High Dietary Kuding Tea Extract Supplementation Induces Hepatic Xenobiotic-Metabolizing Enzymes-A 6-Week Feeding Study in Mice

Neuroprotective properties of Betulin, Betulinic acid, and Ursolic acid as triterpenoids derivatives: a comprehensive review of mechanistic studies

Cognitive deficits are the main outcome of neurological disorders whose occurrence has risen over the past three decades. Although there are some pharmacologic approaches approved for managing neurological disorders, it remains largely ineffective. Hence, exploring novel nature-based nutraceuticals is a pressing need to alleviate the results of neurodegenerative diseases, such as Alzheimer's disease (AD) and other neurodegenerative disorders. Some triterpenoids and their derivates can be considered potential therapeutics against neurological disorders due to their neuroprotective and cognitive-improving effects. Betulin (B), betulinic acid (BA), and ursolic acid (UA) are pentacyclic triterpenoid compounds with a variety of biological activities, including antioxidative, neuroprotective and anti-inflammatory properties. This review focuses on the therapeutic efficacy and probable molecular mechanisms of triterpenoids in damage prevention to neurons and restoring cognition in neurodegenerative diseases. Considering few studies on this concept, the precise mechanisms that mediate the effect of these compounds in neurodegenerative disorders have remained unknown. The findings can provide sufficient information about the advantages of these compounds against neurodegenerative diseases.

Reduced iron and cobalt levels in response to curcumin supplementation are not responsible for the prolonged larval development and do not affect the oxidative stress tolerance and polyamine status of D. melanogaster

Recent reports indicated that the phytochemical curcumin possesses iron-chelating activity. Here, by employing the fruit fly Drosophila melanogaster, we conducted feeding studies supplementing curcumin or, as a control, the iron chelator bathophenanthroline (BPA). First, the absorption and further metabolization of dietary curcuminoids were proved by metabolomics analyses. Next, we found that 0.2% dietary curcumin, similar to BPA, lowered the iron but also the cobalt content, and to a lesser extent affected the manganese and zinc status. Supplementation during larval stages was required and sufficient for both compounds to elicit these alterations in adult animals. However, curcumin-induced retarded larval development was not attributable to the changed trace metal status. In addition, a reduction in the iron content of up to 70% by curcumin or BPA supplementation did not reduce heme-dependent catalase activity and tolerance toward H2 O2 in D. melanogaster. Moreover, polyamines were not influenced by curcumin treatment and decreased iron levels. This was confirmed for selected organs from 0.2% curcumin-treated mice, except for the spleen. Here, elevated spermidine level and concomitant upregulation of genes involved in polyamine production were associated with a putatively anemia-derived increased spleen mass. Our data underline that the metal-chelating property of curcumin needs to be considered in feeding studies.

Ursolic acid nanoparticles for glioblastoma therapy

BACKGROUND

Glioblastoma multiforme (GBM) is the most common and fatal primary tumor in the central nervous system (CNS). The effect of chemotherapy of GBM is limited due to the existence of blood-brain barrier (BBB). The aim of this study is to develop self-assembled nanoparticles (NPs) of ursolic acid (UA) for GBM treatment.

METHODS

UA NPs were synthesized by solvent volatilization method. Western blot analysis fluorescent staining and flow cytometry were launched to explore the anti-glioblastoma mechanism of UA NPs. The antitumor effects of UA NPs were further confirmed in vivo using intracranial xenograft models.

RESULTS

UA were successfully prepared. In vitro, UA NPs could significantly increase the protein levels of cleaved-caspase 3 and LC3-II to strongly eliminate glioblastoma cells through autophagy and apoptosis. In the intracranial xenograft models, UA NPs could further effectively enter the BBB, and greatly improve the survival time of the mice.

CONCLUSIONS

We successfully synthesized UA NPs which could effectively enter the BBB and show strong anti-tumor effect which may have great potential in the treatment of human glioblastoma.

