Malic acid biodegradability

Poly(malic acid) is of pharmaceutical interest because its chemical derivatives may harbor both tissue-specific homing molecules and therapeutic effectors to be used for tissue (tumor) targeting in chemotherapy [2]. Because of its efficient production by fermentation, its biodegradability and nontoxicity, it is also considered as raw material in the industrial production of detergents, glues, and plastic materials. 

Poly(malic acid) is a biodegradable and bioadsorbable water-soluble polyester having a carboxylic acid in the side chain. The chemoenzymatic synthesis of poly(malic acid) was achieved by the lipase-catalyzed polymerization of benzyl (3-malolactonate, followed by the debenzylation. The molecular weight of poly(benzyl (3-malolactonate) increased on copolymerizafion with a small amount of (3-PL using lipase CR catalyst. ... 

Poly-j3-malate is readily degraded completely to L-malic acid under both acid and base conditions [108], and it can also be hydrolyzed by enzymes within the cell [105,106]. Recently, several bacteria were isolated which were able to utilize poly-/i-malate as sole carbon source for growth [109]. Because the polymer is biodegradable and bioadsorbable, it is of considerable interest for pharmaceutical applications, especially in controlled-release drug delivery systems [97,98]. Chemical routes to poly-/ -malate are expected to provide materials with various properties [110]. 

Chemoenzymatic synthesis of biodegradable poly(malic acid) was performed by lipase-catalyzed polymerization of benzyl /J-malolactone, followed by the debenzylation [72]. The addition of a small amount of /J-PL (17 mol % for the monomer) increased Mw up to 3 x 104 [73]. 

Coulembier O, Degee Ph, Hedrick JL, Dubois Ph (2006) From controlled ring-opening polymerization to biodegradable aliphatic polyester especially poly(P-malic acid) derivatives. Prog Polym Sci 31 723-747... 

In a subsequent investigation by the author [1] biodegradable microparticles such as poly(l-lactic-co-glycolic-co-d,l-malic acid), (1), were prepared and used as a drag delivery agent for the acetate salt of Lanreotide . 

Similar to fumaric acid, L-malic acid is also a naturally occurring four-carbon dicarboxyhc acid and an intermediate in the TCA cycle. It has been used in many food products, primarily as an acidulant. L-Malic acid is compatible with all sugars with low hygroscopicity and good solubihty. In addition, it has therapeutic value for the treatment of hyperammoemia and liver dysfunction and as a component for amino acid infusion. L-Malic acid has been the subject of interest because of its increased application in the food industry as a citric acid replacement and its potential use as a raw material for the manufacture of biodegradable polymers. 

Li, G., Yao, D., and Zong, M. (2008) Lipase-catalyzed synthesis of biodegradable copolymer containing malic acid units in solvent-free system. Eur. Polym.J., 44 (4), 1123-1129. 

Fluorescence spectra of phenanthrene in LMWOA solution Control experiments showed that malic acid, citric acid and butylic acid had little effect on the spectral characteristics of phenanthrene or its fluorimetric determination. Measurement of phenanthrene biodegradation by fluorescence method. 50.0 mL MSM were added to each incubation flask the final concentration of phenanthrene was 1000 u g/L. After sterilization at 121 C for 15 min, the bacterial strain was inoculated into individual incubation flasks and incubated on a rotary shaking incubator at 25 °C and 150 rpm in the dark. The biodegradation rate of phenanthrene was monitored directly by the fluorescence method without solvent extraction. 

Biodegradation of phenanthrene in MSM solution with or without malic acid, citric acid and butylic acid (LMWOA 1600 pmol/L) are shown in Fig. 3. 

From Fig. 3, it can be seen that biodegradation rate of phenanthrene were increased within the presence of both malic acid and citric acid, but decreased within the presence of butylic acid. The biodegradation rate of phenanthrene under the effect of citric acid was a little bit higher than that under the effect of malic acid. 

Effects of LMWOA on phenanthrene biodegradation using a fluorescence method are reported in this work. It can be concluded that both malic acid and citric acid have positive effect on biodegradation of pheneanthrene. However, butylic acid restrained the biodegradation of phenanthrene. Further research is needed to explain the results in these experiments and discover the mechanism in it. 

Fig. 4. Effects of malic acid on phenanthrene biodegradation (malic acid a, 400 b, 1200 c, 2400 pmol/L).

Lactic bacteria from the genera Leuconostoc and Lactobacillus are likely to develop in wine, in spite of its high alcohol concentration and low pH. When there is no more sugar left in the wine, the most easily biodegradable molecule is malic acid. Consequently, malolactic fermentation is the first sign that lactic bacteria are developing. Malolactic fermentation improves the quality of red wines and certain white wines, producing small quantities of volatile acidity, mainly due to the breakdown of citric acid. 

Brand, C., and Vert, M., 1993, Poly(p-malic acid) based biodegradable polyesters aimed at pharmacological uses. Trends in Polym. Sci. 3 57-65... 

Fcadlev, S.R.. Davies, M.C., Vert, M., Brand, C Paul, A.J., Shard, A.G. and Watts, J.F. (in preparation b) Probing the surface cliemical structure of the novel biodegradable polymrer poly (j8-malic acid) using ToF-SIMS and XPS. In preparation. 

Several biodegradable polymers have been investigated as drug carriers [47, 48] (1) poly(lactic acid)/poly(lactic acid-co-glycolic acid), (2) poly(anhydrides), (3) poly (ortho esters), (4) poly(yS-malic acid-co-benzyl malate), and (5) poly(alkylcyanoacry-lates). 

Poly(glutamic acid), poly (u-ly sine), poly(aspartamides), and poly((W-hydroxyethyl)-L-glutamine) (PHEG) are examples of poly(amino acids) [13]. An analog polymer is poly(malic acid) that exhibits an ester linkage instead of a polyamide backbone. This is biodegradable in analogy to natural polypeptides. Other natural polymers are normally polysaccharides like dextran or chitosan. 

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