kit weight at birth and weaning in the treatments than controls in the two pregnancies, and DL was greater in 1st pregnancy. Progesterone concentrations in mid-pregnancy rose significantly in VitE+DL during 1st pregnancy and DL in 2nd pregnancy. Malondialdehyde concentrations dropped significantly in VitE and VitE+DL in mid-pregnancy in the two pregnancies. Eventually, the integration of VitE and DL displayed their unique properties for improving productive and reproductive performance in nulliparous rabbits.

Plant Essential Oils as Healthy Functional Ingredients of Nutraceuticals and Diet Supplements: A Review

Essential oils (EOs) are mixtures of volatile molecules endowed with health-promoting biological activities that go beyond their role as aromas and natural preservatives and can be exploited to develop functional foods and diet supplements. Their composition is briefly addressed along with regulatory aspects. The potential health benefit of human diet supplementation with EOs is outlined through a review of the recent literature on available clinical trials and preclinical research concerning EOs activity towards: (1) irritable bowel syndrome; (2) inflammatory bowel disease; (3) regulation of microbiota; (4) gastroprotection; (5) hepatoprotection; (6) protection of the urinary tract and diuresis; (7) management of metabolic disorders including hyperglycemia and hyperlipidemia; (8) anti-inflammatory and pain control; (9) immunomodulation and protection from influenza; and (10) neuroprotection and modulation of mood and cognitive performance. The emerging potential in such activities of selected EOs is given focus, particularly green and black cumin, bergamot, orange, myrtle, peppermint, sage, eucalyptus, lavender, thyme, lemon balm, ginger, and garlic.

D-Limonene Promotes Anti-Obesity in 3T3-L1 Adipocytes and High-Calorie Diet-Induced Obese Rats by Activating the AMPK Signaling Pathway

D-limonene (LIM) is a common monoterpene compound, principally found in citrus essential oils. This study investigated the anti-obesity effect of LIM on the 5′-adenosine monophosphate (AMP)-activated protein kinase (AMPK) signaling pathway in 3T3-L1 adipocytes and high-calorie diet-induced obese rats and confirmed the optimally effective dose of LIM. The 3T3-L1 adipocytes were treated with 0.05−0.4 mg/mL LIM for 10 days and oil red O and triglyceride (TG) content were used to determine the levels of lipid accumulation. The results showed that more than 0.05 mg/mL LIM inhibited lipid accumulation by reducing oil red O in 3T3-L1 adipocytes. Masses of 0.2 and 0.4 mg/mL LIM also decreased the TG contents in 3T3-L1 adipocytes. On the other hand, Wistar rats were given high-calorie diets, combined with LLIM (154 mg/kg) and HLIM (1000 mg/kg) treatments, for 16 weeks. The result shows that LLIM and HLIM decreased body weight, total fat tissue weight, and serum low-density lipoprotein-cholesterol (LDLc) levels. HLIM reduced serum TG and increased serum lipase and high-density lipoprotein-cholesterol (HDLc) levels. Moreover, the anti-obesity metabolic pathway showed that LIM (>0.05 mg/mL) in 3T3-L1 adipocytes and LIM (>154 mg/kg) in high-calorie diet-induced obese rats could activate the AMPK signaling pathway. The activated AMPK regulated the mRNA expression related to adipogenesis (PPARγ, C/EBPα, FABP4), lipogenesis (SREBP-1c, ACC, FAS), and lipolysis (ATGL, HSL) to inhibit obesity. This finding demonstrates that LIM has anti-obesity properties. Namely, it is seen that LIM acts by regulating the AMPK signaling pathway in 3T3-L1 adipocytes and high-calorie diet-induced obese rats. In terms of dose−response, LIM (154 mg/kg) would be an optimal effective dose for anti-obesity induced by a high-calorie diet.

Identification of D-Limonene Metabolites by LC-HRMS: An Exploratory Metabolic Switching Approach in a Mouse Model of Diet-Induced Obesity

Metabolic switching has been raised as an important phenomenon to be studied in relation to xenobiotic metabolites, since the dose of the exposure determines the formation of metabolites and their bioactivity. Limonene is a monoterpene mostly found in citrus fruits with health activity, and its phase II metabolites and activity are still not clear. The aim of this work was to evaluate the effects of D-limonene in the development of diet-induced obesity in mice and to investigate metabolites that could be generated in a study assessing different doses of supplementation. Animals were induced to obesity and supplemented with 0.1% or 0.8% D-limonene added to the feed. Limonene phase I and II metabolites were identified in liver and urine by LC-ESI-qToF-MS/MS. To the best of our knowledge, in this study three new phase I metabolites and ten different phase II metabolites were first attributed to D-limonene. Supplementation with 0.1% D-limonene was associated with lower weight gain and a trend to lower accumulation of adipose tissue deposits. The metabolites limonene-8,9-diol, perillic acid and perillic acid-8,9-diol should be explored in future research as anti-obesogenic agents as they were the metabolites most abundant in the urine of mice that received 0.1% D-limonene in their feed.

