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Review

Natural Products from Octocorals of the Genus Dendronephthya (Family Nephtheidae)

by
Yung-Husan Chen
1,
Yu-Chia Chang
2,
Yu-Hsin Chen
3,
Li-Guo Zheng
3,4,
Pin-Chang Huang
3,4,
Thanh-Hao Huynh
3,5,
Bo-Rong Peng
3,4,6,
You-Ying Chen
3,5,
Yu-Jen Wu
7,
Lee-Shing Fang
5,8,9,
Jui-Hsin Su
3,10,
Chang-Min Hsu
11,* and
Ping-Jyun Sung
3,5,10,12,13,*
1
Department of Pharmacy, Xiamen Medical College, Xiamen 361023, Fujian, China
2
Research Center for Chinese Herbal Medicine, Graduate Institute of Healthy Industry Technology, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan 333324, Taiwan
3
National Museum of Marine Biology and Aquarium, Pingtung 944401, Taiwan
4
Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University, Kaohsiung 804201, Taiwan
5
Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung 804201, Taiwan
6
Doctoral Degree Program in Marine Biotechnology, Academia Sinica, Taipei 115201, Taiwan
7
Department of Food Science and Nutrition, Meiho University, Pingtung 912009, Taiwan
8
Center for Environmental Toxin and Emerging-Contaminant Research, Cheng Shiu University, Kaohsiung 833301, Taiwan
9
Super Micro Mass Research and Technology Center, Cheng Shiu University, Kaohsiung 833301, Taiwan
10
Graduate Institute of Marine Biology, National Dong Hwa University, Pingtung 944401, Taiwan
11
Department of Immunology & Rheumatology, Antai Medical Care Corporation Antai Tian-Sheng Memorial Hospital, Pingtung 928004, Taiwan
12
Chinese Medicine Research and Development Center, China Medical University Hospital, Taichung 404394, Taiwan
13
Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung 807378, Taiwan
 
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*
Authors to whom correspondence should be addressed.
Molecules 2020, 25(24), 5957; https://doi.org/10.3390/molecules25245957
Submission received: 24 November 2020 / Revised: 14 December 2020 / Accepted: 15 December 2020 / Published: 16 December 2020
(This article belongs to the Section Natural Products Chemistry)
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Abstract

:
In this review, 170 natural substances, including steroid, diterpenoid, sesquiterpenoid, peptide, prostaglandin, base, chlorolipid, bicyclolactone, amide, piperazine, polyketide, glycerol, benzoic acid, glycyrrhetyl amino acid, hexitol, pentanoic acid, aminoethyl ester, octadecanone, alkaloid, and a 53-kD allergenic component from octocorals belonging to genus Dendronephthya, were listed. Some of these compounds displayed potential bioactivities.

1. Introduction

Octocorals of the genus Dendronephthya (phylum Cnidaria, class Anthozoa, subclass Octocorallia, order Alcyonacea, suborder Alcyoniina, family Nephtheidae) [1], distributed in the Indo-Pacific Ocean, have been investigated. Since the initial study in 1999 discovered four antifouling seco-steroids, isogosterones A–D (1–4), from an octocoral Dendronethphya sp. collected off the Izu Peninsula, Japan [2] (Figure 1), subsequent studies over the past two decades have yielded a series of interesting secondary metabolites, particularly steroid metabolites. In this article, different types of compounds isolated from Dendronephthya spp., were summarized.

