Asterosaponins from the starfish Protoreaster nodosus

Five asterosaponins (1-5), including one new compound named protonodososide (1), were isolated from the methanol extract of the starfish Protoreaster nodosus, after subjecting to various chromatographic separations. The structural elucidation was confirmed by careful analysis of the 1D, 2D NMR, and HR ESI QTOF mass spectra. The cytotoxicity of isolated compounds was evaluated on five human cancer cell lines including HepG2, KB, MCF7, LNCaP, and SK-Mel2.

Acylated flavonoid glycosides from Barringtonia pendula and their inhibition on lipopolysaccharide-induced nitric oxide production in RAW264.7 cells

Six new acylated flavonoid glycosides namely barringosides J - O (1-6) along with tephrokaempferoside and barringoside D were isolated from the branches and leaves of Barringtonia pendula. The structural elucidation was confirmed by extensive analysis of their spectroscopic data including HRQTOFMS, 1D and 2D NMR experiments. Moderate inhibitory effects on LPS-induced NO production in RAW264.7 cells were observed for barringosides M (4) and N (5) with IC50 values of 48.40 ± 3.01 and 56.61 ± 3.87 μM, whereas weak inhibition was found for compounds 1-3, 6, and 7 with IC50 values ranging from 64.91 ± 3.68 to 79.80 ± 3.90 μM.

Isoryanodane diterpene derivatives from Barringtonia macrocarpa

From the MeOH residue of Barringtonia macrocarpa branches and leaves, one new isoryanodane diterpene, barringisol (1), and two new isoryanodane diterpene glucosides, barringisosides A and B (2 and 3), were obtained using various chromatographic isolations. The structural characterization was confirmed by spectroscopic methods including 1D, 2D NMR and HR-ESI-QTOF-MS. This is the first isolation of isoryanodane diterpene derivatives from Barringtonia species. Moreover, the in vitro cytotoxicity of 1-3 on three human cancer cell lines (HepG2, LNCaP and MCF7) was also accessed using SRB assays.

Triterpene Tetraglycosides From Stichopus Herrmanni Semper, 1868

Using various column chromatographic methods, 5 triterpene tetraglycosides (1−5), including one new compound, namely holothurin A6 (1), were obtained from the water soluble part of the methanol extract of the sea cucumber Stichopus herrmanni. Their structures were confirmed by careful analysis of the 1D and 2D NMR, and HR ESI QTOF mass spectra. Noteworthily, 24-dehydroechinoside A (3) showed potent cytotoxicity to 5 human cancer cell lines {HepG2 (hepatoma cancer), KB (epidermoid carcinoma), LNCaP (prostate cancer), MCF7 (breast cancer), and SK-Mel2 (melanoma)} with IC50 values ranging from 0.19 ± 0.03 to 1.17 ± 0.18 µM.

Phenolic glycosides from Oroxylum indicum

Two new phenolic glycosides, oroxylumosides A (1) and B (2), along with four known compounds darendoside A (3), leucosceptoside A (4), acteoside (5) and decaffeoylacteoside (6) were isolated from the stem bark of Oroxylum indicum. Their structures were elucidated by extensive analysis of the 1 D and 2 D NMR as well as HR-ESI-QTOF-MS. In addition, compounds 1 - 4 exhibited inhibitory effects on NO production in LPS-stimulated BV2 microglial cell line with IC₅₀ values of 58.2 ± 2.9, 70.6 ± 3.5, 56.8 ± 2.8 and 61.1 ± 3.1 µM, respectively.