Alpha-Phellandrene and Alpha-Phellandrene-Rich Essential Oils: A Systematic Review of Biological Activities, Pharmaceutical and Food Applications

Alpha-phellandrene is a very common cyclic monoterpene found in several EOs, which shows extensive biological activities. Therefore, the main focus of the present systematic review was to provide a comprehensive and critical analysis of the state of the art regarding its biological activities and pharmaceutical and food applications. In addition, the study identified essential oils rich in alpha-phellandrene and summarized their main biological activities as a preliminary screening to encourage subsequent studies on their single components. With this review, we selected and critically analyzed 99 papers, using the following bibliographic databases: PubMed, SciELO, Wiley and WOS, on 8 July 2022. Data were independently extracted by four authors of this work, selecting those studies which reported the keyword "alpha-phellandrene" in the title and/or the abstract, and avoiding those in which there was not a clear correlation between the molecule and its biological activities and/or a specific concentration from its source. Duplication data were removed in the final article. Many essential oils have significant amounts of alpha-phellandrene, and the species Anethum graveolens and Foeniculum vulgare are frequently cited. Some studies on the above-mentioned species show high alpha-phellandrene amounts up to 82.1%. There were 12 studies on alpha-phellandrene as a pure molecule showed promising biological functions, including antitumoral, antinociceptive, larvicidal and insecticidal activities. There were 87 research works on EOs rich in alpha-phellandrene, which were summarized with a focus on additional data concerning potential biological activities. We believe this data is a useful starting point to start new research on the pure molecule, and, in particular, to distinguish between the synergistic effects of the different components of the OEs and those due to alpha-phellandrene itself. Toxicological data are still lacking, requiring further investigation on the threshold values to distinguish the boundary between beneficial and toxic effects, i.e., mutagenic, carcinogenic and allergenic. All these findings offer inspiration for potential applications of alpha-phellandrene as a new biopesticide, antimicrobial and antitumoral agent. In particular, we believe our work is of interest as a starting point for further studies on the food application of alpha-phellandrene.

Health-beneficial aroma and taste compounds in a newly developed kombucha using a Huanglongbing-tolerant mandarin hybrid

Huanglongbing (HLB) is a destructive citrus greening disease; no commercially applicable measures exist. 'LB8-9' Sugar Belle^® (SB), originally developed for the fresh market, is the most HLB-tolerant cultivar among commercially available varieties. Due to the limited capacity of the fresh fruit market, there is a need to increase the demand for SB juice. Kombucha is a fermented tea beverage with black tea and sugar, and is considered a healthy drink with an increasing market. Therefore, we aim to study the potential of using SB juice in kombucha production. Regular (black tea with no citrus juice added), Hamlin (black tea with Hamlin juice added), and SB kombucha (black tea with SB juice added) were prepared and analyzed to observe the composition of aroma and taste compounds in the kombuchas. Aroma and taste compounds in the kombuchas were analyzed using gas chromatography-mass spectrometry/olfactometry and liquid chromatography-triple quadrupole mass spectrometry, respectively. For aroma compounds, SB kombucha was characterized by high concentrations of terpenes and their derivatives, which have mandarin-like aroma characteristics and health benefits such as antidiabetic and antioxidant effects. For taste compounds, SB kombucha contained higher amount of fructose and organic acids, which have the potential to increase the intensity of sweetness and sourness, and flavonoids. This would support the potential benefits of using SB to make kombucha. This study provides valuable information about the aroma and taste compounds in SB kombucha and its potential health benefits, compared with regular and Hamlin kombucha. PRACTICAL APPLICATION: This experiment provided valuable information on the elevated aroma and taste compounds, their potential health benefits, and the changes of those compounds during kombucha fermentation in 'LB8-9' Sugar Belle^® kombucha, compared to regular and Hamlin kombucha. In the absence of an effective cure or therapy for HLB, this can be the first step for developing alternative citrus product to help the citrus industry mitigate the negative impacts from HLB.

Isolation and characterization of antioxidative monoterpenes from Cynanchum atratum roots

One novel monoterpene rhamnoside (1) and 7 known monoterpenes (2-8) were isolated from the ethanol extract of Cynanchum atratum for the first time. Their structures were identified by comprehensive spectroscopic data analysis such as nuclear magnetic resonance, high-resolution electrospray ionization mass spectra, optical rotatory dispersion, and acid hydrolysis. In the subsequent antioxidant assay, compound 8 exhibited obvious 2,2-diphenyl-2-picrylhydrazyl hydrate radical scavenging activity.

