Study of Ligmed-A, an antidiarrheal drug based on lignin, on rat small intestine enzyme activity and morphometry

The Inhibition of Hepatic and Renal Glucuronidation of p-Nitrophenol and 4-Methylumbelliferone by Oil Palm Empty Fruit Bunch Lignin and Its Main Oxidation Compounds

Background:

In order to develop oil palm empty fruit bunch (EFB) lignin as a nutraceutical and health supplement, the investigation of its potential in interacting with other drugs via inhibition of drug-metabolizing enzymes (DMEs) would ensure product safety.

Objective:

The study was aimed to investigate the in vitro effect of oil palm EFB lignin and its main oxidation compounds on phase II DME UDP-glucuronosyltransferases (UGTs) in rat liver and kidney microsomes.

Materials and Methods:

The p-nitrophenol (p-NP) and 4-methylumbelliferone (4-MU) were employed as probe substrates in glucuronidation assays. The effect of soda oil palm EFB lignin on V_max, K_m, CL_int, K_i, and mode of inhibition of 4-MU glucuronidation in RLM was also determined.

Results:

The inhibitory potency of oil palm EFB lignin for both p-NP and 4-MU glucuronidation in rat liver microsome (RLM) and rat kidneys microsomes (RKM) was found to be in the rank order of soda > kraft > organosolv. However, the inhibitory potency of its main oxidation compounds were in the rank order of vanillin > syringaldehyde > p-hydroxybenzaldehyde. Soda oil palm EFB lignin exhibited mixed-type inhibition against 4-MU glucuronidation in RLM, showing the change in apparent V_max and with only a minor effect on K_m compared with control.

Conclusions:

The findings showed that effect of oil palm EFB lignin on both p-NP and 4-MU glucuronidation in RLM and RKM was enhanced by the presence of vanillin as well as flavonoids. Kinetic study showed that soda oil palm EFB lignin exhibited strong inhibition on UGT activity in RLM with mixed-type inhibition mode.

SUMMARY

The inhibitory potential of oil palm EFB lignin extracts for p-NP and 4-MU glucuronidation in RLM and RKM can be listed in the following rank order: soda > kraft > organosolv

The inhibitory potential of oil palm EFB lignin main oxidation compounds for p-NP and 4-MU glucuronidation in RLM and RKM can be listed in the following rank order: vanillin > syringaldehyde > p-hydroxybenzaldehyde

Results suggested that the effect of oil palm EFB lignin on p-NP and 4-MU glucuronidation activity in both RLM and RKM was enhanced by the presence of vanillin as well as total flavonoid content

Results also suggested that oil palm EFB lignin may inhibit glucuronidation of substrate by UGT enzymes, especially UGT1A6, particularly in rat liver

Abbreviations used:p-NP: p-Nitrophenol, 4-MU: 4-Methylumbelliferone, EFB: Empty fruit bunch, DME: Drug-metabolizing enzymes, UGT: UDPglucuronosyltransferase, V_max: Maximal reaction velocity, K_m: Michaelis-Menten constant, CLint: Intrinsic clearance, K_i: Dissociation constant of an inhibitor enzyme complex, 4-MUG: 4-Methylumbelliferone glucuronide, DMSO: Dimethyl sulfoxide, IC50: Half maximal inhibitory concentration, p-NPG: p-Nitrophenol glucuronide, RKM: Rat kidneys microsomes, RLM: Rat liver microsome, UDPGA: UDPglucuronic acid, TCA: trichloroacetic acid, MPA: mycophenolic acid

Antibacterial and antispasmodic activities of a dichloromethane fraction of an ethanol extract of stem bark of Piliostigma reticulatum

OBJECTIVES

This study presents the antispasmodic and antibacterial properties of an ethanol extract and fractions the of stem bark of Piliostigma reticulatum.

MATERIALS AND METHODS

The antispasmodic effects of the extract and its fractions were performed on isolated rabbit duodenum. The antibacterial properties were determined as minimal inhibitory and bactericidal concentration of the extract and fractions of P. reticulatum on susceptible and resistant strains of Escherichia coli, Vibrio cholerae, Staphylococcus aureus, Shigella dysenteriae and Salmonella tiphymurium.

