Cycloartane triterpenoids from Astragalus bicuspis

Four new cycloartane-type triterpenoids from the leaves of Combretum mellifluum Eichler: assessment of their antioxidant and antileishmanial activities

The beneficial pharmacological actions including antioxidant effects as an antileishmanial, antibacterial, antifungal, antidiabetic, anti-inflammatory, antitumor, antiviral, and analgesic of compounds isolated from Combretum mellifluum Eichler (Combretaceae) are well established. The aim of the present study was to determine the phytochemistry as well as assess the antioxidant and antileishmanial activities of the leaves from Combretum mellifluum Eichler (Combretaceae). Analysis of ethanolic extract resulted in isolation and identification of two epimeric mixtures of four previously unknown cycloartane-type triterpenoids, methyl quadrangularate M and methyl 24-epiquadrangularate M, and 2α,3β,24β-trihydroxy-cycloart-25-ene and 2α, 3β, 24α-trihydroxy-cycloart-25-ene, and eight known compounds. Their structures were using one-dimensional nuclear magnetic resonance (1D NMR), 2D NMR and high-resolution electrospray ionization mass spectroscopy (HRESIMS) analysis. Further, the extract and fractions were tested for antioxidant potential. The ethyl acetate and aqueous fractions demonstrated the highest antioxidant activity against 2,2-dipheny-1-picrylhydrazl (DPPH) free radicals, which correlated directly with total flavonoid content. All extracts and fractions from C. mellifluum Eichler were assessed for antileishmanial activity. The supernatant fraction exhibited highest potential, inhibiting the growth of Leishmania amazonensis with IC₅₀ value 31.29 μg/ml. Our findings provide information on the chemical composition of C. mellifluum and the potential beneficial therapeutic usefulness as an antioxidant agent in various diseases.

Astragalus species: Insights on its chemical composition toward pharmacological applications

Astragalus L. is widely distributed throughout the temperate regions of Europe, Asia, and North America. The genus is widely used in folk medicine and in dietary supplements, as well as in cosmetics, teas, coffee, vegetable gums, and as forage for animals. The major phytoconstituents of Astragalus species with beneficial properties are saponins, flavonoids, and polysaccharides. Astragalus extracts and their isolated components exhibited promising in vitro and in vivo biological activities, including antiaging, antiinfective, cytoprotective, antiinflammatory, antioxidant, antitumor, antidiabesity, and immune-enhancing properties. Considering their proven therapeutic potential, the aim of this work is to give a comprehensive summary of the Astragalus spp. and their active components, in an attempt to provide new insight for further clinical development of these xenobiotics. This is the first review that briefly describes their ethnopharmacology, composition, biological, and toxicological properties.

A Study on the Mechanism of Milkvetch Root in the Treatment of Diabetic Nephropathy Based on Network Pharmacology

Diabetic nephropathy (DN) is one of the most common complications of diabetes mellitus. Owing to its complicated pathogenesis, no satisfactory treatment strategies for DN are available. Milkvetch Root is a common traditional Chinese medicine (TCM) and has been extensively used to treat DN in clinical practice in China for many years. However, due to the complexity of botanical ingredients, the exact pharmacological mechanism of Milkvetch Root in treating DN has not been completely elucidated. The aim of this study was to explore the active components and potential mechanism of Milkvetch Root by using a systems pharmacology approach. First, the components and targets of Milkvetch Root were analyzed by using the Traditional Chinese Medicine Systems Pharmacology database. We found the common targets of Milkvetch Root and DN constructed a protein-protein interaction (PPI) network using STRING and screened the key targets via topological analysis. Enrichment of Gene Ontology (GO) pathways and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were analyzed. Subsequently, major hubs were identified and imported to the Database for Annotation, Visualization and Integrated Discovery for pathway enrichment analysis. The binding activity and targets of the active components of Milkvetch Root were verified by using the molecular docking software SYBYL. Finally, we found 20 active components in Milkvetch Root. Moreover, the enrichment analysis of GO and KEGG pathways suggested that AGE-RAGE signaling pathway, HIF-1 signaling pathway, PI3K-Akt signaling pathway, and TNF signaling pathway might be the key pathways for the treatment of DN; more importantly, 10 putative targets of Milkvetch Root (AKT1, VEGFA, IL-6, PPARG, CCL2, NOS3, SERPINE1, CRP, ICAM1, and SLC2A) were identified to be of great significance in regulating these biological processes and pathways. This study provides an important scientific basis for further elucidating the mechanism of Milkvetch Root in treating DN.

