Tuberculosis (TB) is one of the main causes of mortality and morbidity globally. According to the World Health Organisation (WHO), Mycobactrium tuberculosis (Mtb) has infected approximately one-third of the world’s population, producing more than nine million new cases and two million deaths annually; the rest of the infected people remain asymptomatic.
Major problems associated with current TB treatment, like the duration and complexity of treatment, resulting in non-adherence to treatment, leading to suboptimal response (failure and relapse), and the emergence of persistent Mycobacterium tuberculosis (multidrug-resistant tuberculosis MDR and extensively drug-resistant tuberculosis XDR) have made the search for new drugs and alternative natural remedies imperative.
Medicinal plants and herbs serve as leads for new drugs, holding potential for exploitation. In particular, bitter leaf, bitter kola, Picralina nitida, Mitracapus villosus and Securidaca longipedunculata have been used in the treatment of TB infection in traditional folklore medicine.
Commonly referred to as ‘abeere’ in Yoruba and ‘Osi-Igwe’ in Igbo, Picralina nitida is used in traditional medicine for the treatment and management of malaria, abscesses, hepatitis, pneumonia, diabetes, hypertension, malaria, pneumonia, and other chest conditions. The seeds, which are usually hard, are usually ground to a fine powder and added to foods such as ‘ogi’ (pap) or taken as an infusion. Some take it with water, while others soak the seeds or its powder in coconut water and drink.
The leaves of Mitracarpus villosus are widely used in West African traditional medicine for the management of toothaches, amenorrhoea, dyspepsia, hepatic diseases, venereal diseases, sore throats, skin diseases, wound dressing, leprosy, as well as neurological disorders such as headaches. It is called ‘obuobwa’ in Igbo, ‘irawo ile’ in Yoruba, and ‘gogamasu’ in Hausa.
Securidaca longipedunculata, commonly called violet tree, is used in traditional medicine for treating sexually transmitted infections, hernias, coughs, fever, ascariasis, constipation, headaches, rheumatism, stomach aches, tuberculosis, pain, epilepsy, pneumonia, and skin infections. It is locally known as ‘Uwar magunguna’ (Hausa), ‘ezeogwu’ (Igbo), and ‘Ipeta’ (Yoruba).
More importantly, experts’ assessments of these medicinal plants, particularly against persistent TB-causing germs, found bitter kola and bitter leaf to have better potency in boosting the effectiveness of Rifampicin, one of the antibiotics used for treating TB.
Bitter leaf and bitter kola in a suitable ratio exert synergistic anti-tubercular activity and interact with Rifampicin to inhibit resistant tubercular bacilli growth.
The synergistic ratios of bitter leaf and bitter kola of 1:1, 2:1, 4:1, and 8:1 produced enhanced activity. In fact, high concentrations of these plants in the blood interacted with Rifampicin to exhibit anti-tubercular activity in a resistant strain of the disease-causing germ.
This 2023 study in the International Journal of Pharmaceutical Sciences and Research involved researchers at Nnamdi Azikiwe University in Awka, Anambra State and the University of Nigeria, Enugu Campus in Enugu State.
For the study, the researchers collected bitter kola seeds, Picralina nitida fruits, bitter leaves, the whole plant of Mitracapus villosus, and the bark and roots of Securidaca longipeduculata, and their chemical constituents were extracted with ethanol.
Different concentrations of the extracts were made and given alongside rifampicin to two groups of albino Wistar rats. It included males and non-pregnant females, with three animals per group weighing between 126 and 134 grammes.
Blood samples were collected from the animals in each group at different times after treatment with the extracts and rifampicin and tested on eggs of the persistent TB strain.
While the extract of bitter kola and bitter leaf and Mitracarpus villosus displayed the ability to inhibit the growth of tuberculosis in a dose- and time-dependent manner, other herbs like Picralina nitida and Securidaca longipedunculata did not show activity against M. tuberculosis.
Interestingly, these two most promising herbs with the highest anti-tubercular activity (bitter kola and bitter leaf) are commonly used among many tribes in the south-eastern part of Nigeria as hospitality edibles and in the preparation of a local delicacy, “bitter leaf soup”.
A preliminary study done with the two plants on conventional bacteria showed that the two plants’ extracts exhibited synergism and provided a broad spectrum of antibacterial coverage for many diseases, including the treatment of pneumonia-like infection caused by Streptoccocus pneumonae.
However, the hybrid mix can be formulated into a palatable liquid dosage drink that can be taken with conventional anti-tubercular drugs like Rifampicin for the treatment of resistant tuberculosis infections.
According to the researchers, the bitter leaf and bitter kola extracts can be formulated into a palatable liquid dosage drink that can be taken with conventional anti-tubercular drugs like Rifampicin for the treatment of resistant tuberculosis infections.
“By presenting the preparation as a nutriceutical liquid drink, it will definitely entice the patient and encourage compliance. Such a nutriceutical drink being able to boost the action of conventional tuberculosis medication will be an added advantage,” they stated.
According to them, using the liquid drink hybrid with conventional tuberculosis medication will provide multiple drug options in the treatment of tuberculosis infections to limit or prevent resistant development.
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