Therapeutic significance and pharmacological activities of antidiarrheal medicinal plants mention in Ayurveda: A review.

Diarrhea is a serious problem affecting 3-5 billion people per year around the world, especially children of below 5 years. 70% of the world population uses traditional and indigenous medicine for their primary health care. The facts of these indigenous remedies are passed verbally and sometimes as documents. Since ancient time, Ayurveda is the main system of healing in South East Asian countries. Indian literature from ayurvedic texts and other books claim the potency of several plants in the treatment of diarrhea. As the global prospective of ayurvedic medicine is increasing, interest regarding the scientific basis of their action is parallely increasing. Researchers are doing experiments to establish the relation between the claimed action and observed pharmacological activities. In the present article, an attempt was made to compile the scientific basis of medicinal plants used to cure diarrhea in Ayurveda. Literature was collected via electronic search (PubMed, ScienceDirect, Medline, and Google Scholar) from published articles that reports antidiarrheal activity of plants that were mentioned in Ayurveda classics. A total of 109 plant species belonging to 58 families were reported for their antidiarrheal activity. Several Indian medicinal plants have demonstrated promising antidiarrheal effects, but the studies on the antidiarrheal potentials of these plants are not taken beyond proof of concept stage. It is hoped that the article would stimulate future clinical studies because of the paucity of knowledge in this area.

INTRODUCTION

Gastroenteritis is a clinico-pathological term that refers to inflammation and oxidative stress of the intestines which leads to disturbance in the balance of secretory and absorptive function of the intestines resulting in diarrhea [1,2]. Hence, diarrhea can be defined as a gastrointestinal disorder in which there is a rapid transit of gastric contents through the intestine, which is characterized by abnormal fluidity and high frequency of fecal evacuation, usually semisolid or watery fecal matter, three or more times/day [1-3]. There is an increase in flow rate of feces with or without the presence of blood and mucus, accompanied by increased secretion and decreased absorption of fluid, leading to loss of water and electrolytes [2,4]. The major causative agents of diarrhea in human beings include a variety of enteric pathogenic bacteria such as Salmonella typhi, Shigella flexneri, Escherichia coli, Staphylococcus aureus, Vibrio cholerae, and Candida albicans [4,5]. Viruses, protozoans, helminths, intestinal disorders, immunological factor, and medications can also cause diarrhea in human being [6-8]. Etiological factors for diarrhea include the food intolerances, contaminated drinking water, undercooked meat and eggs, inadequate kitchen hygiene, poor sanitation [9], bile salts, hormones, irritable bowel syndrome, and intoxication [10]. According to the World Health Organization (WHO), diarrhea affects 3-5 billion people/year worldwide and causes 5 million deaths per annum [11]. Children, however, are more susceptible to the disease, which is the one of the leading causes of death in infants and children below 5 years of age [12].

Due to high mortality and morbidity, especially in children, the WHO together with the United Nations Children’s Fund has initiated Diarrhea Disease Control Program to control diarrhea in developing countries. Oral rehydration solution [13], zinc solution [14], probiotics [15], and specific antibiotics have reduced mortality rate in diarrheal disease. However, chronic diarrhea is still a life challenging problem in some regions of the world. Unfortunately, the program does not reach to the needy, and the disease is still a major challenge in front of primary health practitioner as well as researcher. Therefore, the different traditional systems of medicines such as Chinese medicine [16], Japanese medicine [17], acupuncture therapy [18], and ayurvedic medicine [19] are included in this program.

Since ancient time’s medicinal plants have been used to treat different ailments due to their accessibility, availability, inherited practice, economic feasibility, and perceived efficacy [20]. Nowadays, use of medicines from plant source increases significantly with conventional therapies. Hence, the plants are gaining more attention by the researchers to find out new and effective agents for different diseases. Several medicinal plants in the different regions of the world have been used to cure diarrhea [19,21].

The knowledge of indigenous medicines is passing from generation to generation orally worldwide [22]. It is, therefore, documentation of such knowledge as well as reported the scientific basis of their pharmacological potential is necessary since they are usually consider as free from adverse effects. A range of medicinal plants were reported for their effectiveness in diarrhea [23-27]. The protective role of these plants is probably due to their anti-inflammatory, antioxidant, and astringent properties [28]. India has a rich plant resources providing valuable medicine, which are conveniently used in Ayurveda, Unani, and other system of medicines for the treatment of various diseases [29]. Keeping this in view, the present article was initiated, with an aim to compile the scientific basis of medicinal plants used to cure diarrhea. A variety of curative agents from these indigenous plants has been isolated. These isolated compounds are belonging to different phytochemical classes such as flavonoids, saponins, terpenoids, steroids, phenolic compounds, and alkaloids [30-32]. Flavonoids and saponins inhibit the release of prostaglandins, autocoids, and contractions caused by spasmogens as well as motility and hydroelectrolytic secretions [33,34] while saponins may prevent release of histamine [35]. Polyphenols and tannins provide strength to intestinal mucosa, decrease intestinal secretion, intestinal transit and promotes balance in water transport across the mucosal cells [36].

Previously, we enumerated a large number of plants, which are used in the ayurvedic system as antidiarrheal [19]. A majority of these plants have been investigated pharmacologically with respect to the potential antidiarrheal activity. In this review, we present ethnopharmacological data of 109 plant species belonging to 58 families mentioned in ayurvedic texts for controlling diarrhea with their possible mechanism of action [Table 1 and Figure 1]. Mostly, leaf (23%), root (14%), barks (11%), fruit (9%), and seed (8%) of the plants are used for antidiarrheal activity [Figure 2].