Polyhydroxylated steroid derivatives from the starfish Pentaceraster regulus

A new polyhydroxysteroid glycoside, regulusoside D (1), and a new polyhydroxylated steroid, (24S)-cholestane-3β,5,6β,8,15α,24-hexol (2), together with seven known compounds were purified from the starfish Pentaceraster regulus collected near Con Co Islands, Vietnam. The structure elucidation was confirmed by extensive analysis of their NMR and HR-QTOF mass experiments. Among isolated compounds, regulusoside D (1), (24S)-cholestane-3β,5,6β,8,15α,24-hexol (2), granulatoside A (4), 5α-cholestane-3β,6β,7α,15α,16β,26-hexol (6), 5α-cholestane-3β,6β,7α,8β,15α,16β,26-heptol (7) and 5α-cholestane-3β,6α,8,15α,16β,26-hexol (8) exhibited strong inhibitory effects on LPS-induced NO production in RAW264.7 cells with IC₅₀ values of 9.13 ± 1.17, 9.19 ± 0.77, 8.63 ± 3.31, 12.61 ± 0.51, 14.83 ± 3.02 and 10.98 ± 1.22 µM, respectively.

Limonoids From Choerospondias axillaris

Eight limonoids (1-8), including 1 new compound named as axillariol A (1), were isolated from the dichloromethane extract of Choerospondias axillaris branches and leaves using various chromatographic separations. Their structures were confirmed by detailed analysis of the 1-dimensional (1D), 2D nuclear magnetic resonance, and high-resolution electrospray ionization quadrupole time-of-flight mass spectra. In addition, toonaciliatins N (6) and toonaciliatins O (7) showed selective and significant cytotoxicity on the rhabdomyosarcoma human cancer cell line with half-maximal inhibitory concentration values of 9.12 and 7.79 µM, respectively.

Acylated flavonoid glycosides from Barringtonia racemosa

Using various chromatographic separations, three new acylated flavonoid glycosides, namely barringosides G-I (1-3), were isolated from the water-soluble extract of Barringtonia racemosa branches and leaves. The structure elucidation was performed by extensive analysis of the 1D and 2D NMR and HR-QTOF-MS data. Of the isolated compounds, barringoside I (3) showed moderate inhibitory effects on LPS-induced NO production in RAW264.7 cells with an IC₅₀ of 52.48 ± 1.04 µM.

Anthraquinone and Butenolide Constituents from the Crinoid Capillaster multiradiatus

Seven anthraquinones including two new compounds namely capillasterquinones A and B (1 and 2) and one new butenolide namely capillasterolide (8) were isolated and structurally elucidated from the crinoid Capillaster multiradiatus. The inhibitory effect of compounds 1-8 on lipopolysaccharide (LPS)-induced nitric oxide (NO) production as well as inhibition of 1 on expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) proteins in RAW264.7 cells were also evaluated. As the obtained results, capillasterquinone A (1) showed strong NO production inhibitory activity with an IC₅₀ of 5.89±0.11 µM. In addition, compound 1 reduced the LPS-induced iNOS and COX-2 expressions in a dose-dependent manner.

Triterpene tetraglycosides from the sea cucumber Stichopus horrens

Using various chromatographic separations, three triterpene tetraglycosides (1-3), including one new compound, namely stichorrenoside E (1) along with thelenotoside B (2) and deacetyl thelenotoside B (3), were isolated from the MeOH extract of the Vietnamese sea cucumber Stichopus horrens. Their structures were confirmed by spectroscopic experiments, such as 1D and 2D NMR and HR-ESI-MS. Deacetylated thelenotoside B (3) is firstly isolated as a natural product. Among these compounds, thelenotoside B (2) showed strong cytotoxicities against five human cancer cell lines as HepG2, KB, LNCaP, MCF7 and SK-Mel2 with the IC₅₀ values from 0.95 ± 0.08 to 1.90 ± 0.13 μM, whereas stichorrenoside E (1) and deacetyl thelenotoside B (3) exhibited significant activities with the IC₅₀ values from 6.87 ± 0.25 to 11.62 ± 1.05 μM.