2. Dendronephthya gigantea (Verrill, 1864)

The Dendronephthya genus includes one common species, D. gigantea. Yoshikawa and colleagues isolated five polyhydroxylated sterols, including two new metabolites, dendronesterols A (5) and B (6), along with three known analogues, (22E,24S)-24-methyl-cholesta-7,22-diene-3β,5α, 6β,9α-tetrol (7) [3], (22E)-cholesta-7,22-diene-3β,5α,6β,9α-tetrol (8) [3], and (22E)-24-norcholesta-7, 22-diene-3β,5α,6β-triol (9) [4,5] (Figure 2), from D. gigantea collected off the coast of Tokushima, Japan [6]. The study also established the structures of new sterols 5 and 6 by spectroscopic methods. A cytotoxic assay showed that sterol 6 had an IC50 value of 5.2 µg/mL in the treatment of L1210 (mouse lymphocytic leukemia) cells [6].
In 2004, three new steroids, dendronesterones A–C (10–12), along with a known steroid, cholest-1-ene-3,22-dione (13) [7], were isolated from D. gigantea, collected at Green Island, off Taiwan [8] (Figure 3). Structures of steroids 10–13 were established by spectroscopic methods, and the 1H and 13C chemical shifts at C-23 and C-24 in steroid 13 were revised in this study. In the cytotoxic testing, steroids 10 and 13 had ED50 values of 9.84 and 8.93 µM, respectively, in the treatment of P-388 (mouse lymphoma) cells, and 13 was cytotoxic toward HT-29 (human colorectal adenocarcinoma) cells with an ED50 value of 9.03 µM [8].
Furthermore, two known metabolites, including a monoalkyl glycerol ether (±)-1-non- adecyloxy-2,3-propanediol (14) [9], a ceramide, (2S,3R,4E,8E)-N-hexadecanoyl-2-amino-4,8- octadecadiene-1,3-diol (15) [10,11,12,13,14], as well as two bases, thymine (16) and uracil (17), (Figure 4), were isolated from the organic extract of D. gigantea, collected in the area of Jeju Island, Korea [15]. The structures of metabolites 14–17 were established by spectroscopic methods and by comparison of their physical and spectral data with those of literature values and glycero 14 was found to be cytotoxic toward A549 (human lung epithelial carcinoma), HT-29, HT-1080 (human connective tissue epithelial fibrosarcoma), and SNU-638 (human gastric adenocarcinoma) cells with IC50 values of 15.1, 14.5, 13.7, and 15.5 µg/mL, respectively [15]. Glycerol 14 was not optically active ( [ α ] D 25 0.00 (c 0.134, MeOH)), indicating that this compound is a racemic mixture. Thus, the stereogenic center C-2 in 14 was not determined [15]. Sphingolipid 15 showed cytotoxicity against human peripheral blood mononuclear cells (PBMC) with an ED50 of 20 µg/mL [13].
Eight well known secondary metabolites, including (2S,3R,4E,8E)-N-hexadecanoyl-2-amino-4,8- octadecadiene-1,3-diol (15) [10,11,12,13,14] (Figure 4), (2S,3R,4E)-N-hexadecanoyl-2-amino-4-octadecane-1,3- diol (18) [10,16], N-phenethylacetamide (19) [17,18,19,20,21], cyclo-(Leu-Pro) (20), cyclo-(Ala-Pro) (21), cyclo- (Val-Pro) (22) [22], 2,4-dichlorobenzonic acid (23) [23], thymidine (24) [24,25,26,27,28,29,30,31,32], 2′-deoxyuridine (25) [27,28,29,30,32,33], and cholesterol (26) [30] (Figure 5), were isolated from D. gigantea, collected from the South China Sea [34]. The structures of compounds 15 and 18–26 were elucidated by spectral data and by comparison with the spectral and physical data of other known compounds [34].
In 2012, six steroids, including three new compounds, 3-oxocholest-1,22-dien-12β-ol (27), 3- oxocholest-1,4-dien-20β-ol (28), 3-oxocholest-1,4-dien-12β-ol (29), along with three known analogues, (20S)-20-hydroxyergosta-1,4,24-trien-3-one (30) [35], 5α,8α-epidioxycholesta-6,22-dien-3β-ol (31) [36], and 5-cholestene-3β,12β-diol (32) [37] (Figure 6), were isolated from D. gigantea, collected near Geo-Je Island, South Korea [38]. The structures for steroids 27–32 were established by spectroscopic methods. Steroids 27–31 displayed inhibitory activity against farnesoid X-activated receptor (FXR) with IC50′s 14, 15, 100, 22, and 61 µM, respectively, and were not cytotoxic toward the CV-1 cells (Cercopithecus aethiops, African green monkey kidney cells) [38].
In 2017, Jeon and Lee’s group reported the isolation of a mixture consisting nine 3β-hydroxy- Δ5-steroidal congeners, including 26,27-dinorergosta-5,22-dien-3β-ol (33) [39], cholesta-5,22-dien- 3β-ol (including 22-trans form 34 and 22-cis form 35) [40], cholest-5-en-3β-ol (= cholesterol) (26) [30] (Figure 5), ergosta-5,22-dien-3β-ol (36) [41], stigmasta-5,24-dien-3β-ol (= fucosterol) (37) [42,43,44,45,46,47,48], stigmasta-5,22-dien-3β-ol (38) [48], stigmasta-5-en-3β-ol (39) [48], and 22,23-methylenecholesterol (40) [49] (Figure 7), from D. gigantea collected from Jeju Island, South Korea [50]. The structures for all sterols 26 and 33–40 were determined by GC-MS/MS analysis. In lipopolysaccharides (LPS)- stimulated RAW cells, this mixture inhibited nitric oxide (NO) and prostaglandin E2 (PGE2) production via the downregulation of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) inflammatory mediators. This sterol-rich mixture also suppressed the expression of proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β), and interleukin 6 (IL-6). The anti-inflammatory effects of this sterol-rich mixture was confirmed in an LPS-stimulated in vivo zebrafish model by the downregulation of iNOS and COX-2 expression, inhibition of NO and reactive oxygen species (ROS) levels, and increased cytoprotective effects against LPS-induced toxicity [50]. Furthermore, this sterol-rich fraction was found to exhibit cytotoxicity toward HL-60 (human acute promyelocytic leukemia) and MCF-7 (Michigan Cancer Foundation-7, human invasive ductal carcinoma) cells with IC50 values of 13.59 and 29.41 µg/mL [51], and one of the mixtures, stigmasta-5-en-3β-ol (39), displayed cytotoxicity on HL-60 and MCF-7 cells with IC50 values of 37.82 and 45.17 µg/mL, respectively [52].
Fifteen steroids, including four new compounds, 7-dehydroerectasteroid F (41), 11α- acetoxyarmatinol A (42), 22,23-didehydroarmatinol A (43), and 3-O-acetylhyrtiosterol (44), as well as 11 known steroids, 24-methylene-5-cholesten-3β,7β-diol (45) [53], 24-methylene-5-cholesten-3β, 19-diol (= litosterol) (46) [54], 24-methylene-5-cholesten-3β,19-diol-7β-monoacetate (47) [55], 5,6- epoxylitosterol (48) [54], armatinol A (49) [56], hyrtiosterol (50) [57,58], (2β,3β,4α,5α,8β,11β)-4- methylergost-24-ene-2,3,8,11-tetrol (51) [58], and erectasteroids C–F (52–55) [59] (Figure 8), were isolated from D. gigantea, collected from the inner coral reef of Meishan, Hainan Province, China [60]. The structures of new steroids 41–43 were elucidated by comprehensive spectroscopic analysis and steroid 41 was found to show protection against hydrogen-peroxide (H2O2)-induced oxidative damage in neuron-like PC-12 (rat adrenal gland pheochromocytoma) cells by promoting nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and enhancing the expression of heme oxygenase-1 (HO-1) [60].

3. Dendronephthya griffini (Roxas, 1933)

Ten new steroids, griffinisterones A–I (56–64) and griffinipregnone (65) (Figure 9), were obtained from D. griffini specimens collected by a bottom trawl net at depths from 200 to 100 m at Taiwan Straight in December 2004 [61,62]. The structures of steroids 56–65 were determined by spectroscopic methods and the configuration of griffinisterone A (56) was further confirmed by a single-crystal X-ray diffraction analysis [61,62]. The absolute stereochemistry of griffinisterone E (60) was determined by the application of a modified phenylglycine methyl ester (PGME) method [61]. Anti-inflammatory assays revealed that griffinisterones A–D (56–59), F–H (61–63), and griffinipregnone (65), reduced the levels of iNOS protein to 49.7, 48.9, 8.1, 29.8, 13.4, 6.5, 15.4, and 59.6%, respectively, at a concentration of 10 µM [61,62]. At the same concentration, griffinisterones F (61), G (62), and griffinipregnone (65), reduced the levels of COX-2 protein to 61.7, 31.5, and 52.3%, respectively [62].
Furthermore, two new interesting polychlorolipids, (2R,3S,4R,5S,6S,7R)-2,3,5,6,7-pentachloro- pentadec-14-en-4-yl hydrogen sulfate (66), (2R,3S,4R,5S,6S,7R)-2,3,5,6,7-pentachloropentadec-14- en-4-ol (67), and a new natural substance, (2R,3S,4R,5S,6S,7R,E)-2,3,5,6,7,15-hexachloropentadec- 14-en-4-ol (68) [63,64], along with a known analogue, chlorosulfolipid (69) [63,64] (Figure 10), were obtained from D. griffini [65]. The structures of chlorolipids 66–69 were determined by extensive spectroscopic analysis and by comparison of the NMR data with those of known compounds. It was found that chlorolipid 68 has been prepared from the hydrolysis of 69 [63] and by a total synthesis of racemic 68 [64]. Chlorolipid 68 was isolated for the first time from a natural source and the compounds of this type was isolated for the first time from the soft corals [65].

