## 2 Classes of Secondary Metabolites  
### Diterpenes  
_Sarcophyton etherepgi_ dichloromethane extract yielded sarcophytol T **1**, (1\(E\),3\(E\),7\(E\),11_R_*12_R_*)-15-(acetylmethyl)cembra-11,12-epoxy-1,3,7-triene **2**, and (115*,125*)-15-(acetylmethyl) cembra-3,4:11,12-diepoxy-1,7-diene **3**, together with known isoneochemrene A **4**, an isomer to neochemrane A **5**, and (25*,11R*,12R*)-isosarcophytoxide **6**. Compound **2** was found to possess several structural similarities with the former two isolates in conjugated diene system (C-1 and C-4) and \(\Delta^{7,8}\) double bond and 11,12-epoxy functional group [27]. Another three cembrenolide diterpenes identified as crassolide **7**, sarcocrassolide A **8**, and 13-acetylsexocorassolide **9**, alongside known cembrenolide dencitulatolide **10**, were reported from _S. crassocaule_[28]. From _S. trocheliophorum_, the isolation of 7,8-epoxy-1(_E_),3(_E_),11(_E_)cembratrien-15-ol **11**, 7,8-epoxy1(_E_),3(_E_),11(_E_)-cembratriene **12**, and sarcophin **13** was reported, and the absolute configuration of sarcophin **13** was investigated through modified Mosher's assay [29]. Using chromatographic techniques, cembrane alcohol identified as acutanol **14** beside scerophytol A **15** and sarcophytol A acetate **16** were isolated from _S. actungulum_ extract. The absolute configuration of sarcophytol A **15** was assessed with the use of many chiral anisotropic reagents, as 1-naphthylmethoxyacetic acid [30]. Four cembranes, (15,2\(E\),_AR_,6\(E\),85_,115,125)-11,12-Epoxy-2,6-cembrane-4,8-diol **17**, (15,2\(E\),_AR_,6\(E\),8_,115,125)-11,12-Epoxy-2,6-cembrane-4,8-diol **18**, (15,2\(E\),_AR_,75)-11,12-Epoxy-2,8(19)-cembradiene-4,7-diol **19**, and (15,2\(E\),_AR_,7R_)-11,12-Epoxy-2,8(19)-cembradiene-4,7-diol **20**, were isolated from _Sarcophyton_ sp. It is worth noticing that these metabolites were not previously found in nature. Their absolute configurations were validated with X-ray analysis [31]. The hydroperoxide cembrane diterpenoid, sarcophycrassolide A **21**, together with sacophyllocrassolide B **22** and compound **8**, was reported from _S. crassocaule_. Identification of compound **21** was resolved by using X-ray diffraction and spectral analysis [32]. Three furano-cembranoids and two seco-cembranoid acetates, which were identified as 13-dehydroaysarcoglaucl **23**, 13-dehydroaysarcoglaucl-16-one **24** and sarcogluc16-one **25**, (3_E_)-7-hydroxy-4,8,15,15-tetramethyl-1-1(_E_)-12-methyl-10-oxo-12-pentenyl]-3,8-decadienyl acetate **26**, (3_E_)-7-hydroxy-4,8,15,15-tetramethyl-1-1(_Z_)-12-methyl-10-oxo-12-pentenyl]-3,8-decadienyl acetate **27** beside sarcoglucal **28**, and decarijo1 **29**, were isolated form _S. chernonieri_. Spectral data showed that compound **25** was a 16-keto derivative of compound **28** and the 13-hydroxy derivative of compound **24**[33]. The absolute configuration of compound **25** was investigated similarly to compound **13** by using the modified Mosher's method [34]. Another two bicyclic cembranoides metabolites, with infrequent structures in marine literature, having a 12\(Z\) double bond, identified as (4\(Z\),\(8\),\(S\),9_,12\(Z\),14_E_)-9-Hydroxy-1-isopropyl-8,12-dimethyl-oxabicyclo [9.3.2]-hexadeca-4,12,14-trien-18-one **30**, and (4\(Z\),12\(Z\),14_E_)-sarcophytolide **31**, in addition to sarcophytolide **32**, (4\(Z\),\(8\),9\(R\),12\(E\),14_E_)-9-Hydroxy-1-isopropyl-8,12-dimethyloxabicyclo[9.3.2]-hexadeca-4,12,14-trien-18-one **33** and (4\(Z\),_8\(S\),9\(R\),12\(E\),14_E_)-1-Isopropyl-8,12-dimethyl-18-oxo-oxabicyclo[9.3.2]-hexadeca-4,12,14-trien-2-yl acetate **34**, were reported from _Sarcophyton_ new sp. Additionally, the authors presented biosynthetic pathways for all isolated compounds which resulted from the common acyclic precursor (all-_E_)-geranylgeranyl pyrophosphate (GGPP), by converting geranyl-PP [GGPP] into geranyleryl-PP [GNPP], using diterpene synthase, followed by cyclization to cembranoid ring with a 12\(Z\) double bond [35].