Polar steroid derivatives from the Vietnamese starfish Astropecten polyacanthus

Five polar steroid derivatives, including one new glycosylated polyhydroxysteroid namely polyacanthoside A (1), were isolated from the water-soluble materials from the MeOH extract of the Vietnamese starfish Astropecten polyacanthus using various chromatographic separations. The structure elucidation was confirmed by spectroscopic experiments such as HR-ESI-MS, 1D and 2D NMR. Among the isolated compounds, (20R,24S)-3β,6α,8,15β,24-pentahydroxy-5α-cholestane (3) showed significant cytotoxic effect against five human cancer cell lines as HepG2, KB, LNCaP, MCF7 and SK-Mel2 with the IC₅₀ values from 18.03 ± 2.63 to 21.59 ± 3.23 μM.

Cytotoxic triterpene diglycosides from the sea cucumber Stichopus horrens

Using various chromatographic separation techniques, eight triterpene diglycosides (1-8), including four new compounds namely stichorrenosides A-D (1-4), were isolated from a methanol extract of the Vietnamese sea cucumber S. horrens. Their structures were elucidated based on spectroscopic analyses, including HR ESI MS, 1D and 2D NMR. Their in vitro cytotoxic activity against five human cancer cell lines, Hep-G2 (hepatoma cancer), KB (epidermoid carcinoma), LNCaP (prostate cancer), MCF7 (breast cancer), and SK-Mel2 (melanoma), was evaluated using SRB methods. Stichorrenoside D (4), stichoposide A (5), and 3β-O-[β-d-xylopyranosyl-(1→2)-β-d-xylopyranosyl]-23S-acetoxyholost-7-ene (7) showed strong cytotoxicity on all five tested cancer cell lines, whereas significant effect was observed for stichorrenoside C (3) and stichoposide B (6).

Steroid glycosides from the starfish Pentaceraster gracilis

Using combined chromatographic separations, two new steroid glycosides namely pentacerosides A (1) and B (2), and four known compounds were isolated from the methanol extract of the starfish Pentaceraster gracilis. Their structures were determined on the basis of spectroscopic data (¹H and ¹³C NMR, HSQC, HMBC, ¹H-¹H COSY, ROESY, and FT-ICR-MS) and by comparing obtained results to the literature values. Among the isolated compounds, only maculatoside (5) showed significant cytotoxic effect against Hep-G2 (IC₅₀ = 16.75 ± 0.69 μM) and SK-Mel2 (IC₅₀ = 19.44 ± 1.45 μM) cell lines and moderate effect on KB (IC₅₀ = 36.53 ± 0.78 μM), LNCaP (IC₅₀ = 39.75 ± 3.34 μM), and MCF7 (IC₅₀ = 47.34 ± 7.01 μM) cell lines.

Asterosaponins and glycosylated polyhydroxysteroids from the starfish Culcita novaeguineae and their cytotoxic activities

Using combined chromatographic methods, two asterosaponins (compounds 1 and 2), including a new compound novaeguinoside E (compound 1), and six glycosylated polyhydroxysteroids (compounds 3-8) were isolated from a methanol extract of the starfish Culcita novaeguineae. Their structures were determined on the basis of spectroscopic data ((1)H and (13)C NMR, HSQC, HMBC, (1)H-(1)H COSY, ROESY, and HRESI-MS) and by comparison with the literature values. The new compound 1 represents the third example of asterosaponins containing the 5α-cholesta-9(1l)-en-3β,6α,20,22-tetraol aglycone. Among isolated compounds, 4-7 exhibited moderate to weak cytotoxic activities against five human cancer cell lines such as Hep-G2 (hepatoma), KB (epidermoid carcinoma), LNCaP (prostate cancer), MCF7 (breast cancer), and SK-Mel2 (melanoma).

Triterpene Saponins from the Sea Cucumber Stichopus chloronotus

Sea cucumbers have been used as a dietary delicacy and important ingredient in Asian traditional medicine and functional foods over many centuries. Using combined chromatographic methods, six triterpene saponins (1-6), including a new compound, stichloroside F (1), were isolated from a methanol extract of the sea cucumber Stichopus chloronotus Brandt. Their structures were determined on the basis of spectroscopic (1H and 13C NMR, HSQC, HMBC, 1H-1H COSY, ROESY) and FTICR-MS data and by comparison with literature values.