New 18-oxygenated polyhydroxy steroid from a South China Sea soft coral Sarcophyton sp

The application and sustainable development of coral in traditional medicine and its chemical composition, pharmacology, toxicology, and clinical research

This review discusses the variety, chemical composition, pharmacological effects, toxicology, and clinical research of corals used in traditional medicine in the past two decades. At present, several types of medicinal coral resources are identified, which are used in 56 formulas such as traditional Chinese medicine, Tibetan medicine, Mongolian medicine, and Uyghur medicine. A total of 34 families and 99 genera of corals are involved in medical research, with the Alcyoniidae family and Sarcophyton genus being the main research objects. Based on the structural types of compounds and the families and genera of corals, this review summarizes the compounds primarily reported during the period, including terpenoids, steroids, nitrogen-containing compounds, and other terpenoids dominated by sesquiterpene and diterpenes. The biological activities of coral include cytotoxicity (antitumor and anticancer), anti-inflammatory, analgesic, antibacterial, antiviral, immunosuppressive, antioxidant, and neurological properties, and a detailed summary of the mechanisms underlying these activities or related targets is provided. Coral toxicity mostly occurs in the marine ornamental soft coral Zoanthidae family, with palytoxin as the main toxic compound. In addition, nonpeptide neurotoxins are extracted from aquatic corals. The compatibility of coral-related preparations did not show significant acute toxicity, but if used for a long time, it will still cause toxicity to the liver, kidneys, lungs, and other internal organs in a dose-dependent manner. In clinical applications, individual application of coral is often used as a substitute for orthopedic materials to treat diseases such as bone defects and bone hyperplasia. Second, coral is primarily available in the form of compound preparations, such as Ershiwuwei Shanhu pills and Shanhu Qishiwei pills, which are widely used in the treatment of neurological diseases such as migraine, primary headache, epilepsy, cerebral infarction, hypertension, and other cardiovascular and cerebrovascular diseases. It is undeniable that the effectiveness of coral research has exacerbated the endangered status of corals. Therefore, there should be no distinction between the advantages and disadvantages of listed endangered species, and it is imperative to completely prohibit their use and provide equal protection to help them recover to their normal numbers. This article can provide some reference for research on coral chemical composition, biological activity, chemical ecology, and the discovery of marine drug lead compounds. At the same time, it calls for people to protect endangered corals from the perspectives of prohibition, substitution, and synthesis.

Cytotoxic polyhydroxy sterols from the Egyptian Red Sea soft coral Sarcophyton acutum

The methanolic extract and its sub-extracts (viz, n-hexane, DCM, EtOAc and MeOH) of the soft coral Sarcophyton acutum were evaluated as anti-Leishmania major and as anticancer (against the HepG2, MCF-7, and A549 cell lines) using the MTT assay. Six polyhydroxy sterols (1-6) were isolated from the most active cytotoxic and anti-leishmanial EtOAc-soluble fraction. Their structures were established as two new polyhydroxy sterols, acutumosterols A (1) and B (2), and four known structural analogues (3-6) by intensive spectroscopic analyses, and by comparison with data of related compounds. Compound 4 exerted noticeable cytotoxicity against HepG2 cell line (IC₅₀ 17.2 ± 1.5 μg/mL), while the other pure isolates showed weak to moderate cytotoxicity (24.8 ± 2.8-57.2 ± 5.2). The results were discussed in relation to the structural features of these closely related sterols.

Chemical Diversity in Species Belonging to Soft Coral Genus Sacrophyton and Its Impact on Biological Activity: A Review

One of the most widely distributed soft coral species, found especially in shallow waters of the Indo-Pacific region, Red Sea, Mediterranean Sea, and also the Arctic, is genus Sacrophyton. The total number of species belonging to it was estimated to be 40. Sarcophyton species are considered to be a reservoir of bioactive natural metabolites. Secondary metabolites isolated from members belonging to this genus show great chemical diversity. They are rich in terpenoids, in particular, cembranoids diterpenes, tetratepenoids, triterpenoids, and ceramide, in addition to steroids, sesquiterpenes, and fatty acids. They showed a broad range of potent biological activities, such as antitumor, neuroprotective, antimicrobial, antiviral, antidiabetic, antifouling, and anti-inflammatory activity. This review presents all isolated secondary metabolites from species of genera Sacrophyton, as well as their reported biological activities covering a period of about two decades (1998-2019). It deals with 481 metabolites, including 323 diterpenes, 39 biscembranoids, 11 sesquiterpenes, 53 polyoxygenated sterols, and 55 miscellaneous and their pharmacological activities.

