The effect of Myrtus communi, Conocarpus, and Rosa canina L on blood glucose and lipids and meat shelf life in rabbits

Received: 07-Mar-2024, Manuscript No. IJMRHS-24-129100; Editor assigned: 11-Mar-2024, Pre QC No. IJMRHS-24-129100 (PQ); Reviewed: 26-Mar-2024, QC No. IJMRHS-24-129100; Revised: 29-Apr-2025, Manuscript No. IJMRHS-24-129100 (R); Published: 06-May-2025

Introduction

In recent decades, the prevalence of diabetes, especially type 2 diabetes, has increased in the world and it is believed that this disease will accelerate in the next 15 years. Diabetes is an endocrine disorder which is characterized by an increase in blood glucose levels due to insufficient insulin secretion, insulin resistance, or both. The use of chemical drugs, apart from their beneficial effects, has many side effects. From this point of view, herbal medicines for the treatment of diabetes have fewer side effects. Other diabetic complications are including disorders in fat metabolism, lack of regulation of lipoproteins in the body, neurological disorders, cardiovascular issues and defects in the body's antioxidant system). Also, hyperlipidemia, unhealthy diet, physical inactivity, diabetes and hypertension are important risk factors for cardiovascular diseases. Plants still are a valuable source of therapeutic agents especially against certain types of chronic diseases. In modern medicine, global attention has been directed to these types of plants due to their safety. Oxidative stress plays a very important role in the pathogenesis of many diseases, including diabetes and hyperglycemia. This abnormal physiological stress can be reduced by using enzyme systems such as ascorbate enzymes, α-tocopherol and vitamins A, C, E and many polyphenolic compounds obtained mainly from plant origin. Recently, various plant extracts have been widely used by patients with diabetes, cancer, atherosclerosis and many other diseases due to their strong natural antioxidant properties and without any side effects compared to synthetic antioxidant pharmaceutical agents. In addition, in most cases, the use of medicinal plants can control secondary complications caused by diabetes and long-term use of these plants can affect the concentration of glucose and lipids in the blood, as well as body fat. Conocarpus erectus is a common ornamental plant in tropical and semitropical regions which contains bioactive compounds such as alkaloids, saponin, tannin, phenolic compounds, resin, terpenes, glycosides and antibacterial activity. Some of the natural properties of this plant include liver protection, antioxidant and anti-cancer. The Conocarpus plant is notable for its therapeutic potential, including the treatment of diabetes. Also, this plant can reduce oxidative stress [[1-4].

Myrtle, Myrtus communi, belongs to the Myrtaceae family and is one of the most valuable medicinal plants in traditional medicine and pharmaceutical industries. The leaves of this plant contain substances such as tannin, coumarin, glucoside, caffeic acid, gallic acid, ellagic acid and various terpenoids. Its fruits contain citric acid, malic acid, caffeic acid, tannin, resin, anthocyanin arabinoside, anthocyanin glucoside, kaempferol, flavonols and quercetin. Based on several animal models and some human studies, flavonoids appear to be involved in many metabolic processes involved in type II diabetes. In clinical and laboratory studies, the strong effects of the hydroalcoholic extract of myrtle leaves on reducing blood glucose have been shown. It has been reported that myrtle leaf extract is one of the strongest extracts with high antioxidant properties and can reduce blood fat and relieve pain and inflammation [5].