4. Dendronephthya hemprichi (Klunzinger, 1877)

Chemical investigation of the extract of D. hemprichi, collected from the Red Sea, Egypt, delivered a novel glycyrrhetyl amino acid, dendrophen (70), a new sterol, dendrotriol (71), along with the well-known metabolites, cholesterol (26) [30] (Figure 4) and hexitol (72) [66]. The structures of new compounds 70 and 71 were established by spectroscopic methods, although the stereocehmsitry for C-24 stereogenic center in 71 was not determined [66]. Furthermore, chromatography separation of the low-polarity components of D. hemprichi extract afforded 4-oxo- pentanoic acid (73), 2-methyl-acrylic acid 2-diethylaminoethyl ester (74), juniper camphor (75), and 2-octadecanone (76) (Figure 11) [66].

5. Dendronephthya mucronata (Pütter, 1900)

A new pregane-type steroid 5α-pregn-20-en-3,6-dione (77), along with five known steroids, 5α- pregn-20-en-3β-ol (78) [67,68,69], 1,4,20-pregnatrien-3-one (79) [70,71,72,73,74], 15β-acetoxypregna-1,4,20-trien-3-one (80) [73,75], 5α-cholestan-3,6-dione (81) [76,77,78], and 5α-cholest-22-en-3,6-dione (82) [79], (Figure 12), were isolated from D. mucronate collected from waters off Phu Quoc Islands, Kien Giang, Vietnam in 2018 [80]. The structure of new steroid 77 was elucidated by spectroscopic method. Steroids 78 and 81 showed moderate inhibitory effects on LPS-induced NO formation in RAW264.7 murine macrophage cells with IC50 values of 30.15 and 35.97 µM, respectively.
Furthermore, three new bicyclo lactones, dendronephthyones A–C (83–85), along with a known analogue, suberosanone B (86) [81] (Figure 13), were isolated from the methanol extract of the same target material D. mucronata [82]. Structures of lactones 83–86 were established by spectroscopic methods and these four compounds exhibited cytotoxicity toward HeLa (human papillomavirus-related endocervical adenocarcinoma) cells with IC50 values of 32.48, 30.12, 35.45, and 14.45 µM, respectively [82].

6. Dendronephthya nipponica (Utinomi, 1952)

A red soft-coral D. nipponica cause spiny lobster fisherman living along the coast of Miyazaki Prefecture, Japan to develop occupational allergies. In order to understand the allergic mechanism, a new 53-kD allergenic component (Den n 1) (87) was purified and the N-terminal amino of this allergen component was determined and identified as Asp-Asp-IIe-Asn-Arg-Tyr-Ala-Phe-Asp-Asn-Lys-IIe-Asn-Asp-Lys-Leu-Phe-Asp-His-Trp-Gln-Ser [83].

7. Dendronephthya puetteri (Kükenthal, 1905)

In 2018, Jeon’s group reported the isolation of a 3β-hydroxy-Δ5-steroidal congener, consisting of six sterols, cholesterol (26) [30] (Figure 4), cholesta-5,22-dien-3β-ol (34) [40], ergosta-5,22-dien-3β-ol (36) [41], stigmasta-5-en-3β-ol (39) [48], 22,23-methylenecholesterol (40) [49] (Figure 7), and cholesta-5,24-dien-3β-ol (88) [84] (Figure 14), from D. puetteri, collected from the Jeju Island, South Korea [85]. The structures for all sterols 26, 34, 36, 39, 40, and 88 were determined by GC-MS/MS analysis [85]. In lipopolysaccharides (LPS)-stimulated RAW264.7 cells, this mixture inhibited nitric oxide (NO) production with an IC50 value of 6.54 µg/mL. Moreover, this congener reduced the level of PGE2 TNF-α, IL-1β, and IL-6. The anti-inflammatory effects of this sterol-rich mixture was confirmed in an LPS-stimulated in vivo zebrafish model by the downregulation of NO, iNOS, COX-2, ROS production and cell death [85,86], and this sterol rich congener showed cytotoxicity toward HL-60 and MCF-7 cells with IC50 values of 25.27 and 22.81 µg/mL, respectively [87].

8. Dendronephthya rubeola (Henderson, 1909)

Four new acetoxycapnellenes, 2α,8β,13-triacetoxycapnell-9-ene-10α-ol (89), 3α,8β,14-tri- acetoxycapnell-9-ene-10α-ol (90), 3α,14-diacetoxycapnell-9-ene-8β,10α-diol (91), 3α,8β-di- acetoxycapnell-9-ene-10α-ol (92), and the first epoxyprecapnellene, 3α,4α-epoxyprecapnell-10- ene (93), as well as two known analogues, capnell-9-ene-8β,10α-diol (94) [88,89] and 8β-acetoxy- capnell-9-ene-10α-ol (95) [88,90] (Figure 15), were obtained from D. rubeola, collected from the waters near Bali, Indonesia [91]. Structures of 89–95 were established by spectroscopic methods. Compounds 94 and 95 displayed antiproliferative activity against L-929 (murine connective tissue fibroblasts) (GI50 = 6.8, 20.9 µM) [91]; 94 displayed cytotoxicity toward HL-60, K-562 (human chronic myelogenous leukemia), G-402 (human renal leiomyoblastoma), MCF-7, HT-115 (human colon carcinoma), and A-2780 (human ovarian endometrioid adenocarcinoma) cells with IC50 values of 51, 0.7, 42–51, 93, 63, and 9.7 µM, respectively [89]. Compounds 94 and 95 also showed cytotoxicity toward HeLa cells (CC50 = 7.6, 9.4 µM) [91]. It is interesting to note that compound 94 (capnell-9-ene-8β,10α-diol) inhibited the interaction of oncogenic transcription factor Myc (a family of regulator genes and proto-oncogenes that code for transcription factors) with its partner protein Max (inhibition = 77%) in yeast [91].

9. Dendronephthya studeri (Ridley, 1884)

Eleven steroids, including eight new metabolites, (22E)-19-norcholesta-1,3,5,22-tetraen-3-ol (96), (22E)-19,24-dinorcholesta-1,3,5,22-tetraen-3-ol (97), (22E)-24,26-cyclo-19-norcholesta-1,3,5 (10),22-tetraen-3-ol (98), 24-methylene-19-norcholesta-1,3,5,22-tetraen-3-ol (99), (22E,24S)-24- methyl-19-norcholesta-1,3,5,22-tetraen-3-ol (100), (22E,24R)-24-methyl-19-norcholesta-1,3,5, 22-tetraen-3-ol (101), 24-methylenecholesta-1,4,22-trien-3-one (102), and (22E)-24-cholesta-1,4,22- trien-3-one (103), which all were found to be characterized by either the presence of an aromatic ring or a cross-conjugated dienone system in ring A, as well as three known steroids, methyl spongoate (104) [92], 19-norcholesta-1,3,5-trien-3-ol (105) [93,94], and dendronesterone C (12) (Figure 3) [8], were obtained from D. studeri, collected off the coast of Xiaodong Sea, Hainan Province, China [95] (Figure 16). Structures of isolates 12 and 96–105 were established by spectroscopic analysis and by comparison of their NMR data with those reported in the literature. Steroid 104 exhibited cytotoxicity against BEL-7402 (human papillomavirus-related endocervical adenocarcinoma), A-549, HT-29, and P-388 cells with IC50 values of 0.14, 5, 5, and 3.8 µg/mL [92].

