Studies of selected plant raw materials as alternative sources of triterpenes of oleanolic and ursolic acid types

Recent advances in the chemistry and biology of oleanolic acid and its derivatives

The pentacyclic triterpenes represent a significant class of plant bioactives with a variety of structures and a wide array of biological activities. These are biosynthetically produced via the mevalonate pathway although occasionally mixed pathways may also occur to introduce structural divergence. Oleanolic acid is one of the most explored bioactive from this class of compounds and possesses a broad spectrum of pharmacological and biological activities including liver protection, anti-cancer, atherosclerosis, anti-inflammation, antibacterial, anti-HIV, anti-oxidative, anti-diabetic etc. This review provides an overview of the latest research findings, highlighting the versatile medicinal and biological potential of oleanolic and its future prospects.

In vitro micropropagation and conservation of endangered medicinal plant Nepeta asterotricha Rech.f. (Lamiaceae): genetic fidelity, phytochemical and biological assessment

An efficient in vitro protocol was introduced for the conservation of Nepeta asterotricha, a vulnerable and endangered medicinal species found in the central of Iran for the first time. Growth, phytochemical, and biological traits of in vitro regenerated plant (RP) and acclimated plant (AP) were compared to the mother plant (MP). In addition, the genetic stability of AP was assessed by using inter-simple sequence repeats (ISSR) markers. The highest number of lateral branches (4.25) was obtained from the medium with 3 mg/mL kinetin (KIN), while the highest length of lateral branches (13.25 cm) was achieved on the medium culture fortified with 3 mg/mL thidiazuron (TDZ) and 6-benzylaminopurine (BAP). The highest number of leaves (20.25) and main branch length (12.25 cm) were obtained from the medium containing 3 mg/mL TDZ. The highest number of roots (46.25) and root length (2.25 cm) was measured from the medium fortified with 1 mg/mL indole-3-butyric acid (IBA) and 0.6 mg/mL indole-3-acetic acid (IAA), respectively. RP was successfully acclimated (85%) in vivo. Molecular analysis showed that the AP was true to the type of the MP. cis-Sabinene hydrate (26.8-57.7), 1,8-cineole (6.2-24.1), 4aα,7β,7aα-nepetalactone (4.1-12.3), and terpinene-4-ol (3.2-15.0) were the major essential oils compounds. The studied samples contained rosmarinic acid (2.55-5.97 mg/g DW), cichoric acid (1.68-12.7 mg/g DW), chlorogenic acid (1.91-64.21 mg/g DW), rutin (0.59-1.09 mg/g DW), apigenin (0.52-0.72 mg/g DW), betulinic acid (0.17-2.20 mg g DW), oleanolic acid (0.84-5.37 mg/g DW) and ursolic acid (3.46-15.70 mg/g DW). Acclimated plant exhibited the highest antioxidant activity (IC50 = 196.4 μg/mL), while the methanolic extract of MP displayed the highest antibacterial activity (MIC = 8 mg/mL) against Staphylococcus aureus.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-024-01416-x.

Ursolic acid: biological functions and application in animal husbandry

Ursolic acid (UA) is a plant-derived pentacyclic triterpenoid with 30 carbon atoms. UA has anti-inflammatory, antioxidative, antimicrobial, hepato-protective, anticancer, and other biological activities. Most studies on the biological functions of UA have been performed in mammalian cell (in vitro) and rodent (in vivo) models. UA is used in animal husbandry as an anti-inflammatory and antiviral agent, as well as for enhancing the integrity of the intestinal barrier. Although UA has been shown to have significant in vitro bacteriostatic effects, it is rarely used in animal nutrition. The use of UA as a substitute for oral antibiotics or as a novel feed additive in animal husbandry should be considered. This review summarizes the available data on the biological functions of UA and its applications in animal husbandry.

Ursolic Acid against Prostate and Urogenital Cancers: A Review of In Vitro and In Vivo Studies

Prostate cancer is the second most diagnosed form of cancer in men worldwide and accounted for roughly 1.3 million cases and 359,000 deaths globally in 2018, despite all the available treatment strategies including surgery, radiotherapy, and chemotherapy. Finding novel approaches to prevent and treat prostate and other urogenital cancers effectively is of major importance. Chemicals derived from plants, such as docetaxel and paclitaxel, have been used in cancer treatment, and in recent years, research interest has focused on finding other plant-derived chemicals that can be used in the fight against cancer. Ursolic acid, found in high concentrations in cranberries, is a pentacyclic triterpenoid compound demonstrated to have anti-inflammatory, antioxidant, and anticancer properties. In the present review, we summarize the research studies examining the effects of ursolic acid and its derivatives against prostate and other urogenital cancers. Collectively, the existing data indicate that ursolic acid inhibits human prostate, renal, bladder, and testicular cancer cell proliferation and induces apoptosis. A limited number of studies have shown significant reduction in tumor volume in animals xenografted with human prostate cancer cells and treated with ursolic acid. More animal studies and human clinical studies are required to examine the potential of ursolic acid to inhibit prostate and other urogenital cancers in vivo.

LC-HR/MS Analysis of Lipophilic Extracts from Calendula arvensis (Vaill.) L. Organs: An Unexplored Source in Cosmeceuticals

As part of a project aimed at promoting the use of Calendula arvensis (Vaill.) L. (field marigold, Asteraceae) phytocomplexes in cosmeceutical formulations, the chemical composition in apolar specialized metabolites is herein elucidated. Furthermore, the screening of the cytotoxicity of the apolar extracts was evaluated in order to underline their safety as functional ingredients for cosmetics. After dissection of Calendula organs (florets, fruits, leaves, bracts, stems, and roots), ultrasound-assisted maceration in n-hexane as an extracting solvent allowed us to obtain oil-like mixtures, whose chemical composition has been highlighted through a UHPLC-ESI-QqTOF-MS/MS approach. Twenty-nine metabolites were tentatively identified; different compounds, among which the well-known poly-unsaturated fatty acids, and oxylipins and phosphatides were detected for the first time in Calendula genus. The screening of the dose-response cytotoxicity of the apolar extracts of C. arvensis highlighted the concentration of 10 μg/mL as the most suitable for the formulation of cosmeceutical preparations. Sera enriched with leaf and fruit apolar extracts turned out to have the best activity, suggesting it can be used as a new source in skin care thanks to their higher content in fatty acids.

