Chemistry and Biological Activities of Naturally Occurring and Structurally Modified Podophyllotoxins

Plants containing podophyllotoxin and its analogues have been used as folk medicines for centuries. The characteristic chemical structures and strong biological activities of this class of compounds attracted attention worldwide. Currently, more than ninety natural podophyllotoxins were isolated, and structure modifications of these molecules were performed to afford a variety of derivatives, which offered optimized anti-tumor activity. This review summarized up to date reports on natural occurring podophyllotoxins and their sources, structural modification and biological activities. Special attention was paid to both structural modification and optimized antitumor activity. It was noteworthy that etoposide, a derivative of podophyllotoxin, could prevent cytokine storm caused by the recent SARS-CoV-2 viral infection.

Gene regulation of intracellular adhesion molecule-1 (ICAM-1): A molecule with multiple functions

Intracellular adhesion molecule 1 (ICAM-1) is one of the most extensively studied inducible cell adhesion molecules which is responsible for several immune functions like T cell activation, extravasation, inflammation, etc. The molecule is constitutively expressed over the cell surface and is regulated up / down in response to inflammatory mediators like cellular stress, proinflammatory cytokines, viral infection. These stimuli modulate the expression of ICAM-1 primarily through regulating the ICAM-1 gene transcription. On account of the presence of various binding sites for NF-κB, AP-1, SP-1, and many other transcription factors, the architecture of the ICAM-1 promoter become complex. Transcription factors in union with other transcription factors, coactivators, and suppressors promote their assembly in a stereospecific manner on ICAM-1 promoter which mediates ICAM-1 regulation in response to different stimuli. Along with transcriptional regulation, epigenetic modifications also play a pivotal role in controlling ICAM-1 expression on different cell types. In this review, we summarize the regulation of ICAM-1 expression both at the transcriptional as well as post-transcriptional level with an emphasis on transcription factors and signaling pathways involved.

Mutual Prodrugs of 5-Fluorouracil: From a Classic Chemotherapeutic Agent to Novel Potential Anticancer Drugs

The development of potent antitumor agents with a low toxicological profile against healthy cells is still one of the greatest challenges facing medicinal chemistry. In this context, the “mutual prodrug” approach has emerged as a potential tool to overcome undesirable physicochemical features and mitigate the side effects of approved drugs. Among broad‐spectrum chemotherapeutics available for clinical use today, 5‐fluorouracil (5‐FU) is one of the most representative, also included in the World Health Organization model list of essential medicines. Unfortunately, severe side effects and drug resistance phenomena are still the primary limits and drawbacks in its clinical use. This review describes the progress made over the last ten years in developing 5‐FU‐based mutual prodrugs to improve the therapeutic profile and achieve targeted delivery to cancer tissues.

Derivatives of Deoxypodophyllotoxin Induce Apoptosis through Bcl-2/Bax Proteins Expression

BACKGROUND

Deoxypodophyllotoxin, isolated from the Traditional Chinese Medicine Anthriscus sylvestris, is well-known because of its significant anti-tumor activity with strong toxicity in vitro and in vivo.

OBJECTIVE

In this article, a series of deoxypodophyllotoxin derivatives were synthesized and their anti-tumor effectiveness was evaluated.

METHODS

The anti-tumor activity of deoxypodophyllotoxin derivatives was investigated by the MTT assay method. Apoptosis percentage was measured by flow cytometer analysis using Annexin-V-FITC.

RESULTS

The derivatives revealed obvious cytotoxicity in the MTT assay by decreasing the number of late cancer cells. The decrease of Bcl-2/Bax could be observed in MCF-7, HepG2, HT-29, and MG-63 using Annexin V-FITC. The ratio of Bcl-2/Bax in the administration group was decreased, which was determined by the ELISA kit.

CONCLUSION

The derivatives of deoxypodophyllotoxin could induce apoptosis in tumor cell lines by influencing Bcl-2/Bax.

Naturally occurring cell adhesion inhibitors

This paper reviews naturally occurring cell adhesion inhibitors derived from a plant, microbial and marine origin. Plant-derived inhibitors are classified according to a type of structure. Microbially and marine-derived inhibitors were described according to age. In addition, effects of inhibitors on cell proliferation and that of standards on cell adhesion are listed as much as possible.

Synthesis of hybrid 4-deoxypodophyllotoxin-5-fluorouracil compounds that inhibit cellular migration and induce cell cycle arrest

A series of deoxypodophyllotoxin-5-fluorouracil hybrid compounds were synthesized, and their cytotoxic activity was evaluated using four human cancer cell lines (HeLa, A549, HCT-8, and HepG2) and the human normal cell line WI-38. The synthesized compounds exhibited greater cytotoxic activity in tumor cells and reduced toxicity in the normal cell line compared with the anticancer drug VP-16 and 5-FU. Additionally, the most potent of these compounds-4'-O-demethyl-4-deoxypodophyllotoxin-4'-yl 4-((6-(2-(5-fluorouracil-yl) acetamido) hexyl) amino)-4-oxobutanoate (compound 22)-induced cell-cycle arrest in the G2/M phase by regulating levels of cdc2, cyclinB1, and p-cdc2 in A549 cells. Furthermore, compound 22 may inhibited the migration of A549 cells via down-regulation of MMP-9 and up-regulation of TIMP-1.

