Zanzibar yam (Dioscorea sansibarensis Pax) isolates exhibit cyclooxygenase enzyme and lipid peroxidation inhibitory activities

The genus Dioscorea L. (Dioscoreaceae), a review of traditional uses, phytochemistry, pharmacology, and toxicity

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Dioscorea, a member of the Dioscoreaceae family, comprises approximately 600 species and is widely distributed across temperate and tropical regions such as Asia, South Africa, and North America. The traditional medicinal uses of Dioscorea have been documented in Asian and African pharmacological systems. In Asia, this genus is traditionally used to treat respiratory illnesses, rheumatism, diabetes, diarrhea, dysentery, and other conditions. In Africa, this genus has been used to treat human immunodeficiency virus and ring worms. However, the traditional medicinal practices in North America rarely mention the use of this genus.

AIM OF THE STUDY

The aim of this review is to comprehensively review the genus Dioscorea, focusing on its traditional uses, phytochemical constituents, pharmacological activities, and potential toxicities. The research also aims to highlight the valuable bioactive compounds within Dioscorea and emphasize the need for further investigations into acute and chronic toxicity, activity mechanisms, molecular markers, and other relevant factors to contribute to the discovery of novel pharmaceuticals.

MATERIALS AND METHODS

A search for available information on Dioscorea was conducted using scientific databases, including PubMed, ISI-WOS, Scopus, and Google Scholar, as well as recent academic publications from reputable publishers and other literature sources. The search was not limited by language and spanned the literature published between 1950 and 2022.

RESULTS

This article provides a comprehensive review of the Dioscorea genus, focusing on its traditional uses, phytochemical constituents, pharmacological activities, and potential toxicities. Extensive research has been conducted on this genus, resulting in the isolation and examination of over 1000 compounds, including steroids, terpenoids, and flavonoids, to determine their biological activities. These activities include anti-tumor, anti-inflammatory, immunomodulatory, neuroprotective, hypoglycemic, and hypolipidemic effects. However, some studies have indicated the potential toxicity of high doses of Dioscorea, highlighting the need for further investigations to assess the safety of this genus. Additionally, this review explores potential avenues for future research and discusses the challenges associated with a comprehensive understanding of the Dioscorea genus.

CONCLUSIONS

Based on the existing literature, it can be concluded that Dioscorea is a valuable source of bioactive compounds that have the potential to treat various disorders. Future research should prioritize the investigation of acute and chronic toxicity, activity mechanisms, molecular markers, and other relevant factors. This review provides a comprehensive analysis of the Dioscorea genus, emphasizing its potential to enable a deeper exploration of the biological activity mechanisms of these plants and contribute to the discovery of novel pharmaceuticals.

Isolation and identification of active ingredients and biological activity of Dioscorea nipponica Makino

This study reported the isolation and identification of bioactive compounds from Dioscorea nipponica Makino, a plant used in traditional medicine for various ailments. Nine compounds were isolated, including a new compound named as diosniposide E, which was elucidated by analyzing its ¹H-NMR, ¹³C-NMR, DEPT, COSY, HMBC and MS data and comparing them with data available in literature. The other eight compounds were identified as known compounds. Theoretical calculations of energy and the generation of a molecular electrostatic potential surface map were employed to assess the antioxidant capacity of nine compounds, the calculation results exhibited that compounds 5 and 6 had strong antioxidant capacities. To further evaluate the antioxidant activities of the investigated compounds, the DPPH and ABTS assays were conducted. The results from the DPPH scavenging activity test revealed that compounds 4-6 exhibited enhanced scavenging activities compared to L-ascorbic acid, while displaying similar efficacy to trolox. Moreover, the ABTS scavenging activities of compounds 4-6 were found to surpass those of L-ascorbic acid and trolox. In terms of α-glucosidase inhibition, compounds 3 and 4 displayed remarkable inhibitory activities that surpassed the effects of acarbose. Additionally, compound 2 exhibited potent anticholinesterase activities, outperforming donepezil. This research provides insights into the potential bioactive compounds present in Dioscorea nipponica Makino and may contribute to its use in traditional medicine.