10. Dendronephthya spp.

Dendronephthya is a genus of octocoral belonging to the family Nephtheidae and there are over 250 described species in this genus. In 1990, Katrich and colleagues identified the correlation between the number of particular phospholipids (PhLs) and prostaglandins (PGs) that influenced the prostaglandin-like activities of the extracts from (1) Dendronephthya sp., collected in the region of the Great Barrier Reef, Australia and (2) Dendronephthya sp., collected in Vietnam [96].
An acetone extract from Dendronephthya sp., collected in 1990, off the Chichi-jima and Haha-jima Islands in the Ogasawara Islands, Japan, showed a high level of antifouling activity against the blue mussel Mytilus edulis [97]. Purification of the extract gave mixtures of sterols and fatty acids as active components. In the sterol mixture, there are several sterols, (24S)-24-methylcholesta-5(E),22- dien-3β-ol (= pincsterol) or (24R)-24-methylcholesta-5(E),22-dien-3β-ol (= brassicasterol) (106) [98], cholesterol (26) [30] (Figure 5), β-sitosterol (stigmasta-5-en-3β-ol) (39) [48], and β-cholestanol (5α- cholestan-3β-ol) (107) [99] were identified and sterol 39 in this study [97] was found to contain 35% of a 24S epimer (clionasterol) (108) [100,101] (Figure 17). Sterol 39 had the highest antifouling activity among sterols 26, 39, and 107 [97]. Moreover, a fatty acid mixture, showing the presence of saturated and unsaturated fatty acids with a chain length of C12 to C22, being rich in C16 and C18 acids as active constituents in antifouling activity [97].
Kawamata et al. isolated an antifouling substance, trigonelline (109) (Figure 18), from Dendronephthya sp. collected at Chichijima Island in the Ogasawara Islands [102]. The structure of 109 was elucidated by spectroscopic methods and this compound showed the same level of settling-inhibitory activity against the acorn barnacle Balanus amphitrite larvae as CuSO4 [102,103].
In 1999, the ethanol extract of two soft coral specimens Dendronephthya (Roxasia) sp. and Dendronephthya (Morchellana) sp., collected off the Gopalpur coast, Bay of Bengal, were found to display attachment inhibitory activity against the settlement of cyprids of barnacle Balanus amphitrite [104], and the extract was claimed to contain natural non-toxic antifouling agents, although no natural products was reported to be active components.
Research by a group in Japan identified four new antifouling seco-steroids, isogosterones A–D (1–4) (Figure 1) from an octocoral identified as Dendronethphya sp. collected off the Izu Peninsula, Japan [2], and their structures were elucidated on the basis of spectroscopic data. This is the first time to isolate naturally occurring 13,17-secosteroids. It is interesting to note that secosteroids 3 and 4 were interconvertible in CHCl3 and 3 was detected as the hydrolyzed product of 4 [2]. These four secosteroids displayed activity to inhibit the settlement of B. amphitrite cyprid larvae with an EC50 values of 2.2 µg/mL
Furthermore, a new steroid, methyl 3-oxochola-4,22-dien-24-oate (110) (Figure 19) [105], from Dendronephthya sp. collected off the Kii Peninsula, Japan, and determined its structure using spectroscopic methods [105]. Steroid 110 was lethal to cyprids of B. amphitrite at 100 µg/mL (LD100) but did not inhibit larval settlement of B. amphitrite [105].
Four new brominated oxylipins, (4S,5E,7Z,12R,14Z,17Z)-4-hydroxy-17,18-didehydrobromo- vulone-3 (111), (4S,5E,7Z,12R,14Z,17Z)-4-(α-d-glucopyranosyloxy)-17,18-didehydrobromovulone-3 (112), (4R,5E,7Z,12R,14Z,17Z)-4-hydroxy-17,18-didehydrobromovulone-3 (113), and (4R,5E,7Z,12R, 14Z,17Z)-4-(β-D-glucopyranosyloxy)-17,18-didehydrobromovulone-3 (114), (Figure 20) were isolated from Dendronephthya spp. (red variety—for compounds 111 and 112; yellow variety—for compounds 113 and 114) collected in the Gulf of Aqaba in the Red Sea (Eilat, Israel) [106]. The structures, including the absolute configurations of oxylipins 111–114, were determined by spectroscopic and chemical methods. All the isolates showed significant inhibition of the growth of crown gall tumors on potato disks inoculated with Agrobacterium tumefaciens and gave positive responses in a brine shrimp toxicity toward Artemia salina; these compounds showed antibacterial activity against the Gram-(+) bacteria Staphylococcus aureus and Bacillus subtilis [106].
Fifteen steroids, including five new compounds, (22E)-3-O-β-formylcholest-5,22-diene (115), (22E)-3-O-β-formyl-24-methyl-cholest-5,22-diene (116), 2-ethoxycarbonyl-2-β-hydroxy-A-nor- cholest-5-ene-4-one (117), (22E)-2-ethoxycarbonyl-2-β-hydroxy-A-nor-cholest-5,22-diene-4-one (118), (22E)-2-ethoxycarbonyl-2-β-hydroxy-24-methyl-A-nor-cholest-5,22-diene-4-one (119), a new natural steroid, 3-β-formyloxycholest-5-ene (120) [107], as well as nine known steroids, 3β,7β-dihydroxy- cholest-5-ene (121) [108,109], (22E)-3β,7α-dihydroxy-cholest-5,22-diene (122) [110], 3β,7α- dihydroxy-24-methylene-cholest-5-ene (123) [109], 3β,7α-dihydroxy-24-methyl-cholest-5,22-diene (124) [110], 3β,7α-dihydroxy-cholest-5-ene (125) [110,111,112], cholest-4-ene-3-one (126) [113,114,115], 24- methylene-cholest-4-ene-3-one (127) [116,117], (22E)-cholest-4,22- dien-3-one (128) [116], and (22E)-24-methyl-cholest-4,22-dien-3-one (129) [118] (Figure 21), were isolated from the soft coral Dendronephthya sp. collected off coral reef in Sanya, Hainan Province, South China Sea of People’s Republic of China [119]. The structures of steroids 115–129 were elucidated by spectroscopic methods and by comparison of their spectroscopic data with those reported previously. However, the configuration of Me-28 at stereogenic center C-24 in steroids 116, 119, 124, and 129 were not determined in this study. Steroids 115, 116, and 120 belonging to 3-O-formylated cholesterol analogues and steroids 117–119 are unique ring A-contracted steroids [119].
A chemical examination of a soft coral identified as Dendronephthya sp., collected from the inner coral reef in Sanya Bay, Hainan Island of China, resulted in the isolation of 20 cembrane-type diterpenoids [120], including 15 new metabolites, dendronpholides C–F (130–133), I–R (134–143), and (–)-sandensolide (144) (an enantiomer of sandensolide) [120,121,122,123,124], along with five known compounds, 11-episinulariolide (145) [125,126,127,128,129,130], and sinulaflexiolides E, F, J, K (146–149) [128] (Figure 22). The structures of all isolates 130–149 were determined through spectroscopic methods and by comparison with those reported in literature [120]. Cembranoid dendronpholides C (130), J (135), and sinulaflexiolide E (146) showed cytotoxicity toward BGC-823 (human papillomavirus-related endocervical adenocarcinoma) cells with IC50 values of 0.05, 0.20, 0.02 µg/mL, respectively, whereas the other compounds were not active. A comparison of the cytotoxic data between 130 and 144 revealed that the methyl ester functionality plays a crucial role in the inhibition of BGC-823 cells compared to the the ε-lactone functionality. This is the first report of cembrane-type diterpenoids from the soft corals belonging to the genus Dendronephthya [120].
In 2010, two tetrahydroxylated sterols, including a new compound, 23-nor-ergost-24-ene- 3β,5α,6β,7β-tetrol (150) and a known analogue, ergost-24-ene-3β,6β,9α,19β-tetrol (151) [131], were isolated from Dendronephthya sp. collected from Naozhou Islands of the South China Sea [132] (Figure 23). The structures of sterols 150 and 151 were identified by spectroscopic methods [132]. Sterol 150 showed cytotoxicity toward the BEL-7402, MCG (human plasma cell myeloma), MCF, LoVo (human colorectal adenocarcinoma), and Hep G2 (human hepatocellular carcinoma) cells with IC50 values of 32.2, 20.5, 2.0, 5.5, and 18.6 µg/mL, respectively, and sterol 151 was cytotoxic against MCG and LoVo cells (IC50 = 22.0, 13.8 µg/mL), respectively [132].
Three new ylangene-type sesquiterpenoids, dendronephthols A–C (152–154) (Figure 24), together with two known steroids, dendronesterone A (10) [8] (Figure 3) and cholesterol (26) [30] (Figure 5), were isolated from a Red Sea soft coral Dendronephthya sp., collected near the coast of Hurghada, Egypt [133]. The structures of new sesquiterpenoids 152–154 were established by spectroscopic methods and 152 and 154 were found to be cytotoxic against L5178Y (mouse lymphoma) cells with ED50 values of 8.4 and 6.8 µg/mL, respectively [133].
Furthermore, two new steroids, dendronesterones D (155) and E (156), featuring with 1,4-dienone moiety, together with three known steroids, methyl 3-oxochola-4,22-dien-24-oate (110) [105] (Figure 19), 5α,8α-epidioxy-24(S)-methylcholesta-6,22-dien-3β-ol (157), and 5α,8α-epidioxy- 24(S)-methylcholesta-6,9,22-trien-3β-ol (158) [36,134], were isolated from an octocoral Dendronephthya sp., collected off the northeast coast of Taiwan [135] (Figure 25). The structures of new steroids 155 and 156 were elucidated by using spectroscopic methods and 155 was found to suppress the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) to 24.2 and 70.4% at a concentration of 10 µM [135].
Two new 2,5-piperazinedione derivatives, janthinolides A (159) and B (160), as well as a new natural product, deoxymycelianamide (161) [136,137], and two known metabolites, griseofulvin (162) [138,139,140,141,142], and dechlorogriseofulvin (163) [142,143,144], were isolated from the fermentation broths of the endophytic fungus Penicillium janthinellum, isolated from a soft coral identified as Dendronephthya sp., collected in the South China Sea [145]. The structures of metabolites 159–163 were determined by spectroscopic data analysis and compound 162 displayed inhibitory concentration at 2.75 and 20 µg/mL against the fungal pathogen Alternaria solani and ascomycetous pathogen Pyricularia oryzae, respectively [145] (Figure 26).
Moreover, seven isoechinulin-type alkaloids, neoechinulin A (164) [146,147,148,149,150,151,152,153,154], preechinulin (165) [155,156], isoechinulin A (166) [149,157], tardioxopiperazine A (167) [158], variecolorin L (168) [159], dihydroxyisoechinulin A (169) [160], and L-alanyl-L-tryptophan anhydride (170) [161] (Figure 27), were isolated from the fermentation broths of an endophytic fungus Nigrospora oryzae isolated from a soft coral identified as Dendronephthya sp. collected in the South China Sea [162]. The structures of 164–170 were determined by their spectroscopic data and by comparison with those reported in the literature. In the antifouling activity against the larval settlement of barnacle Balanus amphitrite, compound 166 showed activity with an IC50 value of 5.92 µg/mL [162].

