Development of a peptide-containing chewing gum as a sustained release antiplaque antimicrobial delivery system

Important Roles and Potential Uses of Natural and Synthetic Antimicrobial Peptides (AMPs) in Oral Diseases: Cavity, Periodontal Disease, and Thrush

Numerous epithelial cells and sometimes leukocytes release AMPs as their first line of defense. AMPs encompass cationic histatins, defensins, and cathelicidin to encounter oral pathogens with minimal resistance. However, their concentrations are significantly below the effective levels and AMPs are unstable under physiological conditions due to proteolysis, acid hydrolysis, and salt effects. In parallel to a search for more effective AMPs from natural sources, considerable efforts have focused on synthetic stable and low-cytotoxicy AMPs with significant activities against microorganisms. Using natural AMP templates, various attempts have been used to synthesize sAMPs with different charges, hydrophobicity, chain length, amino acid sequence, and amphipathicity. Thus far, sAMPs have been designed to target Streptococcus mutans and other common oral pathogens. Apart from sAMPs with antifungal activities against Candida albicans, future endeavors should focus on sAMPs with capabilities to promote remineralization and antibacterial adhesion. Delivery systems using nanomaterials and biomolecules are promising to stabilize, reduce cytotoxicity, and improve the antimicrobial activities of AMPs against oral pathogens. Nanostructured AMPs will soon become a viable alternative to antibiotics due to their antimicrobial mechanisms, broad-spectrum antimicrobial activity, low drug residue, and ease of synthesis and modification.

Potential Combinatory Effect of Cannabidiol and Triclosan Incorporated into Sustained Release Delivery System against Oral Candidiasis

Candida albicans is a common fungal pathogen. Biofilm formation on various surfaces is an important determinant of C. albicans pathogenicity. Our previous results demonstrated the high potential of cannabidiol (CBD) to affect C. albicans biofilms. Based on these data, we investigated the possibility of incorporating CBD and/or triclosan (an antimicrobial agent that is widely utilized in dentistry) in a sustained-release varnish (SRV) (SRV-CBD, SRV-triclosan) to increase their pharmaceutical potential against C. albicans biofilm, as well as that of the mixture of the agents into SRV (SRV-CBD/triclosan). The study was conducted in a plastic model, on agar, and in an ex vivo tooth model. Our results demonstrated strong antibiofilm activity of SRV-CBD and SRV-triclosan against C. albicans in all tested models. Both formulations were able to inhibit biofilm formation and to remove mature fungal biofilm. In addition, SRV-CBD and SRV-triclosan altered C. albicans morphology. Finally, we observed a dramatic enhancement of antibiofilm activity when combined SRV-CBD/triclosan was applied. In conclusion, we propose that incorporation of CBD or triclosan into SRV is an effective strategy to fight fungal biofilms. Importantly, the data demonstrate that our CBD/triclosan varnish is safe, and is not cytotoxic for normal mammalian cells. Furthermore, we propose that CBD and triclosan being in mixture in SRV exhibit complementary antibiofilm activity, and thus can be explored for further development as a potential treatment against fungal infections.

Development and evaluation of a chewing gum containing antimicrobial peptide GH12 for caries prevention

The purpose of this study was to develop a chewing gum containing a novel antimicrobial peptide GH12 and evaluate its biocompatibility, antimicrobial activity, and caries-preventive effects in vivo and in vitro. GH12 chewing gum was developed using a conventional method and its extracts were prepared in artificial saliva. GH12 concentration in the extracts was determined by high-performance liquid chromatography; extracts were used for growth curve assay, time-kill assay, crystal violet staining assay, scanning electron microscopy, and Cell Counting Kit-8 assay. A rat caries model was established, and molars were treated topically with extracts for 5 weeks. Weight gain monitoring, hematoxylin-eosin staining, micro-computed tomography, and Keyes scoring were conducted. Significant inhibition of Streptococcus mutans growth and biofilm formation was observed. Extracts displayed low cytotoxicity against human gingival epithelial cells. No significant differences in weight gain or signs of harm to the mucosal tissues in any of the rats were observed. Keyes scores of caries lesions in the GH12 chewing gum group were lower than those of the negative control group. It was concluded that GH12 chewing gum showed good biocompatibility, antimicrobial activity, and caries-preventive effects, exhibiting great potential to prevent dental caries as an adjuvant to regular oral hygiene.