Rosa canina L, Dog rose, is a perennial plant in the form of an erect or wide shrub. Rosa canina has been noted for having antioxidant compounds. The fruits of rose (Rosa canina) have been used in herbal remedies since ancient times. They are rich in biologically active substances such as vitamins C, B1, B2, P, K, vitamin E (in seeds), carotene (provitamin A), lycopene, pectin, flavonoids (kaempferol, quercetin, rutin), anthocyanin content, potassium, calcium, salts of phosphorus, magnesium, manganese, sodium and iron, which activate enzymes in the body, also has high antioxidant activity. The results of several studies showed that Rosa canina has anti-inflammatory, anti-cancer, antimicrobial and antioxidant properties. Consumption of Rosa canina can help to reduce pain, diabetes and hyperlipidemia. It is reported that saponin present in plants has anti-diabetic properties, increase glycogen accumulation and reduce triacylglycerol storage in the liver. This effect may indicate the positive effect of many traditional medicinal plants used in the treatment of diabetes and obesity. For this purpose, this study was designed to investigate the effects of Conocarpus, Myrtle and Rosa canina medicinal plants on blood sugar and lipids and meat antioxidant in rabbits [6].

Materials and Methods

In this project, 20 New Zealand rabbits with an average weight of 250 kg and 1.5 months age were used. The rabbits were randomly divided into four groups. The diet of the studied rabbits was adjusted based on weight and according to the table of rabbit nutrient requirements (Table 1). Rabbits were fed with a control diet, diet containing 25% Conocarpus plant, diet containing 25% Myrtle plant and diet containing 25% Rosa canina for 30 days. The daily feed was weighed and uniformly provided to the rabbits in two meals, morning and afternoon. At the end of the experiment period, meat and blood samples of each treatment were taken [7].

Table 1 Food ingredients and chemical composition of experimental diets (% dry matter)

Analysis of blood parameters

To investigate the effect of experimental treatments on blood parameters, at the end of the experimental period, 4 rabbits were randomly selected from each treatment and blood was taken from their hearts. Blood samples were collected in 10 ml tubes containing 10% EDTA and immediately transferred to the laboratory. Then, blood samples were centrifuged (3000 rpm for 10 minutes) and plasma stored in a freezer at -20 degrees Celsius. Analysis of blood plasma (glucose, cholesterol, liver enzymes, triglycerides, LDL, and HDL) was performed using laboratory kits of a Roman company and a Hitachi 902 machine [8].

Antioxidant capacity of rabbit meat by thiobarbituric acid method

At the end of the experimental period, 4 rabbits from each treatment were killed. Antioxidant activity of thigh meat was investigated in storage in refrigerator and in freezers. To measure the antioxidant of meat by thiobarbiotic acid method, the amount of thiobarbiotic acid in the sample was measured by colorimetric method [9].

200 mg of the homogenized rabbit thigh sample was transferred to a 25 ml balloon and then made up to volume with 1-butanol, 5 ml of this mixture was transferred to a dry falcon tube with a lid and 5 ml of TBA reagent was added to it (TBA reagent is the means of dissolving 200 mg of TBA in 100 ml of butanol solvent is obtained after filtering by filter paper.) The tubes are placed in a hot water bath with a temperature of 95 degrees Celsius for 2 hours and after cooling to room temperature, absorption was read at 530 nm by spectrophotometer (Bio-Rad, Libra S22, England) against distilled water and the amount of thiobarbituric acid was calculated according to the following formula [10].

The analysis of the results was done using the statistical software SAS version 9.4 in the form of a completely randomized design and using the GLM procedure, and the comparison of means was done by Duncan's multiple range test at the 5% level.

The statistical model of the design was as following:

Y_ij=μ+ T_j+ ε_ij

In this model, Y_i was the measured value of each observation, μ was the population mean, T_j was the treatment effect and ε_ij was the measurement error [11].

Results and Discussion

The concentration of malondialdehyde (meat antioxidant measurement index) of rabbits fed with myrtle, Conocarpus and Rosa canina are shown in Table 2. The meat of rabbits that fed myrtle, Conocarpus and Rosa canina showed lower malondialdehyde concentration when stored in the refrigerator and in the freezer compared to the control (P<0.05). The meat of rabbits fed Rosa canina had more antioxidant properties than other treatments, which proves the greater antioxidant properties of Rosa canina than Conocarpus and myrtle plants (P<0.05) [12].

