Vernonia amygdalina Del: A Mini Review

 

Suleiman Danladi^1*, Mohammed Alkassim Hassan¹, Idris Aliyu Masa’ud², Umar Idris Ibrahim³

¹Department of Pharmaceutical and Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Bayero University, Kano. Nigeria.

²Department of Pharmacognosy and Herbal Medicine, Faculty of Pharmaceutical Sciences, Bayero University, Kano. Nigeria.

³Department of Clinical Pharmacy and Pharmacy Practice, Faculty of Pharmaceutical Sciences, Bayero University, Kano. Nigeria.

 

ABSTRACT:

Phytomedicines are medicinal products of plant origin that have been used since ancient times till date for the prophylaxis and treatment of various ailments. Vernonia amygdalina Del (Asteraceae) is a perennial shrub that is widely distributed in tropical parts of Africa. It is popularly known as bitter leaf and consumed as a vegetable and for medicinal purposes. The plant has been used in folkloric medicine for the treatment of several diseases owing to its diverse pharmacological applications. The plant has low toxicity profile; thus, making it a potential drug candidate. Scientific investigations have shown that, V. amygdalina Del possesses potent pharmacological activities such as antidiabetic, anthelminthic, antiplasmodial, antimicrobial, antioxidant and antianaemic activities. Moreover, V. amygdalina Del contains various phytochemical compounds which may be associated with its potent pharmacological properties. The present study is a review of the therapeutic benefits as well as phytochemicals isolated from V. amygdalina Del.

 

 

 

INTRODUCTION:

Herbal medicines, otherwise called phytomedicines, are medicinal products of plants or plant parts such as roots, leaves, flowers, barks, seeds and fruits which are used to treat diseases and to improve health. They are used as complementary or alternative medicines; in the prophylactic treatment and alleviation of diseases and their symptoms.¹ Medicinal plants play a vital role in the treatment of various diseases as evident by their long history of use. They have been used in both ancient and recent times by all culture for curing several diseases²

 

 

 

 

Vernonia amygdalina Del is among the medicinal plants used for the treatment of various diseases in different parts of the world. It has been reported that V. amygdalina Del plant is used for the treatment of diabetes, yellow fever, dysentry, constipation, malaria and stomach ache in Africa and Asia.^2,3 Moreover, the plant is widely used in Africa as a source of food as vegetable and culinary herb in soup.⁴

 

V. amygdalina Del belongs to the family Asteraceae. It is widely distributed throughout Tropical Africa andcultivated as foodsupplement in West Africa including Nigeria.^2,5 The common name of V. amygdalina Del  is ‘bitter leaf’, locally known as ‘Shuwaka’ in Hausa Language and ‘Ewuro’ in Yoruba Language.⁶

 

In this research various activities as well as phytochemical constituents of V. amygdalina Del were reviewed. The data were searched from online sources; Pubmed, googlescholar and science direct. The key word used for searching information was V. amygdalina Del.

Taxonomy:

Vernonia amygdalina Del. is a small tree growing up to 3 m high. The picture of  V. amygdalina Del in its natural habitat is  shown in figure 1.0. It grows throughout the African Tropics⁷.

 

 

Figure 1.0: Vernonia amygdalina Del plant

 

V. amygdalina commonly called bitter leaf is a perennial shrub belonging to the family Asteraceae. It grows throughout Tropical Africa.⁸Its taxonomic classification⁶ is preseted in Table 1.0.

 

Table 1.0: Taxonomic classification of V. amygdalinaDel

Kingdom	Plantae
Class	Angiospermae
Order	Asterales
Family	Asteraceae
Genus	Vernonia
Species	amygdalina Del

 

Phytochemistry of V. amygdalina Del:

Qualitative phytochemical screening of V. amygdalina Delhave detected heavy presence of polyphenols and moderate presence of alkaloids, saponins, flavonoids and steroids⁵. Phytochemicalstudy of the leaves of V. amygdalina Delshowed that, the plant contains two sesquiterpene lactones; vernolide and vernodalol.⁷ Vernoniosides D and Vernoniosides E were isolated from the leaves of V. amygdalina Del⁹.

 

 

 

 

 

 

 

Vernoniosides D

Vernoniosides E

Figure 1: Some compounds isolated from V. amgdalina

 

Antidiabetic activity:

V. amygdalina Del, demonstrated positive antidiabetic activty when administered through various routes of administration. Intraperitoneal administration of aqueous leaf extract of V. amygdalina, Del, produced hypoglycaemic effects which was comparable to tolbutamide. Additionally, when aqueous leaf extract of V. amygdalina, was given to normoglycaemic rabbits, the fasting blood sugar reduced from 96 mg% to 48 mg% in 4 h.¹⁰ Similarly, administration of the leaf extract via gastric intubation to alloxan induced rats provided significant reduction of blood and serum glucose.¹¹ V. amygdalina Del has been reported to contain high amount of polyphenols.¹¹ Accordingly, phenolic extract of V. amygdalina Del was found to have significant effect on the key enzymes linked to type-2 diabetes thereby inhibiting the activities of α-amylase and α-glucosidase in vitro in a concentration-dependent manner.¹² Okolie et al. (2008)¹³ assessed the antidiabetic effect of V. amygdalina Del in human subjects using standard laboratory testing (fasting blood glucose, glucose tolerance test and postprandial blood glucose). It was found that V. amygdalina Del caused significant reductions in blood glucose levels atmost postprandial time points and for area-under-curve.¹³

 

The polyherbal combination of V. amygdalina Del and Azadirachta indica constituents gave a synergistic antidiabeticc effect in diabetic rat.³ In another study, combination of V. amygdalina Del and Gongronema latifolium provided significant reduction of serum glucose in streptozotocin (STZ)-induced diabetic Wistar rats. This effect was comparable to that of insulin.¹⁴

 

Atangwho et al. (2010)¹¹ suggested that, the mechanism of antidiabetic activity of V. amygdalina Del may be due to the regeneration of pancreatic β-cell.