In Vitro and In Vivo Antidiabetic Potential of Monoterpenoids: An Update

Diabetes mellitus (DM) is a chronic metabolic condition characterized by persistent hyperglycemia due to insufficient insulin levels or insulin resistance. Despite the availability of several oral and injectable hypoglycemic agents, their use is associated with a wide range of side effects. Monoterpenes are compounds extracted from different plants including herbs, vegetables, and fruits and they contribute to their aroma and flavor. Based on their chemical structure, monoterpenes are classified into acyclic, monocyclic, and bicyclic monoterpenes. They have been found to exhibit numerous biological and medicinal effects such as antipruritic, antioxidant, anti-inflammatory, and analgesic activities. Therefore, monoterpenes emerged as promising molecules that can be used therapeutically to treat a vast range of diseases. Additionally, monoterpenes were found to modulate enzymes and proteins that contribute to insulin resistance and other pathological events caused by DM. In this review, we highlight the different mechanisms by which monoterpenes can be used in the pharmacological intervention of DM via the alteration of certain enzymes, proteins, and pathways involved in the pathophysiology of DM. Based on the fact that monoterpenes have multiple mechanisms of action on different targets in in vitro and in vivo studies, they can be considered as lead compounds for developing effective hypoglycemic agents. Incorporating these compounds in clinical trials is needed to investigate their actions in diabetic patients in order to confirm their ability in controlling hyperglycemia.

Monoterpenes: current knowledge on food source, metabolism, and health effects

Monoterpenes, volatile metabolites produced by plants, are involved in the taste and aroma perception of fruits and vegetables and have been used for centuries in gastronomy, as food preservatives and for therapeutic purposes. Biological activities such as antimicrobial, analgesic and anti-inflammatory are well-established for some of these molecules. More recently, the ability of monoterpenes to regulate energy metabolism, and exert antidiabetic, anti-obesity and gut microbiota modulation activities have been described. Despite their promising health effects, the lack of reliable quantification of monoterpenes in food, hindered the investigation of their role as dietary bioactive compounds in epidemiological studies. Moreover, only few studies have documented the biotransformation of these compounds and identified the monoterpene metabolites with biological activity. This review presents up-to-date knowledge about the occurrence of monoterpenes in food, their bioavailability and potential role in the modulation of intermediate metabolism and inflammation, focusing on novel findings of molecular mechanisms, underlining research gaps and new avenues to be explored.

A Review of Research Progress on Agathis dammara and its Application Prospects for Cardiovascular Diseases and Fatty Liver Disease

Cardiovascular diseases and fatty liver disease have become the leading causes of death in modern society. However, the currently existing drugs do not solve all issues related to these diseases; thus, it is expected that more potential drugs for clinical use will be developed. Undeniably, natural products have attracted increasing attention. It is of great significance to identify effective active monomer components for drug discovery and disease prevention. As a pure natural product, Agathis dammara (AD) has antioxidant, hypolipidemic, hypoglycemic, antitumor, and anti-inflammatory activities. However, at present, there are few reports regarding the effects of AD on chronic inflammatory cardiovascular diseases, such as aneurysm, atherosclerosis, myocardial ischemia-reperfusion injury, and cardiac hypertrophy and liver diseases such as fatty liver disease. AD and products derived from it have a very broad application prospect for cardiovascular diseases and fatty liver disease.

Isoprenoid Derivatives of Lysophosphatidylcholines Enhance Insulin and GLP-1 Secretion through Lipid-Binding GPCRs

Insulin plays a significant role in carbohydrate homeostasis as the blood glucose lowering hormone. Glucose-induced insulin secretion (GSIS) is augmented by glucagon-like peptide (GLP-1), a gastrointestinal peptide released in response to ingesting nutriments. The secretion of insulin and GLP-1 is mediated by the binding of nutrients to G protein-coupled receptors (GPCRs) expressed by pancreatic β-cells and enteroendocrine cells, respectively. Therefore, insulin secretagogues and incretin mimetics currently serve as antidiabetic treatments. This study demonstrates the potency of synthetic isoprenoid derivatives of lysophosphatidylcholines (LPCs) to stimulate GSIS and GLP-1 release. Murine insulinoma cell line (MIN6) and enteroendocrinal L cells (GLUTag) were incubated with LPCs bearing geranic acid (1-GA-LPC), citronellic acid (1-CA-LPC), 3,7-dimethyl-3-vinyloct-6-enoic acid (GERA-LPC), and (E)-3,7,11-trimethyl- 3-vinyldodeca-6,10-dienoic acid (1-FARA-LPC). Respective free terpene acids were also tested for comparison. Besides their insulin- and GLP-1-secreting capabilities, we also investigated the cytotoxicity of tested compounds, the ability to intracellular calcium ion mobilization, and targeted GPCRs involved in maintaining lipid and carbohydrate homeostasis. We observed the high cytotoxicity of 1-GERA-LPC and 1-FARA-LPC in contrast 1-CA-LPC and 1-GA-LPC. Moreover, 1-CA-LPC and 1-GA-LPC demonstrated the stimulatory effect on GSIS and 1-CA-LPC augmented GLP-1 secretion. Insulin and GLP-1 release appeared to be GPR40-, GPR55-, GPR119- and GPR120-dependent.