Table 2 The effects of Rosa canina, Conocarpus and myrtle on the shelf life of rabbit meat

The myrtle plant contains compounds such as tannin, resin, anthocyanins, kaempferol, flavonols, and quercetin. The improvement of the antioxidant status of meat in livestock after feeding diets rich in phenolic and antioxidant compounds has been reported in several studies. The results of a report showed that the extract of nutmeg (rich in vitamin C), ginger (rich in antioxidant compounds) and thyme (containing tannin and saponin) can be used as a natural antioxidant to increase the shelf life of rabbit meat. Das, et al. reported that using myrtle leaves in a goat diet can have a positive effect on antioxidant and raw meat quality. Also, the findings of Dal Bosco, et al. showed that the licorice plant extract (containing flavonoid and saponin compounds) in rabbit diet can have a significant effect on increasing the antioxidant activity of rabbit meat. Ramezani-Qara, et al. investigated the antioxidant properties of 10 species of medicinal plants and concluded that myrtle is one of the plants with the highest antioxidant power after thyme and Teucrium polium and these findings agree with the results of this experiment. Studies show that phenolic compounds can have a reducing effect on meat lipid oxidation. It has been observed that the antioxidant capacity of many natural flavonoids is even stronger than vitamins E and C. It has also been reported that myrtle leaf extract is one of the strongest extracts with high antioxidant properties. Therefore, maybe the effect of this plant on the concentration of malondialdehyde in rabbit meat is due to the presence of compounds such as flavonoid compounds and its high antioxidant properties. High antioxidant activity of Cenocarpus erectus extract from leaves, stems, fruits, and flowers is due to the presence of phenolic compounds, tannins and flavonoids. The medicinal properties of this plant include antioxidant and anti-inflammatory activity and protective effects of the plant related to compounds such as flavonoids and saponins [13].

It has been reported that compounds such as flavonoids and tannins play a role in preventing and dealing with oxidative stress as well as reducing cell damage associated with free radicals. The antioxidant property depends on the presence and concentration of different types of phenolic compounds. The most important phenolic compounds are flavonoids, anthocyanins, tannins and phenolic acids. An increase in superoxide dismutase activity and a decrease in malondialdehyde levels were observed with saponin administration. Also, in the study of the effects of alfalfa flavonoids on performance, meat quality and lipid oxidation of growing rabbits, they concluded that the use of alfalfa extract significantly improved the oxidation stability of rabbit meat by reducing the amount of malondialdehyde in the meat. Also, the use of Moringa oleifera leaf (rich in antioxidant compounds) in the rabbit diet had a beneficial effect on performance, antioxidant capacity, and nutritional value of rabbit meat. Effective compounds in Rosa canina include vitamin C, carotenoids, tocopherol, tannin, pectin, organic acids, amino acids, essential oils, oleic acid and palmitic acid. This plant is an effective antioxidant and antimicrobial source due to the presence of phenolic compounds such as quercetin, catechin, myrstein and anthocyanins including cyanidin and glucosidase, so the antioxidant effects and inhibition of hydroxyl radicals can be attributed to the presence of these compounds. The presence of free plant polyphenols has a better effect on oxidant properties because they are freely available and easily absorbed. It is also stated that Rosa canina has the greatest effect in preventing the oxidation of lipids. Oxidative stress is associated with a wide range of chronic diseases and metabolic disorders, including diabetes, with a change in the status of antioxidant enzymes, a decrease in vitamin C levels, and a disruption in glutathione metabolism. Animal and human studies have shown that the use of nutritional supplements rich in antioxidants reduces the incidence of type 2 diabetes and also reduces insulin resistance (68 and 69), as well as the positive effects of foods containing antioxidants in the improvement of cardiovascular diseases in clinical and laboratory research has been reported. Therefore, according to the mentioned results, it can be said that antioxidants are effective both in preventing diabetes and in treating the complications of diabetes and cardiovascular diseases.