First report of bioactive sterols from the muricid gastropod Chicoreus ramosus

Two unusual △⁵ sterols with unprecedented skeletons were isolated from the organic extract of muricid gastropod Chicoreus ramosus collected off the Gulf of Mannar Coast. This is the first report of isolation of bioactive sterols endowed with anti-inflammatory potentials from this species. The compounds were characterized as (5Z)-24a-homo-cholesta-5,24a¹(24a²) dien-3β-ol (1) and 27(25 → 23)-abeo-(5Z)-3β-hydroxy-24-isopropyl cholesteno-26,23-lactone (2) by the interpretation of a series of spectroscopic techniques involving two-dimensional nuclear magnetic resonance and mass spectral data. The compound 1 is unusual in that it has an ethylene attachment stemming from the additional methylene group at the 24a position of the steroid side chain, whereas compound 2 has a unique side chain bearing a γ-valerolactone ring. The △⁵ sterol bearing ethylene group (1) displayed comparatively better antidiabetic activity as characterized by inhibitory effects towards α-amylase and α-glucosidase enzymes (IC₅₀ 1.97 mM and 1.78 mM, respectively), whereas the cholestenolactone analogue (2) manifested higher anti-inflammatory activity (IC₅₀ 1.42 mM) as determined by in vitro 5-lipoxygenase inhibitory potential. Structure-activity correlation study showed that the biological activities of the studied sterols were directly related to their electronic properties. The homosterol (1) exhibiting improved antidiabetic properties showed higher lipophilic character coupled with lesser steric restrictions.

Previously undisclosed bioactive sterols from corbiculid bivalve clam Villorita cyprinoides with anti-inflammatory and antioxidant potentials

The estuarine Corbiculid bivalve black clam, Villorita cyprinoides collected from the Southwestern coastline regions of Arabian Sea are significant resources of nutritional and bioactive pluralities. The purification of ethyl acetate:methanol (EtOAc:MeOH) extract of V. cyprinoides characterized a previously undisclosed specialized abeo-pregnane-type sterol derivative 19 (10 → 5) abeo-20-methyl-pregn-10-en-3β-yl-hex-(3'E)-enoate (1) along with two cholestenols (22E),(24¹E)-24¹,24²-dihomocholesta-5,22,24¹-trien-3β-ol (2) and (22E)-24¹-homocholesta-5,22-dien-(3β,24¹β)-diol (3). These compounds were characterized by comprehensive spectroscopic investigations. The anti-inflammatory (anti-cyclooxygenase-1, 2/5-lipoxidase) activities of 1 were considerably higher (IC₅₀ < 1.10 mg/mL) than 2-3 (IC₅₀ > 1.10 mg/mL). These studied compounds registered greater selectivity indices (∼1.03) against cyclooxygenase-2 than cyclooxygenase-1. The antioxidant property of abeo-pregnane-type sterol as determined by in vitro 2,2'-azino-bis-(3-ethyl-benzthiazoline-6-sulfonic acid) quenching potential was significantly greater (IC₅₀ 0.94 mg/mL) than those of substituted dihomocholesta-trien-ol (2) and homocholesta-dien-diol (3) (IC₅₀ > 1.00 mg/mL). Structure-activity relationship studies demonstrated that bioactive potentials of the titled compounds were linearly related to their electronic factors along with optimum hydrophobic factors. In addition, molecular docking studies were performed in the active sites of COX-2 and their binding energies and docking scores were well correlated with in vitro anti-COX-2 potentials.

New sterols with anti-inflammatory potentials against cyclooxygenase-2 and 5-lipoxygenase from Paphia malabarica

Marine bivalves occupy a leading share in the total edible molluscs at the coastline regions of south-eastern Asia, and are found to possess significant nutritional and biological potential. Various in vitro evaluation (antioxidant and anti-inflammatory) guided purification of ethyl acetate-methanol (EtOAc-MeOH) extract of bivalve clam, Paphia malabarica characterised two new sterol derivatives as 23-gem-dimethylcholesta-5-en-3β-ol (1) and (22E)-24¹,24²-methyldihomocholest-5,22-dien-3β-ol (2) collected from the south-west coast of Arabian Sea. Their structures were unambiguously assigned on the basis of 1D, 2D NMR spectroscopy and mass spectrometry. The antioxidant and anti-inflammatory activities of 2 as determined by DPPH/ABTS⁺ radical scavenging and anti-cyclooxygenase-2/5-lipoxygenase assays were significantly greater (IC₅₀ < 1 mg/mL) than 1 (IC₅₀ > 1 mg/mL). Structure-activity relationship analysis revealed that the bioactivities of these compounds were directly proportional to the electronic and lipophilic parameters. This is the first report of the occurrence and characterisation of 23-gem-dimethyl-3β-hydroxy-Δ⁵-cholestane nucleus and C-30 dihomosterol from marine organisms.

Marine natural products

This review covers the literature published in 2013 for marine natural products (MNPs), with 982 citations (644 for the period January to December 2013) 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 (1163 for 2013), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.

A review of steroids from Sarcophyton species

This review reports the structural diversity of steroids from Sarcophyton species based on literature from the beginning of marine steroid research until now. There are 65 compounds studied from eight species. Most of them are polyhydroxy-type steroids of C-27-C-31 carbon skeleton. Their biological activities are highly diverse ranging from cytotoxic, antibacterial, antifungal, antiviral, anti-inflammatory, antidiabetic to antiosteoporosis properties.