Molecular Targets and Mechanisms of 6,7-Dihydroxy-2,4-dimethoxyphenanthrene from Chinese Yam Modulating NF-κB/COX-2 Signaling Pathway: The Application of Molecular Docking and Gene Silencing

Chinese yam (Dioscorea opposita) tuber has a significant effect of invigorating the intestine and improving the symptoms of long-term diarrhea according to the records of the Chinese Pharmacopoeia. Phenanthrene polyphenols from Chinese yam, with higher inhibition of cyclooxygenase-2 (COX-2) than anti-inflammatory drugs, are an important material basis in alleviating ulcerative colitis via nuclear factor kappa-B (NF-κB)/COX-2 pathway, based on our previous research. The present study further explored the target and molecular mechanisms of phenanthrenes' modulation of the NF-κB/COX-2 signaling pathway by means of molecular docking and gene silencing. Firstly, interleukin-8 (IL-8) and tumor necrosis factor-α (TNF-α) expression of 6-hydroxy-2,4,7-trimethoxyphenanthrene (PC2)/6,7-dihydroxy-2,4-dimethoxyphe-nanthrene (PC4) were compared on TNF-α induced human colon adenocarcinoma (Caco-2) cells. Secondly, molecular docking and dynamics simulation were implemented for PC2/PC4 and COX-2. Finally, COX-2 silencing was performed on TNF-α induced Caco-2 cells to confirm the target of PC4 on NF-κB/COX-2 pathway. Lower expression of IL-8 and TNF-α in PC4 treated Caco-2 cells indicated that PC4 had stronger anti-inflammatory activity than PC2. The binding of PC4 and COX-2 was stronger due to the hydrogen bond between hydroxyl group and Tyr385. No significant differences were found in phosphorylation nuclear factor kappa-B inhibitor alpha (pIkBα), phosphorylation NF-κB (pNF-κB) and phosphorylation extracellular signal-regulated kinase 1/2 (pERK1/2) expression between control and PC4 group after silencing, while these protein expressions significantly decreased in PC4 group without silencing, which confirmed that COX-2 was the important target for PC4 in alleviating ulcerative colitis. These findings indicate that PC4 was supposed to have inhibited NF-κB pathway mediated inflammation via suppression of positive feedback targeting COX-2.

Shuangyu Tiaozhi decoction alleviates non-alcoholic fatty liver disease by improving lipid deposition, insulin resistance, and inflammation in vitro and in vivo

Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases worldwide. Our previous studies have found that Shuangyu Tiaozhi Decoction (SYTZD) could produce an improvement in NAFLD-related indicators, but the underlying mechanism associated with this improvement remains unclear. The study aimed to investigate the potential mechanism of SYTZD against NAFLD through network pharmacology and experimental verification. The components of SYTZD and SYTZD drug containing serum were analyzed using ultra-performance liquid chromatography to quadrupole/time-of-flight mass spectrometry (UPLC-Q/TOF-MS). Active components and targets of SYTZD were screened by the traditional Chinese medical systems pharmacology (TCMSP) and encyclopedia of traditional Chinese medicine (ETCM) databases. NAFLD-related targets were collected from the GeneCards and DisGeNET databases. The component-disease targets were mapped to identify the common targets of SYTZD against NAFLD. Protein-protein interaction (PPI) network of the common targets was constructed for selecting the core targets. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of the core targets was performed using the database for annotation, visualization, and integrated discovery (DAVID) database. Furthermore, animal and cell models were constructed for validating the predictions of network pharmacology. Lipid accumulation, liver histopathology, insulin resistance, and core gene expression were measured by oil red O staining, hematoxylin and eosin staining, insulin tolerance test, real-time quantitative polymerase chain reaction, and Western blotting, respectively. Two components and 22 targets of SYTZD against NAFLD were identified by UPLC-Q/TOF-MS and relevant databases. PPI analysis found that ESR1, FASN, mTOR, HIF-1α, VEGFA, and GSK-3β might be the core targets of SYTZD against NAFLD, which were mainly enriched in the thyroid hormone pathway, insulin resistance pathway, HIF-1 pathway, mTOR pathway, and AMPK pathway. Experimental results revealed that SYTZD might exert multiple anti-NAFLD mechanisms, including improvements in lipid deposition, inflammation, and insulin resistance. SYTZD treatment led to decreases in the lipid profiles, hepatic enzyme levels, inflammatory cytokines, and homeostatic model assessment for insulin resistance (HOMA-IR). SYTZD treatment affected relative mRNA and protein levels associated with various pathways. Our findings reveal that SYTZD could alleviate NAFLD through a multi-component, multi-target, and multi-pathway mechanism of action.