The results of using myrtle, Conocarpus and Rosa canina on blood biochemical parameters showed in Table 3. Rosa canina, Conocarpus and myrtle significantly reduce the amount of cholesterol, triglyceride, LDL, HDL and glucose (P<0.05), but no significant difference was observed in the concentration of aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase between the treatments (p>0.05) [14].

Table 3 The effects of Rosa canina, Conocarpus and myrtle on the blood parameters of rabbits

Studies show that one of the most important symptoms of metabolic disorders, including diabetes, is inflammation and oxidative damage that will involve liver and pancreas tissues. Therefore, natural compounds with antiinflammatory and antioxidant properties can reduce the diabetes complications. Natural compounds can be used to treat diseases without causing side effects. Also, plants are enriched with alpha-glucosidase inhibitors and show their anti-diabetic potential by improving the physiological condition. Among the many medicinal plants that have beneficial effects on diabetes, the presence of two substances, beta-carotene and saponin, has significant effect. Based on the structural features, it seems that these two substances can be useful for improving the symptoms of diabetes. Today, the trend in diabetes treatment is to control the blood glucose and reduce the complications caused by oxidative stress. Most of the effective plants have antioxidant properties and can affect the concentration of glucose and lipids in the blood if used for a long time. Also, myrtle plants, Conocarpus and Rosa canina contain flavonoid compounds with strong antioxidant properties and probably inhibit oxygen free radicals and resolve metabolic disorders by reducing of blood lipids. Therefore, the reduction of triglycerides can be attributed to the antioxidant properties of the compounds in Conocarpus, Myrtle, and Rosa canina and their involvement in preventing the harmful effects of environmental stress [15].

Tannin can affect lipoproteins and lead to a decrease in LDL by reducing triglycerides. In many studies, the importance of reducing triglyceride and LDL in the prevention of cardiovascular diseases in diabetic patients has been proven and it has been determined that LDL can be effective in the progression of atherosclerosis by penetrating endothelial cells. By preventing the oxidation of LDL, flavonoids reduce the risk of heart disease. It is also stated that flavonoids can reduce fat. In a study, blood triglyceride levels in diabetic patients decreased with Kelussia odoratissima (containing phenolic compounds). The decrease in cholesterol levels may be due to active ingredients such as unsaturated fatty acid found in the plant, which reduces the synthesis of cholesterol by liver cells and its absorption from the small intestine [16].

According to the results of this study, Menafi, et al. and Tariq’s studies on the effect of myrtle plant compounds showed that injecting 5.77 mg of myrtle plant extract into mice can have a significant effect on reducing cholesterol and triglycerides in the blood of the tested mice. Also, it has been reported that the hydroalcoholic extract of the myrtle plant as strong antioxidant has anti-glycemic properties reduces blood lipids. Phenolic acids and flavonoids of myrtle plant are associated with potential health benefits, including antioxidant, anticancer, and anti-inflammatory activities and reduction of cardiovascular disease. Flavonoids may have beneficial effects on diabetes by increasing insulin. Flavonoids were also shown to regulate carbohydrate digestion, insulin secretion and glucose uptake in insulin-sensitive tissues. Therefore, it seems that part of the important and favorable effect of myrtle plant extract on these complications was related to its antioxidant effects of the phenolic compounds. According to the results of this research, it is also reported that the hydroalcoholic extract of the myrtle plant can be introduced as a plant for the treatment of diabetes, especially type II diabetes n blood glucose in the tested mice. The study of the effects of removing hydroethanol from myrtle essential oil on blood glucose in mice showed an anti-diabetic effect [17].

Conocarpus plant contains bioactive compounds such as alkaloids, saponins and tannins. The effectiveness of Conocarpus plant extract in controlling blood glucose levels has been proven. Saponin can also help control diabetes and high blood pressure. In a report, blood LDL reduction has been proven in diabetic rats consuming saponin. Also, due to the dense tannins found in the Conocarpus plant, it has the potential to lower blood sugar, anti-hypertensive, anti-inflammatory and urease inhibitor [18].

