Immunomodulatory activity of Dioscorea membranacea Pierre rhizomes and of its main active constituent Dioscorealide B

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.

Effects of Wild Yam Root (Dioscorea villosa) Extract on the Gene Expression Profile of Triple-negative Breast Cancer Cells

BACKGROUND/AIM

Wild yam extract [Dioscorea villosa, (WYE)] is consistently lethal at low IC₅₀s across diverse cancer-lines in vitro. Unlike traditional anti-cancer botanicals, WYE contains detergent saponins which reduce oil-water interfacial tensions causing disintegration of lipid membranes and causing cell lysis, creating an interfering variable. Here, we evaluate WYE at sub-lethal concentrations in MDA-MB-231 triple-negative breast cancer (TNBC) cells.

MATERIALS AND METHODS

Quantification of saponins, membrane potential, lytic death and sub-lethal WYE changes in whole transcriptomic (WT) mRNA, miRNAs and biological parameters were evaluated.

RESULTS

WYE caused 346 differentially expressed genes (DEGs) out of 48,226 transcripts tested; where up-regulated DEGS reflect immune stimulation, TNF signaling, COX2, cytokine release and cholesterol/steroid biosynthesis. Down-regulated DEGs reflect losses in cell division cycle (CDC), cyclins (CCN), cyclin-dependent kinases (CDKs), centromere proteins (CENP), kinesin family members (KIFs) and polo-like kinases (PLKs), which were in alignment with biological studies.

CONCLUSION

Sub-lethal concentrations of WYE appear to evoke pro-inflammatory, steroid biosynthetic and cytostatic effects in TNBC cells.

Therapeutic efficacy of a Dioscorea membranacea extract in a rat model of hepatocellular carcinoma: Histopathological aspects

Hepatocellular carcinoma (HCC) is most common in adults and has a high mortality rate because of a lack of effective treatment options. We investigated the effect of a medicinal plant as a potential source of drugs against HCC. The rhizomes of Dioscorea membranacea Pierre (DM), Hua-Khao-Yen in Thai, are commonly used as ingredients for alternative treatment of cancer in Thailand. In this study, the anticancer effects of DM extract in HCC-bearing rats were evaluated with respect to gross morphology, histopathology, and leakage of liver enzymes. In untreated HCCs, typical features of liver cancer, including hepatic nodules, thick-cell cords, and pseudoglandular cell arrangements, were observed. In addition, the HCCs showed abnormal reticulin patterns and a high glypican3 expression. In HCC-bearing rats treated with DM the cancer areas and reticulin expression were significantly reduced compared to the untreated group (p < 0.01). Sorafenib, the standard drug to treat HCC, reduced the cancer area further, but increased leakage of liver enzymes and decreased serum albumin concentration, indicating liver toxicity. These findings suggest that DM has an anticancer effect on HCCs in an animal model in vivo with potentially less severe side effects than sorafenib. Therefore, further studies of DM’s mechanism of action in HCC should be carried out.

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DM exerted a mitigating effect on histopathology and membrane damage of HCC in rats.

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Its effect was similar to that of the standard drug sorafenib.

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It reduced the volume of cancer nodules without the serious hepatotoxic side effects seen after SF treatment.

Medicinal Plants and Isolated Molecules Demonstrating Immunomodulation Activity as Potential Alternative Therapies for Viral Diseases Including COVID-19

Plants have been extensively studied since ancient times and numerous important chemical constituents with tremendous therapeutic potential are identified. Attacks of microorganisms including viruses and bacteria can be counteracted with an efficient immune system and therefore, stimulation of body's defense mechanism against infections has been proven to be an effective approach. Polysaccharides, terpenoids, flavonoids, alkaloids, glycosides, and lactones are the important phytochemicals, reported to be primarily responsible for immunomodulation activity of the plants. These phytochemicals may act as lead molecules for the development of safe and effective immunomodulators as potential remedies for the prevention and cure of viral diseases. Natural products are known to primarily modulate the immune system in nonspecific ways. A number of plant-based principles have been identified and isolated with potential immunomodulation activity which justify their use in traditional folklore medicine and can form the basis of further specified research. The aim of the current review is to describe and highlight the immunomodulation potential of certain plants along with their bioactive chemical constituents. Relevant literatures of recent years were searched from commonly employed scientific databases on the basis of their ethnopharmacological use. Most of the plants displaying considerable immunomodulation activity are summarized along with their possible mechanisms. These discussions shall hopefully elicit the attention of researchers and encourage further studies on these plant-based immunomodulation products as potential therapy for the management of infectious diseases, including viral ones such as COVID-19.

