1. Introduction

Tamarindus indica L. or tamarind as it is commonly known, is a medium-sized tree that belongs to the Caesalpinaceae family. It is a multipurpose tropical tree used primarily for its fruits, which are eaten fresh or processed. The fruit is also used as a seasoning or spice and make medicinal beverages [2]. In fact, Tamarind fruits are the most studied and valuable medicinal part of the plant, which has often been reported as curative in several pharmacopoeias [3]. This millenary tree has been taken into consideration from ancient times; documented evidence about its cultivation appear in Egypt around 400 BC, and it is mentioned in the Indian Brahma Samhita Scripture between 1200-200 BC. Also about 370-287 BC Theophrastus wrote on plants and two descriptions refer to tamarind, even though not by name [4].

Tamarindus indica L is probably indigenous to tropical Africa, [5] but has been cultivated for so long on the Indian subcontinent that it is sometimes also reported to be indigenous there [6]. It grows wild in Africa in locales as diverse as Sudan, Cameroon, Nigeria and Tanzania [7]. In Arabia, it is found growing wild in Oman, especially in Dhofar, where it grows on the sea-facing slopes of mountains. It reached South Asia likely through human transportation and cultivation several thousand years prior to the Common Era. [8, 9]. It is widely distributed throughout the tropical belt, from Africa to South Asia, Northern Australia, and throughout Oceania, Southeast Asia, Taiwan and China [10].

In the 16th century, it was heavily introduced to Mexico, and to a lesser degree to South America, by Spanish and Portuguese colonists, to the degree that it became a staple ingredient in the region's cuisine. [11]. Today, India is the largest producer of tamarind. [12] The consumption of tamarind is widespread due to its central role in the cuisines of the Indian subcontinent, South East Asia and the Americas, particularly in Mexico.

Thai traditional medicine recognizes T. indica fruit as digestive, carminative, laxative, expectorant and blood tonic [13]. Many other properties have been also reported like hypolipemic and antioxidant [14], anti-inflammatory [15], antimicrobial [16], cytotoxic [17], against gastrointestinal spasms [17] and modifying the complement system [18].

These extraordinary properties of tamarind fruits along with the interest on the polysaccharide and antioxidant seed compounds, keep the attention of the scientific community on the tamarind tree, leaving relegated to a secondary level the other parts of the plant.

On the other hand, tamarind leaves retain a more empiric use. Like the fruit, tamarind leaves are also edible and are used to make curries, salads, stews and soups in many countries, but especially in times of scarcity, even when their protein ratios (4,0-5,8%) [9] are not too far from those reported for fruits (2,0-7,1%) [19]. In fact, most of the chemical studies of tamarind leaves are focused on their edible properties, with flavonoid compounds as the only exception, which have been reported with certain frequency [20, 21]. Other classes of compounds reported are the triterpenoids lupanone and lupeol [22], and some essential oils with benzyl benzoate and limonene as major compounds [23].

In recent years, the description of the pharmacological potential of tamarind leaves is coming out. The hepatoprotective and the antimicrobial activity look like the most prominent activities, both associated with flavonoid and/or phenol presence. Owing to the relative poor knowledge about the chemical composition of tamarind leaves, no specific association compound/activity is suggested, giving rise to this investigation in which an exploration of the phytochemical analysis is proposed.

2. Material and Methods

Plant material:

Tamarind leaves were collected in May 2016 from a Tamarind tree in Black Bush Polder, Region 6, Guyana. The collected leaves were shadow dried and then powdered by using Thomas-Wiley Laboratory Mill Model 4 at Central Chemistry Laboratory, Department of Chemistry, Faculty of Natural Science, University of Guyana, Turkeyen Campus. The powdered samples (100g) were stored in airtight brown coloured bottles in dry conditions throughout the experiments.

Phytochemical analysis:

The preliminary phytochemical analysis of leaf extracts of Tamarindus indica were performed by [24] were evaluated for the presence of phytochemicals such as alkaloids, flavonoids, saponins, phenols, steroids, tannins, triterpenoids, glycosides, carbohydrates, phlobatannins, thiols, anthroquinone, protein and amino acids, resins, fixed oils & fats and phytosterols. The qualitative determination of these secondary metabolites was carried out by standard methods [25]. Chromatographic study of the different extracts was also done using standard methods [26].

Heavy metals and N.P.K. analysis:

Crude leaves powder was used in Gas Chromatography/ Mass Spectrometry (GC/MS) to analyse heavy metals such as Zn, Cu, Ni, Mn, Fe, Ca, and Mg at acceptable levels. The Nitrogen (N), Phosphorous (P) quantitative test was done by total Kjeldal digests by UV-VIS spectrophotometry and Potassium (K) in Kjeldhal digest by Flame photometry method at Central Agricultural Laboratory, Guyana Sugar Corporation Inc. La Bonne Intention (LBI), Guyana.

3. Result and Discussion

Qualitative estimation of phytochemicals was performed in leaves of T. indica. The results were tabled and represented as ‘+’ for presence and ‘–‘ for absence of the phytochemicals in Table 1. Quantitative analysis was done to determine in the presence of heavy metals in leaves of T. indica by using Gas Chromatography/Mass Spectrometry (GC/MS). Heavy metals estimated in mg per kg in Table 2, and analysis N.P.K in % Table in 3.

Table 1. Phytochemical analysis in the leaves of T. indica

Qualitative estimation of phytochemicals in leaves of T. Indica shows that Alkaloids, Flavonoids, Tannins, Aminoacids, Carbohydrates, Phenols, Triterpenoids, Saponins, Resins and Phytosterols are present, whereas Thiols, Glycosides, Fixed oils, fats, Steroids, Phlobatannins and Anthroquinone phytochemicals are absent.

Table 2. Heavy metal analysis in Tamarind (T. indica) leaves in mg/ kg

Heavy metal analysis was done in leaves of T. indica by using Gas Chromatography/Mass Spectrometry (GC/MS). It shows the highest amounts was that of Mg (347 .80 mg/kg), followed by Fe (228.69mg/kg), whereas the least amount was that of Cu (3.59 mg/kg). GC/MS did not detect Ni.

Table 3. N.P. K. analysis in Tamarind (T. indica) leaves in percentage (%)

N.P.K. analysis shows the highest percentage was that of nitrogen in T. Indica leaves, followed by potassium; the least percentage of Phosphorus.

4. Conclusions

The antioxidant and antimicrobial activity of T. indica leaves has been reported worldwide, but it has not been possible to establish a relationship with the chemical composition due to the scarcity information availed. In this study, we detected seven components of heavy metals not previously reported, and confirmed the high Mg and Fe presence in T. indica leaves. In addition high percentage of nitrogen and some useful phytochemcials are available in T. indica leaves. This information give light to the present intention to find chemical proof that supports the pharmacological activities of T. indica leaves.

ACKNOWLEDGMENTS

The authors wish to thank Guyana Sugar Corporation Inc. LBI, Guyana, for allowing the use of research station facilities for the analysis of heavy metals, and N.P.K.