Confectionery Xylitol Gum-Containing Tablets for Medical Application and the Sintering Effect on Gum Tablets

Confectionery ingredients are expected to enhance the medication adherence of pediatric patients taking bitter-tasting drugs when adequate pediatric medicines are not available in practical settings. Gum is a familiar confectionery, and several drug-loaded gums are on the market as medicated chewing gums. In this study, medical gum tablets composed of confectionery xylitol gum and a drug (ibuprofen or acetaminophen) were prepared and evaluated for the purpose of potential hospital applications. The effect of the sintering process, a heating treatment, on the physical properties of the solid materials was also examined. The sintering process markedly improved the hardness of the gum tablets. The sintering temperature and time affected the hardness of both ibuprofen- and acetaminophen-loaded gum tablets, whereas heat treatment around the melting point of ibuprofen or xylitol and longer heat treatment resulted in failure of the preparation or a reduction in hardness. The sintered gum tablets exhibited a delayed drug release profile in artificial saliva after an in vitro chewing test. The current results provide basic and useful information about the preparation of gum-containing tablets in future clinical settings.

Efficacy of chitosan-based chewing gum on reducing salivary S. mutans counts and salivary pH: a randomised clinical trial

OBJECTIVE

To determine chitosan-based chewing gum role on reducing salivary S. mutans counts and salivary pH.

MATERIALS AND METHODS

The present double-blind randomised clinical trial with the trial registration number of IRCT20190724044319N1 was conducted on 36 dental students. The volunteers were, randomly, divided into two groups (n = 18) including: G1: intervention group (chitosan chewing gum) and G2: control group (placebo chewing gum). Each participant was given eight pieces of the chewing gum, and was asked to chew each gum piece for 5 min and this was repeated for eight times. Their Saliva was collected before and after chewing gums and the number of S. mutans colonies and salivary pH were determined. Data were analysed using SPSS (ver.21) and independent student t test. p Value less than .05 was set as significant.

RESULTS

There was significant difference between two groups for the number of salivary S. mutans colonies (3.31*105  in the intervention group compared to 13.94*105 in the Control group) (p < .001). The salivary pH evaluation showed that salivary pH mean value in intervention group was not significant in compared with control group (p = .17). However, the chitosan chewing gum led to an increase in salivary pH by 0.17, which was statistically significant (p = .01).

CONCLUSION

Results of this study showed that chitosan chewing gum has a positive effect on the reduction of numbers of salivary S. mutans colonies but had no considerable effect on the increase of salivary pH.

Four-day plaque regrowth evaluation of a peptide chewing gum in a double-blind randomized clinical trial

OBJECTIVE

Antimicrobial peptide, KSL-W, formulated as an antiplaque chewing gum (APCG), was tested to evaluate the dental plaque inhibition activity and safety in an IRB approved and FDA regulated 4-day plaque regrowth clinical study.

METHODS

This Phase 2 two-armed placebo-controlled, double blind, randomized (1:1), multiple dose, and single-center study was evaluated in a proof of concept for the APCG containing 30 mg antimicrobial peptide KSL-W. Twenty six generally healthy subjects were consented and randomized into the study. The subjects were administered a dose three times per day for four treatment days following a complete dental prophylaxis. Participants were prohibited from conducting oral hygiene care (teeth brushing, flossing, and/or mouth wash rinse) for the duration of the trial. Twelve to 16 hr prior to the baseline visit, the subjects were to abstain from oral hygiene care. The Quigley-Hein Turesky plaque index (QHT) score and the oral soft tissue clinical exams were obtained at both Day 0 and Day 4.

RESULTS

All randomized study subjects that received either APCG or placebo gum completed the study with no significant adverse events recorded. The APCG significantly inhibited the regrowth of dental plaque over the course of 4 days. The whole mouth data demonstrated a difference in the QHT between the APCG and the placebo gum of 1.14 (SE = 0.27) and 95% confidence bounds of 0.58, 1.70 with a two-tailed P value of .0003.

CONCLUSION

Considering the limited sample size, the proof of concept analysis in this Phase 2 study confirmed that APCG is effective against dental plaque formation and safe for human use. (ClinicalTrials.gov Study ID# NCT02864901).

