Identification of Sokotrasterol Sulfate As a Novel Proangiogenic Steroid

Sokotrasterol Sulfate Suppresses IFN-γ-Induced PD-L1 Expression by Inhibiting JAK Activity

PD-1/PD-L1 monoclonal antibodies exhibit promising therapeutic effectiveness in multiple cancers. However, developing a simple and efficient non-antibody treatment strategy using the PD-1/PD-L1 signaling pathway still remains challenging. In this study, we developed a flow cytometry assay to screen bioactive compounds with PD-L1 inhibitory activity. A total of 409 marine natural products were screened, and sokotrasterol sulfate (SKS) was found to efficiently suppress the IFN-γ-induced PD-L1 expression. SKS sensitizes the tumor cells to antigen-specific T-cell killing in the T cell-tumor cell coculture system. Mechanistically, SKS directly targeted Janus kinase (JAK) to inhibit the downstream activation of signal transducer and activator of transcription (STAT) and the subsequent transcription of PDL1. Our findings highlight the immunological role of SKS that may act as a basis for a potential immunotherapeutic agent.

Antitumor and hepatoprotective activity of natural and synthetic neo steroids

In this review, steroids with a tertiary butyl group, which are usually called neo steroids, are a small group of natural lipids isolated from higher plants, fungi, marine sponges, and yeast. In addition, steroids with a tertiary butyl group have been synthesized in some laboratories in Canada, USA, Europe, and Japan and their biological activity was studied. Some natural neo steroids demonstrate antitumor or hepatoprotective activities. In addition, synthetic neo steroids exhibit anticancer and neuroprotective properties. However, to confirm the above data, both practical and clinical experimental studies are necessary. Nevertheless, the results may be useful for pharmacologists, chemists, biochemists, and the pharmaceutical industry.

New Trisulfated Steroids from the Vietnamese Marine Sponge Halichondria vansoesti and Their PSA Expression and Glucose Uptake Inhibitory Activities

Seven new unusual polysulfated steroids—topsentiasterol sulfate G (1), topsentiasterol sulfate I (2), topsentiasterol sulfate H (3), bromotopsentiasterol sulfate D (4), dichlorotopsentiasterol sulfate D (8), bromochlorotopsentiasterol sulfate D (9), and 4β-hydroxyhalistanol sulfate C (10), as well as three previously described—topsentiasterol sulfate D (7), chlorotopsentiasterol sulfate D (5) and iodotopsentiasterol sulfate D (6) have been isolated from the marine sponge Halichondria vansoesti. Structures of these compounds were determined by detailed analysis of 1D- and 2D-NMR and HRESIMS data, as well as chemical transformations. The effects of the compounds on human prostate cancer cells PC-3 and 22Rv1 were investigated.

SULFATION PATHWAYS: Sources and biological activities of marine sulfated steroids

Marine environment is rich in structurally unique molecules and can be an inspiring source of novel drugs. Currently, six marine-derived drugs are in the market with FDA approval and several more are in the clinical pipeline. Structurally diverse and complex secondary metabolites have been isolated from the marine world and these include sulfated steroids. Biological activities of nearly 150 marine sulfated steroids reported from 1978 to 2017 are compiled and described, namely antimicrobial, antitumor, cardiovascular and antifouling activities. Structure-activity relationship for each activity is discussed.

A glycan-based approach to therapeutic angiogenesis

Angiogenesis, the sprouting of new blood vessels from existing vasculature, involves multiple complex biological processes, and it is an essential step for hemostasis, tissue healing and regeneration. Angiogenesis stimulants can ameliorate human disease conditions including limb ischemia, chronic wounds, heart disease, and stroke. The current strategies to improve the bioavailability of pro-angiogenic growth factors, including VEGF and FGF2, have remained largely unsuccessful. This study demonstrates that small molecules, termed click-xylosides, can promote angiogenesis in the in vitro matrigel tube formation assay and the ex ovo chick chorioallantoic membrane assay, depending on their aglycone moieties. Xyloside treatment enhances network connectivity and cell survivability, thereby, maintaining the network structures on matrigel culture for an extended period of time. These effects were achieved via the secreted xyloside-primed glycosaminoglycans (GAG) chains that in part, act through an ERK1/2 mediated signaling pathway. Through the remodeling of GAGs in the extracellular matrix of endothelial cells, the glycan approach, involving xylosides, offers great potential to effectively promote therapeutic angiogenesis.

