dihydromaltophilin dihydromaltophilin dihydromaltophilin, or heat stable anti-fungal factor (hsaf), is a secondary metabolite of streptomyces sp. and lysobacter enzymogenes. hsaf is a polycyclic tetramate lactam containing a single tetramic acid unit and a 5,5,6-tricyclic system. hsaf has been shown to have anti-fungal activity mediated through the disruption of the biosynthesis of sphingolipid's by targeting a ceramide synthase unique to fungi. dihydromaltophilin names iupac name (3e,5s,7s,8r,9s,10s,11s,13r,15r,16s,18z)-11-ethyl-7,24,28-trihydroxy-10-methyl-21,26-diazapentacyclooctacosa-1(28),3,18-triene-2,20,27-trione systematic iupac name (3e,5s,7s,8r,9s,13r,15r,16s)-11-ethyl-7,28-dihydroxy-8,10-dimethyl-21,26-diazapentacyclooctacosa-1(28),3-diene-2,27-dione other names heat-stable anti-fungal factor (hsaf) identifiers cas number 203304-22-7 3d model (jsmol) interactive image chemspider 34227627 pubchem cid 101934630 inchi inchi=1s/c29h40n2o6/c1-3-15-11-17-12-19-18-5-4-6-23(35)30-10-9-21(33)27-28(36)26(29(37)31-27)20(32)8-7-16(18)13-22(34)25(19)24(17)14(15)2/h4,6-8,14-19,21-22,24-25,27,32-34h,3,5,9-13h2,1-2h3,(h,30,35)(h,31,37)/b6-4-,8-7+,26-20?/t14-,15-,16+,17+,18-,19+,21?,22-,24+,25-,27?/m0/s1key: vycdznhssdxaci-sgxradkasa-n smiles cc1c2c34c/c=c\c(=o)nccc(c5c(=c(c(=o)/c=c/4c(321c)o)c(=o)n5)o)o properties chemical formula c29h40n2o6 molar mass 512.647 g·mol−1 except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). infobox references biosynthesis the backbone of hsaf is formed through a hybrid pks-nrps cluster containing one nonribosomal peptide synthase (nrps) module and one polyketide synthase (pks) module. the single pks module functions in a non-canonical fashion in that it is an iterative type i pks responsible for the generation of the two unique polyketides needed in the backbone of hsaf using malonyl-coa as both the starter and extender unit, while the nrps module is responsible for the linking of the polyketides to an l-ornithine unit and the initial cyclization to create the tetramate back bone. the coding region related to hsaf production contains a pks-nrps with a total of 9 domains, (ks-at-dh-kr-acp-c-a-pcp-te), while a cascade of fad-dependent redox reactions (ox1-ox4) flank the pks-nrps cluster proposed to be responsible for formation of the 5,5,6-tricyclic system, there are additional coding regions for a putative regulator, an arginase for l-ornithine production from arginine, and a transporter which flank the pks-nrps. figure 1. proposed mechanism of hsaf biosynthesis figure 2. schematic of the function of the hybrid pks-nrps in the biosynthesis of hsaf