Medicated Chewing Gums (MCGs): Composition, Production, and Mechanical Testing

Medicated chewing gums (MCGs) represent a unique platform for drug delivery. They have been defined as solid single-dose preparations, which may contain more than one active pharmaceutical ingredient (API) with base consisting primarily of gum that has to be chewed for a certain period of time. They mainly contain a tasteless masticatory gum base as the core with other minor nonmasticatory ingredients, such as flavors and sweeteners. Despite their advantages in drug delivery, MCGs remain a niche product due to the complexity of their formulation, lack of acceptable testing methods, and intricacy of their manufacturing. Few studies have been reported on their use, and most of the information on their composition and production could be found in patent search. The aim of this review is to provide an overview of gum composition, manufacturing process, and characterization. Due to the scarcity of studies concerning the evaluation of the mechanical properties of MCGs, greater emphasis was placed on the available performance tests and procedures for the estimation of their mechanical and textural properties. While very few tests have been recommended by the official pharmacopeias, several tests have been suggested for assessing the mechanical properties of MCGs in vitro. Properties, such as chewiness, elasticity, and firmness, of chewing gums during mastication are imperative quality attributes that have been found to strongly correlate with gum composition and mouth feel.

Ecological Approaches to Dental Caries Prevention: Paradigm Shift or Shibboleth?

Contemporary paradigms of dental caries aetiology focus on the ecology of the dental plaque biofilm and how local environmental factors can modulate this to cause disease. The crucial role that a healthy oral microbiome plays in preventing caries and promoting oral health is also being increasingly recognized. Based on these concepts, several ecological preventive approaches have been developed that could potentially broaden the arsenal of currently available caries-preventive measures. Many of these ecological approaches aim for long-term caries control by either disrupting cariogenic virulence factors without affecting bacterial viability, or include measures that can enhance the growth of health-associated, microbially diverse communities in the oral microbiome. This paper argues for the need to develop ecological preventive measures that go beyond conventional caries-preventive methods, and discusses whether these ecological approaches can be effective in reducing the severity of caries by promoting stable, health-associated oral biofilm communities.

Development of a Sustained Antiplaque and Antimicrobial Chewing Gum of a Decapeptide

The objective of this paper was to design a chewing gum formulation delivery system in situations where typical dental hygiene practice is not practical. Thus, an analog of decapeptide KSL (KSL-W), known to possess antimicrobial and antiplaque activity, was incorporated into a chewing gum formulation containing cetylpyridinium chloride (CPC). The effect of the excipients, xylitol, and peppermint oil on active ingredients in vitro release was also assessed. Gum formulations were prepared with different excipient parameters, including heating xylitol and gum base at 65 or 85°C, using ground and unground xylitol, and the addition of 1.5, 3, and 7% peppermint oil, to determine the effect of these changes on the in vitro release of KSL-W and CPC using a chewing machine. The antimicrobial and antiplaque activities of solutions released from chewed gum formulation as well as prepared standard solutions with different concentrations were tested against placebo. The optimal temperature to avoid crystallization of xylitol during preparation was 65°C. Grinding xylitol to 104.5 μm improved release of active ingredients as compared to commercially unground xylitol. Peppermint oil had opposite effects on release of KSL-W and CPC. Peppermint oil at 1.5% was determined to be suitable (91 and 88% of KSL-W and CPC released, respectively, after 40 min). The gum formulation illustrated good sustained release of KSL-W and CPC with antibacterial and antiplaque activities after chewing. An effective antimicrobial and antiplaque chewing gum formulation was developed. This formulation has the potential to overcome oral hygiene issues in those unable to follow normal dental protocols.

In Vivo Release Kinetics and Antibacterial Activity of Novel Polyphenols-Enriched Chewing Gums

Chewing gums may be particularly effective means for delivering and maintaining bioactive molecules, included in the gum formulation, able to have an anti-cariogenic effect. The purposes of this study were: to develop novel chewing gums containing quercetin (Qt); to evaluate their release using in vivo trial; finally, to test their in vivo antibacterial effect against oral Streptococcus mutans strains. A preliminary study was performed to produce new gums, enriched with the polyphenol quercetin. Then, a first in vivo experimental study was assessed to test the percentages of Qt released in the saliva of young volunteers. Moreover, a second clinical trial was performed to analyze the antibacterial capability of these enriched chewing gums against S. mutans strains after 14 days of daily consumption. The release analysis showed that a more effective release of Qt occurs in the first minutes of chewing, and it does not change saliva pH values. Moreover, Qt included in gums demonstrates an effective antibacterial activity, showing a reduction of the concentration of S. mutans strains in saliva samples, especially after 7 days. Qt included in experimental chewing gums could be efficiently released into the oral cavity and could promote an effective anti-caries concentration in volunteer's saliva, without changing salivary pH values.