Marigold Metabolites: Diversity and Separation Methods of Calendula Genus Phytochemicals from 1891 to 2022

Marigold (Calendula), an important asteraceous genus, has a history of many centuries of therapeutic use in traditional and officinal medicines all over the world. The scientific study of Calendula metabolites was initiated at the end of the 18th century and has been successfully performed for more than a century. The result is an investigation of five species (i.e., C. officinalis, C. arvensis, C. suffruticosa, C. stellata, and C. tripterocarpa) and the discovery of 656 metabolites (i.e., mono-, sesqui-, di-, and triterpenes, phenols, coumarins, hydroxycinnamates, flavonoids, fatty acids, carbohydrates, etc.), which are discussed in this review. The identified compounds were analyzed by various separation techniques as gas chromatography and liquid chromatography which are summarized here. Thus, the genus Calendula is still a high-demand plant-based medicine and a valuable bioactive agent, and research on it will continue for a long time.

Evidence of the Beneficial Effects of Ursolic Acid against Lung Cancer

Lung cancer is the leading cause of cancer-related deaths globally. Despite current treatment approaches that include surgery, chemotherapy, radiation and immunotherapies, lung cancer accounted for 1.79 million deaths worldwide in 2020, emphasizing the urgent need to find novel agents and approaches for more effective treatment. Traditionally, chemicals derived from plants, such as paclitaxel and docetaxel, have been used in cancer treatment, and in recent years, research has focused on finding other plant-derived chemicals that can be used in the fight against lung cancer. Ursolic acid is a polyphenol found in high concentrations in cranberries and other fruits and has been demonstrated to have anti-inflammatory, antioxidant and anticancer properties. In this review, we summarize recent research examining the effects of ursolic acid and its derivatives on lung cancer. Data from in vitro cell culture and in vivo animal studies show potent anticancer effects of ursolic acid and indicate the need for clinical studies.

Biochemical and Molecular Investigation of the Effect of Saponins and Terpenoids Derived from Leaves of Ilex aquifolium on Lipid Metabolism of Obese Zucker Rats

Ilex paraguariensis, the holly tree, is a plant with recognized biological properties, whose aqueous infusions are known as “Yerba mate”, that regulate lipid metabolism, reduce obesity, and improve brain stimulation. In the present study, the effect of standardized saponin and terpenoid fractions of a European taxon, Ilex aquifolium, on blood biochemical parameters in a rat model of metabolic disorder, (fa/fa) Zucker, are presented. The profiles of the volatile fractions of two species and six European varieties of Ilex were investigated. After selecting the best variety, the saponin and terpenoid fractions were isolated and standardized, and animals were fed 10 mg kg−1 b.w. for 8 weeks. A statistically significant decrease in liver adiposity was observed, confirmed by histology and quantitative identification (gas chromatography−mass spectrometry analyses of hepatic lipids. RT-qPCR analysis of gene expression in the aorta revealed that the administration of the terpenoid fraction downregulated LOX-1, suggesting a reduction in atherosclerotic stimuli. In addition, a statistically significant reduction (p < 0.05) in PPARγ for the saponin fraction was observed in the liver. The expression of the ACAT-1 gene in the liver, responsible for the formation of cholesterol esters, increased significantly in the group receiving the terpenoid fraction compared to the control, which was also confirmed by the analysis of individual blood biochemical parameters. The opposite effect was observed for saponins. Taking the above into account, it is shown for the first time that Ilex aquifolium can be a source of compounds that positively influence lipid metabolism.

Characteristics of Selected Silphium Species as Alternative Plants for Cultivation and Industry with Particular Emphasis on Research Conducted in Poland: A Review

This article reviews the available research results of selected species of the genus Silphium L. (Asteraceae) as alternative plants for crops and industry. Silphium species have valuable qualities across a wide range of uses, which is very important in considering plant resources as a green alternative to a sustainable future. Species of the genus Silphium are tall perennials found in fields, prairies, open forests, and groves in the central and eastern parts of the United States and Canada. Various tribes of Native North American used Silphium for medicinal purposes. The cup plant Silphium perfoliatum L. is the most popular species of the genus Silphium due to its attractive ornamental, honey−giving, healing, and forage qualities. As the literature review shows, species of the genus Silphium are characterized by a high production potential in terms of yields and contain significant amounts of nutrients, i.e., carbohydrates, proteins, and L-ascorbic acid, as well as minerals and biologically active substances, e.g., terpenoids and essential oils, flavonoids, phenolic acids, and oleanosides. In addition, the research confirmed the possibility of using Silphium for fodder, as honeybee forage, phytoremediation plants, for reclamation of degraded land, as plants for energy purposes (biomass, biogas), and as plants that provide components with antimicrobial activity. This review largely takes into account many years of research experience conducted in Poland.

Advances in production and structural derivatization of the promising molecule ursolic acid

Ursolic acid (UA) is a ursane-type pentacyclic triterpenoid compound, naturally produced in plants via specialized metabolism and exhibits vast range of remarkable physiological activities and pharmacological manifestations. Owing to significant safety and efficacy in different medical conditions, UA may serve as a backbone to produce its derivatives with novel therapeutic functions. This review aims to provide ideas for exploring more diverse structures to improve UA pharmacological activity and increasing its biological yield to meet the industrial requirements by systematically reviewing the current research progress of UA. We first provides an overview of the pharmacological activities, acquisition methods and structural modifications of UA. Among them, we focused on the synthetic modifications of UA to yield valuable derivatives with enhanced therapeutic potential. Furthermore, harnessing the essential advances for green synthesis of UA and its derivatives by advent of metabolic engineering and synthetic biology are of great concern. In this regard, all pivotal advances for enhancing the production of UA have been discussed. In combination with the advantages of UA biosynthesis and transformation strategy, large-scale microbial production of UA is a promising platform for further exploration.

