Hyaluronidase inhibitory saponins and a trypanocidal isoflavonoid from the aerial parts of Oxytropis lanata

Isolation of Antiplasmodial Oxazoles and Isoflavonoids from the Roots of Oxytropis trichophysa and Total Synthesis of Oxazole-type Alkaloids

A chemical examination of a root extract of Oxytropis trichophysa led to the isolation and identification of 23 compounds, including oxazole-type alkaloids and isoflavonoid derivatives. Notably, three oxazole-type alkaloids (1, 2, and 3) and two isoflavonoid derivatives (7 and 10) were obtained from a natural source for the first time. In addition, O. trichophysa derived 2,5-diphenyloxazoles and their derivatives were synthesized. Despite their potential activity, the antiplasmodial activities of naturally occurring 2,5-diphenyloxazoles and certain isoflavonoids remain unexplored. Therefore, the antiplasmodial activities of both the naturally occurring and synthesized compounds were evaluated against Plasmodium falciparum strain 3D7. Among the tested compounds, three naturally occurring oxazole-type alkaloids (1, 5, and 6), one synthesized alkaloid (34), and two isoflavonoid derivatives (13 and 15) demonstrated significant inhibitory effects, with half-maximal inhibitory concentration (IC50) values ranging from 3.1 to 6.2 μM and selective indices between 0.9 and 18.8. Compound 1 showed the most potent inhibitory activity, with an IC50 of 3.1 μM, while its cytotoxic concentration 50% value against human foreskin fibroblasts was found to be 8.5 μM. The oxazole-type alkaloids and isoflavonoids isolated from this plant provide valuable insights into its chemical composition and may help elucidate the antiplasmodial properties of O. trichophysa.

The genus Oxytropis DC: application, phytochemistry, pharmacology, and toxicity

OBJECTIVES

Oxytropis DC is a perennial plant of Fabaceae family, which is widely distributed in the northern temperate zone. It is known as "locoweed" because of its toxic component swainsonine. However, it is widely used in Tibetan medicine and Mongolian medicine, mainly for the treatment of heat-clearing and detoxifying, pain-relieving, anti-inflammatory, hemostasis, and other diseases. To provide a basis for the further development and utilization of Oxytropis DC, the pieces of literature about the application, phytochemistry, pharmacological action, and toxicity of Oxytropis DC were reviewed and analyzed.

KEY FINDINGS

A total of 373 chemical constituents were found from Oxytropis DC, including flavonoids, alkaloids, steroids, terpenoids, and others. Pharmacological actions mainly include antitumor, antioxidation, anti-inflammatory, analgesic, antibacterial, antifibrosis, and other pharmacological actions, among them, the antitumor effect is particularly prominent.

SUMMARY

At present, studies on its pharmacological effects are mainly concentrated on the extracts, some flavonoids, and alkaloids. In the follow-up studies, research on the pharmacological activities of the other chemical constituents in Oxytropis should be strengthened. It has the potential to pave the way for research and development of novel Oxytropis medicines.

Astraoleanosides E-P, oleanane-type triterpenoid saponins from the aerial parts of Astragalus membranaceus Bunge and their β-glucuronidase inhibitory activity

Historically, Astragalus membranaceus Bunge has been used as a beneficial medicinal plant, particularly in the Asian traditional medical systems, for the treatment of various human diseases such as stomach ulcers, diarrhea, and respiratory issues associated with phlegm. In this study, a phytochemical characterization of the aerial parts of A. membranaceusled to the isolation of 29 oleanane-type triterpenoid saponins, including 11 new compounds named astraoleanosides E-P (6-9, 13, 14, 18-22), as well as 18 known ones. The structures of these compounds were elucidated using nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectrometry. Among them, astraoleanoside H (9) and cloversaponin III (15) demonstrated the most potent β-glucuronidase inhibitory activities, with IC50 values of 21.20 ± 0.75 and 9.05 ± 0.47 µM, respectively, compared to the positive control d-saccharic acid 1,4-lactone (IC50 = 20.62 ± 1.61 µM). Enzyme kinetics studies were then conducted to investigate the type of inhibition exhibited by these active compounds. In addition, the binding mechanism, key interactions, binding stability, and dynamic behavior of protein-ligand complexes were investigated through in silico approaches, such as molecular docking and molecular dynamics simulations. These findings highlight the promising potential of triterpenoid saponins from A. membranaceus as lead compounds for β-glucuronidase inhibitors, offering new possibilities for the development of therapeutic agents targeting various diseases where β-glucuronidase plays a crucial role.

