**3.14. Meliaceae –** *Azadirachta indica* **A. Juss.**

The neem tree *A. indica* is originally from the Asian subcontinent and is now grown in various tropical and semi-tropical regions. The bitter-tasting shoots and flowers are incorporated into various dishes, while preparations from leaves, bark, and fruits are consumed during many Hindu ceremonies, festivals, and commemorations.

*A. indica* leaves and seeds contain potent antiparasitic, insecticidal, and antimicrobial compounds such as the limonoids azadirachtin and nimbinin [167]. For this reason, dried neem leaves are placed in cupboards and storage facilities for grains to prevent damage from insects and burned to keep away mosquitoes, while the seed oil is used as a key ingredient of nonsynthetic ecofriendly pesticides in agriculture, acting as an antifeedant, repellent, and egglaying deterrent for insects [168]. The seed cake that remains after oil extraction is used as a fertilizer, enriching the soil with organic matter, and at the same time reducing nitrogen loss by inhibiting nitrification and averting damage to crops by termites and nematodes [168]. Neem oil is also a valuable ingredient of a large variety of cosmetics such as soaps, shampoos, balms, creams as well as toothpastes and nail polishes [169].

Parts of *A. indica* have been used for centuries in traditional and alternative medicinal systems in India and Suriname against a wide variety of diseases ranging from microbial infections and malaria to diabetes mellitus and hypertension [45, 170]. Some of these applications are supported by the results from pharmacological studies and may be related to the actions of, among others, azadirachtin and nimbinin [167, 171].

Indications for efficacy against hypertension of *A. bilimbi* came from the decreased contractility of isolated guinea pig atria precontracted with norepinephrine upon exposure to an aqueous extract from the leaves [180]. Such an extract also produced a substantial antihypertensive effect in an *in vivo* study with cats [181]. The mechanisms underlying these observations may be associated with a decrease in cardiac output following alterations in intracellular calcium metabolism and/or phenomena involving the muscarinic receptor [180]. It is also possible that the relatively high levels of oxalate in these preparations [176] promote diuresis. A third possible mechanism involves inhibition of ACE activity, as suggested by the *in vitro* ACE-inhibitory effect of an *A. bilimbi* leaf ethanol extract which was comparable to

Plant-Based Ethnopharmacological Remedies for Hypertension in Suriname

http://dx.doi.org/10.5772/intechopen.72106

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**Figure 8.** Oxalidaceae – *Averrhoa bilimbi* L. (from: https://goo.gl/images/THfTgV).

This chapter has addressed the plants that are used in Suriname for treating hypertension. About 60 of the approximately 800 medicinal plants in Suriname are used against this condition ([45–55]; **Table 1**), indicating both the high need of antihypertensive medications and the high demand for traditional plant-derived for treating this condition in the country. As mentioned above, the prevalence of hypertension and other cardiovascular diseases is relatively high in Suriname [32, 36, 37], while most Surinamese have a long tradition of using

However, an extensive evaluation of 15 plants that are commonly used against hypertension in Suriname indicates that there is little scientific evidence for clinical efficacy against this condition. As shown in **Table 2**, 3 of the 15 plants (*A. graveolens*, *C. nucifera*, and *C. sativus*) had undergone preclinical as well as clinical evaluation against hypertension and turned out positive in at least some of the clinical studies. However, the clinical studies merely comprised a handful, although those with 3-n-butylphthalide in *A. graveolens* were sufficiently encourag-

ethnopharmacological preparations for treating their diseases [21, 44].

ing to prepare larger scale clinical evaluations [90–92].

that of captopril [182].

**4. Concluding remarks**

Indications for a potential antihypertensive effect of *A. indica* preparations were provided by the inhibitory effect of *A. indica* yogurt on ACE activity *in vitro* [172], and the blood pressurelowering effect of leaf extracts in (salt-induced) rat models [173, 174]. Studies with laboratory rabbits suggested that these effects might also be due to vasodilation mediated through a combination of Ca2+ channel blockade, NO-inhibitory mechanisms, and cardiac depressant activity [175].