Kleinhospitine E and Cycloartane Triterpenoids from Kleinhovia hospita

A novel cycloartane triterpenoid alkaloid, kleinhospitine E (1), six new cycloartane triterpenoids (2-7), three known cycloartane triterpenoids (8-10), and taraxerone (11) were isolated from a methanol extract of Kleinhovia hospita. Their structures were elucidated by 1D- and 2D-NMR spectroscopy as well as HRMS analysis. The absolute configurations of all isolated compounds were determined from their ECD spectra by comparison with theoretical values. Kleinhospitine E (1) is the first cycloartane alkaloid possessing an unusual γ-lactam with an oxopropylidene side chain. Compounds 2, 3, and 6 were assigned as cycloartane triterpenoids with a 9α,10α-cyclopropyl ring, which is found rarely among naturally occurring compounds, while 4 and 5 were established as isomers of compound 3 containing a 21,23-diacetal side chain. Biological evaluation revealed that compounds 4 and 9 exhibited more potent antiproliferative activities against a multidrug-resistant tumor cell line compared with its parent chemosensitive cell line. Furthermore, compound 6 exhibited submicromolar anti-HIV activity.

Chemical constituents from Licania cruegeriana and their cardiovascular and antiplatelet effects

Three new lupane-type triterpenoids: 6β,30-dihydroxybetulinic acid glucopyranosyl ester (4), 6β,30-dihydroxybetulinic acid (5) and 6β-hydroxybetulinic acid (6), were isolated from Licania cruegeriana Urb. along with six known compounds. Their structures were elucidated on the basis of spectroscopic methods, including IR, ESIMS, 1D- and 2D-NMR experiments, as well as by comparison of their spectral data with those of related compounds. All compounds were evaluated in vivo for their effects on the mean arterial blood pressure (MABP) and heart rate (HR) of spontaneously hypertensive rats (SHR) and also in vitro for their capacity to inhibit the human platelet aggregation. None of the isolated flavonoids 1-3 showed cardiovascular effects on SHR and among the isolated triterpenoids 4-9 only 5 and 6 produced a significant reduction in MABP (60.1% and 17.2%, respectively) and an elevation in HR (11.0% and 41.2%, respectively). Compounds 3, 4, 5 and 6 were able to inhibit human platelet aggregation induced by ADP, collagen and arachidonic acid with different selectivity profiles.

A review of recent research progress on the astragalus genus

Astragalus L., is one of the largest genuses of flowering plants in the Leguminosae family. Roots of A. membranaceus Bge. var. mongholicus (Bge.) Hsiao, A. membranaceus (Fisch.) Bge. and its processed products are listed in the China Pharmacopeia for “qi deficiency” syndrome treatment. However, more and more researches on other species of Astragalus have been conducted recently. We summarize the recent researches of Astragalus species in phytochemistry and pharmacology. More than 200 constituents, including saponins and flavonoids, obtained from 46 species of Astragalus genus were collected for this article. In pharmacological studies, crude extracts of Astragalus, as well as isolated constituents showed anti-inflammatory, immunostimulant, antioxidative, anti-cancer, antidiabetic, cardioprotective, hepatoprotective, and antiviral activities. The goal of this article is to provide an overview of chemical and pharmacological studies on the Astragalus species over the last 10 years, which could be of value to new drug or food supplement research and development.

Smith degradation, an efficient method for the preparation of cycloastragenol from astragaloside IV

Cycloastragenol (CA) is the genuine sapogenin of astragaloside IV (ASI). This study focuses on the preparation of CA from ASI. Five hydrolysis methods were compared including H2SO4 hydrolysis, HCl hydrolysis, two-phase acid hydrolysis, mild acid hydrolysis, and Smith degradation. Seven hydrolysis products were purified, and five of them were identified as new compounds. The results indicated that Smith degradation was the most effective approach to prepare CA. In contrast, mild acid hydrolysis produced CA at a low yield, accompanied with the artificial sapogenin astragenol. The other three acid hydrolysis methods mainly produced astragenol. Furthermore, the reaction conditions for Smith degradation were optimized as follows: ASI was dissolved in 60% MeOH-H2O solution, oxidized with 5 equiv. NaIO4 for 12h, followed by reduction with 3 equiv. NaBH4 for 4h, and finally acidified with 1M H2SO4 at pH2 for 24h. Under the optimal conditions, CA could be prepared from ASI at a yield of 84.4%.

Substituted benzenediol Schiff bases as promising new anti-glycation agents

A feature of diabetes is that the rate of protein glycation and the formation of advanced glycation endproducts (AGEs) increases spontaneously due to the abnormally elevated levels of sugar in the blood. The glycation of proteins is associated with a large number of late diabetic complications (retinopathy, neuropathy, atherosclerosis, end stage renal diseases, rheumatoid arthritis and neurodegenerative diseases). The increase in diabetic complications is a major cause of morbidity and mortality, which has increased significantly in the last two decades. Therefore, there is a considerable recent interest in the identification of lead molecules, which can inhibit the glycation process or slow it down considerably. A new class of anti-glycation agents has been identified, based on the spectrofluorimetric analysis of fluorescent advanced glycation endproducts (AGEs), benzenediol Schiff bases, and their structure-activity relationships have been studied. Some of these compounds have shown a promising anti-glycation potential in vitro.

Triterpenoids

This review covers the isolation and structure determination of triterpenoids including squalene derivatives, protostanes, lanostanes, holostanes, cycloartanes, dammaranes, euphanes, tirucallanes, tetranortriterpenoids, lupanes, oleananes, friedelanes, ursanes, hopanes, isomalabaricanes and saponins; 574 references are cited.