Identification of resveratrol derivative 3,3',4,4',5,5'-hexamethoxy- trans-stilbene as a novel pro-angiogenic small-molecule compound

The potential to promote neovascularization in ischemic tissues using exogenous agents is an attractive avenue for therapeutics. To identify novel pro-angiogenic small-molecule compound, we screened a series of resveratrol methylated derivatives and identified 3,3',4,4', 5,5'-hexamethoxy-trans-stilbene (3,3',4,4',5,5'-HMS) potently promotes proliferation, migration, invasion and tube formation of human umbilical vein VECs (HUVECs) in vitro. Furthermore, 3,3',4,4',5,5'-HMS accelerates neo-vessels sprouting of rat aortic rings ex vivo, and neovascularization of chick chorioallantoic membrane (CAM) and mouse matrigel plugs in vivo. Microarray analyses show that the level of early growth response 1 (EGR-1), an inducible pro-angiogenic gene regulatory factor, was upregulated. The upregulation of EGR-1 was confirmed by semiquantitative RT-PCR, quantitative real-time PCR and western blotting analyses. In addition, the levels of several pro-angiogenic factors including transforming growth factor β1 (TGF-β1), vascular endothelial growth factor (VEGF), nitric oxide (NO), and the activity of endothelial NO synthase (eNOS) were elevated in 3,3',4,4',5,5'-HMS-treated HUVECs. Inhibition of NO synthase by l-NAME blocked the pro-angiogenic effects of 3,3',4,4',5,5'-HMS. Our research shows that 3,3',4,4',5,5'-HMS dramatically promoted angiogenesis in vitro, ex vivo and in vivo, which might represent a novel potential agent for the development of therapeutic drugs to treat ischemic diseases.

Synthesis and acetylcholinesterase inhibitory activity of polyhydroxylated sulfated steroids: structure/activity studies

Disulfated and trisulfated steroids have been synthesized from cholesterol and their acetylcholinesterase inhibitory activity has been evaluated. In our studies we have found that the activity was not only dependent on the location of the sulfate groups but on their configurations. 2β,3α,6α-trihydroxy-5α-cholestan-6-one trisulfate (18) was the most active steroid with an IC50 value of 15.48 μM comparable to that of 2β,3α-dihydroxy-5α-cholestan-6-one disulfate (1). Both compounds were found to be less active than the reference compound eserine. The butyrylcholinesterase activity of 1 and 18 was one magnitude lower than that against acetylcholinesterase revealing a selective inhibitor profile.

Engineering vascularized tissues using natural and synthetic small molecules

Vascular growth and remodeling are complex processes that depend on the proper spatial and temporal regulation of many different signaling molecules to form functional vascular networks. The ability to understand and regulate these signals is an important clinical need with the potential to treat a wide variety of disease pathologies. Current approaches have focused largely on the delivery of proteins to promote neovascularization of ischemic tissues, most notably VEGF and FGF. Although great progress has been made in this area, results from clinical trials are disappointing and safer and more effective approaches are required. To this end, biological agents used for therapeutic neovascularization must be explored beyond the current well-investigated classes. This review focuses on potential pathways for novel drug discovery, utilizing small molecule approaches to induce and enhance neovascularization. Specifically, four classes of new and existing molecules are discussed, including transcriptional activators, receptor selective agonists and antagonists, natural product-derived small molecules, and novel synthetic small molecules.

(2S,3S)-sulfated pterosin C, a cytotoxic sesquiterpene from the Bangladeshi mangrove fern Acrostichum aureum

Two new sesquiterpenes, (2R,3S)-sulfated pterosin C (1) and (2S,3S)-sulfated pterosin C (2), along with two known derivatives, (2S,3S)-pterosin C and (2R)-pterosin P, were isolated from a methanolic extract of the aerial parts of Acrostichum aureum. The structures of 1 and 2 were determined by the interpretation of their spectroscopic data. The isolated pterosins were evaluated for their cytotoxic activity against the AGS, HT-29, MDA-MB-231, and MCF-7 human cancer cell lines and the NIH3T3 normal mouse fibroblast cell line, using the MTT assay. Compound 2 showed IC50 values in the range 23.9-68.8 μM. The lowest IC50 value (23.9 μM) was recorded against AGS gastric adenocarcinoma cells. Compound 2 was found to exert an apoptotic effect on AGS cells within 24 h of treatment, which increased with time and was greater than the positive control, cycloheximide. The cytotoxicity of 2 seems to be due in part to the sulfate group on C-14 and the configuration at C-2.

