Mechanism of action
Pseudomonic acid inhibits isoleucine tRNA synthetase in bacteria, leading to depletion of isoleucyl-tRNA and accumulation of the corresponding uncharged tRNA. Depletion of isoleucyl-tRNA results in inhibition of protein synthesis. The uncharged form of the tRNA binds to the aminoacyl-tRNA binding site of ribosomes, triggering the formation of (p)ppGpp, which in turn inhibits RNA synthesis. The combined inhibition of protein synthesis and RNA synthesis results in bacteriostasis. This mechanism of action is shared with furanomycin, an analog of isoleucine. Biosynthesis
Mupirocin is a mixture of several pseudomonic acids, with pseudomonic acid A (PA-A) constituting greater than 90% of the mixture. Also present in mupirocin are pseudomonic acid B with an additional hydroxyl group at C8, pseudomonic acid C with a double bond between C10 and C11, instead of the epoxide of PA-A, and pseudomonic acid D with a double bond at C4` and C5` in the 9-hydroxy-nonanoic acid portion of mupirocin. Biosynthesis of pseudomonic acid A
The 74 kb mupirocin gene cluster contains six multi-domain enzymes and twenty-six other peptides (Table 1). Four large multi-domain type I polyketide synthase (PKS) proteins are encoded, as well as several single function enzymes with sequence similarity to type II PKSs. Therefore, it is believed that mupirocin is constructed by a mixed type I and type II PKS system. The mupirocin cluster exhibits an atypical acyltransferase (AT) organization, in that there are only two AT domains, and both are found on the same protein, MmpC.
Tolnaftate (INN) is a synthetic thiocarbamate used as an anti-fungal agent that may be sold  without medical prescription in most jurisdictions. It is supplied as a cream, powder, spray, liquid, and liquid aerosol. Tolnaftate is used to treat fungal conditions such as jock itch, athletes foot and ringworm. Mechanism
Although the exact mechanism of action is not entirely known, it is believed to inhibit squalene epoxidase, an important enzyme in the biosynthetic pathway of ergosterol (a key component of the fungal cell membrane) in a similar way to terbinafine. Uses
Tolnaftate has been found to be generally slightly less effective than azoles when used to treat tinea pedis (athletes foot). It is, however, useful when dealing with ringworm, especially when passed from pets to humans. Side effects
Side effects that may occur include:
allergic reactions like:
skin rash
itching or hives
swelling of the face, lips, or tongue
inflammation, redness, or pain at the affected areaLess severe side effects include:
dry skin
mild skin irritation, burning, or itching at the affected area

See also
Liranaftate, a similar thiocarbamate antifungal

References
External links
Medlines entry for tolnaftate