11. Conclusions

Ever since the seco-steroids, isogosterones A–D (1–4) were obtained from a specimen of the octocoral Dendronephthya collected off the Izu Peninsula, Japan [2], 170 interesting secondary metabolites, including 96 steroids (56.47%), 20 cembranes (11.76%), 11 sesquiterpenoids (6.47%), 11 amides (6.47%), 4 chlorolipids (2.35%), 4 bicyclic lactones (2.35%), 4 prostaglandins (2.35%), 4 bases (2.35%), 3 peptides (1.76%), 2 polyketides (1.18%), 2 ceramides (1.18%), 1 glycerol (0.59%), 1 glycyrrhetyl amino acid (0.59%), 1 benzoic acid (0.59%), 1 trigonelline (0.59%), 1 hexitol (0.59%), 1 pentanoic acid (0.59%), 1 octadecanone (0.59%), 1 aminoethyl ester (0.59%), and a 53-KD allergenic component (0.59%), were produced by Dendronephthya spp., and extensive biomedical activities, especially in cytotoxicity and anti-inflammatory activity, were related to these natural substances (Figure 28).
All the secondary metabolites from Dendronephthya spp., reported between 1999 and 2019 were obtained from the octocorals distributed in the Indo-Pacific Ocean and Red Sea. As more than 56% of the compounds obtained from the Dendronephthya genus are steroids, based on above findings, these results suggest that continuing the investigation of new steroid analogues with the potential bioactivities from this marine organism are worthwhile for further development. The octocoral Dendronephthya sp. had been transplanted to culturing tanks located in the National Museum of Marine Biology and Aquarium, Taiwan, for the extraction of additional natural products to establish a stable supply of bioactive material.