 

Anthelminthic activity:

The acetone extract of V. amygdalina Delwas found to inhibit parasitic larva of Haemonchus contortus. It was also reported to inhibit nematode eggs and nematode larvae¹⁵. In another study, fifty West African dwarf goats were used to compare the antihelminthic activity of some standard drugs namely albendazole, levamisole and ivermectin with that of the aqueous extract of bitter leaf using the Faecal Egg Count Reduction (FECR) assay. The aqueous extract demonstrated highest FECR (100%) compared to the standard drugs (albendazole, 99%; levamisole, 96%; ivermectin, 96%) against the nematodes (Haemonchus contortus, Trichostrongylus spp.,Ostertagiaostertagi, Oesophagostomum spp., Chabertia sp., Strongyloides, and Paramphistomum spp.) tested.¹⁶

 

Antiplasmodial activity:

The aqueous and ethanolic leaf extracts of V. amygdalina Del were analysed in vivo (in rats) and in vitro (cell lines) using bioassay guided fractionation for the isolation of molecules with antimalarial activity. Both extracts demonstrated antiplasmodial activities at both sexual and asexual blood stages of the parasite .¹⁷V. amygdalina Del leaf was reported to have antiplasmodial activity in vitro which was attributed to its phytochemical constituents¹⁸.

 

Antimicrobialactivity:

Vernolide and vernodalol; the chemical compounds isolated from the leaves of V. amygdalina Del demonstrated a significant bactericidal activity against Gram positive bacteria. However, they failed to show efficacy against the Gram negative strains.⁷ Moreover, vernolide and vernodalolshowed highand moderate activity respectively against some fungal species. In contrast, they were ineffective against Fusarium oxysporum⁷.

 

Antioxidant activity:

Methanolic extract of V. amygdalina Del prevented lipid peroxidation induced by tert-butyl hydroperoxide.¹⁹ It was also reported that, the methanolic extract of V. amygdalina exhibited significant free radical scavenging and antioxidant activities²⁰.

 

 

Antianaemicactivity:

Methanolic extract of V. amygdalina Del lowered erythrocytes lysis induced by tert-butyl hydroperoxide.¹⁹ Therefore, anti-haemolytic effect of V. amygdalina Del suggests that the plant can be used as antianaemic agent.

 

Effect on fertility:

The reproductive effect of saponin extract of V. amygdalina Del studied on male Wistar rats at different doses for 14 days showed that sperm cell motility and concentration were enhanced (at higher doses) without a reduction in the percentage of morphologically abnormal sperm cells²¹.

 

Immunomodulatory effect:

V. amygdalina Del has been studied for its modulatory effect on the immune system. In one study, the immunomodulatory effect of the leaf extract of the plant, Immunace® and a combination of both were observed in human immunodeficiency virus (HIV) patients on Anti-Retroviral Therapy (ART). A combination of the extract with Immunace® improved the CD₄⁺ counts and packed cell volume (PCV) while reducing the development of skin rashes of patients when compared to control (patients on ART only).²² Similarly, Ezeonu et al.(2016)²³ analysed the leaf extract of V. amygdalina Del for its immunological effect in rats and reported a remarkable improvement on CD₄⁺counts, haematological parameters and lipid profiles.

 

Cardiovascular Activity:

The cardiovascular activity of the aqueous leaf extract of V. amygdalina Del was investigated in rabbits fed with artherogenic diet. There was no significant improvement of lipid profile when the bitter leaf-artherogenic diet co-fed rabbits were compared to control.²⁴

 

Safety and Toxicities Profile:

Olujimi et al. (2017)²⁵ analyzed concoctions containing ten medicinal plants (including bitter leaf) with potential antidiabetic activity for the presence of toxic elements. They were found to be safe from the risk of the toxic metals and trace elements investigated. There was no death or any physical pathology observed at doses of up to 600 mg/kg when aqueous extract of V. amygdalina Delwas administered to rats.²⁶ The histopathology and microscopy of the liver, kidney, small intestine, lung and heart did not show any significant damage except for mild congestion in the kidney after oral administration of V. amygdalina Del extract in rats. Biochemical analysis revealed that V. amygdalina Del has the potential to elevate some liver enzymes (ALT, AST and ALP) and cholesterol in bitter leaf extract-treated rats.²⁶ Interestingly, in an in vitro study against plasmodium parasite V. amygdalina Del leaf extract has been shown to have no sign of toxicity¹⁸.

CONCLUSION:

V. amygdalina Del is a versatile plant that possesses several prophylactic and therapeutic potentials. This review highlighted many of the pharmacological activities of the plant. Interestingly V. amygdalina Del leaf was reported to have low toxicity profile, thus making it a potential drug candidate. However, further researches are required to standardize extracts of the plant and to unravel further medicinal and nutraceutical properties of the plant particularly on the root, stem and bark.

 

CONFLICT OF INTEREST:

No conflict of interest.

 

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Accepted on 07.08.2018          © RJPT All right reserved

Research J. Pharm. and Tech 2018; 11(9): 4187-4190.