SUBSTANCES PRODUCED BY HIGHER PLANTS 217 



Osborn (696) examined as many as 2,300 different flowering plants, 

 of which 134 species gave positive results. The activity against gram- 

 positive bacteria was far greater than against gram-negative forms 5 

 cabbage, cauliflower, broccoli, and kohlrabi gave the greatest effect 

 upon both groups of bacteria. The Ranunculaceae were most active of 

 all the plants. The stability of the substances as regards wilting and dry- 

 ing varied greatly. Extracts of honeysuckles {Lonicera tartar jia), espe- 

 cially of the roots, are very active (583). 



Antibacterial substances are thus found to be widely distributed 

 among higher plants. Some of these substances have been isolated and 

 even crystallized. Allicin, a diallyl sulfoxide, was isolated from Allium 

 sativum (iij). Crepin, an a3-unsaturated lactone, has been isolated 

 from Crefis taraxacifoUa; the empirical formula C14H16O4 has been 

 suggested for it. It is active against both gram-positive and gram- 

 negative bacteria (391). Protoanemonin, obtained from buttercups, 

 Ranunculus J is active against various bacteria and fungi (847). Toma- 

 tin, an antibiotic occurring in the tomato plant, was found (456a) to be 

 active against a variety of gram-positive bacteria and fungi, including 

 both plant and animal pathogens. 



Lichens were also found capable of producing antibacterial activity. 

 Of about 100 forms tested, 52 could inhibit either B. subtilis or S. au- 

 reus or both ; gram-negative bacteria are generally not susceptible. Al- 

 though certain lichen constituents were found to possess antibiotic prop- 

 erties, no specific agent has been isolated (100). Spanish moss also pro- 

 duces an antibiotic effect (999). 



Unbleached wheat flour was shown (889) to contain a protein which 

 had bacteriostatic and bactericidal activity in vitro; although its activ- 

 ity was greater against gram-positive organisms, it also had some ac- 

 tivity against gram-negative types. The antimicrobial action of this 

 protein can be neutralized by means of a phosphatide (1033), a reac- 

 tion which may be due to the formation of a lipoprotein that has no 

 longer any antibiotic activity. 