Effects of Essential Oils and Some Constituents from Ingredients of Anti-Cellulite Herbal Compress on 3T3-L1 Adipocytes and Rat Aortae

Cellulite is associated with a complex array of adipocytes under the skin and vascular system. A herbal compress that was previously developed was proven to have an anti-cellulite effect in healthy volunteers within 2 weeks of treatment. However, its mechanism and ingredients responsible for reducing cellulite were not known. The purpose of this study was to investigate the activity of eight essential oils in, and two water extracts from, the ingredients of the herbal compress together with nine monoterpenoid constituents on the 3T3-L1 adipocytes. The vasodilatory effect on rat aortae was also studied. The adipocytes were induced by dexamethasone, 3-isobutyl-1-methylxanthine and insulin. At all concentrations tested, all essential oils, water extracts and their monoterpenoid constituents significantly inhibited lipid accumulation activity (p < 0.05) and decreased the amount of triglycerides when compared to untreated cells (p < 0.01). In addition, our results showed that the mixed oil distilled from the herbal compress mixed ingredients could relax the isolated rat aorta (EC₅₀ = 14.74 ± 2.65 µg/mL). In conclusion, all essential oils, extracts and chemical constituents tested showed effects on adipogenesis inhibition and lipolysis induction on the cultured adipocytes with the mixed oil demonstrating vasorelaxation activity, all of which might be the mechanisms of the anti-cellulite effects of the herbal compress.

Rapid qualitative profiling and quantitative analysis of phenolics in Ribes meyeri leaves and their antioxidant and antidiabetic activities by HPLC-QTOF-MS/MS and UHPLC-MS/MS

Ribes meyeri leaves are used as traditional Kazakh medicine in China. However, no study on the characterization of the phenolic compounds in R. meyeri leaves has been reported, resulting in the lack of quality control measures and poor standardization. This study was conducted to identify the phenolic compounds in R. meyeri leaves and evaluate their antioxidant and antidiabetic activities. A total of 77 phenolics were tentatively identified by liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry. Ultra-high performance liquid chromatography coupled with triple quadrupole mass spectrometry was applied to simultaneously quantify 12 phenolics in R. meyeri leaves. Rutin, epigallocatechin, isoquercitrin, epicatechin, protocatechuic acid, and kaempferol-3-O-rutinoside were abundant in the R. meyeri leaves. The methanol extract and four different extracts enhanced the glucose uptake in 3T3-L1 adipocytes. The ethyl acetate extracts showed a total phenolic content of 966.89 ± 3.59 mg gallic acid equivalents/g, a total flavonoid content of 263.58 ± 17.09 mg catechin equivalents/g, and good protein-tyrosine phosphatase-1B inhibitory activities (IC₅₀ : 0.60 ± 0.03 μg/mL). To our knowledge, this work is the first to identify and quantify the major phenolics in R. meyeri leaves.

D-limonene: A multifunctional compound with potent therapeutic effects

D-limonene or 4-isopropenyl-1-methylcyclohexene (C₁₀ H₁₆ ) is a monocyclic monoterpene abundant in citrus plants like lemon, orange, and grape. The application of D-limonene in the form of flavor and fragrance additive in perfumes, soaps, foods, and beverages is consistently increased due to its high-quality fragrance property. This review is intended to analyze and delineate every possible available evidence and details about D-limonene with the special focus on its therapeutic efficacy. Many studies have reported that D-limonene effectively plays a valuable role in the prevention of several chronic and degenerative diseases. This review provides worthy information about the beneficial effects of D-limonene such as antioxidant, antidiabetic, anticancer, anti-inflammatory, cardioprotective, gastroprotective, hepatoprotective, immune modulatory, anti-fibrotic, anti-genotoxic etc. This could in turn help in the application of D-limonene for clinical studies. PRACTICAL IMPLICATIONS: Various plant families contain Terpenes as their secondary metabolites. Monoterpenes constitute an important part of these secondary metabolites. D-limonene is a well-identified monoterpene that is commonly applied as a fragrance ingredient in essential oils. D-limonene is known to possess remarkable biological activities. It can be effectively used for treating various ailments and diseases. Due to its diverse functions, it can be efficiently utilized for human health.