Bee Collected Pollen and Bee Bread: Bioactive Constituents and Health Benefits

Bee products were historically used as a therapheutic approach and in food consumption, while more recent data include important details that could validate them as food supplements due to their bioproperties, which support their future use as medicines. In this review data, data collected from bee pollen (BP) and bee bread (BB) essays will be discussed and detailed for their nutritional and health protective properties as functional foods. Dietary antioxidants intake derived from BP and BB have been associated with the prevention and clinical treatment of multiple diseases. The beneficial effects of BP and BB on health result from the presence of multiple polyphenols which possess anti-inflammatory properties, phytosterols and fatty acids, which play anticancerogenic roles, as well as polysaccharides, which stimulate immunological activity. From the main bioactivity studies with BP and BB, in vitro studies and animal experiments, the stimulation of apoptosis and the inhibition of cell proliferation in multiple cell lines could be one of the major therapeutic adjuvant effects to be explored in reducing tumor growth. Tables summarizing the main data available in this field and information about other bio-effects of BP and BB, which support the conclusions, are provided. Additionally, a discussion about the research gaps will be presented to help further experiments that complete the tree main World Health Organization (WHO) Directives of Efficiency, Safety and Quality Control for these products.

Immunomodulatory activity of a water-soluble polysaccharide obtained from highland barley on immunosuppressive mice models

A water-soluble polysaccharide (BP-1) was extracted and purified from highland barley (Hordeum vulgare L.) and its average molecular weight was about 6.7 × 104 Da. In this study, the immunomodulatory activity of BP-1 on the immunosuppressive BALB/c mice model and its molecular mechanism were elucidated. It was found that the weight indexes of spleen and thymus were significantly increased by BP-1 (80 mg kg-1 and 160 mg kg-1) treatment in the immunosuppressive mice model. The results showed that BP-1 (80 mg kg-1 and 160 mg kg-1) could significantly increase the number of bone marrow cells (BMC) and peripheral blood white blood cells (WBC) in the immunosuppressive mice model. In addition, the result further confirmed that BP-1 could increase the serum levels of IL-2, TNF-α and IFN-γ, so as to improve the immune function of immunosuppressive mice. The results showed that BP-1 (80 mg kg-1 and 160 mg kg-1) could promote the proliferation of spleen cells and the natural killer (NK) cell activity in vivo. The quantitative real-time polymerase chain reaction (qRT-PCR) and ELISA results revealed that BP-1 (80 mg kg-1 and 160 mg kg-1) could enhance the production of IL-2, TNF-α, IFN-γ, IgG and IgM in the spleen of immunosuppressive mice. The HE (hematoxylin and eosin) stained histopathological images showed that BP-1 (80 mg kg-1 and 160 mg kg-1) could repair the damage induced by CTX in the spleen cells of immunosuppressive mice. The result of macrophages showed that BP-1 (80 mg kg-1 and 160 mg kg-1) could promote the proliferation and phagocytosis activity of macrophages in immunosuppressive mice. Furthermore, BP-1 could activate macrophages by the TLR-4, TRAF6, TAK1 and nuclear factor κB (NF-κB) p65 pathways in vivo. These results suggested that BP-1 has a remarkable immunomodulatory activity on the immunosuppressive mice model.

The immunomodulatory activity and mechanism of docosahexenoic acid (DHA) on immunosuppressive mice models

In this study, the immunomodulatory activity of docosahexaenoic acid (DHA) on the immunosuppressive BALB/c mice model and its molecular mechanism are elucidated. It was found that the weight indexes of the spleen and thymus were significantly increased by DHA (44.0 mg kg-1 and 88.0 mg kg-1) treatment in the prevention or cure groups. The result of macrophages showed that DHA (44.0 mg kg-1 and 88.0 mg kg-1) could promote the proliferation and phagocytosis activity of macrophages in the prevention or cure groups. In addition, DHA could activate macrophages by the G-protein coupled cell membrane receptor GPR120- Mitogen-Activated Protein Kinases (MAPKs)-nuclear factor κB (NF-κB) p65 pathway in vivo. The result of the spleen showed that DHA (44.0 mg kg-1 and 88.0 mg kg-1) could promote the proliferation of spleen cells and the natural killer (NK) cells activity in vivo. In the prevention or cure groups, the quantitative real-time polymerase chain reaction (qRT-PCR) results revealed that DHA (44.0 mg kg-1 and 88.0 mg kg-1) could enhance the production of cytokines IL-1β, IL-2, TNF-α and IFN-γ in the spleen of immunosuppressive mice. The HE (hematoxylin and eosin) stained histopathological images showed that DHA could repair the damage induced by CTX in the spleen cells of the prevention or cure groups. These results suggested that DHA has a remarkable immunomodulatory activity on the immunosuppressive mice model in the prevention or cure groups.

