Capgermacrenes D-G, new sesquiterpenoids from a Bornean soft coral, Capnella imbricata

An Overview of Secondary Metabolites from Soft Corals of the Genus Capnella over the Five Decades: Chemical Structures, Pharmacological Activities, NMR Data, and Chemical Synthesis

There has been no specific review on the secondary metabolites from soft corals of the genus Capnella till now. In this work, all secondary metabolites from different species of the title genus were described. It covered the first work from 1974 to May 2024, spanning five decades. In the viewpoint of the general structural features, these chemical constituents were classified into four groups: sesquiterpenes, diterpenes, steroids, and lipids. Additionally, the 1H and 13C NMR data of these metabolites were provided when available in the literature. Among them, sesquiterpenes were the most abundant chemical compositions from soft corals of the genus Capnella. A variety of pharmacological activities of these compounds were evaluated, such as cytotoxic, antibacterial, antifungal, and anti-inflammatory activities. In addition, the chemical synthesis works of several representative sesquiterpenes were provided. This review aims to provide an up-to-date knowledge of the chemical structures, pharmacological activities, and chemical synthesis of the chemical constituents from soft corals of the genus Capnella.

Chemical composition and antibacterial activity of 12 medicinal plant ethyl acetate extracts using LC-MS feature-based molecular networking

INTRODUCTION

Widespread use of antibiotics has led to an increase in bacterial multiple drug resistance, thereby searching for natural antimicrobial agents from plants becomes an effective and alternative approach. In the present study, we selected six foodborne bacteria to evaluate the antibacterial activities of 12 medicinal plants ethyl acetate (EA) extracts.

OBJECTIVE

This study aims to search for natural antibiotic substitutes from plant extracts. The antibacterial components were further discussed through chemometric and mass spectroscopic analyses.

METHODOLOGY

Agar well diffusion and the microdilution methods were used to test the antibacterial activity. Total phenolic content (TPC) and total flavonoid content (TFC) were used to judge the active phytochemicals. To further characterise the potential antibacterial components, an ultra-performance liquid chromatography-quadrupole-time of flight-mass spectrometry (UPLC-Q-TOF-MS) coupled with Pearson correlation and feature-based molecular network (FBMN) were proposed.

RESULTS

Most of the plant extracts possessed antibacterial activity against Bacillus subtilis and Salmonella typhi. Toona sinensis shoots and Firmiana simplex barks showed high inhibitory activities against Staphylococcus aureus, Shigella dysenteriae, and Escherichia coli strains with minimum inhibitory concentrations (MICs) of 1.56, 0.78, and 0.39 mg/mL, respectively. Salmonella typhi was highly sensitive to Firmiana simplex barks with an inhibitory diameter up to 21.67 ± 0.95 mm, and MIC at 0.78 mg/mL. Moreover, Toona sinensis shoots and Firmiana simplex barks had the highest TPCs.

CONCLUSION

Our results indicated that Toona sinensis shoots, Koelreuteria paniculate seeds, and Firmiana simplex barks could be supplied as potential sources of antimicrobial agents. Furthermore, 36 potential bioactive compounds were identified mainly as polyphenols, glycosides, and terpenoids.

Cytotoxic Sesquiterpenoids From Soft Soral Capnella imbricata

A new sesquiterpene, capgermacrene H (1) was isolated together with 7 other compounds, capgermacrenes A-G (2-8), from a population of soft coral Capnella imbricata collected from Mantanani Island, Sabah, Malaysia. The structure of this metabolite was elucidated based on spectroscopic data such as nuclear magnetic resonance and high-resolution electrospray ionization mass spectrometry. Capgermacrene A (2) showed potent cytotoxicity against adult T-cell leukemia, S1T cells at half-maximal inhibitory concentration of 0.79 µg/mL.

Recent Updates on Corals from Nephtheidae

Marine natural products display a wide range of biological activities, which play a vital role in the innovation of lead compounds for the drug development. Soft corals have been ranked at the top in regard to the discovery of bioactive metabolites with potential pharmaceutical applications. Many of the isolated cembranoids revealed diverse biological activities, such as anticancer, antidiabetic and anti-osteoporosis. Likewise, sterols from soft corals exhibited interesting biological potential as anti-inflammatory, antituberculosis and anticancer. Consequently, investigating marine soft corals will definitely lead to the discovery of a large number of chemically varied secondary metabolites with countless bioactivities for possible applications in medicine and pharmaceutical industry. This review provides a complete survey of all metabolites isolated from the family Nephtheidae, from 2011 until November 2018, along with their natural sources and biological potential whenever possible.

Bioactive Cembranoids from the Soft Coral Genus Sinularia sp. in Borneo

Soft corals are known to be prolific producers of a wide spectrum of biologically active cembranoids. One new cembranoid, sinularolide F (2), along with three known compounds, cembranolide (1), (E,E,E)-6,10,14-trimethyl-3-methylene-cis-3α,4,5,8,9,12,13,15α-octahydrocyclo tetradeca[β]furan-2(3H)-one (3), and denticulatolide (4), were isolated from the Bornean soft coral Sinularia sp. Compounds 2 and 4 showed potential anti-inflammatory activities against lipopolysaccharide-stimulated RAW 264.7 with IC₅₀ values less than 6.25 µg/mL and anticancer activity against HL60 cell lines. The compounds' mechanisms of action were investigated via the Western blot evaluation of their protein markers. These activities could be attributed to the presence of tertiary methyl at C-8 and the compounds' 3D configurations.

A New Cembrane, from Soft Coral Genus Sarcophyton in Borneo

One new cembrane diterpene, (1 S, 2 E, 4 R, 6 E, 8 S, 11 S, 12 S)-11,12-epoxy-8-hydroperoxy-4-hydroxy-2,6-cembradiene (1) was isolated from a population of Bornean soft coral genus Sarcophyton collected from the coastal waters Bohey Dulang, Sabah, Malaysia. Its structure was elucidated based on extensive spectroscopic analysis including NMR and HRESIMS spectra. Cytotoxic, anti-inflammatory and antibacterial activities were tested.