High species diversity of the soft coral family Xeniidae (Octocorallia, Alcyonacea) in the temperate region of Japan revealed by morphological and molecular analyses

The pro-apoptotic activity of sinueracasbanone D isolated from Sinularia Leptoclados in hepatocellular carcinoma cells

The soft-bodied corals of the genera Sarcophyton and Sinularia (Alcyoniidae) are known as a warehouse of casbane and cembranoid diterpenoids with remarkable antitumor effects. Two casbane-type diterpenoids (1, 2) along with four cembrane-type diterpenoids (3-6) were isolated from the diethyl ether soluble fraction of the organic extracts of the Red Sea soft corals Sinularia leptoclados and Sarcophyton glaucum, respectively. The antiproliferative activity of all isolated compounds (1-6) against three hepatocellular carcinoma cells, namely, Huh-7, SNU 499, and HepG2, along with the normal cells EA.hy 926, was evaluated. Sinueracabanone D (1) displayed a remarkable antiproliferative effect against the examined cancer cell lines, especially HepG2 cells with IC₅₀ of 4.0 ± 0.37 µM. Cell cycle analysis indicated compound 1 caused the accumulation of HepG2 cells in the G2/M-phase. Further, compound 1 exhibited significant pro-apoptotic activities in HepG2 cells as evidenced by annexin V staining, enhanced mRNA expression of Bax, cytochrome C, and caspase 3, as well as inhibition of Bcl2 expression. Also, challenging HepG2 cells with sinueracabanone D (1) enhanced the active oxygen species generation and decreased mitochondrial membrane potential. In conclusion, compound 1 possesses potent antiproliferative activities against HepG2 cells. These antiproliferative activities are mediated, at least partly, by their ability to induce apoptosis, mitochondrial dysfunction, and oxidative stress.

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.

A Comprehensive In Silico Study of New Metabolites from Heteroxenia fuscescens with SARS-CoV-2 Inhibitory Activity

Chemical investigation of the total extract of the Egyptian soft coral Heteroxenia fuscescens, led to the isolation of eight compounds, including two new metabolites, sesquiterpene fusceterpene A (1) and a sterol fuscesterol A (4), along with six known compounds. The structures of 1–8 were elucidated via intensive studies of their 1D, 2D-NMR, and HR-MS analyses, as well as a comparison of their spectral data with those mentioned in the literature. Subsequent comprehensive in-silico-based investigations against almost all viral proteins, including those of the new variants, e.g., Omicron, revealed the most probable target for these isolated compounds, which was found to be M^pro. Additionally, the dynamic modes of interaction of the putatively active compounds were highlighted, depending on 50-ns-long MDS. In conclusion, the structural information provided in the current investigation highlights the antiviral potential of H. fuscescens metabolites with 3β,5α,6β-trihydroxy steroids with different nuclei against SARS-CoV-2, including newly widespread variants.

Xeniakonohana sp. nov. (Cnidaria, Octocorallia, Alcyonacea), a new soft coral species in the family Xeniidae from Miyazaki, Japan

A new soft coral species, Xeniakonohana sp. nov. (Alcyonacea, Xeniidae), is described from Miyazaki in the warm-temperate region of Japan. This new species has conspicuous and unique spindle sclerites in addition to the simple ellipsoid platelet-shaped sclerites typically found in the genus Xenia. These unique spindles are a specific key morphological characteristic for this new species and for differentiating this species among congeneric species.

High taxonomic resolution surveys and trait-based analyses reveal multiple benthic regimes in North Sulawesi (Indonesia)

As coral reef communities change and reorganise in response to increasing disturbances, there is a growing need for understanding species regimes and their contribution to ecosystem processes. Using a case study on coral reefs at the epicentre of tropical marine biodiversity (North Sulawesi, Indonesia), we explored how application of different biodiversity approaches (i.e., use of major taxonomic categories, high taxonomic resolution categories and trait-based approaches) affects the detection of distinct fish and benthic communities. Our results show that using major categories fails to identify distinct coral reef regimes. We also show that monitoring of only scleractinian coral communities is insufficient to detect different benthic regimes, especially communities dominated by non-coral organisms, and that all types of benthic organisms need to be considered. We have implemented the use of a trait-based approach to study the functional diversity of whole coral reef benthic assemblages, which allowed us to detect five different community regimes, only one of which was dominated by scleractinian corals. Furthermore, by the parallel study of benthic and fish communities we provide new insights into key processes and functions that might dominate or be compromised in the different community regimes.

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.

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.