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Polysaccharides from Marine Micro- and Macro-Organisms
Published in Se-Kwon Kim, Marine Biochemistry, 2023
Kannan Kamala, Pitchiah Sivaperumal, Gopal Dharani
Alginate was discovered in 1881 by Stanford, and he claimed alginate as a pharmaceutical agent in his patent. Commercially alginate was extracted from Macrocystis pyrifera by Kelco in 1929, but the worldwide production did not take place until 1959 (Barbosa et al., 2019). Generally, alginate was used as a solidifying agent that has biomedical applications and personal care uses (Tonnesen and Karlsen, 2002: Brownlee et al. 2005). The water retains capacity, gelling, and viscosifying properties, and the stabilizing quality will enhance the commercial quality of alginate (Gomez et al., 2009). In addition, alginate took advantage of the specific biological processes of hypolipidemic hypocholesterolemic effects (Smit, 2004). Also the alginate demands in the area of biotechnology and biomedicinal research have been examined. Chitosan performs well in cationic drug release by hydrogel formation into the stable complex. Also, chitosan supports the tight junction properties and allows the drugs to interact with the cell membrane (Farkas, 1990). The fabricated chitosan nanoparticles are used in oral consumption (Prego et al., 2005, 2006). Marine-derived chitosan improved the drug transport into the tight junction between the epithelial cells (Ranaldi et al., 2002; Yeh et al., 2011; Sonaje et al., 2011). The amine and hydroxyl group in chitosan will enhance the hydrogen bond interaction with drugs and mucus by electrostatic interaction with sulfonic and sialic acids of the mucus layer, which is proven by the mucosal drug delivery research (Senel et al., 2000; Dyer et al., 2002; Sonaje et al., 2011; Dash et al., 2011). The mucoadhesive activity of chitosan is the reason for the prolonged activity of drugs on the surface membrane of the intestine (Qi et al., 2005). In addition, chitosan has a wide range of antimicrobial and antioxidant activity (Leuba and Stossel, 1986; Park et al., 2003; Schnurch and Thiomers, 2005). The low-molecular-weight chitosan nanoparticles penetrate into the cell membrane to bind with DNA and prevent messenger RNA (mRNA) synthesis and DNA transcription (Greene, 1977; Sudarshan et al., 1992). The mucoadhesive property of chitosan is nontoxic in nature and is the reason to use it as a nasal spray, buccal drug delivery, and vaginal tablet to deliver vaccines (Farkas, 1990).
Mucoadhesive drug delivery systems: a promising noninvasive approach to bioavailability enhancement. Part II: formulation considerations
Published in Expert Opinion on Drug Delivery, 2023
Radha Kulkarni, Suraj Fanse, Diane J. Burgess
The past four decades have seen a substantial increase in the number of mucoadhesive polymers with enhanced specificity coupled with the rise of newer technologies, leading to complex MDDS with target specificity and controlled drug release. Analysis of the aforementioned parameters have resulted into the following considerations. Polymers with a molecular weight of about 100 kDa with a substantial crosslinking density are preferred for a longer residence time (of the formulation). The degree of ionization and subsequently the mucoadhesion of ionic polymers is dependent on the pH conditions at the target site and is a crucial aspect for selection. For instance, chitosan adheres to mucin via electrostatic interactions and therefore needs to be dissociated in the tissue microenvironment for good mucoadhesion. On the other hand, polyacrylates such as carbopol show better affinity to mucin when their (carboxylic acid) functional groups are undissociated. The critical attributes of drugs and polymers and the clinical application of the formulation should be considered for selection of an appropriate polymer. For example, specific polymers such as lectins should be used for highly targeted drug delivery applications. Second-generation and third-generation thiomers exhibit improved mucoadhesion and other properties such as P-glycoprotein pump inhibition, and in situ gelation makes them excellent vehicles for oral delivery. However, additional improvements in the design of thiomers should be made to address their stability and concentration-dependent toxicity issues.
Thiolation of arabinoxylan and its application in the fabrication of pH-sensitive thiolated arabinoxylan grafted acrylic acid copolymer
Published in Drug Development and Industrial Pharmacy, 2019
Hira Ijaz, Ume Ruqia Tulain, Farooq Azam, Junaid Qureshi
Arabinoxylan was extracted from the seeds of Plantago ovate via alkali extraction with wide range of applications in pharmaceutical industry. It is employed in sustained release and controlled release matrix [4]. Treatment of seed husks with caustic alkali solution results in gel-like substance known as arabinoxylan. Arabinoxylan is hemicellulose with attached arabinose side chains to a linear backbone (β-(1 → 4)-linked D-xylopyranosyl units) [5,6]. Variety of unmodified polymers was employed in pharmaceutical technology for various drug delivery systems. In new era, further research work lead to development of Thiomers or Thiolated polymers. Incorporation of thiol group in thiolated polymer upgrade various additive attributes like improving contact time with GIT mucosa, improving solubility and permeability of drugs [4]. Nowadays, thiomers found broad range of promising applications as pharmaceutical excipient. Thiomers are employed in various controlled release drug delivery systems and found its applications in gastrointestinal, oral, nasal, buccal, and ophthalmic drug delivery system [7].
In situ gelling and mucoadhesive polymers: why do they need each other?
Published in Expert Opinion on Drug Delivery, 2018
Forouhe Zahir-Jouzdani, Julian Dominik Wolf, Fatemeh Atyabi, Andreas Bernkop-Schnürch
Oxidative crosslinking represents a promising approach to provide in situ gel formation. Especially thiolated polymers – designated thiomers – exhibit in situ gelling properties due to their capability of forming inter- and intramolecular disulfide bonds by oxidation of thiol groups as schematically shown in Figure 2(d). The gelling properties of thiomers depend on the degree of thiolation and the reactivity of thiol groups being determined by their pKa value. The higher the pKa of the sulfhydryl group is, the more reactive they are [9,37–39]. Thiomers exhibit comparatively high in situ gelling properties. Sakloetsakun et al., for instance, could show an even more than 10,000-fold increase in dynamic viscosity of a thiolated chitosan gel due to disulfide bond formation within minutes [39]. Addressing stability issues of aqueous solutions caused by disulfide formation prior to application, thiomers were recently S-protected via linkage with 2-mercaptonicotinic acid or 2-mercaptonicotinamide. Besides sufficient stability, further improvement of in situ gelling properties upon contact with mucus was achieved by this modification [40,41].