Chemical Composition and Assessment of Antimicrobial Activity of Lavender Essential Oil and Some By-Products

The producers of essential oils from the Republic of Moldova care about the quality of their products and at the same time, try to capitalize on the waste from processing. The purpose of the present study was to analyze the chemical composition of lavender (Lavanda angustifolia L.) essential oil and some by-products derived from its production (residual water, residual herbs), as well as to assess their “in vitro” antimicrobial activity. The gas chromatography-mass spectrometry analysis of essential oils produced by seven industrial manufacturers led to the identification of 41 constituents that meant 96.80–99.79% of the total. The main constituents are monoterpenes (84.08–92.55%), followed by sesquiterpenes (3.30–13.45%), and some aliphatic compounds (1.42–3.90%). The high-performance liquid chromatography analysis allowed the quantification of known triterpenes, ursolic, and oleanolic acids, in freshly dried lavender plants and in the residual by-products after hydrodistillation of the essential oil. The lavender essential oil showed good antibacterial activity against Bacillus subtilis, Pseudomonas fluorescens, Xanthomonas campestris, Erwinia carotovora at 300 μg/mL concentration, and Erwinia amylovora, Candida utilis at 150 μg/mL concentration, respectively. Lavender plant material but also the residual water and ethanolic extracts from the solid waste residue showed high antimicrobial activity against Aspergillus niger, Alternaria alternata, Penicillium chrysogenum, Bacillus sp., and Pseudomonas aeroginosa strains, at 0.75–6.0 μg/mL, 0.08–0.125 μg/mL, and 0.05–4.0 μg/mL, respectively.

Ursolic and Oleanolic Acids: Plant Metabolites with Neuroprotective Potential

Ursolic and oleanolic acids are secondary plant metabolites that are known to be involved in the plant defence system against water loss and pathogens. Nowadays these triterpenoids are also regarded as potential pharmaceutical compounds and there is mounting experimental data that either purified compounds or triterpenoid-enriched plant extracts exert various beneficial effects, including anti-oxidative, anti-inflammatory and anticancer, on model systems of both human or animal origin. Some of those effects have been linked to the ability of ursolic and oleanolic acids to modulate intracellular antioxidant systems and also inflammation and cell death-related pathways. Therefore, our aim was to review current studies on the distribution of ursolic and oleanolic acids in plants, bioavailability and pharmacokinetic properties of these triterpenoids and their derivatives, and to discuss their neuroprotective effects in vitro and in vivo.

Two Novel Energy Crops: Sida hermaphrodita (L.) Rusby and Silphium perfoliatum L.—State of Knowledge

Current global temperature increases resulting from human activity threaten many ecosystems and societies, and have led to international and national policy commitments that aim to reduce greenhouse gas emissions. Bioenergy crops provide one means of reducing greenhouse gas emissions from energy production and two novel crops that could be used for this purpose are Sida hermaphrodita (L.) Rusby and Silphium perfoliatum L. This research examined the existing scientific literature available on both crops through a systematic review. The data were collated according to the agronomy, uses, and environmental benefits of each crop. Possible challenges were associated with high initial planting costs, low yields in low rainfall areas, and for Sida hermaphrodita, vulnerability to Sclerotinia sclerotiorum. However, under appropriate environmental conditions, both crops were found to provide large yields over sustained periods of time with relatively low levels of management and could be used to produce large energy surpluses, either through direct combustion or biogas production. Other potential uses included fodder, fibre, and pharmaceutical uses. Environmental benefits included the potential for phytoremediation, and improvements to soil health, biodiversity, and pollination. The review also demonstrated that environmental benefits, such as pollination, soil health, and water quality benefits could be obtained from the use of Sida hermaphrodita and Silphium perfoliatum relative to existing bioenergy crops such as maize, whilst at the same time reducing the greenhouse gas emissions associated with energy production. Future research should examine the long-term implications of using Sida hermaphrodita and Silphium perfoliatum as well as improve knowledge on how to integrate them successfully within existing farming systems and supply chains.

Delivery of phytochemicals by liposome cargos: recent progress, challenges and opportunities

Bio-availability is a major concern in delivery of dietary phytochemicals for better bio-efficacy. The reduced bio-availability of food bioactive compounds is evident due to degradation during human digestion process which involves liberation, absorption, distribution, metabolism and elimination. The bio-efficacy of any nutrient can be increased by increasing bio-availability. Different technologies are available for engineered efficient delivery systems; still many challenges remain with advancement of delivery systems. The ease of preparedness and adaptability of liposomes has resulted in wide-range of applicability and acceptability in scientific field, especially as delivery vehicles. In view, of properties like biocompatibility and biodegradability, liposomes have been modified with different usable methodologies for delivery of phytochemicals. The aim of this review is to abridge liposomes, methods of preparation, their application as delivery cargo in dietary phytochemicals, result of using different preparation techniques on properties.

Synthesis and biological evaluation of novel oleanolic acid analogues as potential α-glucosidase inhibitors

Considerable interest has been attracted in oleanolic acid and its analogues because of their hypoglycemic activity. In this study, a series of novel oleanolic acid analogues against α-glucosidase were synthesized and their biological activities were evaluated in vitro and in vivo. In vitro α-glucosidase inhibition activity results indicated that most of the designed analogues exhibited prominent inhibition activities, especially compounds 10, 15, 16 and 26 which with the IC₅₀ values of 0.33 ± 0.01, 0.98 ± 0.06, 0.69 ± 0.01 and 0.72 ± 0.21 μM, respectively. Enzyme kinetic studies on the most potent compounds reveled that derivatives 10, 15, 16 and 26 were noncompetitive inhibitors. Moreover, the docking studies were carried out to prove that the four compounds could interact with the hydrophobic region of the active pocket and form hydrogen bonds to enhance the binding affinity of them with the α-glucosidase. Cytotoxicity evaluation assay demonstrated a high level of safety profile of the active compounds (10, 15, 16 and 26) against normal 3T3 cell line. Furthermore, the in vivo actual pharmacological potential studies on derivatives 10, 15, 16 and 26 showed that the hypoglycemic effects of them were comparable to that of positive control, acarbose.

