Limits...
Intramolecular modulation of serine protease inhibitor activity in a marine cyanobacterium with antifeedant properties.

Matthew S, Ratnayake R, Becerro MA, Ritson-Williams R, Paul VJ, Luesch H - Mar Drugs (2010)

Bottom Line: Extracts of the Floridian marine cyanobacterium Lyngbya cf. confervoides were found to deter feeding by reef fish and sea urchins (Diadema antillarum).The cyclization resulted in diminished activity, but to different extents against two serine proteases tested.This finding suggests that cyanobacteria can endogenously modulate the activity of their protease inhibitors.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicinal Chemistry, University of Florida, Gainesville, FL 32610, USA. susmatt@ufl.edu

ABSTRACT
Extracts of the Floridian marine cyanobacterium Lyngbya cf. confervoides were found to deter feeding by reef fish and sea urchins (Diadema antillarum). This antifeedant activity may be a reflection of the secondary metabolite content, known to be comprised of many serine protease inhibitors. Further chemical and NMR spectroscopic investigation led us to isolate and structurally characterize a new serine protease inhibitor 1 that is formally derived from an intramolecular condensation of largamide D (2). The cyclization resulted in diminished activity, but to different extents against two serine proteases tested. This finding suggests that cyanobacteria can endogenously modulate the activity of their protease inhibitors.

Show MeSH

Related in: MedlinePlus

Expanded regions of the 13C NMR spectra (125 MHz) of 1 in CD3OD (bottom panel) and 1:1 CD3OD/CD3OH (top) showing peak splitting for carbons attached to the free hydroxyl groups.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC2901826&req=5

f3-marinedrugs-08-01803: Expanded regions of the 13C NMR spectra (125 MHz) of 1 in CD3OD (bottom panel) and 1:1 CD3OD/CD3OH (top) showing peak splitting for carbons attached to the free hydroxyl groups.

Mentions: The organic extracts from separate samples of the marine cyanobacterium L. cf. confervoides collected from two different locations from reefs near Ft. Lauderdale (Florida, USA) were subjected to HP-20 fractionation and subsequent HPLC purification to yield either largamide D (2) [24] or a new intramolecular condensation product, largamide D oxazolidine (1) (Figure 1). The structure of 2 was established by comparison with reported data [24]. Compound 1 displayed a pseudomolecular ion [M + Na]+ peak at m/z 1236.4745 and an [M + 2 + Na]+ isotope peak of similar intensity characteristic for bromine, which was consistent with a molecular formula of C56H80BrN9NaO16. The 1H and 13C NMR spectra (Table 1), featuring typical signals for a peptide, were suggestive of a close analog of largamide D (2). A detailed analysis of the 2D NMR (COSY, HSQC, HMBC and TOCSY) spectral data of 1 in DMF-d7 clearly supported the structural fragments and enabled the connectivity of the depsipeptide along with the side chain, similar to 2. The major chemical shift differences between 1 and 2 were observed around the Ahp and Thr-1 units. The remaining 1H and 13C NMR data of 1 in MeOH-d4 (Table 1) were in close agreement with the reported data for 2 [24]. Most pronounced were the ~11 ppm downfield shifts relative to 2 of the signals for C-6 of the Ahp unit (δC 88.6) and C-3 of Thr-1 (δC 77.4), indicative of alkylation and, to be in agreement with the molecular formula, consistent with a formal condensation of Ahp and Thr-1 resulting in an oxazolidine and overall in a fused bicyclic system. A 13 A 13C NMR experiment carried out in a mixture of CD3OD/CD3OH clearly showed doubling of signals attributable to carbons attached to the hydroxyl groups in glyceric acid (Ga, δC 74.2 and 65.6). Singlets at δC 88.6 (C-6, Ahp) and 77.4 (C-3, Thr-1) supported the absence of exchangeable protons in both Ahp and Thr-1 where cyclization has occurred (Figure 3). A second set of resonances in a solvent-dependent ratio (1:0.3 in DMF-d7 and 1:0.7 in MeOH-d4) was observed in the NMR spectra, indicating the presence of conformers.


