﻿564 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  194 
  3 
  

  

  acid 
  is 
  believed 
  to 
  be 
  a 
  quinonoid 
  compound 
  and 
  puberulic 
  acid 
  the 
  

   corresponding 
  quinol. 
  

  

  Both 
  compounds 
  inhibit 
  the 
  growth 
  of 
  a 
  number 
  of 
  Gram-positive 
  

   bacteria, 
  puberulic 
  acid 
  being 
  somewhat 
  more 
  effective 
  than 
  puber- 
  

   ulonic. 
  Neither 
  shows 
  much 
  activity 
  against 
  Gram-negative 
  species. 
  

  

  Unnamed 
  substances. 
  — 
  Several 
  workers 
  have 
  obtained 
  evidence 
  of 
  

   the 
  production 
  of 
  antibacterial 
  substances 
  by 
  other 
  molds. 
  In 
  one 
  

   survey 
  of 
  100 
  fungal 
  species, 
  30 
  were 
  found 
  to 
  exhibit 
  activity, 
  with 
  

   the 
  added 
  possibility 
  that 
  some 
  of 
  the 
  negative 
  species 
  might 
  well 
  give 
  

   positive 
  results 
  under 
  different 
  cultural 
  conditions 
  or 
  against 
  test 
  

   bacteria 
  other 
  than 
  those 
  employed. 
  In 
  view 
  of 
  the 
  existence 
  of 
  

   thousands 
  of 
  species 
  of 
  molds, 
  it 
  seems 
  certain 
  that 
  many 
  other 
  anti- 
  

   bacterial 
  agents 
  produced 
  by 
  these 
  organisms 
  remain 
  to 
  be 
  discovered. 
  

   Some 
  yeasts, 
  too, 
  have 
  been 
  found 
  to 
  produce 
  bacteriolytic 
  substances. 
  

  

  PROSPECT 
  

  

  Of 
  the 
  score 
  or 
  more 
  products 
  of 
  microbial 
  origin 
  which 
  have 
  been 
  

   described 
  here, 
  the 
  antibiotic 
  activity 
  of 
  the 
  great 
  majority 
  has 
  been 
  

   discovered 
  only 
  within 
  the 
  last 
  2 
  or 
  3 
  years. 
  Most 
  of 
  them 
  have 
  not 
  

   yet 
  been 
  studied 
  sufficiently 
  to 
  determine 
  what 
  therapeutic 
  applica- 
  

   tions 
  may 
  eventually 
  be 
  made. 
  It 
  is, 
  therefore, 
  highly 
  encouraging 
  

   that 
  some 
  of 
  these 
  agents, 
  particularly 
  penicillin 
  and 
  tyrothricin, 
  al- 
  

   ready 
  offer 
  definite 
  promise 
  of 
  practical 
  utility. 
  However, 
  even 
  

   though 
  none 
  of 
  the 
  presently 
  known 
  substances 
  should 
  ultimately 
  be 
  

   found 
  of 
  use 
  in 
  itself, 
  the 
  value 
  of 
  the 
  rapidly 
  increasing 
  knowl- 
  

   edge 
  in 
  this 
  field 
  is 
  very 
  great. 
  This 
  is 
  true 
  for 
  two 
  reasons: 
  

   in 
  the 
  first 
  place, 
  the 
  identification 
  of 
  a 
  compound 
  possessing 
  some 
  

   of 
  the 
  properties 
  desirable 
  in 
  a 
  chemotherapeutic 
  agent, 
  even 
  though 
  

   it 
  may 
  at 
  the 
  same 
  time 
  have 
  other 
  undesirable 
  characteristics, 
  opens 
  

   the 
  door 
  for 
  the 
  chemist 
  to 
  manipulate 
  the 
  molecular 
  architecture 
  

   so 
  as 
  to 
  enhance 
  the 
  one 
  and 
  suppress 
  the 
  other 
  ; 
  secondly, 
  studies 
  of 
  the 
  

   mode 
  of 
  action 
  of 
  the 
  available 
  inhibitory 
  agents 
  upon 
  micro-organisms 
  

   may 
  suggest 
  the 
  use 
  of 
  other 
  substances, 
  which, 
  while 
  chemically 
  un- 
  

   related, 
  will 
  exert 
  similar 
  biological 
  effects. 
  

  

  A 
  wide 
  range 
  of 
  chemical 
  types 
  is 
  represented 
  among 
  the 
  limited 
  

   number 
  of 
  antimicrobial 
  agents 
  of 
  which 
  the 
  composition 
  has 
  been 
  

   even 
  partially 
  elucidated: 
  proteins 
  (notatin, 
  lysozyme), 
  polypep- 
  

   tides 
  (gramicidin, 
  tyrocidine), 
  fatty 
  acids 
  (pyocyanic 
  acid, 
  isovaleric 
  

   acid, 
  oleic 
  acid, 
  possibly 
  actinomycetin), 
  organic 
  bases 
  (streptothri- 
  

   cin, 
  proactinomycin), 
  quinones 
  (citrinin, 
  fumigatin, 
  spinulosin, 
  pos- 
  

   sibly 
  puberulonic 
  acid), 
  heterocyclic 
  compounds 
  (gliotoxin, 
  actino- 
  

   mycin 
  A, 
  pyocyanine, 
  a-hydroxyphenazine). 
  Obviously, 
  complete 
  

   knowledge 
  of 
  the 
  constitution 
  is 
  necessary 
  before 
  the 
  relationship 
  be- 
  

   tween 
  structure 
  and 
  biological 
  properties 
  can 
  be 
  studied. 
  

  

  