Phenelfamycins G and H are new members of the family of elfamycin antibiotics with the basic structure of phenelfamycins E and F, respectively, which are also well known as ganefromycins a and b. Phenelfamycins G and H differ from phenelfamycins E and F by an additional hydroxy group at position C-30, which is not described so far for any of the elfamycin-type antibiotics. The actinomycete strain that produced phenelfamycins G and H was identified to be Streptomyces albospinus based on its 16S rRNA gene sequence. Phenelfamycins G and H exhibit a narrow antibacterial spectrum with a pronounced inhibitory activity against Propionibacterium acnes. The Journal of Antibiotics (2011) 64, 257-266; doi:10.1038/ja2010.170; published online 2 February 2011 Keywords: elfamycin antibiotics; ganefromycin; phenelfamycin; Propionibacterium acnes; Streptomyces
INTRODUCTIONEnvironmental samples were collected from untapped Malaysian ecological niches to isolate actinomycetes strains, which were investigated within our HPLC-diode array screening program for the production of secondary metabolites with the aim of detecting novel drugs for pharmaceutical applications. 1 Strain Acta 3619 was isolated from a soil collected from the rhizosphere of bamboo trees in the tropical rainforest of the University of Malaya Field Station at Gombak, Selangor, Malaysia. The strain was found to be of special interest, as it gave two significant peaks in the HPLC analysis of an extract of the culture filtrate having congruent UV-vis spectra that differed from all 937 reference compounds stored in our HPLC-UVvis database. 2 Structure elucidation of the two isolated compounds revealed a relationship with phenelfamycins E and F and therefore were named as phenelfamycins G (1) and H (2), respectively. Their structures are shown in Figure 1.Phenelfamycins belong to the elfamycin family of antibiotics, which inhibit protein synthesis of bacteria by an interaction with elongation factor Tu, demonstrated in prokaryotic cells. [3][4][5] Hence they derived their name from this interaction. Elfamycins can be subdivided into three types according to their structure. Type 1 includes kirromycin 6 (mocimycin), aurodox, 7,8 heneicomycin 9 and efrotomycin. 10 Type 2, elfamycin, is represented by kirrothricin with an open tetrahydrofuran ring in the aglycone. 11 Finally, type 3 contains the phenelfamycins with a phenylacetyl substitution at position C-22 or C-23 and C-33 O-glycosylation with mono-(phenelfamycins A and B), di-(phenelfamycins C and D) or trisaccharide units (phenelfamycins E and F, also named as ganefromycins a and b). 12,13 All elfamycins show a very narrow antibacterial spectrum against human pathogens and most of them show excellent activities as growth-promoting agents in animals. 14 In this paper we report on the new phenelfamycins 1 and 2, the taxonomy of the producing strain, their fermentation, isolation, structure elucidation and biological activity.
RESULTS
Taxonomy of the producing strainStrain Acta 3619 was isolated from the rhizosphere so...