Isolation, antimicrobial and antitumor activities of a new polyhydroxysteroid and a new diterpenoid from the soft coral Xenia umbellata

Sesquiterpenoids from Meliaceae Family and Their Biological Activities

Sesquiterpenoids, an important class of natural products possessing three isoprene-derived units, are widely distributed across plants and have a variety of biological activities. All sesquiterpenoids are derived from farnesyl pyrophosphate (FPP), a biosynthesis precursor that can form various carbon skeletons. In order to provide a reference for further research and development of these compounds, this review focused on the increasing number of isolated and volatile sesquiterpenoids found to be produced by plants of the Meliaceae family between 1968 and 2023. The related articles were collected from SciFinder, Google Scholar, and PubMed. According to a literature review, several studies were started for more than 55 years on the plant's stem barks, twigs, leaves, flowers, seeds, and pericarps, where approximately 413 sesquiterpenoid compounds from several groups such as eudesmane, aromadendrane, cadinane, guaiane, bisabolane, furanoeremophilane, humulene, germacrane, and oppositane-type were isolated and identified with some minor products. Additionally, the hypothetical route of sesquiterpenoids biosynthesis from this family was identified, and eudesmane-type was reported to be 27% of the total compounds. The antimicrobial, antidiabetic, antioxidant, antiplasmodial, antiviral, and cytotoxic activities of the isolated compounds and major volatile sesquiterpenoids constituent on essential oil were also evaluated. The result showed the fundamental of using the sesquiterpenoid compounds from the Meliaceae family in traditional medicine and the discovery of new drugs.

Bioactivity of a polyhydroxy gorgostane steroid from Xenia umbellata

A C-30 steroid, 3β-,5α-,6β-,11α-,20β-pentahydroxygorgosterol was isolated from the soft coral Xenia umbellata Lamarck (Xeniidae). The chemical structure was elucidated by examining the NMR spectral data and comparison with the previously published data. Compound 1 inhibited the growth of ovarian cancer (SKOV-3), breast cancers (MCF-7 and MDA-MB-231) and hepatocellular carcinoma (HepG2) using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay. Notably against HepG2, compound 1 showed significant effect with an IC50 value of 19.70 ± 1.98 µg/mL. It significantly increased the population in the SubG1 phase for 2.01- and 2.05-folds, respectively, compared to untreated cells. Additionally, it showed potent inhibitory activities of superoxide dismutase (384.6 vs 8594.2 U/g protein in dimethyl sulfoxide-treated cells), catalase (0.3 vs 0.07 U/g protein), decreased the level of reduced glutathione (1.7 vs 0.6 mg/g protein) and the activity of matrix metalloproteases (MMP-2 and MMP-9 [0.5-fold of change in MMP activity]) in HepG2 cells. The results indicated the potent antiproliferative activity of the gorgostane derivative (1) against HepG2 cells. This study provides a scientific basis of the antiproliferative effects of steroidal compound with gorgostane nucleus against hepatocellular carcinoma cells.

Structural diversity of bioactive steroid compounds isolated from soft corals in the period 2015-2020

Marine soft corals are known as a good source of biologically active compounds, among which a large number of steroid compounds are identified. Structures and activities of these compounds have been used in drug discovery and development. From 2015 to 2020, 179 new steroid compounds were isolated from soft corals and structurally characterized. In this review, we report the structural classification and bioactivities of these compounds. The largest group of steroids from soft corals are hydroxysteroids, while the most common biological activity is anticancer. Besides, anticancer hydroxysteroids from soft corals exhibit anti-inflammatory and antibacterial activity. Unlike anticancer and antibacterial activity that can be observed in a number of steroid classes, antioxidant activity and antileishmanial effect were observed only in 19-oxygenated steroids, antiviral activity in pregnane-type steroids and spirosteroids, immunosuppressive activity in epoxy- and epidioxysteroids, and antibacterial activity in two steroid classes, hydroxysteroids and ketosteroids. This systematically analyzed link between the structure and activity of natural marine steroids is a good starting point for future drug design.

In Silico Mining of Terpenes from Red-Sea Invertebrates for SARS-CoV-2 Main Protease (Mpro) Inhibitors

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent for the COVID-19 pandemic, which generated more than 1.82 million deaths in 2020 alone, in addition to 83.8 million infections. Currently, there is no antiviral medication to treat COVID-19. In the search for drug leads, marine-derived metabolites are reported here as prospective SARS-CoV-2 inhibitors. Two hundred and twenty-seven terpene natural products isolated from the biodiverse Red-Sea ecosystem were screened for inhibitor activity against the SARS-CoV-2 main protease (Mpro) using molecular docking and molecular dynamics (MD) simulations combined with molecular mechanics/generalized Born surface area binding energy calculations. On the basis of in silico analyses, six terpenes demonstrated high potency as Mpro inhibitors with ΔGbinding ≤ -40.0 kcal/mol. The stability and binding affinity of the most potent metabolite, erylosides B, were compared to the human immunodeficiency virus protease inhibitor, lopinavir. Erylosides B showed greater binding affinity towards SARS-CoV-2 Mpro than lopinavir over 100 ns with ΔGbinding values of -51.9 vs. -33.6 kcal/mol, respectively. Protein-protein interactions indicate that erylosides B biochemical signaling shares gene components that mediate severe acute respiratory syndrome diseases, including the cytokine- and immune-signaling components BCL2L1, IL2, and PRKC. Pathway enrichment analysis and Boolean network modeling were performed towards a deep dissection and mining of the erylosides B target-function interactions. The current study identifies erylosides B as a promising anti-COVID-19 drug lead that warrants further in vitro and in vivo testing.