Author Contributions

Y.-H.C. (Yung-Husan Chen), C.-M.H., and P.-J.S. contributed in terms of writing the manuscript. Y.-C.C., Y.-H.C. (Yu-Hsin Chen), L.-G.Z., P.-C.H., T.-H.H., B.-R.P., Y.-Y.C., Y.-J.W., L.-S.F., and J.-H.S., conceived and designed the format of the manuscript. All authors have read and agreed to the published version of the manuscript.

Funding

This research was supported by grants from the National Museum of Marine Biology and Aquarium; the Ministry of Science and Technology (Grant Nos. MOST 109-2320-B-276-002-MY3, 107-2320-B-291-001-MY3, 109-2320-B-291-001-MY3), Taiwan, awarded to Yu-Jen Wu and Ping-Jyun Sung.

Conflicts of Interest

The authors declare no conflict of interest.

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Molecules 25 05957 g001 550
Figure 1. Structures of isogosterones A–D (1–4).
Figure 1. Structures of isogosterones A–D (1–4).
Molecules 25 05957 g001
Molecules 25 05957 g002 550
Figure 2. Structures of dendronesterols A (5) and B (6), (22E,24S)-24-methyl-cholesta-7,22-diene-3β, 5α,6β,9α-tetrol (7), (22E)-cholesta-7,22-diene-3β,5α,6β,9α-tetrol (8), and (22E)-24-norcholesta-7,22- diene-3β,5α,6β-triol (9).
Figure 2. Structures of dendronesterols A (5) and B (6), (22E,24S)-24-methyl-cholesta-7,22-diene-3β, 5α,6β,9α-tetrol (7), (22E)-cholesta-7,22-diene-3β,5α,6β,9α-tetrol (8), and (22E)-24-norcholesta-7,22- diene-3β,5α,6β-triol (9).
Molecules 25 05957 g002
Molecules 25 05957 g003 550
Figure 3. Structures of dendronesterones A–C (10–12) and cholest-1-ene-3,22-dione (13).
Figure 3. Structures of dendronesterones A–C (10–12) and cholest-1-ene-3,22-dione (13).
Molecules 25 05957 g003
Molecules 25 05957 g004 550
Figure 4. Structures of (±)-1-nonadecyloxy-2,3-propanediol (14) and (2S,3R,4E,8E)-N-hexadecanoyl- 2-amino-4,8-octadecadiene-1,3-diol (15), thymine (16), and uracil (17).
Figure 4. Structures of (±)-1-nonadecyloxy-2,3-propanediol (14) and (2S,3R,4E,8E)-N-hexadecanoyl- 2-amino-4,8-octadecadiene-1,3-diol (15), thymine (16), and uracil (17).
Molecules 25 05957 g004
Molecules 25 05957 g005 550
Figure 5. Structures of (2S,3R,4E)-N-hexadecanoyl-2-amino-4-octadecane-1,3-diol (18), N-phenethyl -acetamide (19), cyclo-(Leu-Pro) (20), cyclo-(Ala-Pro) (21), cyclo-(Val-Pro) (22), 2,4-dichlorobenzonic acid (23), thymidine (24), 2′-deoxyuride (25), and cholesterol (26).
Figure 5. Structures of (2S,3R,4E)-N-hexadecanoyl-2-amino-4-octadecane-1,3-diol (18), N-phenethyl -acetamide (19), cyclo-(Leu-Pro) (20), cyclo-(Ala-Pro) (21), cyclo-(Val-Pro) (22), 2,4-dichlorobenzonic acid (23), thymidine (24), 2′-deoxyuride (25), and cholesterol (26).
Molecules 25 05957 g005
Molecules 25 05957 g006 550
Figure 6. Structures of 3-oxocholest-1,22-dien-12β-ol (27) 3-oxocholest-1,4-dien-20β-ol (28), 3-oxo- cholest-1,4-dien-12β-ol (29), (20S)-20-hydroxyergosta-1,4,24-trien-3-one (30), 5α,8α-epidioxy- cholesta-6,22-dien-3β-ol (31), and 5-cholestene-3β,12β-diol (32).
Figure 6. Structures of 3-oxocholest-1,22-dien-12β-ol (27) 3-oxocholest-1,4-dien-20β-ol (28), 3-oxo- cholest-1,4-dien-12β-ol (29), (20S)-20-hydroxyergosta-1,4,24-trien-3-one (30), 5α,8α-epidioxy- cholesta-6,22-dien-3β-ol (31), and 5-cholestene-3β,12β-diol (32).
Molecules 25 05957 g006
Molecules 25 05957 g007 550
Figure 7. Structures of 26,27-dinorergosta-5,22-dien-3β-ol (33), cholesta-5,22-dien-3β-ol (including 22-trans form 34 and 22-cis form 35), ergosta-5,22-dien-3β-ol (36), stigmasta-5,24-dien-3β-ol (= fucosterol) (37), stigmasta-5,22-dien-3β-ol (38), stigmasta-5-en-3β-ol (39), and 22,23-methylene- cholesterol (40).
Figure 7. Structures of 26,27-dinorergosta-5,22-dien-3β-ol (33), cholesta-5,22-dien-3β-ol (including 22-trans form 34 and 22-cis form 35), ergosta-5,22-dien-3β-ol (36), stigmasta-5,24-dien-3β-ol (= fucosterol) (37), stigmasta-5,22-dien-3β-ol (38), stigmasta-5-en-3β-ol (39), and 22,23-methylene- cholesterol (40).
Molecules 25 05957 g007
Molecules 25 05957 g008 550
Figure 8. Structures of 7-dehydroerectasteroid F (41), 11α-acetoxyarmatinol A (42), 22,23-di- dehydroarmatinol A (43), 3-O-acetylhyrtiosterol (44), 24-methylene-5-cholesten-3β,7β-diol (45), 24- methylene-5-cholesten-3β,19-diol (46), 24-methylene-5-cholesten-3β,19-diol-7β-monoacetate (47), 5,6-epoxylitosterol (48), armatinol A (49), hyrtiosterol (50), (2β,3β,4α,5α,8β,11β)-4-methylergost-24 (28)-ene-2,3,8,11-tetrol (51), and erectasteroids C–F (52–55).
Figure 8. Structures of 7-dehydroerectasteroid F (41), 11α-acetoxyarmatinol A (42), 22,23-di- dehydroarmatinol A (43), 3-O-acetylhyrtiosterol (44), 24-methylene-5-cholesten-3β,7β-diol (45), 24- methylene-5-cholesten-3β,19-diol (46), 24-methylene-5-cholesten-3β,19-diol-7β-monoacetate (47), 5,6-epoxylitosterol (48), armatinol A (49), hyrtiosterol (50), (2β,3β,4α,5α,8β,11β)-4-methylergost-24 (28)-ene-2,3,8,11-tetrol (51), and erectasteroids C–F (52–55).
Molecules 25 05957 g008
Molecules 25 05957 g009 550
Figure 9. Structures of griffinisterones A–I (56–64) and griffinipregnone (65).
Figure 9. Structures of griffinisterones A–I (56–64) and griffinipregnone (65).
Molecules 25 05957 g009
Molecules 25 05957 g010 550
Figure 10. Structures of polychlorolipids 66–69.
Figure 10. Structures of polychlorolipids 66–69.
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Molecules 25 05957 g011 550
Figure 11. Structures of dendrophen (70), dendrotriol (71), hexiol (72), 4-oxo-pentanoic acid (73), 2- methyl-acrylic acid 2-diethylaminoethyl ester (74), juniper camphor (75), and 2-octadecanone (76).
Figure 11. Structures of dendrophen (70), dendrotriol (71), hexiol (72), 4-oxo-pentanoic acid (73), 2- methyl-acrylic acid 2-diethylaminoethyl ester (74), juniper camphor (75), and 2-octadecanone (76).
Molecules 25 05957 g011
Molecules 25 05957 g012 550
Figure 12. Structures of 5α-pregn-20-en-3,6-dione (77), 5α-pregn-20-en-3β-ol (78), 1,4,20-pregna- trien-3-one (79), 15β-acetoxypregna-1,4,20-trien-3-one (80), 5α-cholestan-3,6-dione (81), and 5α- cholest-22-en-3,6-dione (82).
Figure 12. Structures of 5α-pregn-20-en-3,6-dione (77), 5α-pregn-20-en-3β-ol (78), 1,4,20-pregna- trien-3-one (79), 15β-acetoxypregna-1,4,20-trien-3-one (80), 5α-cholestan-3,6-dione (81), and 5α- cholest-22-en-3,6-dione (82).
Molecules 25 05957 g012
Molecules 25 05957 g013 550
Figure 13. Structures of dendronephthyones A–C (83–85) and suberosanone B (86).
Figure 13. Structures of dendronephthyones A–C (83–85) and suberosanone B (86).
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Molecules 25 05957 g014 550
Figure 14. Structure of cholesta-5,24-dien-3β-ol (88).
Figure 14. Structure of cholesta-5,24-dien-3β-ol (88).
Molecules 25 05957 g014
Molecules 25 05957 g015 550
