## 2 Classes of Secondary Metabolites
### Diterpenes
The absolute configurations of sarcophyolides B-E **181-184** were approved by single-crystal X-ray diffraction assay, using [PERSON]'s assay [22], and the structure of lobocrasol **193** was further studied [70]. From the ethyl acetate extract of _S. elrenbergi_ two diterpenes were isolated, acetyl ehrenberoxide B **194** and ehrenbergol C **195**. Ehrenbergol C **195** shared a structure similar to lobocrasol **193**, isolated from _Lobophytum crassum_[71]. Yet, relative stereochemistry of carbon-7 and carbon-8 in ehrenbergol C **195** differed from lobocrasol **193** in hydroxy group and a conjugated enone evidenced by the IR spectrum at 3444 and 1696 cm\({}^{-1}\), respectively [72]. An oxygenated cembranoid diterpene, sarcophytol W **196**, together with (2E,7E)-4,11-dihydroxy-1,12-oxidochema-2,7-dien **197**, were isolated before from _S. infundibularrome_ and _S. glaucum_, (+)-11,12-epoxy-11,12-dihydro-cembrene-C **198**, (+)-11,12-epoxy-sarcophytol A **199** and sarcolactone A **200**, previously known, were reported from _Sarcophyton_ sp. Structures were determined through spectral data and comparing the reported data. The absolute configuration of sarcophytol W **196** was elucidated based on the modified Mosher's assay [73]. Two diterpenes were isolated from _S. tortuosum_, identified as tortuosenes A and B **201** and **202**. Structural elucidation of compounds **201** and **202** were investigated by spectral data. The absolute configuration of tortuosene A **201** was investigated using TDDFT ECD method. Moreover, the authors proposed a biosynthetic pathway for tortuosenes A and B **201** and **202** from the assumed cembranoidal precursor; (1Z, 3Z, 7E, 11E)-4-isopropyl-1,7,11-trimethylcyclotetradeca-1,3,7,11-tertaene, by oxidation of carbon-20 and the carbon-7/carbon-8 double bond was epoxidize, forming aldehydocarbbrane, a structure related to emblide **81**. The resulting aldehydocarbbrane additionally formed a cycle from carbon-2 to carbon-20 by acid-catalyzed affecting the carbon-1/carbon-2 double bond of the carbonyl moiety [74]. 2-epi-sarcophine **203** and (1R,2E,4S,6E,8R,11R,12R)-2,6-cembradiene-4,8,11,12-tetrol **204**, two diterpenes were isolated from _S. auritum_[75]. An extensive chemical investigation of _Sarcophyton_ sp. extract yielded four cembranoids, sarcophytons A-D **205-208**, along with cembranoids, 2-[(E,E,E)-7',8'-epoxy-4',8',12'-trimethylcyclotetradeca-1',3',11-trienyl]propan-2-ol **209**, (1E,3E,7R*,8R*,11E)-1-(2-methoxy-propan-2-yl)-4,8,12-trimethylboxabicyclo[12.1.0]-pentadeca-1,3,11-triene **210**, cassumol C **211**, and laevigatol A **212**. [76]. Two unique pyrane-based cembranoids, sarcotrocheliol acetate and sarcotrocheliol **213** and **214** were isolated from _S. trocheliorhorn_[77]. Investigation of _S. glaucum_ organic extract resulted in the isolation of sarcophinediol **215**, previously processed semi-synttheticaly [78]. Cembranoid diterpenes, 7-keto-8\(\alpha\)-hydroxy-deepoxysacrophine **216** similar to compound **13**, in which the carbon at carbon-3 and carbon-11 were presumed to be in E configuration established on compound **13** derivatives; this was established through spectral data. 7\(\beta\)-chloro-8\(\alpha\)-hydroxy-12 acetoxy-deepoxysacrophine **217** was close to 7-keto-8\(\alpha\)-hydroxy-deepoxysacrophine **216** except for the disappearance of ketone signal at C-7 which co-exists with the presence of an up fielded signal at 862.9 (C-7), a downfield of C-20 and the presence of carbonyl and methyl group at 170 and 22.2, respectively, were isolated from _S. elrnerbergi_. [79]. From _S. trocheliophorum_, sarsolenane diterpenes and capnosane diterpenes were obtained. Sarsolenane diterpenes are uncommon in nature, symbolized only by sarsolenone isolated from _S. solidum_. Two sarsolenane diterpenes, dihydrosarsolenone **218**, methyl dihydrosarsolenoate **219**, and two capnosane diterpenes, sarsolilides B and C **220** and **221**, together with sarsolilide A **222** were isolated.