## 2 Classes of Secondary Metabolites
### Diterpenes
Through structural analysis, sarccrossacolide N **151** was found to have the same relative configuration of sarccrossacolide M **150**, while sarccrossacolide O **152** was found to be the 13-deacetoxy derivative of sarccrossacolide M **150**[60]. Three more cembranoids, sarccrossacolides P-R **153-155**, were identified, and their structures were investigated by an extensive spectral study [61]. Investigation of n-hexane fraction for _S. ethernegi_ led to the isolation of (+)-7.8-epoxy-7.8-dihydrocembrene C **156**, in which its optical rotation indicated that it was (+)- (7\(S\),8\(S\))-7,8-epoxy-7.8-dihydrocembrene C **156**, not (-)-7,8-Epoxy-7,8-dihydrocembrene C, which was reported previously from _S. crassocaule_[62]. Six cembranoids, (+)-12-carboxy-11\(Z\)-sarcophytoxide **157**, (+)-12-methoxycarbonyl-11\(Z\)-sarcophine **158**, ehrenberoxides A-C **159-161** and lobophynin C **162** were isolated from _S. ethernegi_. Compound **157** has a 2,5-dihydrofuran ring attached to a 14 membered ring at carbon-1 and carbon-2, a carboxylic acid at carbon-12 and an epoxide moiety at carbon-7 and carbon-8. Moreover, the authors mentioned that both ehrenberoxides B and C **160-161** raised from the exact precursor with a 7,8-epoxide through a transannular cleavage of the 7,8-epoxide by both ends of an 11,12-diol, while compound **160** has a unique oxepane ring, which was not detected previously in cembranoid [63] and from _S. infundiuliforme_ diterpenoids cembrene C **163**, sarcophytol B **164**, sarcophytol E **165**, and sarcophytol H **166**, (-)-marasol **167** were reported [64]. A cembrane diterpene identified as 2\(R\),7\(R\),8\(R\)-dihydroxydeepoxysacrophine **168** was isolated from _S. glaucum_[65], and three compounds were reported from its ethyl acetate fraction, of which two were peroxide diterpenes identified as 11(\(S\))-hydroperoxysacroph-12(20)-ene **169**, 12(\(S\))- hydroperoxysacroph-10-ene **170**, and 8-epi-sarcophinone **171**. All structures were investigated by spectral data, and their relative configuration was assigned by X-ray diffraction [66]. Methyl sarcrotates A and B **172** and **173** two diterpenes, along with sarcophytonolide M **174**, a precursor for the former two compounds, were isolated from _S. trocheliophorum_, and their biogenetic pathways were proposed, in which isomaration, cycloaddition followed by oxidation of compound **174** led to the formation of both compounds **172** and **173**. The authors also studied the absolute configuration of methyl sarcomote B **173** through TDDFT ECD calculations, helping in determining the absolute configurations for methyl sarcomote A **172** and sarcophytonolide M **174** by a biogenetic relationship and ECD comparison, respectively [67]. Cembranoid diterpene, identified as (15,2E,4R,6E,8S,11R,12S)-8,11-epoxy-4,12-epoxy- 2,6-cembradiene **175**, (15,2E,4R,6E,8R,11S,12R)-8,12-epoxy-2,6-cembradiene-4,11-diol **176**, and (15,4R,13S)-cembra-2E,7E,11E-trien-4,13-diol **177**, were reported from nature for the first time, from _S. glaucum_[68]. From an acetone extract of _S. elrenbergi_, three cembranoids were isolated. Through full NMR data, the existence of \(\alpha\), \(\beta\) unsaturated ethyl ester and \(\alpha\), \(\beta\) unsaturated methyl ester of both (+)-12-ethoxycarbonyl-11Z-sarcophine; ehrenbergol A and B **178-180** were confirmed. Ehrenbergol B **179** showed a trisubstituted epoxide and two trisubstituted olefins. [69]. Fifteen cembran-type diterpenoids were isolated from _S. elegans_, sarcophyolides B-E **181-184**, along with sarcophytol L **185**, 13\(\alpha\)-hydroxysarcophytol L **186**, sarcophyolide A **187**, sarcophinone **188**, 7\(\alpha\)-hydroxy-\(\Delta\)8(19)-deeposysarcophine **189**, 4\(\beta\)-hydroxy-\(\Delta\)2(3)-sarcophine **190**, 1,15\(\beta\)-epoxy-2-epi-16-deoxysarcophine **191**, sarcophytol Q **192**, and lobocrasol **193**. A detailed structural elucidation was determined by spectral data and reported data.