Valorization of olive tree leaves: Extraction of oleanolic acid using aqueous solutions of surface-active ionic liquids

The global olive oil industry annually generates approximately 750,000-1,500,000 tons of Olea europaea leaves as waste that are typically burned for energy production. Yet, this agricultural by-product is a rich source of oleanolic acid, a high value triterpenic acid with outstanding pharmaceutical and nutraceutical activities. The present study focuses on the extraction of oleanolic acid from dried O. europaea leaves using aqueous solutions of surface-active ionic liquids as alternative solvents. A number of imidazolium-based ionic liquids with variable chain length, different anions and optional side-chain functionalization was synthesized and employed in the extraction of oleanolic acid. Ionic liquids with long alkyl chains remarkably enhance the solubility of oleanolic acid in water, thus being able to compete with the solubilities afforded by molecular organic solvents, such as chloroform. Consequently, they are suitable alternatives for the solid-liquid extraction of triterpenic acids from natural matrices and provide improved extraction yields of up to 2.5 wt% oleanolic acid extracted from olive tree leaves.

Phytochemical Profiles of Alpine Plant Horminum pyrenaicum L. during Phenological Growth Stages

Horminum pyrenaicum L. is a medicinal, aromatic and ornamental plant native to the Pyrenees and Alps. The phytochemical composition is affected by various ecological factors, climatic conditions and cultivating factors, and especially phenological growth stages. Flavonoids, phenolic acids and triterpenic acids were identified and quantified in the above-ground parts of H. pyrenaicum during the phenological stages. The massive flowering was distinguished with the greatest total amounts of phenolic compounds (22232.8 μg/g), and rosmarinic acid was the predominant compound. The amounts of triterpenic compounds were at the lowest during the intense growth stage and significantly increased up to the massive flowering. The prevailing compounds were ursolic acid and betulinic acid, 12092.4 μg/g and 2618.9 μg/g, respectively. The major essential oil compounds were β-phellandrene (56.6%), caryophyllene oxide (5.9%), (Z)-caryophyllene (4.4%), myrcene (4.1%) and thymol (3.6%). Selecting the optimal harvesting time could ensure the herbal raw material rich with preferred bioactive compounds.

Chemical characterization, pharmacological effects, and toxicity of an ethanol extract of Celtis pallida Torr. (Cannabaceae) aerial parts

ETHNOPHARMACOLOGICAL RELEVANCE

Celtis pallida Torr (Cannabaceae) is employed as a folk medicine for the treatment of inflammation, pain, skin infections, and diarrhea, among other diseases.

AIM OF THE STUDY

The purpose of this work was to assess the chemical composition, the in vitro and in vivo toxicity, the antimicrobial, anti-inflammatory, antidiarrheal, antinociceptive, locomotor, and sedative effects of an ethanolic extract obtained from Celtis pallida aerial parts (CPE).

MATERIALS AND METHODS

The composition of CPE was carried out by GC-MS. The in vitro and in vivo toxic activity of CPE was estimated with the comet assay (10-1000 µg/ml) for 5 h in peripheral blood mononuclear cells, and the acute toxicity test (500-5000 mg/kg p.o.), for 14 days, respectively. The antimicrobial effect of CPE was evaluated using the minimum inhibitory concentration (MIC) assay, whereas the antidiarrheal activity (10-200 mg/kg p.o.) was calculated using the castor oil test. The antinociceptive effects of CPE (50-200 mg/kg p.o.) were estimated with the acetic acid and formalin tests, as well as the hot plate test. The sedative and locomotor activities of CPE (50-200 mg/kg p.o.) were assessed with the pentobarbital-induced sleeping time test and the rotarod test, respectively.

RESULTS

The main compound found in CPE was the triterpene ursolic acid (22% of the extract). CPE at concentrations of 100 µg/ml or higher induced genotoxicity in vitro and showed low in vivo toxicity (LD₅₀ > 5000 mg/kg p.o.). Additionally, CPE lacked (MIC > 400 µg/ml) antimicrobial activity but exerts antinociceptive (ED₅₀ = 12.5 ± 1.5 mg/kg) and antidiarrheal effects (ED₅₀ = 2.8 mg/kg), without inducing sedative effects or altering the locomotor activity. The antinociceptive activity of CPE suggests the participation of adrenoceptors, as well as the nitric oxide/cyclic guanosine monophosphate (cGMP) pathway.

CONCLUSION

C. pallida exerts its antinociceptive effects probably mediated by the nitric oxide/cyclic guanosine monophosphate (cGMP) pathway.

Recent developments on the extraction and application of ursolic acid. A review

Ursolic acid (UA) is a pentacyclic triterpenoid widely found in herbs, leaves, flowers and fruits; update information on the major natural sources or agro-industrial wastes is presented. Traditional (maceration, Soxhlet and heat reflux) and modern (microwave-, ultrasound-, accelerated solvent- and supercritical fluid) extraction and purification technologies of UA, as well as some patented process, are summarized. The great interest in this bioactive compound is related to the beneficial effects in human health due to antioxidant, antimicrobial, anti-inflammatory, hepatoprotective, immunomodulatory, anti-tumor, chemopreventive, cardioprotective, antihyperlipidemic and hypoglycemic activities, and others. UA may augment the resistance of the skin barrier to irritants, prevent dry skin and could be suitable to develop antiaging products. The development of nanocrystals and nanoparticle-based drugs could reduce the side effects of high doses of UA in organisms, and increase its limited solubility and poor bioavailability of UA which limit the potential of this bioactive and the further applications. Commercial patented applications in relation to cosmetical and pharmaceutical uses of UA and its derivatives are surveyed.

