About 80% of people living in developing countries practice traditional medicine as an alternative therapy for their health care. Specifically, the use of medicinal plants in therapy (defined as any plant species that can be used for therapeutic purposes due to its composition or whose active ingredients can serve as precursors for the synthesis of new drugs), also known as phytotherapy, is quite widespread worldwide. It is worth noting that around 67% of the species used in these types of therapies come from least developed and developing countries.^1-6

Traditional medicine is based on folk knowledge, which determines its efficacy through observable benefits. This type of medication may pose challenges; for example, in popular phytotherapy, it is very difficult to control the dose and quality of the product, which can lead to risks and damage to health. This problem is mainly explained by the fact that many traditional remedies are made from wild plants whose chemical components can vary due to genetic or environmental reasons.^7,8 It should be noted that ethnobotany has no scientific validation.^9-10

The traditional use of medicinal plants to treat both infectious and non-infectious diseases has been widely accepted since ancient times due to their low cost, accessibility, and low toxicity rates compared to synthetic products.¹¹,¹³ Humans commonly resort to this therapeutic option in the presence of skin irritations, wounds, insect bites, and snake bites.^14,15

Currently, there is an exponential increase in the use of phytotherapy to maintain an adequate state of general health. In this regard, the World Health Organization (WHO) states that more than two thirds of the world's population use or have used at least one medicinal plant to treat some condition.⁴

Chronic non-communicable diseases are a new challenge in the fight to improve global health and are a public health concern despite the progress made by the pharmaceutical industry. Moreover, it should be noted that some populations do not have easy access to medicines and medicinal plants are their first, or even only, treatment option.

In this context, a relevant example of the use of phytotherapy is chaya (Cnidoscolus aconitifolius), a plant of the genus Cnidoscolus that belongs to the family Euphorbiacea, which has been attributed different benefits forthe treatment and control of certain pathologies. The family Euphorbiacea comprises 50 species, of which 20 are considered endemic to Mexico and are distributed mainly in tropical and subtropical zones, Mesoamerica being the area where they are most produced and where their domestication is most frequent.^17-19

Hypoglycemic,²⁰ antioxidant,²¹ analgesic and anti-inflammatory effects^22,24 are the main benefits attributed to chaya. It is commonly used to treat rheumatism, gastrointestinal disorders²⁵ and inflammatory diseases,^26,27 and it has also been reported that it has an important nutritional contribution as poultry feed, especially in Africa.²⁸ In recent years, to measure its efficacy and safety, various investigations have analyzed the components of this plant, the leaves being the most studied part.^29,30

The objective of this research was to review the available literature on the main medical uses and phytochemical components of C. aconitifolius to answer the question:

Is there sufficient scientific evidence on the therapeutic properties of chaya to treat human pathologies?

A literature review on C. aconitifolius was conducted in the BIREME, PubMed/Medline, Elsevier and SciELO databases with the descriptors "Cnidoscolus" and "aconitifolius". The search was limited to articles published until 2017; no articles were excluded because of language restrictions or methodological reasons.

Thirty-three research articles were included and classified according to the year of publication as shown in Figure 3. The largest number of articles about C. aconitifolius were published in 2010 and 2016 (8 each year).

Figure 3 Source: Own elaboration.

By refining the articles and eliminating duplicates, a final sample of 18 articles was obtained with which the constituents (Table 2) and the final analysis of the data was carried out. The publications were organized according to the main phytochemical medicinal properties of C. aconitifolius (Table 3).

Table 2

Authors Year	Type of study	Part of the plant studied	Phytochemical constituents
Donkoh et al.28 1990	Phytochemical study of the dry leaf	Leaves	High dietary protein potential for animals and toxic hydrocyanic glycosides that are degraded by cooking.
Sarmiento-Franco et al.29 2003	Phytochemical study	Leaves	Raw fiber (140 g/kg), protein (305 g/kg), calcium (15.3 g/ kg) and seven amino acids: alanine, arginine, aspartic acid, glutamic acid, leucine, isoleucine, and phenylalanine.
EscaIante-Erosa et al.30 2004	Epicuticular wax study	Tall l eaves	Three triterpenoids: amirenone, B-amyrin acetate, and a-amyrin acetate.
Numa et al.31 2015	Phytochemical study	Leaves	FIavonoids (hispidulin sulfate, eucalyptin and epigallocatechin di-O-gallate), sesquiterpene (triptofordin D1), xanthones (moreolic acid), polyanxanthone c, cadensin g, arvixanthone d and lignan (tiegusanin f).
Oyagbemi et al.32 2011	Phytochemical screening	Leaves	FIavonoids, alkaloids, saponins, tannins, magnesium, manganese, iron, potassium, phosphate, and zinc.
Adaramoye et al.33 2011	Clinical study on protection from liver damage	Leaves	Tannins, alkaloids, saponins, anthraquinones, flavonoids, cardiac glycosides, and phlobatannins.
Jaramillo-Jaramillo et al.34 2015	Phytochemical study	Leaves of adult flowering plants	Fatty acids, triterpenes, and sugars.
Jiménez-Aguilar et al.35 2015	Phytochemical study	Dry leaves	Calcium, magnesium, potassium, phosphorus, sulfur, iron, sodium, vitamin C (more abundant than in other green plants), as well as phenolic compounds at high levels, and flavonoids at medium levels.
Morales-Aivarado et al.36 2016	Phytochemical study	Dehydrated leaves	Cyanogenic glycosides precursors of hydrocyanic acid, although it was proved to be easily eliminated by heat treatment.
Awoyinka et al.37 2007	Phytochemical study	Dry leaves	Alkaloids, tannins, phlobatannins, saponins, and cardiac glycosides.