Synthesis, antimicrobial evaluation and molecular modeling of 5-hydroxyisoquinolinium salt series; the effect of the hydroxyl moiety

In the present paper, we describe the synthesis of a new group of 5-hydroxyisoquinolinium salts with different lengths of alkyl side-chain (C10-C18), and their chromatographic analysis and biological assay for in vitro activity against bacterial and fungal strains. We compare the lipophilicity and efficacy of hydroxylated isoquinolinium salts with the previously published (non-hydroxylated) isoquinolinium salts from the point of view of antibacterial and antifungal versatility and cytotoxic safety. Compound 11 (C18) had to be excluded from the testing due to its low solubility. Compounds 9 and 10 (C14, C16) showed only moderate efficacy against G+ bacteria, notably with excellent potency against Staphyloccocus aureus, but no effect against G- bacteria. In contrast, non-hydroxylated isoquinolinium salts showed excellent antimicrobial efficacy within the whole series, particularly 14 (C14) against G+ strains and 15 (C16) against fungi. The electronic properties and desolvation energies of 5-hydroxyisoquinolinium and isoquinolinium salts were studied by quantum-chemistry calculations employing B3LYP/6-311++G(d,p) method and an implicit water-solvent simulation model (SCRF). Despite the positive mesomeric effect of the hydroxyl moiety reducing the electron density of the quaternary nitrogen, it is probably the higher lipophilicity and lower desolvation energy of isoquinolinium salts, which is responsible for enhanced antimicrobial versatility and efficacy.

Peptide KSL-W-Loaded Mucoadhesive Liquid Crystalline Vehicle as an Alternative Treatment for Multispecies Oral Biofilm

Decapeptide KSL-W shows antibacterial activities and can be used in the oral cavity, however, it is easily degraded in aqueous solution and eliminated. Therefore, we aimed to develop liquid crystalline systems (F1 and F2) for KSL-W buccal administration to treat multispecies oral biofilms. The systems were prepared with oleic acid, polyoxypropylene (5) polyoxyethylene (20) cetyl alcohol (PPG-5-CETETH-20), and a 1% poloxamer 407 dispersion as the oil phase (OP), surfactant (S), and aqueous phase (AP), respectively. We characterized them using polarized light microscopy (PLM), small-angle X-ray scattering (SAXS), rheology, and in vitro bioadhesion, and performed in vitro biological analysis. PLM showed isotropy (F1) or anisotropy with lamellar mesophases (F2), confirmed by peak ratio quantification using SAXS. Rheological tests demonstrated that F1 exhibited Newtonian behavior but not F2, which showed a structured AP concentration-dependent system. Bioadhesion studies revealed an AP concentration-dependent increase in the system’s bioadhesiveness (F2 = 15.50 ± 1.00 mN·s) to bovine teeth blocks. Antimicrobial testing revealed 100% inhibition of multispecies oral biofilm growth after KSL-W administration, which was incorporated in the F2 aqueous phase at a concentration of 1 mg/mL. Our results suggest that this system could serve as a potential vehicle for buccal administration of antibiofilm peptides.

The comparative effect of propolis in two different vehicles; mouthwash and chewing-gum on plaque accumulation and gingival inflammation

Objective:

In general, chemical plaque agents have been used in mouthwashes, gels, and dentifrices. In some situations, application of mouthwashes and dentifrices can be difficult. Therefore, different approaches for oral health-care have been needed. The aim of this study was to evaluate the effect of propolis chewing-gum compared to propolis-containing mouthwash on gingival inflammation and plaque accumulation on patients that refrained from daily oral hygiene procedures for 5 days.