Intramolecular modulation of serine protease inhibitor activity in a marine cyanobacterium with antifeedant properties.

Matthew S, Ratnayake R, Becerro MA, Ritson-Williams R, Paul VJ, Luesch H - Mar Drugs (2010)

Expanded regions of the 13C NMR spectra (125 MHz) of 1 in CD3OD (bottom panel) and 1:1 CD3OD/CD3OH (top) showing peak splitting for carbons attached to the free hydroxyl groups.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2901826&req=5

f3-marinedrugs-08-01803: Expanded regions of the 13C NMR spectra (125 MHz) of 1 in CD3OD (bottom panel) and 1:1 CD3OD/CD3OH (top) showing peak splitting for carbons attached to the free hydroxyl groups.
Mentions: The organic extracts from separate samples of the marine cyanobacterium L. cf. confervoides collected from two different locations from reefs near Ft. Lauderdale (Florida, USA) were subjected to HP-20 fractionation and subsequent HPLC purification to yield either largamide D (2) [24] or a new intramolecular condensation product, largamide D oxazolidine (1) (Figure 1). The structure of 2 was established by comparison with reported data [24]. Compound 1 displayed a pseudomolecular ion [M + Na]+ peak at m/z 1236.4745 and an [M + 2 + Na]+ isotope peak of similar intensity characteristic for bromine, which was consistent with a molecular formula of C56H80BrN9NaO16. The 1H and 13C NMR spectra (Table 1), featuring typical signals for a peptide, were suggestive of a close analog of largamide D (2). A detailed analysis of the 2D NMR (COSY, HSQC, HMBC and TOCSY) spectral data of 1 in DMF-d7 clearly supported the structural fragments and enabled the connectivity of the depsipeptide along with the side chain, similar to 2. The major chemical shift differences between 1 and 2 were observed around the Ahp and Thr-1 units. The remaining 1H and 13C NMR data of 1 in MeOH-d4 (Table 1) were in close agreement with the reported data for 2 [24]. Most pronounced were the ~11 ppm downfield shifts relative to 2 of the signals for C-6 of the Ahp unit (δC 88.6) and C-3 of Thr-1 (δC 77.4), indicative of alkylation and, to be in agreement with the molecular formula, consistent with a formal condensation of Ahp and Thr-1 resulting in an oxazolidine and overall in a fused bicyclic system. A 13 A 13C NMR experiment carried out in a mixture of CD3OD/CD3OH clearly showed doubling of signals attributable to carbons attached to the hydroxyl groups in glyceric acid (Ga, δC 74.2 and 65.6). Singlets at δC 88.6 (C-6, Ahp) and 77.4 (C-3, Thr-1) supported the absence of exchangeable protons in both Ahp and Thr-1 where cyclization has occurred (Figure 3). A second set of resonances in a solvent-dependent ratio (1:0.3 in DMF-d7 and 1:0.7 in MeOH-d4) was observed in the NMR spectra, indicating the presence of conformers.

Bottom Line: Extracts of the Floridian marine cyanobacterium Lyngbya cf. confervoides were found to deter feeding by reef fish and sea urchins (Diadema antillarum).The cyclization resulted in diminished activity, but to different extents against two serine proteases tested.This finding suggests that cyanobacteria can endogenously modulate the activity of their protease inhibitors.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicinal Chemistry, University of Florida, Gainesville, FL 32610, USA. susmatt@ufl.edu

ABSTRACT
Extracts of the Floridian marine cyanobacterium Lyngbya cf. confervoides were found to deter feeding by reef fish and sea urchins (Diadema antillarum). This antifeedant activity may be a reflection of the secondary metabolite content, known to be comprised of many serine protease inhibitors. Further chemical and NMR spectroscopic investigation led us to isolate and structurally characterize a new serine protease inhibitor 1 that is formally derived from an intramolecular condensation of largamide D (2). The cyclization resulted in diminished activity, but to different extents against two serine proteases tested. This finding suggests that cyanobacteria can endogenously modulate the activity of their protease inhibitors.

Show MeSH
Related in: MedlinePlus