Bio-Guided Fractionation Driven by In Vitro α-Amylase Inhibition Assays of Essential Oils Bearing Specialized Metabolites with Potential Hypoglycemic Activity

Type 2 diabetes mellitus (T2DM) is a metabolic disorder characterized by unpaired blood glycaemia maintenance. T2DM can be treated by inhibiting carbohydrate hydrolyzing enzymes (α-amylases and α-glucosidases) to decrease postprandial hyperglycemia. Acarbose and voglibose are inhibitors used in clinical practice. However, these drugs are associated with unpleasant gastrointestinal side effects. This study explores new α-amylase inhibitors deriving from plant volatile specialized metabolites. Sixty-two essential oils (EOs) from different plant species and botanical families were subjected to α-amylase in vitro enzymatic assay and chemically characterized using gas chromatography coupled to mass spectrometry. Several EOs were found to be potential α-amylase inhibitors, and Eucalyptus radiata, Laurus nobilis, and Myristicafragrans EOs displayed inhibitory capacities comparable to that of the positive control (i.e., acarbose). A bio-guided fractionation approach was adopted to isolate and identify the active fractions/compounds of Eucalyptus radiata and Myristica fragrans EOs. The bio-guided fractionation revealed that EOs α-amylase inhibitory activity is often the result of antagonist, additive, or synergistic interactions among their bioactive constituents and led to the identification of 1,8-cineole, 4-terpineol, α-terpineol, α-pinene, and β-pinene as bioactive compounds, also confirmed when they were tested singularly. These results demonstrate that EO oils are a promising source of potential α-amylase inhibitors.

Volatomic analysis identifies compounds that can stratify non-alcoholic fatty liver disease

Background & aims

Analysis of volatile organic compounds (VOCs) in exhaled breath, ‘volatomics’, provides opportunities for non-invasive biomarker discovery and novel mechanistic insights into a variety of diseases. The purpose of this pilot study was to compare breath VOCs in an initial cohort of patients with non-alcoholic fatty liver disease (NAFLD) and healthy controls.

Methods

Breath samples were collected from 15 participants with Child-Pugh class A NAFLD cirrhosis, 14 with non-cirrhotic NAFLD, and 14 healthy volunteers. Exhaled breath samples were collected using an established methodology and VOC profiles were analysed by gas chromatography-mass spectrometry. The levels of 19 VOCs previously associated with cirrhosis were assessed. Peaks of the VOCs were confirmed and integrated using Xcalibur® software, normalised to an internal standard. Receiver-operating characteristic (ROC) curves were used to determine the diagnostic accuracy of the candidate VOCs.

Results

Terpinene, dimethyl sulfide, and D-limonene provided the highest predictive accuracy to discriminate between study groups. Combining dimethyl sulfide with D-limonene led to even better discrimination of patients with NAFLD cirrhosis from healthy volunteers (AUROC 0.98; 95% CI 0.93–1.00; p <0.001) and patients with NAFLD cirrhosis from those with non-cirrhotic NAFLD (AUROC 0.91; 95% CI 0.82–1.00; p <0.001). Breath terpinene concentrations discriminated between patients with non-cirrhotic NAFLD and healthy volunteers (AUROC 0.84; 95% CI 0.68–0.99; p = 0.002).

Conclusion

Breath terpinene, dimethyl sulfide, and D-limonene are potentially useful volatomic markers for stratifying NAFLD; in addition, a 2-stage approach enables the differentiation of patients with cirrhosis from those without. However, these observations require validation in a larger NAFLD population. (ClinicalTrials.gov Identifier: NCT02950610).

Lay summary

Breath malodour has been associated with a failing liver since the ancient Greeks. Analytical chemistry has provided us an insight into ubiquitous volatile organic compounds associated with liver (and other) diseases. This has vastly improved our understanding of the mechanistic processes of liver damage. Our study aims to identify volatile organic compounds which are specific to non-alcoholic fatty liver disease and that can be exploited for rapid diagnostics.

•

Metabolic dysfunction in liver disease is reflected in the biocomposition of exhaled breath.

•

Specific volatile organic compounds can be measured in breath samples (volatomics) and have diagnostic potential in chronic liver disease.

•

Levels of alfa-terpinene, dimethyl sulfide, and D-limonene in exhaled breath can be used to stratify patients with non-alcoholic fatty liver disease.

Natural Monoterpenes: Much More than Only a Scent

Terpenes are a widespread group of secondary metabolites that can be found in various family plants such as the Lamiaceae. In view of their numerous valuable biological activities, the industrial production of concrete terpenes and essential oils rich in the substances is intensively studied. Monoterpenes constitute a significant part of the whole group of the aforementioned secondary metabolites. This is due to their numerous biological activities and their ability to permeate the skin. Despite the fact that these substances have gain popularity, they are not comprehensively characterized. The presented review is based on studies of the biological activities of the most important monoterpenes and the essential oils rich in these compounds. The authors focused attention on antioxidant activity, inhibition towards acetyl- and butyrylcholinesterase, and α-amylase and α-glucosidase, antifungal, hepatoprotective, sedative properties, and their skin permeation enhancement.