Materials and Methods:

10 college students with systemically healthy and very good oral hygiene and gingival health were included in this randomized, single-blind, crossover 5-day plaque regrowth with a 3-day washout period clinical study. After plaque scores were reduced to zero, participants were asked to refrain from oral hygiene procedures and allocated to either propolis mouthwash or chewing-gum group. Chewing-gum was performed after meals 3 times a day for 20 min mouthwash group was instructed to rinse mouthwash 2 times a day for 1 min. On day 5, the clinical periodontal measurements containing plaque and gingival indexes were taken from the participants.

Results:

The both plaque and gingival indexes of propolis mouthwash group were significantly lower than that of the propolis chewing-gum group (P = 0.005).

Conclusion:

It was demonstrated that the propolis mouthwash was more effective than the propolis chewing gum on the plaque inhibition and the gingival inflammation.

Synthesis and disinfection effect of the pyridine-4-aldoxime based salts

A set of new quaternary ammonium compounds based on pyridine-4-aldoxime was synthesized, characterized with analytical data (NMR, EA, HPLC, MS) and tested for in vitro antimicrobial activity (antibacterial, antifungal) and cytotoxicity. Quaternary pyridinium-4-aldoxime salts with length of alkyl side chain from C8 to C20 and belonging to the group of cationic surfactants were investigated in this work. An HPLC experimental protocol for characterization of mixtures of all homologues has been found. Antimicrobial evaluation found that yeast-type fungi were most sensitive towards C₁₄ and C₁₆ analogues, whereas the C₁₆ analogue was completely ineffective against filamentous fungi. Antibacterial assessment showed versatility of C₁₄ and relatively high efficacy of C₁₆ against G+ strains and C₁₄ against G− strains. Notably, none of the studied compounds exceeded the efficacy and versatility of the benzalkonium C₁₂ analogue, and benzalkonium analogues also exhibited lower cytotoxicity in the cell viability assay.

[Antibacterial activity of synthetic antimicrobial decapeptide against oral bacteria]

OBJECTIVE

This study aims to evaluate the antimicrobial activity of decapeptide, a novel antimicrobial peptide, against several major cariogenic and periodontopathogenic bacteria in vitro. METHODS In this study, we investigated the antimicrobial activity of decapeptide against Streptococcus mutans (S. mutans), Streptococcus sobrinus, Lactobacillus acidophilus, Streptococcus sanguis, Streptococcus gordonii, Actinomyces viscosus, Actinomyces naeslundii, Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, Actinobacillus actinomycetemcomitans, and Saccharomyces albicans in vitro using the agar diffusion method and broth dilution method. Furthermore, a time-kill kinetic study of decapeptide against S. mutans was performed.

RESULTS

The results showed that decapeptide exhibited antimicrobial activity against various oral bacteria and fungi. The minimum inhibitory concentration (MIC) of main cariogenic bacteria ranged from 62.5 μg · mL(-1) to 125 μg · mL(-1), and the MIC of periodontopathogenic bacteria tested ranged from 250 μg · mL(-1) to 1,000 μg · mL(-1). Among the bacteria tested, decapeptide had a strong inhibitory effect on cariogenic S. mutans. Results of the time-kill kinetic studies showed that decapeptide reduced the viable counts of S. mutans by more than one order of magnitude after 20 min of incubation, and thoroughly killed S. mutans after 30 min. No viable cells could be detected after 24 h of incubation.

CONCLUSION

This study suggest that decapeptide might have potential clinical application in treating dental caries by killing S. mutans within dental plaque.

Novel formulations for antimicrobial peptides

Peptides in general hold much promise as a major ingredient in novel supramolecular assemblies. They may become essential in vaccine design, antimicrobial chemotherapy, cancer immunotherapy, food preservation, organs transplants, design of novel materials for dentistry, formulations against diabetes and other important strategical applications. This review discusses how novel formulations may improve the therapeutic index of antimicrobial peptides by protecting their activity and improving their bioavailability. The diversity of novel formulations using lipids, liposomes, nanoparticles, polymers, micelles, etc., within the limits of nanotechnology may also provide novel applications going beyond antimicrobial chemotherapy.

