Pharmacological influences of natural products as bioenhancers of silymarin against carbon tetrachloride-induced hepatotoxicity in rats

Evaluation of hepatoprotective and antidiarrheal activities of the hydromethanol crude extract and solvent fractions of Schinus molle L. (Anacardiaceae) leaf and fruit in mice

Background

Liver disease is any disease that negatively affects the normal function of the liver, and it is a major health problem that challenges not only healthcare professionals, but also the pharmaceutical industry and drug regulatory agencies. Similarly, diarrhea is the second leading cause of death among children under five globally next to pneumonia. The available synthetic drugs for the treatment of liver disorders and diarrhoea have limited safety and efficacy.

Objective

To evaluate the in vivo hepatoprotective and antidiarrheal activities of hydroalcoholic leaf and fruit extracts of Schinus molle L. (Anacardiaceae) in mice.

Methods

Hepatoprotective activity of the extracts was evaluated by using CCl4 induced hepatotoxicity in mice model. In this model, mice were divided into groups and treated as follows. The normal control and toxicant control groups were treated with the vehicle used for reconstitution, the positive control was treated with the standard drug (silymarin), and the test groups were treated with different doses of plant extracts daily in the morning for seven days. Additionally, all groups except the normal control were treated with CCl4 (2 mg/kg, IP) on the 4th day of treatment, 30 min post-dose. On the 7th day, blood was collected from each mouse via a cardiac puncture. The collected blood was centrifuged, and serum levels of ALT, AST, and ALP were determined using an automated chemistry analyser. Data were analysed using one-way analysis of variance (ANOVA) followed by Tukey's post-hoc test.The antidiarrheal activity of the extract was investigated using castor oil-induced diarrhoea, enteropooling, and small intestine transit. The test groups received various doses (100, 200, and 400 mg/kg) of the extract, whereas the positive control received loperamide (3 mg/kg), and the negative control received the vehicle (distilled water, 10 ml/kg).

Result

Hepatoprotective activity: The leaf and fruit crude extracts showed significant improvement in the body weight and liver weight of mice compared to the untreated toxicant control. Additionally, treatment with hydromethanol leaf and fruit extracts caused a significant (P < 0.05) improvement in liver biomarkers compared to the toxicant control. Similarly, the n-butanol and chloroform fractions of the fruit extract caused a significant reduction (P < 0.01) in serum AST, ALT, ALP and Bilirubin levels and a significant (P < 0.001) increase in total protein compared to the toxicant control. However, none of the three solvent fractions (n-butanol, chloroform, and aqueous) of the fruit extract significantly affected (P > 0.05) the level of albumin compared with the toxicant control.Antidiarrheal activity: In the castor oil-induced diarrheal model, the 80 % methanol extract delayed the onset of defaecation and significantly reduced the number and weight of faeces at all tested doses compared to the negative control. In the enteropooling test, 80 ME significantly (P < 0.001) reduced the weight and volume of intestinal fluid at all tested doses compared with the negative control. Results from the charcoal meal test revealed that the extracts produced a significant anti-motility effect at all tested doses compared with the negative control.

Conclusion

This study confirmed the hepatoprotective and antidiarrheal activities of hydroalcoholic extracts. The highest test dose produced the maximum hepatoprotective and antidiarrheal activities in all models.

Mechanistic Insights into the Pharmacological Significance of Silymarin

Medicinal plants are considered the reservoir of diverse therapeutic agents and have been traditionally employed worldwide to heal various ailments for several decades. Silymarin is a plant-derived mixture of polyphenolic flavonoids originating from the fruits and akenes of Silybum marianum and contains three flavonolignans, silibinins (silybins), silychristin and silydianin, along with taxifolin. Silybins are the major constituents in silymarin with almost 70–80% abundance and are accountable for most of the observed therapeutic activity. Silymarin has also been acknowledged from the ancient period and is utilized in European and Asian systems of traditional medicine for treating various liver disorders. The contemporary literature reveals that silymarin is employed significantly as a neuroprotective, hepatoprotective, cardioprotective, antioxidant, anti-cancer, anti-diabetic, anti-viral, anti-hypertensive, immunomodulator, anti-inflammatory, photoprotective and detoxification agent by targeting various cellular and molecular pathways, including MAPK, mTOR, β-catenin and Akt, different receptors and growth factors, as well as inhibiting numerous enzymes and the gene expression of several apoptotic proteins and inflammatory cytokines. Therefore, the current review aims to recapitulate and update the existing knowledge regarding the pharmacological potential of silymarin as evidenced by vast cellular, animal, and clinical studies, with a particular emphasis on its mechanisms of action.

PLANT BASED BIOAVAILABILITY ENHANCERS

Many of the synthetic as well as herbal drugs despite of their notable in vitro finding demonstrate insignificant in vivo activity majority of times due to poor bioavailability. As per Biopharmaceutical Classification System (BCS) one of the main concern is low solubility and/or permeation of drugs resulting in reduced absorption and poor bioavailability. To overcome these issues the various strategies have been adopted including use of permeation enhancers which are also known as bioenhancers. Bioenhancers are synthetic or natural compounds that increases the bioavailability of drugs and nutrients such as vitamins, amino acids, minerals, etc. into the systemic circulation and at the site of action for exhibiting improved therapeutic action. By improving bioavailability, bioenhancers can lead to reduction in drug dose, decrease in the treatment period and can circumvent the problem of drug resistance. Numerous studies have reported application of synthetic bioenhancers. On the other hand, owing to the natural origin, plant based bioenhancer can serve as better alternative. Literature review have revealed that the plant-based bioenhancers have been used in with a wide varieties of drugs including antibiotics, antiviral and anti-cancer. These can be categorized based on their sources and the mechanism of activity. This review will provide a systematic and detailed overview of the various plant based bioenhancers and applications.

Chronic Liver Disease and Silymarin: A Biochemical and Clinical Review

Chronic liver disease (CLD) is an under-recognized epidemic that continues to increase in prevalence and is a major health concern. Silymarin, the active compound of Silybum marianum (Milk thistle), has historically been used in CLD. A significant barrier to silymarin use is its poor bioavailability. Attempts at improving the bioavailability of silymarin have led to a better understanding of formulation methods, pharmacokinetics, dosing, and associated drug interactions. Clinically, silymarin exerts its hepatoprotective effects through antioxidative, antifibrotic, anti-inflammatory, antitoxin, and anticancerous mechanisms of actions. Despite the use of silymarin being extensively studied in alcoholic liver disease, metabolic-associated fatty liver disease, viral hepatitis, and drug-induced liver injury, the overall efficacy of silymarin remains unclear and more research is warranted to better elucidate the role of silymarin in CLD, specifically regarding its anti-inflammatory effects. Here, we review the current biochemical and clinical evidence regarding silymarin in CLD.