A novel steroid and cytotoxic constituents from Dioscorea membranacea Pierre against hepatocellular carcinoma and cholangiocarcinoma cells

ETHNOPHARMACOLOGICAL RELEVANCE

The rhizomes of Dioscorea membrancea Pierre have been used in Thai traditional medicine as an ingredient formula for liver cancer and cholangiocarcinoma treatment.

AIM OF THE STUDY

To investigate the cytotoxic activity of ethanolic extract and constituents of D. membrancea to support its traditional use.

MATERIALS AND METHODS

The SRB assay was used to determine the cytotoxic activity against hepatocellular carcinoma (HepG2), cholangiocarcinoma (KKU-M156) cells and one normal human keratinocyte immortal cells (HaCaT) with its ethanolic extract and isolated compounds. Bioassay guided isolation was used for isolating cytotoxic compounds.

RESULTS

The ethanolic extract of D. membranacea rhizome showed weak cytotoxic against KKU-M156 and HepG2 (IC₅₀ at 72h exposure=30.49±0.82 and 38.97±2.04µg/mL respectively). A new steroid [epipanthogenin B (1)], a known steroid [panthogenin B (2)], two napthofuranoxepins [dioscorealide A (3) and dioscorealide B (4)], phenanthraquinone [dioscoreanone (5)] and two phenanthrene [5,6-dihydroxy-2,4-dimethoxy-9,10-dihydrophenanthrene (6) and 2,5,6-trihydroxy-3,4-dimethoxy, 9, 10-dihydrophenanthrene (7)] were isolated from active chloroform fraction. Compound 4 showed the highest cytotoxicity against HepG2 (IC₅₀ at 72h exposure=2.87±0.21µM) and KKU-M156 (IC₅₀ at 72h exposure=1.67±0.10µM) and less toxicity against normal cell line (HaCaT) (IC₅₀ at 72h exposure>100µM). Compound 5 showed selective cytotoxic activity against KKU-M156 (IC₅₀ at 72h exposure=3.46±0.11µM). Compounds 6 and 7 showed weak cytotoxic activity against HepG2 (IC₅₀ at 72h exposure=24.96±2.32 and 51.31±3.52µM). Compounds (1-3) showed no cytotoxic activity against HepG2 and KKU-M156 cell lines (IC₅₀ at 72 h exposure>100µM).

CONCLUSION

Seven compounds were isolated from active chloroform fraction of the ethanolic extract of D. membranacea rhizomes. Only dioscorealide B (4) might be served as a good anticancer agent for liver cancer and cholangiocarcinoma cancer because it can kill cancer cell but not toxic on normal cell. This research support Thai traditional medicine use of D. membranacea for liver cancer and cholangiocarcinoma cancer treatment.

A Review on Hepatoprotective and Immunomodulatory Herbal Plants

The liver is the most important organ that plays an important role in maintaining various physiological processes in the body. Hepatitis is an inflammation of the liver and is characterized by the presence of inflammatory cells in the tissue of the organ. There are five main viruses, referred to as types A, B, C, D, and E. These five types are of the greatest concern because of the burden of illness and death. Liver injury or liver dysfunction is a major health problem that challenges not only health care professionals but also the drug regulatory agencies and the pharmaceutical industry. Herbal medicines have been used in the treatment of liver disease for a long time. The immune system is the part of body that diagnoses the pathogen by using a specific receptor to reveal immediate response by the activation of immune components cells, chemokines, and cytokines, and also the release of the inflammatory mediator. They potentiate and modulate the immune system. The plant-derived phytoconstituents (polysaccharides, proteins and flavanoids, lignans, rotenoids, etc.) stimulate the immune system and maintained hepatic diseases. There are a number of hepatoprotective and immunomodulatory herbs that have been reported. The present review is aimed at compiling data on promising phytochemicals from hepatoprotective and immunomodulatory herbs.