Release of a wound-healing agent from PLGA microspheres in a thermosensitive gel

The purpose of this research was to develop a topical microsphere delivery system in a thermosensitive 20% poloxamer 407 gel (Pluronic F127) to control release of KSL-W, a cationic antimicrobial decapeptide, for a period of 4-7 days for potential application in combat related injuries. KSL-W loaded microsphere formulations were prepared by a solvent extraction-evaporation method (water-oil-water), with poly (D,L-lactic-co-glycolic acid) (PLGA) (50 : 50, low-weight, and hydrophilic end) as the polymeric system. After optimization of the process, three formulations (A, B, and C) were prepared with different organic to water ratio of the primary emulsion while maintaining other components and manufacturing parameters constant. Formulations were characterized for surface morphology, porous nature, drug loading, in vitro drug release, and antimicrobial activity. Microspheres containing 20% peptide with porous surfaces and internal structure were prepared in satisfactory yields and in sizes varying from 25 to 50 μm. Gels of 20% Pluronic F127, which were liquid at or below 24.6°C and formed transparent films at body temperature, were used as carriers for the microspheres. Rheological studies showed a gelation temperature of 24.6°C for the 20% Pluronic F127 gel alone. Gelation temperature and viscosity of formulations A, B, and C as a function of temperature were very close to those of the carrier. A Franz diffusion cell system was used to study the release of peptide from the microspheres suspended in both, phosphate-buffered saline (PBS) and a 20% Pluronic F127 gel. In vitro release of greater than 50% peptide was found in all formulations in both PBS and the gel, and in one formulation there was a release of 75% in both PBS and the gel. Fractions collected from the release process were also tested for bactericidal activity against Staphylococcus epidermidis using the broth microdilution method and found to provide effective antimicrobial activity to warrant consideration and testing in animal wound models for treating combat-related injuries.

Graft copolymer polyelectrolyte complexes for delivery of cationic antimicrobial peptides

Peptides have enormous potential as therapeutic agents for the treatment of infection, in immunomodulation and for other medical applications, but their hydrolytic degradation in biological fluids is a serious limitation to their in vivo performance. Here we demonstrate the potential utility of polyelectrolyte nanoparticle complexes of novel self-assembling anionic graft copolymers for protecting peptides from degradation in human plasma. The anionic graft copolymers are synthesized by covalently attaching pendent polyetheramine chains to poly(alkylacrylic acid) backbones by carbodiimide coupling. The peptide:copolymer nanocomplexes' particle size, zeta-potential, peptide binding, and controlled release of the peptide are shown to be dependent upon the pendent chain graft density, polymer backbone alkyl groups (propyl vs. methyl), and the nanocomplexes' electrostatic charge ratio. The nanocomplexes can provide substantial protection to the bound peptides from degradation in human plasma for at least 24 h and, in standard microbiological assays are shown to retain some or all of the peptide's antimicrobial activity against a clinically relevant strain of Staphylococcus aureus.

Preparation of quinolinium salts differing in the length of the alkyl side chain

Quaternary quinolinium salts differing in alkyl chain length are members of a widespread group of cationic surfactants. These compounds have numerous applications in various branches of industry and research. In this work, the preparation of quinoline-derived cationic surface active agents differing in the length of the side alkyl chains (from C₈ to C₂₀) is described. An HPLC method was successfully developed for distinction of all members of the series of prepared long-chain quinolinium derivatives. In conclusion, some possibilities of intended tests or usage have been summarized. In vitro testing using a microdilution broth method showed good activity of a substance with a C12 chain length against Gram-positive cocci and Candida species.

Preparation of the pyridinium salts differing in the length of the N-alkyl substituent

Quaternary pyridinium salts with chains ranging from C₈ to C₂₀ belong in the large group of cationic surfactants. In this paper, the preparation of such cationic surface active agents based on the pyridinium moiety and differing in the length of the N-alkyl chain is described. Additionally, HPLC technique was established to distinguish each prepared pyridinium analogue. This study represents universal method for preparation and identification of quaternary pyridinium detergents.

Potential therapeutic application of host defense peptides

Host defense peptides (HDPs) are relatively small, mostly cationic, amphipathic, and of variable length, sequence, and structure. The majority of these peptides exhibit broad-spectrum antimicrobial activity and often activity against viruses and some cancer cell lines. In addition, HDPs also provide a range of immunomodulatory activities related to innate immunity defense, inflammation, and wound healing. The development of these multi-faceted molecules and their bioactivities into clinically important therapeutics is being pursued using a number of different approaches. Here we review the role of HDPs in nature and application of this role to the development of novel therapeutics.