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Species belonging to the Vernonia (Asteraceae), the largest genus in the tribe Vernonieae (consisting of about 1,000 species), are widely used in food and medicine. These plants are rich sources of bioactive sesquiterpene lactones and steroid saponins, likely including many as yet undiscovered chemical components. A phytochemical investigation resulted in the separation of three new stigmastane-type steroidal saponins (1 - 3), designated as vernogratiosides A-C, from whole plants of V. gratiosa . Their structures were elucidated based on infrared spectroscopy (IR), one-dimensional (1D) and two-dimensional nuclear magnetic resonance (2D NMR), high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), and electronic circular dichroism analyses (ECD), as well as chemical reactivity. Molecular docking analysis of representative saponins with α-glucosidase inhibitory activity was performed. Additionally, the intended substances were tested for their ability to inhibit α-glucosidase activity in a laboratory setting. The results suggested that stigmastane-type steroidal saponins from V. gratiosa are promising candidate antidiabetic agents.

Mangrove plant endophytic bacteria are prolific sources of bioactive secondary metabolites. In the present study, twenty-three endophytic bacteria were isolated from the fresh roots of the mangrove plant Rhizophora apiculata . The identification of isolates by 16S rRNA gene sequences revealed that the isolated endophytic bacteria belonged to nine genera, including Streptomyces , Bacillus , Pseudovibrio , Microbacterium , Brevibacterium , Microbulbifer , Micrococcus , Rossellomorea , and Paracoccus . The ethyl acetate extracts of the endophytic bacteria's pharmacological properties were evaluated in vitro, including antimicrobial, antioxidant, α-amylase and α-glucosidase inhibitory, xanthine oxidase inhibitory, and cytotoxic activities. Gas chromatography-mass spectrometry (GC-MS) analyses of three high bioactive strains Bacillus sp. RAR_GA_16, Rossellomorea vietnamensis RAR_WA_32, and Bacillus sp. RAR_M1_44 identified major volatile organic compounds (VOCs) in their ethyl acetate extracts. Genome analyses identified biosynthesis gene clusters (BGCs) of secondary metabolites of the bacterial endophytes. The obtained results reveal that the endophytic bacteria from R. apiculata may be a potential source of pharmacological secondary metabolites, and further investigations of the high bioactive strains-such as fermentation and isolation of pure bioactive compounds, and heterologous expression of novel BGCs in appropriate expression hosts-may allow exploring and exploiting the promising bioactive compounds for future drug development.

The bitter melon, Momordica charantia L., was once an important food and medicinal herb. Various studies have focused on the potential treatment of stomach disease with M . charantia and on its anti-diabetic properties. However, very little is known about the specific compounds responsible for its anti-inflammatory activities. In addition, the in vitro inhibitory effect of M . charantia on pro-inflammatory cytokine production by lipopolysaccharide (LPS)-stimulated bone marrow-derived dendritic cells (BMDCs) has not been reported. Phytochemical investigation of M . charantia fruit led to the isolation of 15 compounds ( 1 - 15 ). Their chemical structures were elucidated spectroscopically (one- and two-dimensional nuclear magnetic resonance) and with electrospray ionization mass spectrometry. The anti-inflammatory effects of the isolated compounds were evaluated by measuring the production of the pro-inflammatory cytokines interleukin IL-6, IL-12 p40, and tumor necrosis factor α (TNF-α) in LPS-stimulated BMDCs. The cucurbitanes were potent inhibitors of the cytokines TNF-α, IL-6, and IL-12 p40, indicating promising anti-inflammatory effects. Based on these studies and in silico simulations, we determined that the ligand likely docked in the receptors. These results suggest that cucurbitanes from M . charantia are potential candidates for treating inflammatory diseases.

Stauntonia hexaphylla (Lardizabalaceae) has been used as a traditional herbal medicine in Korea and China for its anti-inflammatory and analgesic properties. As part of a bioprospecting program aimed at the discovery of new bioactive compounds from Korean medicinal plants, a phytochemical study of S. hexaphylla leaves was carried out leading to isolation of two oleanane-type triterpene saponins, 3- O -[ β -d-glucopyranosyl (1→2)- α -l-arabinopyranosyl] oleanolic acid-28- O -[ β -d-glucopyranosyl (1→6)- β -d-glucopyranosyl] ester ( 1 ) and 3- O - α -l-arabinopyranosyl oleanolic acid-28- O -[ β -d-glucopyranosyl (1→6)- β -d-glucopyranosyl] ester ( 2 ). Their structures were established unambiguously by spectroscopic methods such as one- and two-dimensional nuclear magnetic resonance and infrared spectroscopies, high-resolution electrospray ionization mass spectrometry and chemical reactions. Their anti-inflammatory activities were examined for the first time with an animal model for the macrophage-mediated inflammatory response as well as a cell-based assay using an established macrophage cell line (RAW 264.7) in vitro. Together, it was concluded that the saponin constituents, when they were orally administered, exerted much more potent activities in vivo than their sapogenin core even though both the saponins and the sapogenin molecule inhibited the RAW 264.7 cell activation comparably well in vitro. These results imply that saponins from S. hexaphylla leaves have a definite advantage in the development of oral medications for the control of inflammatory responses.

Marine invertebrates and their associated microorganisms are rich sources of bioactive compounds. Among them, coral and its associated microorganisms are promising providers of marine bioactive compounds. The present review provides an overview of bioactive compounds that are produced by corals and coral-associated microorganisms, covering the literature from 2010 to March 2019. Accordingly, 245 natural products that possess a wide range of potent bioactivities, such as anti-inflammatory, cytotoxic, antimicrobial, antivirus, and antifouling activities, among others, are described in this review., Competing Interests: The authors declare no conflicts of interest.

Two new naphtoquinones (smenocerones A and B, 1 and 2) and four known sesquiterpene cyclopentenones (dactylospongenones A-D, 3-6) were isolated from sponge Smenospongia cerebriformis living in the Eastern Sea of Vietnam. Their chemical structures were determined by high resolution electrospray ionization (HR-ESI)-MS, NMR spectroscopic analysis, and in comparison with the reported data. The chiroptical properties of compounds 3-6 were examined by experiment and theoretical calculation of circular dichroism (CD) spectra to prove their absolute configurations. Compound 2 significantly exhibited cytotoxic activity towards lung carcinoma (LU-1), hepatocellular carcinoma (HepG-2), promyelocytic leukemia (HL-60), breast carcinoma (MCF-7), and melanoma (SK-Mel-2) human cancer cells with IC 50 values of 5.5±0.8, 3.2±0.2, 4.0±0.7, 4.1±0.8, and 5.7±1.1 µg/mL, respectively.