Phomactin Phoma

By using an elegant 13C-labeling study that involved incubation of Phoma sp. with 1-13C and 1,2-13C acetate, Oikawa et al. [9], were able to isolate the proposed biosynthetic intermediate phomactatriene (or Sch 49026), with 13C incorporation from singly labeled acetate units as indicated by in Fig. 8.3. Phomactatriene is strikingly reminiscent of taxadiene, a biosynthetic intermediate for Taxol . The net biosynthesis for both involves geranylgeranyl diphosphate (GGDP) cyclization [9]. It is noteworthy that prior to isolation of phomactins, the only known related structure is cleomeolide, a diterpene from the herb Cleome viscosa [10] that remarkably resembles phomactin H. 

Several members of phomactins, a rare cleomane class of diterpenes, were identified from culture filtrate of the marine Deuteromycotina Phoma sp. (Sphaeropsidaceae) isolated from the shell of a Japanese crab, Chionaecetes opilus. The structure of phomactin A (67), the first representative of this series, was elucidated by X-ray analysis [97,98]. The structure of the other representatives was determined on the basis of spectroscopic evidence, X-ray crystallography and chemical conversion [99,100] phomactin B (68 extraction yield 3.5 mg/1), phomactin B1 (69) (a colorless crystal extraction yield 0.07 mg/ml), phomactin B2 (70 extraction yield 1.1 mg/ml), phomactin C (71 a colorless crystal extraction yield 1.6 mg/ml), phomactin D (72 a colorless crystal, extraction yield 0.1 mg/ml), phomactin E (73 extraction yield 1.5 m ml), phomactin F (74 extraction yield 0.04 mg/ml), and phomactin G (75 extraction yield 0.28 mg/ml)). The absolute configurations of phomactins A, B and B1 have been determined. The stereochemistry at C2 of phomactin G is still unknown. A 3-epiphomactin C (Sch 47918) from a Phoma sp. of terrestrial origin has also been described [101,102]. The total synthesis of phomactin D has been reported. ... 

Phomactin A 103 was isolated in 1991 by Sugano and coworkers from the culture filtrate of Phoma sp. (SANK 11486), a parasitic fungus found growing on the shell of a... 

Sugano M, Sato A, lijima Y, Furuya K, Haruyama H, Yoda K, Hata T. Phomactins, novel PAF antagonists from marine fungus Phoma sp. J. Org. Chem. 1994 59 564-569. 

New phomactins phomactin H-J and 13-epi-phomactin I, were obtained through the culture of an xmdetermined species (MPUC 046), but not of the genus Phoma, collected on the Japanese brown algae Ishige okamurae (Ectocarpale). The structure, which has an oxepane cyde, was determined using X-ray diffraction (Koyama et al., 2004 Ishino et al., 2010). 

Some important families of compounds could be specific of some associated phyla, such as leptosins A-N fotmd in Leptosphaeria species associated with brown algae, or phomactins A-H found in Phoma species associated with crustaceans. 

Goldring, W.P.D. and Pattenden, G. (2004) Total synthesis of ( )-phomactin G, a platelet activating factor antagonist from the marine fungus Phoma sp. Org. Biomol. Chem., 2,466-473. 

---