Deoxypodophyllotoxin: a promising therapeutic agent from herbal medicine

BACKGROUND

Recently, biologically active compounds isolated from plants used in herbal medicine have been the center of interest. Deoxypodophyllotoxin (DPT), structurally closely related to the lignan podophyllotoxin, is a potent antitumor and anti-inflammatory agent. However, DPT has not been used clinically yet. Also, DPT from natural sources seems to be unavailable. Hence, it is important to establish alternative resources for the production of such lignan; especially that it is used as a precursor for the semi-synthesis of the cytostatic drugs etoposide phosphate and teniposide.

AIMS AND OBJECTIVES

The update paper provides an overview of DPT as an effective anticancer natural compound and a leader for cytotoxic drugs synthesis and development in order to highlight the gaps in our knowledge and explore future research needs.

APPROACH AND METHODS

The present review covers the literature available from 1877 to 2012. The information was collected via electronic search using Chinese papers and the major scientific databases including PubMed, Sciencedirect, Web of Science and Google Scholar using the keywords. All abstracts and full-text articles reporting database on the history and current status of DPT were gathered and analyzed.

RESULTS

Plants containing DPT have played an important role in traditional medicine. In light of the in vitro pharmacological investigations, DPT is a high valuable medicinal agent that has anti-tumor, anti-proliferative, anti-inflammatory and anti-allergic properties. Further, DPT is an important precursor for the cytotoxic aryltetralin lignan, podophyllotoxin, which is used to obtain semisynthetic derivatives like etoposide and teniposide used in cancer therapy. However, most studies have focused on the in vitro data. Therefore, DPT has not been used clinically yet.

CONCLUSIONS

DPT has emerged as a potent chemical agent from herbal medicine. Therefore, in vivo studies are needed to carry out clinical trials in humans and enable the development of new anti-cancer agents. In addition, DPT from commercial sources seems to be unavailable due to its rarity from natural sources and cumbersome extraction procedures. Hence, it is important to establish alternative, cost-effective and renewable resources, such plant cell cultures and (semi-) synthesis strategies for the production of DPT.

Sulphoraphane inhibited the expressions of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 through MyD88-dependent toll-like receptor-4 pathway in cultured endothelial cells

BACKGROUND AND AIMS

Chronic inflammation plays pivotal roles in both cancer and cardiovascular diseases. A large body of evidence suggests that high intake of cruciferous vegetables is closely related with low risk of these disorders. However, the underlying mechanisms of protection are not fully understood. The aim of this study is to test the protective effects of an isothiocyanate sulphoraphane on inflammatory injury and related regulation pathways in cultured endothelial cells.

METHODS AND RESULTS

The expressions of adhesion molecules were determined by TaqMan real-time polymerase chain reaction (PCR) and Western blot analysis. Nuclear factor-kappa B (NF-кB) translocation was detected by immunofluorescent hybridisation. Other proteins were measured by Western blot analysis. The results demonstrated that sulphoraphane significantly suppresses the expression of intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 stimulated by lipopolysaccharide (LPS) both at the transcriptional and translational levels. In addition, sulphoraphane inhibited the translocation of NF-кB into the nucleus. Sulphoraphane decreased the phosphorylation of extra-cellular signal-regulated kinase (ERK), Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), while further blockade and activation using individually specific agents confirm that p38 MAPK and JNK are mainly involved. Interestingly, sulphoraphane down-regulated Toll-like receptor (TLR)-4, a receptor of LPS located on the membrane. In addition, MyD88, an effector downstream TLR-4 signal pathway was subsequently attenuated.

CONCLUSION

Taken all together, adhesion molecules are confirmed to be the novel targets of sulphoraphane in preventing inflammatory insult to endothelial cells. Sulphoraphane suppressed TLR-4 followed by MyD88 and downstream factors such as p38 MAPK and JNK, ultimately blocking NF-кB translocation and the subsequent expression of adhesion molecules. These data suggested a novel inflammatory pathway mediated by sulphoraphane.

Seasonal variations in the deoxypodophyllotoxin content and yield of Anthriscus sylvestris L. (Hoffm.) grown in the field and under controlled conditions

Deoxypodophyllotoxin (DPT) is the main lignan in Anthriscus sylvestris . For this study two sets of experiments with 16 plants and seeds, collected from a wide geographical range, were carried out. The DPT content in roots was significantly lower (p < 0.05) when the plants were cultivated in a non-native environment. For field-grown plants the highest DPT content was found in March (second year): 0.15% w/w (dry weight) in roots; 0.03% w/w in aerial parts. For plants grown in the climate room, the highest concentration (0.14% w/w) was observed in April (second year) in the roots and in July (first year) in the aerial parts (0.05% w/w). For the isolation of DPT, roots are the most suitable part. The best harvest times are March (second year) for outdoor plants and April (second year) for indoor plants when height content and adequate biomass give the optimal DPT yield.