Figure 15. Structures of 2α,8β,13-triacetoxycapnell-9-ene-10α-ol (89), 3α,8β,14-triacetoxy- capnell-9-ene-10α-ol (90), 3α,14-diacetoxycapnell-9-ene-8β,10α-diol (91), 3α,8β-diacetoxy- capnell-9-ene-10α-ol (92), 3α,4α-epoxyprecapnell-10-ene (93), capnell-9-ene-8β,10α-diol (94), and 8β-acetoxycapnell-9-ene-10α-ol (95).
Figure 15. Structures of 2α,8β,13-triacetoxycapnell-9-ene-10α-ol (89), 3α,8β,14-triacetoxy- capnell-9-ene-10α-ol (90), 3α,14-diacetoxycapnell-9-ene-8β,10α-diol (91), 3α,8β-diacetoxy- capnell-9-ene-10α-ol (92), 3α,4α-epoxyprecapnell-10-ene (93), capnell-9-ene-8β,10α-diol (94), and 8β-acetoxycapnell-9-ene-10α-ol (95).
Molecules 25 05957 g015
Molecules 25 05957 g016 550
Figure 16. Structures of (22E)-19-norcholesta-1,3,5,22-tetraen-3-ol (96), (22E)-19,24-dinor- cholesta-1,3,5,22-tetraen-3-ol (97), (22E)-24,26-cyclo-19-norcholesta-1,3,5,22-tetraen-3-ol (98), 24-methylene-19-norcholesta-1,3,5,22-tetraen-3-ol (99), (22E,24S)-24-methyl-19-norcholesta-1,3,5 (10),22-tetraen-3-ol (100), (22E,24R)-24-methyl-19-norcholesta-1,3,5,22-tetraen-3-ol (101), 24- methylenecholesta-1,4,22-trien-3-one (102), (22E)-24-cholesta-1,4,22-trien-3-one (103), methyl spongoate (104), and 19-norcholesta-1,3,5-trien-3-ol (105).
Figure 16. Structures of (22E)-19-norcholesta-1,3,5,22-tetraen-3-ol (96), (22E)-19,24-dinor- cholesta-1,3,5,22-tetraen-3-ol (97), (22E)-24,26-cyclo-19-norcholesta-1,3,5,22-tetraen-3-ol (98), 24-methylene-19-norcholesta-1,3,5,22-tetraen-3-ol (99), (22E,24S)-24-methyl-19-norcholesta-1,3,5 (10),22-tetraen-3-ol (100), (22E,24R)-24-methyl-19-norcholesta-1,3,5,22-tetraen-3-ol (101), 24- methylenecholesta-1,4,22-trien-3-one (102), (22E)-24-cholesta-1,4,22-trien-3-one (103), methyl spongoate (104), and 19-norcholesta-1,3,5-trien-3-ol (105).
Molecules 25 05957 g016
Molecules 25 05957 g017 550
Figure 17. Structures of pincsterol (24S), brassicasterol (24R) (106), β-cholestanol (107), β-sitosterol (39), and clionasterol (108).
Figure 17. Structures of pincsterol (24S), brassicasterol (24R) (106), β-cholestanol (107), β-sitosterol (39), and clionasterol (108).
Molecules 25 05957 g017
Molecules 25 05957 g018 550
Figure 18. Structure of trigonelline (109).
Figure 18. Structure of trigonelline (109).
Molecules 25 05957 g018
Molecules 25 05957 g019 550
Figure 19. Structure of methyl 3-oxochola-4,22-dien-24-oate (110).
Figure 19. Structure of methyl 3-oxochola-4,22-dien-24-oate (110).
Molecules 25 05957 g019
Molecules 25 05957 g020 550
Figure 20. Structures of oxylipins 112–114.
Figure 20. Structures of oxylipins 112–114.
Molecules 25 05957 g020
Molecules 25 05957 g021 550
Figure 21. Structures of (22E)-3-O-β-formylcholest-5,22-diene (115), (22E)-3-O-β-formyl-24-methyl- cholest-5,22-diene (116), 2-ethoxycarbonyl-2-β-hydroxy-A-nor-cholest-5-ene-4-one (117), (22E)-2- ethoxycarbonyl-2-β-hydroxy-A-nor-cholest-5,22-diene-4-one (118), (22E)-2-ethoxycarbonyl-2-β- hydroxy-24-methyl-A-nor-cholest-5,22-diene-4-one (119), 3-β-formyloxycholest-5-ene (120), 3β,7β- dihydroxycholest-5-ene (121), (22E)-3β,7α-dihydroxy-cholest-5,22-diene (122), 3β,7α-dihydroxy-24- methylene-cholest-5-ene (123), 3β,7α-dihydroxy-24-methyl-cholest-5,22-diene (124), 3β,7α- dihydroxy-cholest-5-ene (125), cholest-4-ene-3-one (126), 24-methylene-cholest-4-ene-3-one (127), (22E)-cholest-4,22-dien-3-one (128), and (22E)-24-methyl-cholest-4,22-dien-3-one (129).
Figure 21. Structures of (22E)-3-O-β-formylcholest-5,22-diene (115), (22E)-3-O-β-formyl-24-methyl- cholest-5,22-diene (116), 2-ethoxycarbonyl-2-β-hydroxy-A-nor-cholest-5-ene-4-one (117), (22E)-2- ethoxycarbonyl-2-β-hydroxy-A-nor-cholest-5,22-diene-4-one (118), (22E)-2-ethoxycarbonyl-2-β- hydroxy-24-methyl-A-nor-cholest-5,22-diene-4-one (119), 3-β-formyloxycholest-5-ene (120), 3β,7β- dihydroxycholest-5-ene (121), (22E)-3β,7α-dihydroxy-cholest-5,22-diene (122), 3β,7α-dihydroxy-24- methylene-cholest-5-ene (123), 3β,7α-dihydroxy-24-methyl-cholest-5,22-diene (124), 3β,7α- dihydroxy-cholest-5-ene (125), cholest-4-ene-3-one (126), 24-methylene-cholest-4-ene-3-one (127), (22E)-cholest-4,22-dien-3-one (128), and (22E)-24-methyl-cholest-4,22-dien-3-one (129).
Molecules 25 05957 g021
Molecules 25 05957 g022 550
Figure 22. Structures of dendronpholides C–F (130–133), I–R (134–143), (−)-sandensolide (144), 11-episinulariolide (145) and sinulaflexiolides E, F, J, K (146–149).
Figure 22. Structures of dendronpholides C–F (130–133), I–R (134–143), (−)-sandensolide (144), 11-episinulariolide (145) and sinulaflexiolides E, F, J, K (146–149).
Molecules 25 05957 g022
Molecules 25 05957 g023 550
Figure 23. Structures of 23-nor-ergost-24-ene-3β,5α,6β,7β-tetrol (150) and ergost-24-ene-3β, 6β,9α,19-tetrol (151).
Figure 23. Structures of 23-nor-ergost-24-ene-3β,5α,6β,7β-tetrol (150) and ergost-24-ene-3β, 6β,9α,19-tetrol (151).
Molecules 25 05957 g023
Molecules 25 05957 g024 550
Figure 24. Structures of dendronephthols A–C (152–154).
Figure 24. Structures of dendronephthols A–C (152–154).
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Molecules 25 05957 g025 550
Figure 25. Structures of dendronesterones D (155) and E (156), 5α,8α-epidioxy-24(S)-methyl- cholesta-6,22-dien-3β-ol (157), and 5α,8α-epidioxy-24(S)-methylcholesta-6,9,22-trien-3β-ol (158).
Figure 25. Structures of dendronesterones D (155) and E (156), 5α,8α-epidioxy-24(S)-methyl- cholesta-6,22-dien-3β-ol (157), and 5α,8α-epidioxy-24(S)-methylcholesta-6,9,22-trien-3β-ol (158).
Molecules 25 05957 g025
Molecules 25 05957 g026 550
Figure 26. Structures of janthinolides A (159), B (160), deoxymycelianamide (161), griseofulvin (162), and dechlorogriseofulvin (163).
Figure 26. Structures of janthinolides A (159), B (160), deoxymycelianamide (161), griseofulvin (162), and dechlorogriseofulvin (163).
Molecules 25 05957 g026
Molecules 25 05957 g027 550
Figure 27. Structures of neoechinulin A (164), preechinulin (165), isoechinulin A (166), tardioxopiperazine A (167), variecolorin L (168), dihydroxyisoechinulin A (169), and L-alanyl-L- tryptophan anhydride (170).
Figure 27. Structures of neoechinulin A (164), preechinulin (165), isoechinulin A (166), tardioxopiperazine A (167), variecolorin L (168), dihydroxyisoechinulin A (169), and L-alanyl-L- tryptophan anhydride (170).
Molecules 25 05957 g027
Molecules 25 05957 g028 550
Figure 28. Biomedical activities of natural products from Dendronephthya spp.
Figure 28. Biomedical activities of natural products from Dendronephthya spp.
Molecules 25 05957 g028
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Chen, Y.-H.; Chang, Y.-C.; Chen, Y.-H.; Zheng, L.-G.; Huang, P.-C.; Huynh, T.-H.; Peng, B.-R.; Chen, Y.-Y.; Wu, Y.-J.; Fang, L.-S.; et al. Natural Products from Octocorals of the Genus Dendronephthya (Family Nephtheidae). Molecules 2020, 25, 5957. https://doi.org/10.3390/molecules25245957