Therapeutic Potential of Ursolic Acid to Manage Neurodegenerative and Psychiatric Diseases

Ursolic acid is a pentacyclic triterpenoid found in several plants. Despite its initial use as a pharmacologically inactive emulsifier in pharmaceutical, cosmetic and food industries, several biological activities have been reported for this compound so far, including anti-tumoural, anti-diabetic, cardioprotective and hepatoprotective properties. The biological effects of ursolic acid have been evaluated in vitro, in different cell types and against several toxic insults (i.e. 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, amyloid-β peptides, kainic acid and others); in animal models of brain-related disorders (Alzheimer disease, Parkinson disease, depression, traumatic brain injury) and ageing; and in clinical studies with cancer patients and for muscle atrophy. Most of the protective effects of ursolic acid are related to its ability to prevent oxidative damage and excessive inflammation, common mechanisms associated with multiple brain disorders. Additionally, ursolic acid is capable of modulating the monoaminergic system, an effect that might be involved in its ability to prevent mood and cognitive dysfunctions associated with neurodegenerative and psychiatric conditions. This review presents and discusses the available evidence of the possible beneficial effects of ursolic acid for the management of neurodegenerative and psychiatric disorders. We also discuss the chemical features, major sources and potential limitations of the use of ursolic acid as a pharmacological treatment for brain-related diseases.

Ursolic acid activates the TGR5 receptor to enhance GLP-1 secretion in type 1-like diabetic rats

Endogenous Takeda G-protein-coupled receptor 5 (TGR5), G-protein-coupled bile acid receptor 1 (GPBAR1), regulates glucose metabolism. In animals, TGR5 activation by a chemical agonist may increase incretin secretion and reduce the blood sugar level. Recently, betulinic acid has been suggested to activate TGR5. Ursolic acid is a well-known pentacyclic triterpenoid that is similar to betulinic acid. It is of special interest to determine the potential effect of ursolic acid on TGR5. Therefore, we transfected cultured Chinese hamster ovary (CHO-K1) cells with the TGR5 gene. The functions of the transfected cells were confirmed via glucose uptake using a fluorescent indicator. Moreover, NCI-H716 cells that secreted incretin were also investigated, and the glucagon-like peptide (GLP-1) levels were quantified using ELISA kits. In addition, streptozotocin (STZ)-induced type 1-like diabetic rats were used to identify the effect of ursolic acid in vivo. Ursolic acid concentration dependently increased glucose uptake in CHO-K1 cells expressing TGR5. In NCI-H716 cells, ursolic acid induced a concentration-dependent elevation in GLP-1 secretion, which was inhibited by triamterene at the effective concentrations to block TGR5. Ursolic acid also increased the plasma GLP-1 level via TGR5 activation, which was further characterized in vivo with type 1-like diabetic rats. Moreover, ursolic acid is more effective than betulinic acid in reduction of hyperglycemia and increase of GLP-1 secretion. Therefore, we demonstrated that ursolic acid can activate TGR5, enhancing GLP-1 secretion in vitro and in vivo. Therefore, ursolic acid is suitable for use in TGR5 activation.

Isorhamnetin and Quercetin Derivatives as Anti-Acetylcholinesterase Principles of Marigold (Calendula officinalis) Flowers and Preparations

Marigold (Calendula officinalis L.) is one of the most common and widespread plants used medicinally all over the world. The present study aimed to evaluate the anti-acetylcholinesterase activity of marigold flowers, detect the compounds responsible and perform chemical analysis of marigold commercial products. Analysis of 23 varieties of C. officinalis flowers introduced into Siberia allowed us to select the Greenheart Orange variety due to the superior content of flavonoids (46.87 mg/g) and the highest inhibitory activity against acetylcholinesterase (IC₅₀ 63.52 µg/mL). Flavonoids, isorhamnetin and quercetin derivatives were revealed as potential inhibitors with the application of high-performance liquid chromatography (HPLC) activity-based profiling. Investigation of the inhibitory activity of isorhamnetin glycosides demonstrated the maximal potency for isorhamnetin-3-O-(2′′,6′′-di-acetyl)-glucoside (IC₅₀ 51.26 μM) and minimal potency for typhaneoside (isorhamnetin-3-O-(2′′,6′′-di-rhamnosyl)-glucoside; IC₅₀ 94.92 µM). Among quercetin derivatives, the most active compound was quercetin-3-O-(2′′,6′′-di-acetyl)-glucoside (IC₅₀ 36.47 µM), and the least active component was manghaslin (quercetin-3-O-(2′′,6′′-di-rhamnosyl)-glucoside; IC₅₀ 94.92 µM). Some structure-activity relationships were discussed. Analysis of commercial marigold formulations revealed a reduced flavonoid content (from 7.18–19.85 mg/g) compared with introduced varieties. Liquid extract was the most enriched preparation, characterized by 3.10 mg/mL of total flavonoid content, and infusion was the least enriched formulation (0.41 mg/mL). The presented results suggest that isorhamnetin and quercetin and its glycosides can be considered as potential anti-acetylcholinesterase agents.

Synthesis and biological evaluation of novel ursolic acid analogues as potential α-glucosidase inhibitors

Ursolic acid (UA) is a major pentacyclic triterpenoid in plants, vegetables and fruits, which has been reported to have a potential anti-diabetic activity. Despite various semi-synthetic ursolic acid derivatives already described, new derivatives still need to be designed and synthesized to further improve the anti-diabetic activity. In the present study, two series of novel UA derivatives, were synthesized and their structures were confirmed. The enzyme inhibition activities of semi-synthesized analogues against α-glucosidase were screened in vitro. The results indicated that most of UA derivatives showed a significant inhibitory activity, especially analogues UA-O-i with the IC50 values of 0.71 ± 0.27 μM, which was more potential than other analogues and the positive control. Furthermore, molecular docking studies were also investigated to verify the in vitro study. Structure modification at the C-3 and C-2 positions of UA was an effective approach to obtain the desired ligand from UA, whose structure was in accordance with the active pocket. Besides, suitable hydrophobic group at the position of C-2 might play an important role for the docking selectivity and binding affinity between the ligand and the homology modelling protein. These results could be helpful for designing more potential α-glucosidase inhibitors from UA in the future.