A review of alpha-glucosidase inhibitors from plants as potential candidates for the treatment of type-2 diabetes

Diabetes mellitus is a multifactorial global health disorder that is rising at an alarming rate. Cardiovascular diseases, kidney damage and neuropathy are the main cause of high mortality rates among individuals with diabetes. One effective therapeutic approach for controlling hyperglycemia associated with type-2 diabetes is to target alpha-amylase and alpha-glucosidase, enzymes that catalyzes starch hydrolysis in the intestine. At present, approved inhibitors for these enzymes are restricted to acarbose, miglitol and voglibose. Although these inhibitors retard glucose absorption, undesirable gastrointestinal side effects impede their application. Therefore, research efforts continue to seek novel inhibitors with improved efficacy and minimal side effects. Natural products of plant origin have been a valuable source of therapeutic agents with lesser toxicity and side effects. The anti-diabetic potential through alpha-glucosidase inhibition of plant-derived molecules are summarized in this review. Eight molecules (Taxumariene F, Akebonoic acid, Morusin, Rhaponticin, Procyanidin A2, Alaternin, Mulberrofuran K and Psoralidin) were selected as promising drug candidates and their pharmacokinetic properties and toxicity were discussed where available.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11101-021-09773-1.

Glycerol Monocaprylate Modulates Gut Microbiota and Increases Short-Chain Fatty Acids Production without Adverse Effects on Metabolism and Inflammation

Glycerol monocaprylate (GMC) is a glycerol derivative of medium-chain fatty acids (MCFAs) and is widely used as a preservative in food processing. However, GMC and its hydrolytic acid (octylic acid) have antibacterial properties that may affect the physiology and intestinal microecology of the human body. Therefore, in this study, the effects of two different dosages of GMC (150 and 1600 mg kg-1) on glucose, lipid metabolism, inflammation, and intestinal microecology of normal diet-fed C57BL/6 mice were comprehensively investigated. The obtained results showed that the level of triglycerides (TGs) in the low-dose group down-regulated significantly, and the anti-inflammatory cytokine interleukin 10 (IL-10) significantly increased, while the pro-inflammatory cytokines monocyte chemotactic protein 1 (MCP-1) and interleukin 1beta (IL-1β) in the high-dose group were significantly decreased. Importantly, GMC promoted the α-diversity of gut microbiota in normal-diet-fed mice, regardless of dosages. Additionally, it was found that the low-dose treatment of GMC significantly increased the abundance of Lactobacillus, while the high-dose treatment of GMC significantly increased the abundance of SCFA-producers such as Clostridiales, Lachnospiraceae, and Ruminococcus. Moreover, the content of short-chain fatty acids (SCFAs) was significantly increased by GMC supplementation. Thus, our research provides a novel insight into the effects of GMC on gut microbiota and physiological characteristics.

Cyclodextrins, Natural Compounds, and Plant Bioactives-A Nutritional Perspective

Cyclodextrins (CDs) are a group of cyclic oligosaccharides produced from starch or starch derivatives. They contain six (αCD), seven (βCD), eight (γCD), or more glucopyranose monomers linked via α-1,4-glycosidic bonds. CDs have a truncated cone shape with a hydrophilic outer wall and a less hydrophilic inner wall, the latter forming a more apolar internal cavity. Because of this special architecture, CDs are soluble in water and can simultaneously host lipophilic guest molecules. The major advantage of inclusion into CDs is increased aqueous solubility of such lipophilic substances. Accordingly, we present studies where the complexation of natural compounds such as propolis and dietary plant bioactives (e.g., tocotrienol, pentacyclic triterpenoids, curcumin) with γCD resulted in improved stability, bioavailability, and bioactivity in various laboratory model organisms and in humans. We also address safety aspects that may arise from increased bioavailability of plant extracts or natural compounds owing to CD complexation. When orally administered, α- and βCD—which are inert to intestinal digestion—are fermented by the human intestinal flora, while γCD is almost completely degraded to glucose units by α-amylase. Hence, recent reports indicate that empty γCD supplementation exhibits metabolic activity on its own, which may provide opportunities for new applications.

Related Pentacyclic Triterpenes Have Immunomodulatory Activity in Chronic Experimental Visceral Leishmaniasis