Design and synthesis of novel xanthone-triazole derivatives as potential antidiabetic agents: α-Glucosidase inhibition and glucose uptake promotion

Inhibiting the decomposition of carbohydrates into glucose or promoting glucose conversion is considered to be an effective treatment for type 2 diabetes. Herein, a series of novel xanthone-triazole derivatives were designed, synthesized, and their α-glucosidase inhibitory activities and glucose uptake in HepG2 cells were investigated. Most of the compounds showed better inhibitory activities than the parental compound a (1,3-dihydroxyxanthone, IC₅₀ = 160.8 μM) and 1-deoxynojirimycin (positive control, IC₅₀ = 59.5 μM) towards α-glucosidase. Compound 5e was the most potent inhibitor, with IC₅₀ value of 2.06 μM. The kinetics of enzyme inhibition showed that compounds 5e, 5g, 5h, 6c, 6d, 6g and 6h were noncompetitive inhibitors, and molecular docking results were consistent with the noncompetitive property that these compounds bind to allosteric sites away from the active site (Asp214, Glu276 and Asp349). On the other hand, the glucose uptake assays exhibited that compounds 5e, 6a, 6c and 7g displayed high activities in promoting the glucose uptake. The cytotoxicity assays showed that most compounds were low-toxic to human normal hepatocyte cell line (LO2). These novel xanthone triazole derivatives exhibited dual therapeutic effects of α-glucosidase inhibition and glucose uptake promotion, thus they could be use as antidiabetic agents for developing novel drugs against type 2 diabetes.

Weight loss effect of sweet orange essential oil microcapsules on obese SD rats induced by high-fat diet

Obesity is one of the most common and major health concerns worldwide. Weight management through dietary supplements with natural plant extracts has become the focus of current research. Sweet orange essential oil (SOEO) is a natural plant extract, with many bioactivities. In order to evaluate the weight loss effect of SOEO microcapsules and investigate the underlying mechanism, we fed high-fat diet-induced obese SD rats with SOEO microcapsules for 15 days and found that SOEO microcapsules reduced body weight gain by 41.4%, decreased total cholesterol level, alleviated liver and adipose tissue pathological alteration. The results of fluorescence quantitative PCR revealed that decreasing the expression of peroxisome proliferators-activated receptor-γ, upregulating of uncoupling protein 2, hormone sensitive lipase and carnitine palmitoyltransferase I, inhibiting the expression of acetyl-CoA carboxylase appear to be the mechanism of SOEO microcapsules to lose weight. This study suggests that SOEO microcapsule is a potential dietary supplement for weight loss.

Abbreviations: SOEO: sweet orange essential oil; TC: total cholesterol; TG: triglyceride; LDL-c: low-density lipoprotein cholesterol; HDL-c: high-density lipoprotein cholesterol; PPARα: peroxisome proliferators-activated receptor-α; PPARγ: peroxisome proliferators-activated receptor-γ; UCP2: uncoupling protein 2; HSL: hormone sensitive lipase; CPT1: carnitine palmitoyltransferase I; ACC: acetyl-CoA carboxylase; NPY: neuropeptide Y; LEP: leptin; INS: insulin; ALT: alanine aminotransferase; AST: aspartate aminotransferase.

Feasibility and acceptability of a beverage intervention for Hispanic adults: results from a pilot randomized controlled trial

OBJECTIVE

To assess the feasibility and acceptability of a beverage intervention in Hispanic adults.

DESIGN

Eligible individuals identified as Hispanic, were 18-64 years old and had BMI 30·0-50·0 kg/m2. Participants were randomized 2:2:1 to one of three beverages: Mediterranean lemonade (ML), green tea (GT) or flavoured water control (FW). After a 2-week washout period, participants were asked to consume 32 oz (946 ml) of study beverage daily for 6 weeks and avoid other sources of tea, citrus, juice and sweetened beverages; water was permissible. Fasting blood samples were collected at baseline and 8 weeks to assess primary and secondary efficacy outcomes.

SETTING

Tucson, AZ, USA.ParticipantsFifty-two participants were recruited over 6 months; fifty were randomized (twenty-one ML, nineteen GT, ten FW). Study population mean (sd) age 44·6 (sd 10·2) years, BMI 35·9 (4·6) kg/m2; 78 % female.

RESULTS

Forty-four (88 %) completed the 8-week assessment. Self-reported adherence was high. No significant change (95 % CI) in total cholesterol (mg/dl) from baseline was shown -1·7 (-14·2, 10·9), -3·9 (-17·2, 9·4) and -13·2 (-30·2, 3·8) for ML, GT and FW, respectively. Mean change in HDL-cholesterol (mg/dl) -2·3 (-5·3, 0·7; ML), -1·0 (-4·2, 2·2; GT), -3·9 (-8·0, 0·2; FW) and LDL-cholesterol (mg/dl) 0·2 (-11·3, 11·8; ML), 0·5 (-11·4, 12·4; GT), -9·8 (-25·0, 5·4; FW) were also non-significant. Fasting glucose (mg/dl) increased significantly by 5·2 (2·6, 7·9; ML) and 3·3 (0·58, 6·4; GT). No significant change in HbA1c was demonstrated. Due to the small sample size, potential confounders and effect modifiers were not investigated.

CONCLUSIONS

Recruitment and retention figures indicate that a larger-scale trial is feasible; however, favourable changes in cardiometabolic biomarkers were not demonstrated.