Screening of Monoamine Oxidase B Inhibitors from Fragaria nubicola by Ligand Fishing and Their Neuroprotective Effects

Fragaria nubicola, known as Tibetan strawberry, is an edible plant possessing various health-promoting effects. However, its functional compositions were rarely studied. In this work, monoamine oxidase B (MAO-B) inhibitors in this plant were rapidly screened using the enzyme-functionalized magnetic nanoparticles coupled with UPLC-QTOF-MS. Two inhibitors, quercetin-3-O-β-d-glucuronide-6″-methyl ester (1) and kaempferol-3-O-β-d-glucuronide-6″-methyl ester (2), were identified from this plant with the IC₅₀ values of 19.44 ± 1.17 and 22.63 ± 1.78 μM, respectively. Enzyme kinetic analysis and molecular docking were carried out to investigate the mechanism of inhibition. Contents of both compounds as well as those of total phenolics and flavonoids were quantified to be 24.76 ± 1.26, 35.59 ± 1.17, 837.67 ± 10.62, and 593.46 ± 10.37 μg/g, respectively. In addition, both compounds exhibited significant neuroprotective effects on 6-hydroxydopamine-induced PC12 cells. This is the first report on the neuroprotective components of F. nubicola, suggesting its potential for developing neuroprotective functional food.

Bioactive Metabolites of Lactiplantibacillus plantarum K014 Against Methicillin-Resistant Staphylococcus aureus ATCC43300 and In Vitro Evaluation of Its Antibacterial, Antioxidant and Anti-inflammatory Activities

This study aims to evaluate the effects of bioactive metabolites produced by lactic acid bacteria against methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300. A total of six lactic acid bacteria (LAB) were selected to evaluate the antimicrobial activity against MRSA ATCC 43300, a skin pathogen that is highly resistant to most antibiotics. The K014 isolate from a fermented vegetable recorded the highest inhibition against MRSA ATCC 43300 at 91.93 ± 0.36%. 16S rRNA sequencing revealed the K014 isolate is closely related to L. plantarum and the sequence was subsequently deposited in the GenBank database with an accession number of MW180960, named as Lactiplantibacillus plantarum K014. The cell-free supernatant (CFS) of L. plantarum K014 had tolerance to high temperature as well as acidic pH. The bioactive metabolites, such as hydrogen peroxide, lactic acid and hyaluronic acid, were produced by L. plantarum K014. Result from ABTS assay showed higher antioxidant activity (46.28%) as compared to that obtained by DPPH assay (2.97%). The CFS had showed anti-inflammatory activity for lipoxygenase (LOX) assay at 43.66%. The bioactive metabolites of L. plantarum K014 showed very promising potential to be used topical skin pathogens.

Paving the way towards effective plant-based inhibitors of hyaluronidase and tyrosinase: a critical review on a structure-activity relationship

Human has used plants to treat many civilisation diseases for thousands of years. Examples include reserpine (hypertension therapy), digoxin (myocardial diseases), vinblastine and vincristine (cancers), and opioids (palliative treatment). Plants are a rich source of natural metabolites with multiple biological activities, and the use of modern approaches and tools allowed finally for more effective bioprospecting. The new phytochemicals are hyaluronidase (Hyal) inhibitors, which could serve as anti-cancer drugs, male contraceptives, and an antidote against venoms. In turn, tyrosinase inhibitors can be used in cosmetics/pharmaceuticals as whitening agents and to treat skin pigmentation disorders. However, the activity of these inhibitors is stricte dependent on their structure and the presence of the chemical groups, e.g. carbonyl or hydroxyl. This review aims to provide comprehensive and in-depth evidence related to the anti-tyrosinase and anti-Hyal activity of phytochemicals as well as confirming their efficiency and future perspectives.

Evaluation of Mongolian compound library for potential antimalarial and anti-Toxoplasma agents

179 compounds in a Mongolian compound library were investigated for their inhibitory effect on the in vitro growth of Plasmodium falciparum and Toxoplasma gondii. Among these compounds, brachangobinan A at a half-maximal inhibition concentration (IC₅₀) of 2.62 μM and a selectivity index (SI) of 27.91; 2-(2'-hydroxy-5'-O-methylphenyl)-5-(2″,5″-dihydroxyphenyl)oxazole (IC₅₀ 3.58 μM and SI 24.66); chrysosplenetin (IC₅₀ 3.78 μM and SI 15.26); 4,11-di-O-galloylbergenin (IC₅₀ 3.87 μM and SI 13.38); and 2-(2',5'-dihydroxyphenyl)-5-(2″-hydroxyphenyl)oxazole (IC₅₀ 6.94 μM and SI 11.48) were identified as potential inhibitors of P. falciparum multiplication. Additionally, tricin (IC₅₀ 12.94 μM and SI > 23.40) was identified as a potential inhibitor of T. gondii multiplication. Our findings represent a good starting point for developing novel antimalarial and anti-Toxoplasma therapeutics from Mongolian compounds.