Rare norisodinosterol derivatives from Xenia umbellata: Isolation and anti-proliferative activity

Two new rare 30-norisodinosterol derivatives, 23,24-dimethylcholest-16-ene-3β,5α,6β,11α,20(R)-pentol 3-monoacetate (1) and 23,24-dimethylcholest-16-ene-3β,5α,6β,20(R)-tertrol 3-monoacetate (2), along with a known steroid, 3β,5α,6β,11α,20β-pentahydroxygorgosterol (3), were identified from Xenia umbellata. The structures of the isolated compounds were determined by analyses of the measured spectra (1D and 2D nuclear magnetic resonance, mass spectrometry, and infrared). The biosynthetic pathway of the new norisodinosterols was proposed. Compound 1 exhibited potent cytotoxicity against HepG2, PC-3, and HT-29 with IC50 values of 4.70 ± 0.2, 5.60 ± 0.6, and 4.00 ± 0.4 μg/mL, respectively. On the contrary, compound 3 showed less potent cytotoxicity against HepG2 with IC50 value of 22.20 ± 1.0 μg/mL. Two DNA-binding dyes have been used for the morphological detection of viable, apoptotic, and necrotic cells. The early apoptotic cell death was observed in all types of treated tumour cells. The late apoptotic cells are highly present in HepG2 cells with compound 3 compared with other cancer cells except for compound 1. The anti-proliferative activity of compounds 1 and 3 warranted further investigation.

Antiproliferative Isoprenoid Derivatives from the Red Sea Alcyonacean Xenia umbellata

From the soft coral Xenia umbellata, seven isoprenoid derivatives were isolated, including a new xenicane diterpene, xeniolide O (5) and a new gorgostane derivative gorgst-3β,5α,6β,11α,20(S)-pentol-3-monoacetate (7), along with three known sesquiterpenes (1-3), a known diterpene (4), and a known steroid (6). The extensive analyses of the NMR, IR, and MS spectral data led to determination of their chemical structures. Compounds 1-7 displayed a cytotoxic effect against breast adenocarcinoma (MCF-7), hepatocellular carcinoma (HepG2), and cervix adenocarcinoma (HeLa), with IC50 values ranging between 1.5 ± 0.1-23.2 ± 1.5; 1.8 ± 0.1-30.6 ± 1.1 and 0.9 ± 0.05-12.8 ± 0.5 μg/mL, respectively. Compound 3 showed potent cytotoxic effects against MCF-7, HepG2, and HeLa with IC50 values = 2.4 ± 0.20, 3.1 ± 0.10 and 0.9 ± 0.05 μg/mL, respectively. Compounds 2, 5, and 7 displayed cytotoxic effect against Hela cells with IC50 values = 12.8 ± 0.50, 6.7 ± 1.00 and 11.5 ± 2.20 μg/mL, respectively. Two DNA binding dyes, acridine orange (AO) and ethidium bromide (EtBr) were used for the detection of viable, apoptotic, and necrotic cells. The early apoptotic cell death was observed in all types of treated cells. The late apoptotic cells were highly present in HepG2 cells. Compounds 5 and 7 induced a high percentage of necrosis towards HepG2 and HeLa cells. The late apoptosis was recorded as a high rate after treatment with 7 on all cancer cells.

Terpenoids from Marine Soft Coral of the Genus Xenia in 1977 to 2019

Members of the marine soft coral genus Xenia are rich in a diversity of diterpenes. A total of 199 terpenes consisting of 14 sesquiterpenes, 180 diterpenes, and 5 steroids have been reported to date. Xenicane diterpenes were reported to be the most common chemical skeleton biosynthesized by members of this genus. Most of the literature reported the chemical diversity of Xenia collected from the coral reefs in the South China Sea and the coastal waters of Taiwan. Although there was a brief review on the terpenoids of Xenia in 2015, the present review is a comprehensive overview of the structural diversity of secondary metabolites isolated from soft coral genus Xenia and their potent biological activity as reported between 1977 to 2019.

Marine natural products

Covering: January to December 2017This review covers the literature published in 2017 for marine natural products (MNPs), with 740 citations (723 for the period January to December 2017) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1490 in 477 papers for 2017), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. Geographic distributions of MNPs at a phylogenetic level are reported.

Cnidarian Jellyfish: Ecological Aspects, Nematocyst Isolation, and Treatment Methods of Sting

Cnidarians play an important role in ecosystem functioning, in the competition among species, and for possible utilization of several active compounds against cardiovascular, nervous, endocrine, immune, infective, and inflammatory disorders or having antitumoral properties, which have been extracted from these organisms. Nevertheless, notwithstanding these promising features, the main reason for which cnidarians are known is due to their venomousness as they have a serious impact on public health as well as in economy being able to affect some human activities. For this reason a preeminent subject of the research about cnidarians is the organization of proper systems and methods of care and treatment of stinging. This chapter aims to present the data about the morphological, ecological, toxicological, epidemiological, and therapeutic aspects regarding cnidarians with the purpose to summarize the existing knowledge and to stimulate future perspectives in the research on these organisms.