Novel nutraceutic therapies for the treatment of metabolic syndrome

Nutraceutic therapies such as berberine, bitter melon, Gymnema sylvestre, Irvingia gabonensis, resveratrol and ursolic acid have been shown to help control metabolic syndrome (MetS). The effect of berberine on glucose and lipid metabolism, hypertension, obesity and MetS has been evaluated in animal models and humans. Most clinical trials involving bitter melon have been conducted to evaluate its effect on glucose metabolism; nevertheless, some studies have reported favorable effects on lipids and blood pressure although there is little information about its effect on body weight. Gymnema sylvestre helps to decrease body weight and blood sugar levels; however, there is limited information on dyslipidemia and hypertension. Clinical trials of Irvingia gabonensis have shown important effects decreasing glucose and cholesterol concentrations as well decreasing body weight. Resveratrol acts through different mechanisms to decrease blood pressure, lipids, glucose and weight, showing its effects on the population with MetS. Finally, there is evidence of positive effects with ursolic acid in in vitro and in vivo studies on glucose and lipid metabolism and on body weight and visceral fat. Therefore, a review of the beneficial effects and limitations of the above-mentioned nutraceutic therapies is presented.

"Ziziphus jujuba": A red fruit with promising anticancer activities

Ziziphus jujuba Mill. (Z. jujuba) is a traditional herb with a long history of use for nutrition and the treatment of a broad spectrum of diseases. It grows mostly in South and East Asia, as well as in Australia and Europe. Mounting evidence shows the health benefits of Z. jujuba, including anticancer, anti-inflammation, antiobesity, antioxidant, and hepato- and gastrointestinal protective properties, which are due to its bioactive compounds. Chemotherapy, such as with cis-diamminedichloroplatinium (CDDP, cisplatin) and its derivatives, is widely used in cancer treatment. It is an effective treatment for human cancers, including ovarian cancer; however, drug resistance is a major obstacle to successful treatment. A better understanding of the mechanisms and strategies for overcoming chemoresistance can greatly improve therapeutic outcomes for patients. In this review article, the bioactive compounds present in Z. jujuba are explained. The high prevalence of many different cancers worldwide has recently attracted the attention of many researchers. This is why our research group focused on studying the anticancer activity of Z. jujuba as well as its impact on chemoresistance both in vivo and in vitro. We hope that these studies can lead to a promising future for cancer patients.

Saponins with highly hydroxylated oleanane-type aglycones from Silphium asteriscus L

Silphium asteriscus L., commonly known as starry rosinweed, is a plant found in prairies, glades, woodlands and savannas of the southeastern United States. The phytochemical investigation of the methanolic extract of S. asteriscus leaves led to the isolation of eighteen saponins with highly hydroxylated oleanane-type aglycones never reported before. Their structures were elucidated by extensive spectroscopic methods including 1D- ((1)H and (13)C) and 2D-NMR (DQF-COSY, HSQC, HMBC, TOCSY and ROESY) experiments as well as ESIMS analysis. The antiproliferative activity of the isolated compounds was evaluated against three cancer cell lines including Hela (human epitheloid cervix carcinoma), Jurkat cells (leukaemic T-cell line) and DLD-1 (colorectal adenocarcinoma). Compounds 1, 5 and 17 displayed weak activity with IC50 values ranging from 50 to 75 μM.

Ursolic acid in cancer prevention and treatment: molecular targets, pharmacokinetics and clinical studies

Discovery of bioactive molecules and elucidation of their molecular mechanisms open up an enormous opportunity for the development of improved therapy for different inflammatory diseases, including cancer. Triterpenoids isolated several decades ago from various medicinal plants now seem to have a prominent role in the prevention and therapy of a variety of ailments and some have already entered Phase I clinical trials. One such important and highly investigated pentacyclic triterpenoid, ursolic acid has attracted great attention of late for its potential as a chemopreventive and chemotherapeutic agent in various types of cancer. Ursolic acid has been shown to target multiple proinflammatory transcription factors, cell cycle proteins, growth factors, kinases, cytokines, chemokines, adhesion molecules, and inflammatory enzymes. These targets can potentially mediate the chemopreventive and therapeutic effects of ursolic acid by inhibiting the initiation, promotion and metastasis of cancer. This review not only summarizes the diverse molecular targets of ursolic acid, but also provides an insight into the various preclinical and clinical studies that have been performed in the last decade with this promising triterpenoid.

Olean-12-eno[2,3-c] [1,2,5]oxadiazol-28-oic acid (OEOA) induces G1 cell cycle arrest and differentiation in human leukemia cell lines

Oleanolic acid (3β-hydroxy-olea-12-en-28-oic acid) is a natural pentacyclic triterpenoic acid found in many fruits, herbs and medicinal plants. In the past decade, increasing evidence has suggested that oleanolic acid exhibits inhibitory activities against different types of cancer including skin cancer and colon cancer, but not leukemia. We report here that a derivative of oleanolic acid, olean-12-eno[2,3-c] [1], [2], [5]oxadiazol-28-oic acid (designated OEOA) effectively blocks the proliferation of human leukemia cells. OEOA significantly reduces cell proliferation without inducing cell death in three types of leukemia cell lines, including K562, HEL and Jurket. Moreover, exposure of K562 cells to OEOA results in G1 cell cycle arrest, with a concomitant induction of cyclin-dependent kinase inhibitor p27 and downregulation of cyclins and Cdks that are essential for cell cycle progression. Interestingly, OEOA also enhances erythroid differentiation in K562 cells through suppressing the expression of Bcr-Abl and phosphorylation of Erk1/2. These findings identify a novel chemical entity for further development as therapeutics against leukemia.