Biological activity evaluations of chemical constituents derived from Mongolian medicinal forage plants and their applications in combating infectious diseases and addressing health problems in humans and livestock

Mongolian nomadic people possess traditional knowledge of wild plants that grow in their areas of habitation. Many of these are forage plants in nature and are consumed by livestock. However, these plants are known to have medicinal and/or toxic properties. To establish a scientific understanding of the plants, and in turn, offer sound knowledge on their applications and effective use, it is essential to collect data pertaining to the chemical constituents of each plant. Therefore, the first objective of this study was to identify and determine the structural constituents of the forage plants that were available to our research group. Furthermore, in an attempt to demonstrate the biological activities of the isolated chemical compounds, we focused on solving some of the social issues affecting Mongolian communities, including protozoan diseases affecting livestock, vectors of infectious diseases, and the general health of humans and their livestock. The results of the chemical constituents derived from Mongolian medicinal plants and their biological activities that were studied in the recent decade are also described herein.

Nutritional Aspects of Ecologically Relevant Phytochemicals in Ruminant Production

This review provides an update of ecologically relevant phytochemicals for ruminant production, focusing on their contribution to advancing nutrition. Phytochemicals embody a broad spectrum of chemical components that influence resource competence and biological advantage in determining plant species' distribution and density in different ecosystems. These natural compounds also often act as plant defensive chemicals against predatorial microbes, insects, and herbivores. They may modulate or exacerbate microbial transactions in the gastrointestinal tract and physiological responses in ruminant microbiomes. To harness their production-enhancing characteristics, phytochemicals have been actively researched as feed additives to manipulate ruminal fermentation and establish other phytochemoprophylactic (prevent animal diseases) and phytochemotherapeutic (treat animal diseases) roles. However, phytochemical-host interactions, the exact mechanism of action, and their effects require more profound elucidation to provide definitive recommendations for ruminant production. The majority of phytochemicals of nutritional and pharmacological interest are typically classified as flavonoids (9%), terpenoids (55%), and alkaloids (36%). Within flavonoids, polyphenolics (e.g., hydrolyzable and condensed tannins) have many benefits to ruminants, including reducing methane (CH4) emission, gastrointestinal nematode parasitism, and ruminal proteolysis. Within terpenoids, saponins and essential oils also mitigate CH4 emission, but triterpenoid saponins have rich biochemical structures with many clinical benefits in humans. The anti-methanogenic property in ruminants is variable because of the simultaneous targeting of several physiological pathways. This may explain saponin-containing forages' relative safety for long-term use and describe associated molecular interactions on all ruminant metabolism phases. Alkaloids are N-containing compounds with vast pharmacological properties currently used to treat humans, but their phytochemical usage as feed additives in ruminants has yet to be exploited as they may act as ghost compounds alongside other phytochemicals of known importance. We discussed strategic recommendations for phytochemicals to support sustainable ruminant production, such as replacements for antibiotics and anthelmintics. Topics that merit further examination are discussed and include the role of fresh forages vis-à-vis processed feeds in confined ruminant operations. Applications and benefits of phytochemicals to humankind are yet to be fully understood or utilized. Scientific explorations have provided promising results, pending thorough vetting before primetime use, such that academic and commercial interests in the technology are fully adopted.

Hyaluronidase and degranulation inhibitors from the edible roots of Oenanthe javanica including seric acids F and G that were obtained by heating

Oenanthe javanica is a vegetable grown in East Asia and Australia in which the roots and aerial parts are boiled together to make certain traditional dishes. Nineteen compounds (1-19) were isolated from O. javanica roots and the chemical structures of 2 new norlignans were determined. The inhibitory effects of the compounds on hyaluronidase and degranulation in RBL-2H3 cells were evaluated to determine antiallergic and antiinflammation activities. Saponins (2-4) and the new norlignan seric acid G (12) were among the active compounds identified. Seric acid G (12), a methoxy derivative of seric acid F (11), was obtained as an interconverting mixture of 3:1 trans-cis isomers. Seric acids F and G (11, 12) were derived from seric acids C (10) and E, respectively, by decarboxylation and dehydration reactions that occurred during heating. It was confirmed by HPLC analysis that all eleven of the O. javanica cultivars contained seric acid C (10).