Source: Own elaboration.

Table 3

Authors Year	MedicinaI potentiaI of the plant described	Animal model	Study element	Main efficacy results
Azeez et al.19 2010.	Antioxidant effect	25 male Wistar rats weighing from 100 to 250 grams	Leaves	C. aconitifolius improved the hematological parameters of alloxan-induced diabetes.
Saba et al.22 2010	Hepatoprotective and antioxidant effect	30 male Wistar rats weighing from 220 to 250 grams	Leaves	C. aconitifolius showed a significant restoration of hematological parameters and a decrease in blood ureic nitrogen and creatinine levels.
Oyagbemi et al.23 2010	Hepatoprotective effect against paracetamol damage	25 healthy male Wistar rats weighing from 220 to 250 grams	Leaf extract obtained from ethanol	C. aconitifolius had a hepatoprotective effect against paracetamol.
Onasanwo et al.24 2011	Analgesic and antiinflammatory effect	30 Sprague-Dawley rats/mice weighing from 140 to 160 grams.	Leaves	C. aconitifolius demonstrated significant anti-inflammatory and analgesic effects.
Adaramoye et al.33 2011	Stimulation of insulin secretion	6-week old male Wistar rats weighing from 170 to 180 grams	Leaves	C. aconitifolius showed hepatoprotective and antioxidant effects, as well as protection against ethanol-induced poisoning.
Jaramillo-Jaramilloet al.34 2015	Antioxidant effect	Male Wistar rats	Leaves	C. aconitifolius had an antioxidant effect but not a hypoglycemic effect.
Sarmiento-Franco et al.38 2002	Fattening effect on corn-fed chickens	Two-week old Hubbard chickens and day-old Ross chickens	Leaf flour	C. aconitifolius improved fattening of chickens on low-protein diets.
Oladeinde et al.39 2007	Hypoglycemic effect	4-8-week-old male mice weighing 25 grams	Leaves	C. aconitifolius stimulated dormant β cells to secrete insulin.
Adaramoye & Aluko40 2011	Nephro-protective effect of metanol extract against chronic etanol exposure.	42 male Wistar rats weighing from 170 to 180 grams	Leaf extract obtained from ethanol	C. aconitifolius had a nephroprotective effect against chronic ethanol exposure and reduced glucose, protein, gammaglutamyltransferase, and creatinine clearance levels.
Achi et al.41 2017	Hypoglycemic, Anticholesterolemic and antihypertriglyceridemic effect.	Albino and healthy male rats weighing 120 to 130 grams	Leaves	C. aconitifolius reduced blood glucose levels, increased weight and serum insulin level, and had a hypoglycemic, antihypercholesterolemic, insulin modulating and antihypertriglyceridemic action.

Source: Own elaboration.

According to the available evidence, there are several investigations on C. aconitifolius¹⁹,^22-24,28-41 that confirm that its use as a medicinal plant has some benefits in the treatment of several diseases or injuries^42,43. Therefore, further studies on the phytochemical properties and posible therapeutic uses of this plant should be conducted to identify new therapeutic alternatives for the treatment of different conditions ^24,37, which will undoubtedly improve the quality of life of communities where traditional medicine is the main form of medical therapy.

Aguilar et al.⁴⁴ state that C. aconitifolius, besides having medicinal properties, is used as a vegetable and as fodder, which coincides with what is reported by Ross-Ibarra & Molina-Cruz.⁴⁵ Furthermore, according to Parra-Tabla et al.,⁴⁶ this plant can be consumed at any time as long as it has not lost more than 50% of its leaves, which depends on the type of climate in which it develops.

Some studies ^22,23,33,40 describe the benefits of C. aconitifolius to treat hepatotoxicity and hematotoxicity since the plant components help reduce toxicity. Likewise, other works^39,41 have shown that chaya plays a key role in reducing high glucose levels in animal models.

It is worth mentioning that the results also show that C. aconitifolius has antioxidant^19,34,35 and antimicrobial^37,47 properties due to its secondary metabolites (flavonoids, tannins, saponins,^30-32 etc.).^48,49 Similarly, it was found that this plant contains phenolic components, which are the most abundant group of non-energy substances in foods of plant origin.⁵⁰

Other species in the genus Cnidoscolus also show health benefits.^42,43 For example, Poot-López et al.⁵¹ reported the diuretic and hypoglycemic effects of Cnidoscolus chayamansa. During this review, we also found that Donkoh et al.⁵² suggested the inclusion of chaya in the food industry as a potential ingredient for poultry diet. In the study by Saba et al.²² on the effects of C. aconitifolius leaf extract in rats with liver damage induced by carbon tetrachloride, it was found that the compounds of the plant restore the levels of hematological parameters, blood ureic nitrogen, and creatinine. Finally, Oyagbemi et al.,²³ In an analysis of the anti-diabetic properties of ethanolic extract of chaya made in male Wistar rats with alloxan-induced diabetes mellitus, showed that C. aconitifolius extract significantly reduces blood glucose and plasma cholesterol levels.

C. aconitifolius is a plant species that has a significant protein content and is rich in flavonoids, tannins, and saponins. These characteristics grant it hypoglycemic, hepatoprotective, nephroprotective, anti-inflammatory and antioxidant properties.

The safety and efficacy of the traditional therapeutic use of chaya is supported by scientific evidence. Therefore, further research should be carried out focusing on the identification of new phytochemical properties of this plant and, thus, establish therapeutic alternatives for different conditions.