A simple GC-MS method for the screening of betulinic, corosolic, maslinic, oleanolic and ursolic acid contents in commercial botanicals used as food supplement ingredients

The occurrence of triterpene pentacyclic acids in plants is extensive, but little is known about their availability in commercial extracts. A simple GC-MS method for the simultaneous determination of betulinic, corosolic, maslinic, oleanolic and ursolic acids was developed and applied to 38 different commercial plant extracts sold as ingredients for dietary supplements. A suitable protocol was set up to perform routine control of a diverse array of samples with different botanical, chemical and physical characteristics. Remarkable quantities of corosolic acid were found in dried extracts from aerial parts of Lagerstroemia speciosa and Ortosiphon stamineus (14233 and 1132 mg/kg, respectively), while oleanolic acid was abundant in O. stamineus and Crataegus monogyna flowers (2774 and 2339 mg/kg); ursolic was identified in O. stamineus, C. monogyna, L. speciosa and Arctostaphylos uva-ursi leaves (7773, 4165, 2108 and 1034 mg/kg). Only L. speciosa was rich in maslinic acid (4958 mg/kg), while minor amounts of betulinic acid (257 and 80 mg/kg) were detected in L. speciosa and C. monogyna extracts. Lower quantities of triterpenic acids were identified in dried extracts of Harpagophyton procumbens root, propolis, Punica granatum root, Styrax benzoin, Vaccinium myrtillus fruits and Vitis vinifera seeds. Decoctions and fluid extracts lacked or contained very low amounts of triterpenic acids. Results are discussed in terms of quality and safety of these ingredients.

Identification and quantification of oleanolic acid and ursolic acid in Chinese herbs by liquid chromatography-ion trap mass spectrometry

A rapid and sensitive method for the identification and quantification of ursolic acid (UA) and oleanolic acid (OA) in Chinese herbs is described. The method combines liquid chromatography (LC) with ion trap-mass spectrometry (IT-MS) detection. The UA and OA standard solution were directly infused into IT-MS for collecting MS(n) spectra. The major fragment ions of UA and OA were confirmed by MS(n) at m/z 455, 407, 391, 377 and 363 in negative ion mode, and m/z 457, 439, 411 and 393 in positive mode, respectively. The possible main cleavage pathway of fragment ions was studied. UA and OA provided good signals corresponding to the deprotonated molecular ion [M - H](-). The method is reliable and reproducible, and the detection limit is 5 ng/mL. The method was validated in the concentration range of 0.04-40 μg/mL; intra- and inter-day precisions ranged from 0.78 to 2.15%, and the accuracy was 96.5-108.2% for UA and OA. The mean recovery of UA and OA was 97.1-106.2% with RSD less than 1.86%. An LC-IT-MS method was successfully applied to determine the UA and OA in nine Chinese herbs.

Immunopotentiation and antitumor effects of a ginsenoside Rg₃-fortified red ginseng preparation in mice bearing H460 lung cancer cells

Antitumor effects of a ginsenoside Rg(3)-fortified red ginseng preparation (Rg(3)-RGP) were investigated in human non-small cell lung carcinoma (H460) cells using in vitro cytotoxicity assay and in vivo nude mouse xenograft model. Immunomodulatory effects of the preparation were also assessed by measuring the facilitating activities on the nitric oxide (NO) release from peritoneal macrophages, in vitro and in vivo lymphocyte proliferation, and the carbon clearance from circulating blood. In a cell level, Rg(3)-RGP exerted H460 cytotoxicity and facilitated splenocyte proliferation at very high concentrations, without affecting NO production. However, oral administration of Rg(3)-RGP (100-300 mg/kg) enhanced carbon particle-phagocytic index of blood macrophages up to 360-397% of control value. In addition, Rg(3)-RGP significantly increased the splenocyte proliferation (23% at 100mg/kg). In tumor-bearing mice, 28-day oral treatment with Rg(3)-RGP (100mg/kg) remarkably suppressed the tumor growth, leading to the decrease of the tumor volume and weight by 30-31%, which was comparable to the effect (27-29% reduction) of doxorubicin (2mg/kg at 3-day intervals). While Rg(3)-RGP did not cause adverse effects, intravenous injection of doxorubicin markedly decreased body and testes weights, and exhibited severe depletion of spermatogenic cells in the atrophic seminiferous tubules. These results indicate that Rg(3)-RGP exerts antitumor activities via indirect immunomodulatory actions, without causing adverse effects as seen in doxorubicin.

Korean red ginseng extract does not cause embryo-fetal death or abnormalities in mice

BACKGROUND

Ginseng has been used for a long time and is well tolerated in humans. However, recent studies have shown that ginsenosides Rb1, Rg1, and Re exert embryotoxicity in in vitro culture systems. We investigated the effects of Korean red ginseng extract (KRGE) on embryonic implantation and fetal development in mice.

METHODS

Mice were orally administered KRGE (20, 200, or 2,000 mg/kg/day) from 2 weeks before mating to gestational day (GD) 18, and implantation rate, fetal mortality, body weights, as well as external, visceral, and skeletal abnormalities were determined by Caesarean section on GD18. Ginsenosides in KRGE and in the blood of dams were identified and quantified by HPLC analysis.

RESULTS

KRGE did not affect embryonic implantation and mortality as well as fetal body weights up to 2,000 mg/kg/day (approximately 200 times clinical doses), the upper-limit dose recommended by the Korea Food and Drug Administration (KFDA). Although the prevalence of supernumerary ribs increased at the medium dose (200 mg/kg/day), no dose-dependent increases in external, visceral, and skeletal abnormalities were observed. Major ginsenosides such as Rb1, Rg1, and Re were not detected in the blood of dams based on their chromatographic profiles.