R-Limonene Enhances Differentiation and 2-Deoxy-D-Glucose Uptake in 3T3-L1 Preadipocytes by Activating the Akt Signaling Pathway

Adipocyte is an important place for lipid storage. Defects in lipid storage in adipocytes can lead to lipodystrophy and lipid accumulation in muscle, liver, and other organs. It is the condition of mixed dyslipidemia which may favor the development of insulin resistance via lipotoxic mechanisms. Our objective of the study was to investigate the potential role of R-limonene (LM) on differentiation, lipid storage, and 2-deoxy-D-glucose (2DG) uptake in 3T3-L1 preadipocytes. Genes and proteins associated with differentiation, lipid accumulation, 2DG uptake and its signaling pathways in the adipocytes were analyzed using qPCR and western blot methods. LM treatment increased differentiation, lipid accumulation, and the expression of adipogenic and lipogenic markers such as C/EBP-α, C/EBP-β, PPARγ, SREBP-1, RXR, FAS, and adiponectin. However, the LM concentration at 10μM decreased (p < 0.05) adipogenesis and lipogenesis via regulating key transcriptional factors. LM treatment increased activation of Akt by increasing its phosphorylation, but p44/42 activation was not altered. MK-2206, an Akt specific inhibitor, reduced the activation of Akt phosphorylation whereas LM treatment aborted the MK-2206 mediated inhibition of Akt activation. LM enhanced glucose uptake in differentiated adipocytes. Overall data suggested that LM treatment favored lipid storage and glucose uptake in adipocytes via activation of key transcriptional factors through activation of Akt phosphorylation in 3T3-L1 adipocytes.

Limonene promotes osteoblast differentiation and 2-deoxy-d-glucose uptake through p38MAPK and Akt signaling pathways in C2C12 skeletal muscle cells

BACKGROUND

Limonene is a cyclic monoterpene (CTL) found in citrus fruits and many plant kingdoms. It has attracted attention as potential molecule due to its diverse biological activities. However, molecular mechanism involved in the osteogenic induction of CTL in C2C12 skeletal muscle cells remain unclear.

PURPOSE

Skeletal development maintains the bone homeostasis through bone remodeling process. It coordinated between the osteoblast and osteoblast process. Osteoporosis is one of the most common bone diseases caused by a systemic reduction in bone mass. Recent osteoporosis treatment is based on the use of anti-resorptive and bone forming drugs. However, long term use of these drugs is associated with serious side effects and strategies on the discovery of lead compounds from natural products for osteoblast differentiation are urgently needed. Therefore, we planned to find out the role of CTL on osteoblast differentiation and glucose uptake in C2C12 cells and its effect on signaling pathways.

METHODS

Cell proliferation, alkaline phosphatase (ALP) activity, calcium deposition, genes, and proteins associated with osteoblast activation and glucose utilization were analysed.

RESULTS

CTL did not affect the cell viability. CTL significantly increased ALP activity, calcium depositions and the expression of osteogenic specific genes such as Myogenin, Myogenic differentiation 1 (MyoD), ALP, Run-related transcription factor 2(RUNX2), osteocalcin (OCN). In addition, CTL induced the mRNA expression of bone morphogenetic proteins (BMP-2 BMP-4 BMP-6 BMP-7 BMP-9). CTL treatment enhanced 2-Deoxy-d-glucose (2DG) uptake. Moreover, CTL stimulated the activation of p38 mitogen activated protein kinase (p38MAPK), Protein kinase B (Akt), Extracellular signal related kinase (ERKs) by increasing phosphorylation. CTL treatment abolished p38 inhibitor (SB203580) mediated inhibition of osteoblast differentiation, but no effect was noted by ERKs specific inhibitor (PD98059).

CONCLUSION

These results suggest that limonene induces osteoblast differentiation and glucose uptake through activating p38MAPK and Akt signaling pathways, confirming the molecular basis of the osteoblast differentiation by limonene in C2C12 skeletal muscle cells.

Antidiabetic Potential of Monoterpenes: A Case of Small Molecules Punching above Their Weight

Monoterpenes belong to the terpenoids class of natural products and are bio-synthesized through the mevalonic acid pathway. Their small molecular weight coupled with high non-polar nature make them the most abundant components of essential oils which are often considered to have some general antioxidant and antimicrobial effects at fairly high concentrations. These compounds are however reported to have antidiabetic effects in recent years. Thanks to the ingenious biosynthetic machinery of nature, they also display a fair degree of structural complexity/diversity for further consideration in structure-activity studies. In the present communication, the merit of monoterpenes as antidiabetic agents is scrutinized by assessing recent in vitro and in vivo studies reported in the scientific literature. Both the aglycones and glycosides of these compounds of rather small structural size appear to display antidiabetic along with antiobesity and lipid lowering effects. The diversity of these effects vis-à-vis their structures and mechanisms of actions are discussed. Some key pharmacological targets include the insulin signaling pathways and/or the associated PI3K-AKT (protein kinase B), peroxisome proliferator activated receptor-γ (PPARγ), glucose transporter-4 (GLUT4) and adenosine monophosphate-activated protein kinase (AMPK) pathways; proinflammatory cytokines and the NF-κB pathway; glycogenolysis and gluconeogenesis in the liver; glucagon-like-1 receptor (GLP-1R); among others.