The results of this research showed that Rosa canina reduced glucose, triglyceride, cholesterol, LDL, and HDL in the tested rabbits. In agreement with this research, the results of a study showed that the consumption of Rosa canina extract decreased the serum concentration of total cholesterol, triglycerides and LDL in diabetic rats. The results of another study also showed that supplementing Rosa canina extract improved glucose tolerance and increased insulin secretion in mice that are genetically diabetic in the pre-diabetic stage. Rosa canina is an excellent source of abundant amounts of ascorbic acid. The flavonoids and organic acid in Rosa canina prevent the oxidation of vitamin C and this factor increases its stability and bioavailability. It has been seen that vitamin C reduces the activity of the aldose reductase enzyme, which increases due to the accumulation of sorbitol in the eyes, nerves and kidneys in diabetes. In a reported study, daily consumption of 1000 mg of vitamin C supplement caused a significant decrease in fasting blood sugar. A 3-month study on vitamin C and E supplements showed that the use of these vitamins reduced blood glucose in diabetic patients. Demir, et al., showed that Rosa canina has volatile phenolic and antioxidant compounds. Therefore, it can be said that Rosa canina is effective in treating diabetes due to its antioxidant activity and effective compounds, including vitamins C and E. On the other hand, it has been found that Rosa canina has unsaturated fatty acids such as linolenic acid and linoleic acid. Therefore, it seems that the hypolipidemic effect of Rosa canina is the interaction of the effective compounds in it [19].

The results of the experiment showed that there was no significant difference in the amount of aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase (P<0.50) (Table 1), so it can be said that the use of Rosa canina, Conocarpus plant and Myrtle did not damage the health of the liver tissue in the feeding of rabbits. According to reports of El Shanti, et al., the lack of change in the number of liver factors aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase indicate no damage in the liver parenchymal tissue [20].

Conclusion

Based on the findings obtained in this research, the use of myrtle, Conocarpus and Rosa canina medicinal plants was able to reduce the serum cholesterol, triglyceride, LDL, HDL and glucose levels favorably, so they may be considered a useful treatment method. Nevertheless, it is suggested that future studies on healthy people and people with diabetes and obesity with a larger sample size and comparing their effect with blood lipid-lowering drugs and diabetes.

References

1. Aba PE and Asuzu IU. Mechanisms of actions of some bioactive anti-diabetic principles from phytochemicals of medicinal plants: A review. Indian Journal of Natural Products and Resources. Vol. 9, No. 2, 2018, pp. 85-96.

   [Crossref] [Google Scholar]

2. Hameed ES, et al. Phytochemical studies and evaluation of antioxidant, anticancer and antimicrobial properties of Conocarpus erectus L. growing in Taif, Saudi Arabia. European Journal of Medicinal Plants. Vol. 2, No. 2, 2012, pp. 93-112.

   [Google Scholar]

3. Adebo OA and Gabriela Medina-Meza I. Impact of fermentation on the phenolic compounds and antioxidant activity of whole cereal grains: A mini review. Molecules. Vol. 25, No. 4, 2020, pp. 927.

   [Crossref] [Google Scholar] [PubMed]

4. Al-Snafi AE. Blood lipids lowering effect of medicinal plants. GSC Biological and Pharmaceutical Sciences. Vol. 19, No. 3, 2022, pp. 015-043.

   [Crossref] [Google Scholar]

5. Asgary S, et al. Effects of alfalfa on lipoproteins and fatty streak formation in hypercholesterolemic rabbits. Pakistan Journal of Pharmaceutical Sciences. Vol. 21, No. 4, 2008.

   [Google Scholar] [PubMed]

6. Bao L, et al. Hypolipidemic effects of flavonoids extracted from Lomatogonium rotatum. Experimental and Therapeutic Medicine. Vol. 11, No. 4, 2016, pp. 1417-1424.