Leishmaniasis is a neglected tropical disease caused by the flagellated protozoa of the genus Leishmania that affects millions of people around the world. Drugs employed in the treatment of leishmaniasis have limited efficacy and induce local and systemic side effects to the patients. Natural products are an interesting alternative to treat leishmaniasis, because some purified molecules are selective toward parasites and not to the host cells. Thus, the aim of the present study was to compare the in vitro antileishmanial activity of the triterpenes betulin (Be), lupeol (Lu), and ursolic acid (UA); analyze the physiology and morphology of affected organelles; analyze the toxicity of selected triterpenes in golden hamsters; and study the therapeutic activity of triterpenes in hamsters infected with L. (L.) infantum as well as the cellular immunity induced by studied molecules. The triterpenes Lu and UA were active on promastigote (IC₅₀ = 4.0 ± 0.3 and 8.0 ± 0.2 μM, respectively) and amastigote forms (IC₅₀ = 17.5 ± 0.4 and 3.0 ± 0.2 μM, respectively) of L. (L.) infantum, and their selectivity indexes (SI) toward amastigote forms were higher (≥13.4 and 14, respectively) than SI of miltefosine (2.7). L. (L.) infantum promastigotes treated with Lu and UA showed cytoplasmic degradation, and in some of these areas, cell debris were identified, resembling autophagic vacuoles, and parasite mitochondria were swelled, fragmented, and displayed membrane potential altered over time. Parasite cell membrane was not affected by studied triterpenes. Studies of toxicity in golden hamster showed that Lu did not alter blood biochemical parameters associated with liver and kidney functions; however, a slight increase of aspartate aminotransferase level in animals treated with 2.5 mg/kg of UA was detected. Lu and UA triterpenes eliminated amastigote forms in the spleen (87.5 and 95.9% of reduction, respectively) and liver of infected hamster (95.9 and 99.7% of reduction, respectively); and UA showed similar activity at eliminating amastigote forms in the spleen and liver than amphotericin B (99.2 and 99.8% of reduction). The therapeutic activity of both triterpenes was associated with the elevation of IFN-γ and/or iNOS expression in infected treated animals. This is the first comparative work showing the in vitro activity, toxicity, and therapeutic activity of Lu and UA in the chronic model of visceral leishmaniasis caused by L. (L.) infantum; additionally, both triterpenes activated cellular immune response in the hamster model of visceral leishmaniasis.

Ursolic acid: A systematic review of its pharmacology, toxicity and rethink on its pharmacokinetics based on PK-PD model

Ursolic acid (UA) is a natural pentacyclic triterpenoid compound existing in various traditional Chinese medicinal herbs, and it possesses diverse pharmacological actions and some undesirable adverse effects, even toxicological activities. Due to UA's low solubility and poor bioavailability, and its interaction with gut microbiota after oral administration, the pharmacokinetics of UA remain elusive, leading to obscurity in the pharmacokinetics-pharmacodynamics (PK-PD) profile and relationship for UA. Based on literatures from PubMed, Google Scholar, ResearchGate, Web of Science and Wiley Online Library, with keywords of "pharmacology", "toxicology", "pharmacokinetics", "PK-PD" and "ursolic acid", herein we systematically review the pharmacology and toxicity of UA, and rethink on its pharmacokinetics on the basis of PK-PD model, and seek to delineate the underlying mechanisms for the characteristics of pharmacology and toxicology of UA, and for the pharmacokinetic features of UA particularly from the organ tropism and the interactions between UA and gut microbiota, and lay a solid foundation for development of UA-derived therapeutic agents in clinical settings.

Chemical Composition, Bioactivity and Safety Aspects of Kuding Tea-From Beverage to Herbal Extract

Kuding tea (KT) is a bitter-tasting herbal tea that has been commonly used in traditional Chinese medicine (TCM). The large-leaved Ku-Ding-Cha (Aquifoliaceae) is composed of its representative species Ilex latifolia Thunb and Ilex kudingcha C.J. Tseng. Because of its potential lipid-lowering, body weight-reducing and blood-glucose-lowering properties, KT has increasingly been recognised for its importance over the past several decades. KT is no longer used only as a beverage, and various extraction methods have been applied to obtain aqueous and ethanolic KT extracts (KTE) or their fractions, which could potentially be used as dietary supplements. The major bioactive components of KT are triterpene saponins and polyphenols, but the composition of KT differs substantially between and among the different KT species. This in turn might affect the physiological effects of KT. KT exhibits antiobesity properties, possibly partly by affecting the intestinal microbiota. In addition, KT may mediate putative antioxidative, anti-inflammatory and anticancer activities. However, there is evidence that high KTE supplementation can adversely affect liver metabolism. The physiological relevance of KT in humans remains rather unclear since the potential health benefits of KT and its constituents reviewed here are mainly derived on the basis of in vitro and animal studies.