RESULTS

The ethanol extract of P. reticulatum and fractions (except for heptane) produced concentration-dependent relaxant effects on isolated duodenum preparations. The IC50 of the extract and dichloromethane, ethyl acetate, butanol and aqueous fractions are 0.88452, 0.2453, 0.2909, 0.3946 and 0.3231 mg/ml respectively. The extract was found to significantly antagonize acetylcholine-induced contraction. The susceptible strains E. coli and V. cholerae were the most inhibited by the dichloromethane fraction at 60 mg/mL, as shown by their diameter of inhibition of 13.2 ± 0.76 and 13.3 ± 0.67 mm respectively. Conversely, the dichloromethane fraction, the most active antibacterial fraction, did not inhibit the resistant strains S. dysenteriae and S. tiphymurium.

CONCLUSION

The results showed that P. reticulatum stem bark possesses spasmolytic and antibacterial properties and this may contribute to its traditional medicinal use for the treatment of diarrhea.

Antidiarrhoeal activity of an ethanol extract of the stem bark of Piliostigma reticulatum (Caesalpiniaceae) in rats

Piliostigma reticulatum (Caesalpiniaceae) is used in Africa as a traditional medicine for the treatment of many diseases, such as malaria, tuberculosis and diarrhoea. We investigated the antidiarrhoeal properties of a crude ethanol extract from the stem bark of Piliostigma reticulatum (EEPR) in Wistar albino rats to substantiate its traditional use and to determine its phytochemical constituents. The antidiarrhoeal activity of the plant extract was evaluated in a castor oil-induced diarrhoea model in rats and compared with loperamide. The effect of the extract on gastrointestinal motility was also determined by the oral administration of charcoal meal and castor oil-induced intestinal fluid accumulation (enteropooling). EEPR showed remarkable dose-dependent antidiarrhoeal activity evidenced by a reduction of defecation frequency and change in consistency. Extracts at 250, 500 and 1000 mg/kg body weight significantly reduced diarrhoeal faeces. EEPR also significantly inhibited gastrointestinal motility and castor oil-induced enteropooling at 500 and 1000 mg/kg, similar to the inhibition obtained in control rats treated by atropine. Phytochemical screening revealed the presence of tannins, flavonoids, polyphenols and reducing sugars in the stem bark of P. reticulatum. No mortality or visible signs of general weakness were observed in the rats following administration of the crude extract in doses up to 6000 mg/kg body weight in an acute toxicity study. Our results show that the stem bark of P. reticulatum possesses antidiarrhoeal activity and strongly suggest that its use in traditional medicine practice could be justified.

Semi-interpenetrating Polymer Networks Containing Polysaccharides. I Xanthan/Lignin Networks

The polysaccharides are important materials in food, pharmaceutical, cosmetic and related biomedical applications. Xanthan gum is a microbial polysaccharide of great commercial significance. It is well known as one of the best thickening polymers due to its high intrinsic stiffness related to the helical conformation stabilized in the presence of excess salt. It is used in a wide variety of foods for a number of important reasons, including emulsion stabilization, temperature stability, compatibility with food ingredients, and its pseudoplastic rheological properties. Due to its properties in thickening aqueous solutions, as a dispersing agent, and stabilizer of emulsions and suspensions, xanthan gum is used in pharmaceutical formulations, cosmetics, and agricultural products, as well as in textile printing pastes, ceramic glazes, slurry explosive formulations, and rust removers. In this work the crosslinking of a mixture of xanthan and lignins in the presence of the epichlorohydrin, leading to superabsorbant hydrogels with high swelling rate in aqueous mediums, was studied. The swelling properties of these composite hydrogels were investigated. Three different types of lignin have been used namely: aspen wood lignin (L), annual fiber crop lignin (GL) and lignin epoxy-modified resin (LER). Semi-interpenetrating polymer network hydrogels in various ratios were prepared. The influence of gravimetric ratio between components of the semi-interpenetrating polymer networks, as well as the kinetics of water sorption will be discussed. The maximum swelling degree of the hydrogels and the swelling rate constant were determined as a function of the hydrogel's composition. It has been established that the nature of lignin significantly influences swelling process, the chemical modified lignin having a particular behavior.