Table 1

Antidiarrheal medicinal plants

Figure 1

Antidiarrheal medicinal plants

Figure 2

Distribution of plant parts investigated for antidiarrheal activity

DISCUSSION

Since ages, human beings have relied on plants as a resource of the therapeutic arsenal in the fight against certain human diseases. Plant-based drugs have formed the basis of traditional medicine systems, i.e., Ayurveda, Siddha, Unani, Homeopathy, and Chinese. Herbal-based therapy is one of the popular and effective practices to overcome the illness. The WHO also promotes utilization of local knowledge of plant-based medicines in health care. It has been reported by the WHO that about 70-80% of the population in developing countries relies on traditional/ethno medicines/for their primary health care. Since ancient time ayurvedic system of medicine is indigenous to and widely practiced in India. Nature has bestowed India with an enormous wealth of medicinal plants. Therefore, their rational uses for combating diseases are described traditionally.

Acharya charaka has mentioned a group of antidiarrheal plants named as Purish-Samgarahaniya Mahakashaya, which includes priyangu (Callicarpa macrophylla), ananta (Hemidesmus indicus R.B.), seed of amra (Mangifera indica), katvanga (Ailanthus excelsa Roxb.), lodhra (Symplocos racemosa), mocharasa (Salmalia malabarica Schott and Endl.), samanga – Rubia cordifolia, flower of dhataki – Woodfordia fruticosa, padma – lotus (Nelumbo nucifera), and filaments of padma – lotus (N. nucifera). Moreover, he also listed some most useful antidiarrheal plants such as katavanga (A. excelsa Roxb.), mustaka (Cyperus rotundus Linn.), amrita (Tinospora cordifolia [Willd.] Miers ex Hook. f. & Thoms.), ativisha (Aconitum heterophyllum Wall. ex. Royle.), bilva (Aegle marmelos Correa), kumuda (N.nucifera Gaertn.), utpala, padma, kutaja bark (Holarrhena antidysenterica [Linn.] Wall.), gambhari fruit (Gmelina arborea Roxb.), prishniparni (Uraria picta [Jacq.] Desv. Ex DC.), and bala (Sida cordifolia) [187]. In addition, Acharya Susuruta mentioned that the vacha (Acorus calamus Linn.) and haridra (Curcuma longa Linn.), etc., are best for amatisara (diarrhea where undigested food matter pass in stool) while ambastha (Cissampelos pareira Linn.) and priyangu (C. macrophylla) are best for pakwatisara (diarrhea where only digested food matter pass in stool) [188].

The ayurvedic Pharmacopoeia mentioned more than 1200 species of plants, nearly 100 minerals and over 100 animal products officially. Although there is no record of pharmacological testing during the period when ayurvedic texts were written. However, nowadays, extensive researches are carried out concerning the phytopharmacological basis of their therapeutic principles. Public, academic as well as government organizations are showing interest in the scientific mechanism of action exerted by these plants. Similar to modern and other traditional medicines, ayurvedic medicines have been also evaluated for their phytopharmacology with the help of advances in science and technology. Scientific screening on laboratory animal and in vitro evaluations supports traditional uses of medicinal plants.

In the present scenario, modern pharmaceuticals offer a number of medicines for diarrhea, but diarrhea still remains a major health threat to the people in tropical and subtropical countries. It is one of the leading causes of mortality in children especially under the age of 5 years [12]. Different factors such as infections, malnutrition, food intolerances, intestinal disorders, and some medications may trigger diarrhea [6-8]. Currently, available pharmacological treatments are seem to be insufficient in diarrhea control. It is because of lack of admittance, high cost, and adverse effects of modern pharmaceuticals as well as therapeutic approaches. Therefore, investigations on drugs from different alternative and complementary medicines along with traditional system of medicines were going on.

Many phytoconstituents such as lupinifolin isolated from Eriosema chinense, -omoneukanrin B, dimethoxyflavone isolated from the stem bark of Stereospermum kunthianum, 6-(4-hydroxy-3-methoxyphenyl)-hexanonic acid, isovanillin, iso-acetovanillon from Pycnocycla spinosa Decne. Ex Boiss., have been evaluated for anti-diarrheal activity. However, in the mentioned list of ayurvedic plants limited isolation of the active constituents have been done which accounts for the numerous scope in this area for analytical, pharmacognostical as well as pharmacological screening of the active principles from these plants. Some of the constituents such as kurryam, koenimbine, koenine, piperine, and berberine are mentioned in the list with reported antidiarrheal activity [189-192].

Newer technologies such as in-silico, docking studies, interaction with enterotoxin from causative oraganism and nanotechnology were also employed in the antidiarrheal agent research works [193,194]. However, unfortunately, such advanced techniques were not used for the above listed ayurvedic plants. However, a few clinical trials reveal that the plants acts via a number of mechanisms, i.e., anti-inflammatory, antisecretory antimicrobial effect against V. cholerae and enterotoxigenic E. coli, rotavirus, detoxification of toxins and constipate, adsorbent, providing a rich source of calories; antimotility and antispasmodics effects [195].

CONCLUSION

The ethnomedicinal approach for diarrhea is a practical, cost-effective, and a logical for its treatment. Present data show that only a few isolated compounds from plants were investigated for antidiarrheal potential. Therefore, a significant research of chemical and biological properties of such less explored plants is still needed to determine their antidiarrheal efficacy which will possibly define their exact mechanism of actions.