   [Crossref] [Google Scholar] [PubMed]

7. Chaudhury A, et al. Clinical review of antidiabetic drugs: implications for type 2 diabetes mellitus management. Frontiers in Endocrinology. Vol. 8, 2017, pp. 6.

   [Crossref] [Google Scholar] [PubMed]

8. Chen SJ, et al. Anti�prediabetic effect of rose hip (Rosa canina) extract in spontaneously diabetic Torii rats. Journal of the Science of Food and Agriculture. Vol. 97, No. 12, 2017, pp. 3923-3928.

   [Crossref] [Google Scholar] [PubMed]

9. Dal Bosco A, et al. The antioxidant effectiveness of liquorice (Glycyrrhiza glabra L.) extract administered as dietary supplementation and/or as a burger additive in rabbit meat. Meat Science. Vol. 158, 2019, pp. 107921.

   [Crossref] [Google Scholar] [PubMed]

10. Das TK, et al. Saponin: role in animal system. Veterinary World. Vol. 5, No. 4, 2012, pp. 48.

    [Crossref] [Google Scholar]

11. Das AK, et al. Antioxidant effect of curry leaf (Murraya koenigii) powder on quality of ground and cooked goat meat. International Food Research Journal. Vol. 18, No. 2, 2011.

    [Google Scholar]

12. Dhungana RR, et al. Prevalence of cardiovascular disease risk factors: A community-based cross-sectional study in a peri-urban community of Kathmandu, Nepal. Indian Heart Journal. Vol. 70, 2018, pp. S20-S27.

    [Crossref] [Google Scholar] [PubMed]

13. Djoussé L, et al. Dietary linolenic acid is inversely associated with plasma triacylglycerol: the National Heart, Lung, and Blood Institute Family Heart Study. The American Journal of Clinical Nutrition. Vol. 78, No. 6, 2003, pp. 1098-1102.

    [Crossref] [Google Scholar] [PubMed]

14. Fattahi A, et al. Antidiabetic mechanisms of Rosa canina fruits: an in vitro evaluation. Journal of Evidence-Based Complementary and Alternative Medicine. Vol. 22, No. 1, 2017, pp. 127-133.

    [Crossref] [Google Scholar] [PubMed]

15. Jemaa HB, et al. Antioxidant activity and α-amylase inhibitory potential of Rosa canina L. African Journal of Traditional, Complementary and Alternative Medicines. Vol. 14, No. 2, 2017, pp. 1-8.

    [Crossref] [Google Scholar] [PubMed]

16. Khalil R, et al. Phenolic acid profiling by RP-HPLC: evaluation of antibacterial and anticancer activities of Conocarpus erectus plant extracts. Biological and Clinical Sciences Research Journal. Vol.10, 2020.

    [Google Scholar]

17. Khodaeian M, et al. Effect of vitamins C and E on insulin resistance in diabetes: a meta�analysis study. European Journal of Clinical Investigation. Vol. 45, No. 11, 2015, pp. 1161-1174.

    [Crossref] [Google Scholar] [PubMed]

18. Lameirão F, et al. Green-sustainable recovery of phenolic and antioxidant compounds from industrial chestnut shells using ultrasound-assisted extraction: Optimization and evaluation of biological activities in vitro. Antioxidants (Basel). Vol. 9, No. 3, 2020, pp. 267.

    [Crossref] [Google Scholar] [PubMed]

19. Malekpour, et al. Effects of the Hydro-Ethanol Extract of Myrtus communis L. On Blood Glucose Level and Histopathological Changes in Alloxan-Induced Diabetic Rats. Middle East Journal of Scientific Research. Vol. 12, No. 4, 2012, pp. 517-522.

    [Google Scholar]

20. Matough FA, et al. The role of oxidative stress and antioxidants in diabetic complications. Sultan Qaboos University Medical Journal. Vol. 12, No. 1, 2012, pp. 5.

    [Crossref] [Google Scholar] [PubMed]