AMA Style

Chen Y-H, Chang Y-C, Chen Y-H, Zheng L-G, Huang P-C, Huynh T-H, Peng B-R, Chen Y-Y, Wu Y-J, Fang L-S, et al. Natural Products from Octocorals of the Genus Dendronephthya (Family Nephtheidae). Molecules. 2020; 25(24):5957. https://doi.org/10.3390/molecules25245957

Chicago/Turabian Style

Chen, Yung-Husan, Yu-Chia Chang, Yu-Hsin Chen, Li-Guo Zheng, Pin-Chang Huang, Thanh-Hao Huynh, Bo-Rong Peng, You-Ying Chen, Yu-Jen Wu, Lee-Shing Fang, and et al. 2020. "Natural Products from Octocorals of the Genus Dendronephthya (Family Nephtheidae)" Molecules 25, no. 24: 5957. https://doi.org/10.3390/molecules25245957

APA Style

Chen, Y.-H., Chang, Y.-C., Chen, Y.-H., Zheng, L.-G., Huang, P.-C., Huynh, T.-H., Peng, B.-R., Chen, Y.-Y., Wu, Y.-J., Fang, L.-S., Su, J.-H., Hsu, C.-M., & Sung, P.-J. (2020). Natural Products from Octocorals of the Genus Dendronephthya (Family Nephtheidae). Molecules, 25(24), 5957. https://doi.org/10.3390/molecules25245957

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