**3.15. Oxalidaceae –** *Averrhoa bilimbi* **L.**

The bilimbi *A. bilimbi* (**Figure 8**) presumably originates from Indonesia. It has been introduced in several Southeast Asian countries, and has spread to Australia as well as the Caribbean, Central America, and South America. The fruits can be eaten raw with salt and spice, pickled to obtain sweet and sour side dishes, incorporated in certain dishes as a souring agent, made into jams, or squashed to obtain a cooling beverage. However, *A. bilimbi* fruits (as well as leaves) contain high levels of oxalate [176] which may cause tubular necrosis and acute kidney failure when the concentrated juice is drunk on a daily basis [177].

Parts of *A. bilimbi* have been important sources of medicines since antiquity. Decoctions, infusions, powders, and pastes have been used in several traditional medicinal systems including those in Suriname for preventing and treating many diseases such as skin eruptions, cough, cold, syphilis, diarrhea, obesity, diabetes mellitus, microbial infections, and hypertension [46, 178]. Physicochemical and pharmacological studies supported some of these uses [179].

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

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 that of captopril [182].