CONCLUSIONS

Considerable developmental toxicities of KRGE, even at the upper-limit dose, were not observed in mice. These results might be due to the negligible blood concentrations of ginsenosides in their original forms following oral administration, suggesting that in vitro experiments to assess the effects of ginsenosides on embryotoxicity may not reliably explain the risks of ginsenosides to in vivo embryo-fetal development.

Pentacyclic triterpene distribution in various plants - rich sources for a new group of multi-potent plant extracts

Pentacyclic triterpenes are secondary plant metabolites widespread in fruit peel, leaves and stem bark. In particular the lupane-, oleanane-, and ursane triterpenes display various pharmacological effects while being devoid of prominent toxicity. Therefore, these triterpenes are promising leading compounds for the development of new multi-targeting bioactive agents. Screening of 39 plant materials identified triterpene rich (> 0.1% dry matter) plant parts. Plant materials with high triterpene concentrations were then used to obtain dry extracts by accelerated solvent extraction resulting in a triterpene content of 50 - 90%. Depending on the plant material, betulin (birch bark), betulinic acid (plane bark), oleanolic acid (olive leaves, olive pomace, mistletoe sprouts, clove flowers), ursolic acid (apple pomace) or an equal mixture of the three triterpene acids (rosemary leaves) are the main components of these dry extracts. They are quantitatively characterised plant extracts supplying a high concentration of actives and therefore can be used for development of phytopharmaceutical formulations.

Rapid and novel discrimination and quantification of oleanolic and ursolic acids in complex plant extracts using two-dimensional nuclear magnetic resonance spectroscopy-Comparison with HPLC methods

A novel strategy for NMR analysis of mixtures of oleanolic and ursolic acids that occur in natural products is described. These important phytochemicals have similar structure and their discrimination and quantification is rather difficult. We report herein the combined use of proton-carbon heteronuclear single-quantum coherence ((1)H-(13)C HSQC) and proton-carbon heteronuclear multiple-bond correlation ((1)H-(13)C HMBC) NMR spectroscopy, in the identification and quantitation of oleanolic acid (OA) and ursolic acid (UA)in plant extracts of the Lamiaceae and Oleaceae family. The combination of (1)H-(13)C HSQC and (1)H-(13)C HMBC techniques allows the connection of the proton and carbon-13 spins across the molecular backbone resulting in the identification and, thus, discrimination of oleanolic and ursolic acid without resorting to physicochemical separation of the components. The quantitative results provided by 2D (1)H-(13)C HSQC NMR data were obtained within a short period of time ( approximately 14min) and are in excellent agreement with those obtained by HPLC, which support the efficiency of the suggested methodology.

Triterpene saponins from Silphium radula

Nine triterpene saponins (1-9) were isolated from leaves and stems of Silphium radula Nutt. (Asteraceae). Their structures were determined by extensive 1D ((13)C, (1)H, DEPT, TOCSY) and 2D NMR (NOESY, HSQC, HMBC) and ESI-MS studies. The compounds were identified as 3beta,6beta,16beta-trihydroxyolean-12-en-23-al-3-O-beta-glucopyranosyl-16-O-beta-glucopyranoside (1), urs-12-ene-3beta,6beta,16beta-triol-3-O-beta-galactopyranosyl-(1-->2)-beta-glucopyranoside (2), 3beta,6beta,16beta-trihydroxyolean-12-en-23-oic acid-3-O-beta-glucopyranosyl-16-O-beta-glucopyranoside (3), urs-12-ene-3beta,6beta,16beta,21beta-tetraol-3-O-beta-glucopyranoside (4), olean-12-ene-3beta,6beta,16beta,21beta-tetraol-3-O-beta-glucopyranoside (5), olean-12-ene-3beta,6beta,16beta,21beta,23-pentaol-3-O-beta-glucopyranosyl-16-O-beta-glucopyranoside (6), olean-12-ene-3beta,6beta,16beta-triol-3-O-beta-glucopyranosyl-16-O-alpha-arabinopyranosyl-(1-->2)-beta-glucopyranoside (7), olean-12-ene-3beta,6beta,16beta,23-tetraol-3-O-beta-glucopyranosyl-16-O-alpha-arabinopyranosyl-(1-->2)-beta-glucopyranoside (8), 3beta,6beta,16beta,21beta-tetrahydroxyolean-12-en-23-al-3-O-beta-glucopyranoside (9). The presence of a 6beta-hydroxyl function was not common in the oleanene or ursene class and the aglycones of these compounds were not found previously in the literature. Moreover, the cytotoxic activities of the isolated compounds were tested against human breast cancer cell line MDA-MB-231. Results showed that compound 2 decreased cell proliferation in a statistically significant manner at 25 microg/ml.

Ursolic acid from the Chinese herb danshen (Salvia miltiorrhiza L.) upregulates eNOS and downregulates Nox4 expression in human endothelial cells

Danshen, the dried root of Salvia miltiorrhiza Bunge (Lamiaceae), is one of the most commonly used traditional Chinese medicines for cardiovascular indications. In EA.hy 926 cells, a cell line derived from human umbilical vein endothelial cells (HUVEC), an aqueous extract of danshen, and also a methanol extract of the plant, increased eNOS promoter activity, eNOS mRNA and protein expression, as well as endothelial NO production. A dichloromethane extract, in contrast, did not change eNOS gene expression. Thus, the active danshen constituent(s) responsible for eNOS upregulation is (are) hydrophilic and/or alcohol-soluble. One such compound is ursolic acid that significantly increased eNOS expression in EA.hy 926 cells and native HUVEC, and enhanced bioactive NO production measured in terms of its cGMP increasing activity. Other tested hydrophilic and alcohol-soluble compounds isolated from danshen had no effect on eNOS expression. Interestingly, ursolic acid also reduced the expression of the NADPH oxidase subunit Nox4 and suppressed the production of reactive oxygen species in human endothelial cells. Upregulation of eNOS and a parallel downregulation of Nox4 lead to an increase in bioactive NO. This in turn could mediate some of the beneficial effects of danshen. Ursolic acid is a prototypical compound responsible for this effect of the plant.