Citrus waste as feedstock for bio-based products recovery: Review on limonene case study and energy valorization

The citrus peels and residue of fruit juices production are rich in d-limonene, a cyclic terpene characterized by antimicrobial activity, which could hamper energy valorization bioprocess. Considering that limonene is used in nutritional, pharmaceutical and cosmetic fields, citrus by-products processing appear to be a suitable feedstock either for high value product recovery or energy bio-processes. This waste stream, more than 10MTon at 2013 in European Union (AIJN, 2014), can be considered appealing, from the view point of conducting a key study on limonene recovery, as its content of about 1%w/w of high value-added molecule. Different processes are currently being studied to recover or remove limonene from citrus peel to both prevent pollution and energy resources recovery. The present review is aimed to highlight pros and contras of different approaches suggesting an energy sustainability criterion to select the most effective one for materials and energy valorization.

Miconia sp. Increases mRNA Levels of PPAR Gamma and Inhibits Alpha Amylase and Alpha Glucosidase

Diabetes mellitus is a public health problem worldwide. For this reason, ethanolic extract of Miconia sp. from Oaxaca, Mexico, was selected in search of an alternative against this disease. The effect of Miconia sp. on mRNA expression of PPARγ on cell line 3T3-L1, its effect on alpha amylase and alpha glucosidase, lipid accumulation during adipogenesis, and cell viability on VERO cells were evaluated. The mRNA levels of PPARγ increased on 1.393 ± 0.008 folds, lipid accumulation was increased by 29.55% with Miconia sp. extract and 34.57% with rosiglitazone, and α-amylase and α-glycosidase were inhibited with IC₅₀ values from 28.23 ± 2.15 μg/mL and 1.95 ± 0.15 μg/mL, respectively; the IC₅₀ on antiproliferative activity on VERO cells was 314.54 ± 45.40 μg/mL. In case of α-amylase and α-glycosidase assays, IC₅₀ (inhibitory concentration 50) refers to necessary extract amounts to inhibit 50% of enzymatic activity. On the other hand, on antiproliferative activity, IC₅₀ (inhibitory concentration 50) refers to necessary extract amounts to inhibit 50% of cell proliferation. It was concluded that the compounds present in Miconia sp. ethanolic extract increase mRNA expression of PPARγ, inhibit α-amylase and α-glucosidase, and increase lipid accumulation. It constitutes an alternative as adjuvant in diabetes mellitus treatment; therefore, we recommend continuing identifying the compounds responsible for its promising in vivo antidiabetic activity.

Metabolomic-Based Strategy for Fingerprinting of Sambucus nigra L. Berry Volatile Terpenoids and Norisoprenoids: Influence of Ripening and Cultivar

The integration of plant metabolomics to support preharvest fruit development studies can provide important insights into the biochemical mechanisms involved and lately support producers on harvesting management. A metabolomic-based strategy for fingerprinting of volatile terpenoids and norisoprenoids from Sambucus nigra L. berries from three cultivars, through ripening, was established. From 42 monoterpenic, 20 sesquiterpenic, and 14 norisoprenoid compounds, 48 compounds are reported for the first time as S. nigra berries components. Chemometric tools revealed that ripening was the factor that influenced more the volatile fraction profile and physicochemical parameters (pH, TS, and TSS), followed by cultivar. For the unripe stages, a higher overall content of the studied metabolites was observed, which gradually decreased over the ripening stages, being consistent for the three cultivars. These trends were mainly ruled by limonene, p-cymene, aromadendrene, β-caryophyllene, and dihydroedulan, which might therefore be used by producers as an additional simple decision making tool in conjunction with physicochemical parameters.

The Antibacterial Activity of Chitosan Products Blended with Monoterpenes and Their Biofilms against Plant Pathogenic Bacteria

This study focuses on the biological activities of eleven chitosan products with a viscosity-average molecular weight ranging from 22 to 846 kDa in combination with the most active monoterpenes (geraniol and thymol), out of 10 tested, against four plant pathogenic bacteria, Agrobacterium tumefaciens, Erwinia carotovora, Corynebacterium fascians, and Pseudomonas solanacearum. The antibacterial activity was evaluated in vitro by the agar dilution technique as a minimum inhibitory concentration (MIC) that was found to be dependent on the type of the microorganism tested. The most active product of chitosan was used for biofilm production enriched with geraniol and thymol (0.1 and 0.5%) and the films were also evaluated against the tested bacteria. The biological bioactivities summarized here may provide novel insights into the functions of chitosan and some monoterpenes and potentially allow their use for food protection from microbial attack.