Totarol

Biochemistry. 2007 Apr 10;46(14):4211-20.

Totarol inhibits bacterial cytokinesis by perturbing the assembly dynamics of FtsZ.[Pubmed: 17348691]

Totarol, a diterpenoid phenol, has been shown to inhibit the proliferation of several pathogenic Gram-positive bacteria including Mycobacterium tuberculosis.
METHODS AND RESULTS:
In this study, Totarol was found to inhibit the proliferation of Bacillus subtilis cells with a minimum inhibitory concentration of 2 microM. It did not detectably perturb the membrane structure of B. subtilis; it strongly induced the filamentation in B. subtilis cells, suggesting that it inhibits bacterial cytokinesis. Totarol (1.5 microM) reduced the frequency of the Z-ring occurrence per micrometer of the bacterial cell length but did not affect the nucleoid frequency, suggesting that it blocks cytokinesis by inhibiting the formation of the Z-ring. The assembly dynamics of FtsZ is thought to play an important role in the formation and functioning of the Z-ring, a machine that engineers cytokinesis in bacteria. Since Totarol was shown to inhibit the proliferation of M. tuberculosis, we examined the effects of Totarol on the assembly dynamics of M. tuberculosis FtsZ (MtbFtsZ) in vitro. Totarol decreased the assembly of MtbFtsZ protofilaments and potently suppressed the GTPase activity of MtbFtsZ. It bound to MtbFtsZ with a dissociation constant of 11 +/- 2.3 microM. It increased the fluorescence intensity of the MtbFtsZ-1-anilinonaphthalene-8-sulfonic acid complex and inhibited the fluorescence intensity of N-(1-pyrene)maleimide-labeled MtbFtsZ, suggesting that Totarol induces conformational changes in MtbFtsZ. The results indicated that Totarol can perturb the assembly dynamics of FtsZ protofilaments in the Z-ring. Totarol exhibited extremely weak inhibitory effects on HeLa cell proliferation. It did not affect microtubule organization in HeLa cells.
CONCLUSIONS:
The results suggest that Totarol inhibits bacterial proliferation by targeting FtsZ and it may be useful as a lead compound to develop an effective antitubercular drug.

J Nat Prod. 1992 Oct;55(10):1436-40.

Antibacterial activity of totarol and its potentiation.[Pubmed: 1453180 ]

Antimicrobial activity of six diterpenoids isolated from the bark of Podocarpus nagi (Podocarpaceae) has been tested against twelve selected microorganisms.
METHODS AND RESULTS:
Totarol [1], the most abundant compound among the six, exhibited potent bactericidal activity only against Gram-positive bacteria, among which Propionibacterium acnes was the most sensitive bacterium. Totarol also showed strong activity against four other Gram-positive bacteria tested: Streptococcus mutans, Bacillus subtilis, Brevibacterium ammoniagenes, and Staphylococcus aureus (both penicillin-resistant and penicillin-susceptible strains). The bactericidal activity of Totarol was enhanced when it was tested in combination with several other natural products. Noticeably, the activity of Totarol against Sta. aureus was increased eightfold when tested in combination with 1/2MIC of anacardic acid [9]. The synergistic activity of anacardic acid caused the minimum bactericidal concentration (MBC) of Totarol to be lowered from 1.56 to 0.2 micrograms/ml.

J Proteomics. 2015 Jan 30;114:247-62.

A comprehensive proteomic analysis of totarol induced alterations in Bacillus subtilis by multipronged quantitative proteomics.[Pubmed: 25464363]

Totarol is a naturally existing diterpenoid, which has the ability to restrain bacterial growth by perturbing the cell division. The present study was conducted to investigate the proteomic alterations in Bacillus subtilis as a consequence of Totarol treatment to decipher its mechanism of action and possible molecular targets.
METHODS AND RESULTS:
Cellular proteome of the Totarol treated B. In silico functional analysis of the identified differentially expressed proteins indicated a possible effect of Totarol on the central metabolism for energy production, heme biosynthesis and chemotaxis. Interestingly, the primary dehydrogenases, which play a vital role in generating the reducing equivalent, were found to be repressed after Totarol treatment indicating an apparent metabolic shutdown. Consequently, multiple cellular assays including resazurin assay and FACS analysis of 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) staining confirmed the effect of Totarol on respiratory activity and cellular metabolism. The exact mechanism of action of Totarol is still unclear and further investigations are essential to identify the molecular/cellular targets of this potential antimicrobial agent. The present study demonstrates the application of differential proteome to decipher the mechanism of action and molecular targets of Totarol in B. subtilis. Our quantitative proteome analysis revealed that Totarol induced alterations in the expression levels of 139 proteins (1.5 fold change and ≥2 peptides) in B. subtilis. Findings obtained from this study indicate that Totarol treatment leads to metabolic shutdown by repressing the major central metabolic dehydrogenases in B. subtilis. In addition, expression levels of universal chaperone proteins, heme biosynthesis, and ribosomal proteins were found to be altered, which caused the filamentation of the bacteria.
CONCLUSIONS:
To the best of our knowledge, this is the foremost inclusive investigation describing Totarol induced alterations in B. subtilis proteome and diverse physiological processes. We anticipate that this in depth proteomic study may contribute to a better understanding of the mode of action of Totarol and its primary molecular and cellular targets.

ACS Med Chem Lett. 2012 Aug 28;3(10):818-822.

The Synthesis and Antimicrobial Activity of Heterocyclic Derivatives of Totarol.[Pubmed: 23119123]

The synthesis and antimicrobial activity heterocyclic analogs of the diterpenoid Totarol are described.
METHODS AND RESULTS:
An advanced synthetic intermediate with a ketone on the A-ring is used to attach fused heterocycles and a carbon-to-nitrogen atom replacement is made on the B-ring by de novo synthesis. A-ring analogs with an indole attached exhibit, for the first time, enhanced antimicrobial activity relative to the parent natural product.
CONCLUSIONS:
Preliminary experiments demonstrate that the indole analogs do not target the bacterial cell division protein FtsZ as had been hypothesized for Totarol.