Synthesis and acetylcholinesterase inhibitory activity of 2β,3α-disulfoxy-5α-cholestan-6-one

Disodium 2β,3α-dihydroxy-5α-cholestan-6-one disulfate (8) has been synthesized using cholesterol (1) as starting material. Sulfation was performed using trimethylamine-sulfur trioxide complex in dimethylformamide as the sulfating agent. The acetylcholinesterase inhibitory activity of compound 8 was evaluated and compared to that of disodium 2β,3α-dihydroxy-5α-cholestane disulfate (10) and diols 7 and 9. Compounds 8 and 10 were active with IC(50) values of 14.59 and 59.65 μM, respectively. Diols 7 and 9 showed no inhibitory activity (IC(50)>500 μM).

Baicalin increases VEGF expression and angiogenesis by activating the ERR{alpha}/PGC-1{alpha} pathway

AIMS

Baicalin is the major component found in Scutellaria baicalensis root, a widely used herb in traditional Chinese medicine. Although it has been used for thousands of years to treat stroke, the mechanisms of action of S. baicalensis have not been clearly elucidated. In this report, we studied the modulation of angiogenesis as one possible mechanism by investigating the effects of these agents on expression of vascular endothelial growth factor (VEGF), a critical factor for angiogenesis.

METHODS AND RESULTS

The effects of baicalin and an extract of S. baicalensis on VEGF expression were tested in several cell lines. Both agents induced VEGF expression in all cells without increasing expression of hypoxia-inducible factor-1α (HIF-1α). The expression of reporter genes was also activated under the control of the VEGF promoter containing either a functional or a defective HIF response element (HRE). Only minimal effects were observed on reporter activation under the HRE promoter. Instead, both agents significantly induced oestrogen-related receptor (ERRα) expression as well as the activity of reporter genes under the control of ERRα-binding element. Their ability to induce VEGF expression was suppressed once ERRα expression was knocked down by siRNA or ERRα-binding sites were deleted in the VEGF promoter. We also found that both agents stimulated cell migration and vessel sprout formation from the aorta.

CONCLUSION

Our results implicate baicalin and S. baicalensis in angiogenesis by inducing VEGF expression through the activation of the ERRα pathway. These data may facilitate a better understanding of the potential health benefits of these agents in the treatment of cardiovascular diseases.

Vascular endothelial growth factors in cardiovascular medicine

The discovery of vascular endothelial growth factors (VEGFs) and their receptors has considerably improved the understanding of the development and function of endothelial cells. Each member of the VEGF family appears to have a specific function: VEGF-A induces angiogenesis (i.e. growth of new blood vessels from preexisting ones), placental growth factor mediates both angiogenesis and arteriogenesis (i.e. the formation of collateral arteries from preexisting arterioles), VEGF-C and VEGF-D act mainly as lymphangiogenic factors. The study of the biology of these endothelial growth factors has allowed a major progress in the comprehension of the genesis of the vascular system and its abnormalities observed in various pathologic conditions (atherosclerosis and coronary artery disease). The role of VEGF in the atherogenic process is still unclear, but actual evidence suggests both detrimental (development of a neoangiogenetic process within the atherosclerotic plaque) and beneficial (promotion of collateral vessel formation) effects. VEGF and other angiogenic growth factors (fibroblast growth factor), although initially promising in experimental studies and in initial phase I/II clinical trials in patients with ischemic heart disease or peripheral arterial occlusive disease, have subsequently failed to show significant therapeutic improvements in controlled clinical studies. Challenges still remain about the type or the combination of angiogenic factors to be administered, the form (protein vs. gene), the route, and the duration of administration.