Medicinal Plants of the Indigenous Tribes in Peninsular Malaysia: Current and Future Perspectives Medicinal Plants of the Indigenous Tribes in Peninsular Malaysia: Current and Future Perspectives

The main aim of this paper is to compile information on plant that is known to be medici- nal to the indigenous tribes in Peninsular Malaysia. Information is compiled from vari-ous sources. Current trends on studies of medicinal plants of the indigenous tribes and threats to the sustainability of the plants are also discussed. Focus of future studies on medicinal plants utilized by the indigenous tribes will also be discussed.


Introduction
The indigenous tribes in Peninsular Malaysia are collectively known as the Orang Asli. The Orang Asli consists of 18 subethnic groups or tribes which anthropologists and administrators grouped into the Semang (Negrito), Senoi, and aboriginal Malay (proto-Malay). Documentation on the plant resources, particularly medicinal plants, utilized by the people is still far from complete as most of the villages of the tribes have not been studied. Documentation on traditional uses of medicinal plants is important because it helps to preserve traditional culture of indigenous tribes, provide leads to the discovery medicinal compounds, and find ways to conserve the medicinal plants.
The main aims of this paper are to compile information on medicinal plants of the indigenous tribes in Peninsular Malaysia based on previous studies and to provide direction for future studies on the medicinal plants of the indigenous tribes.

List of medicinal plants of the indigenous tribes in Peninsular Malaysia
Two hundred and thirteen species of plants ( Table 1) have been reported as medicinal to the indigenous tribes in Peninsular Malaysia. The medicinal plants were based on uses by the tribes Jah Hut, Semai, Semang and Temuan. Information on the plants is compiled from Refs. [1][2][3][4][5][6][7][8]. Leaves and roots are the most common parts that have medicinal uses. Destructive harvest, i.e., those that involve the removal of barks, roots, or whole plants, is among the most susceptible to overharvest because of destruction of the entire plants [9].

Current approaches of research on medicinal plants of indigenous tribes in Peninsular Malaysia
The most common approach to illicit information on the medicinal plants of the indigenous tribes is through semistructure interviews with traditional medicine practitioners known as batin. Two issues that have not been adequately addressed in previous studies are the veracity of information obtained from such approach and the extent of use or usage of medicinal by the indigenous tribes.
The veracity of information on medicinal properties plants utilized by the indigenous tribes in Peninsular Malaysia can be verified by laboratory analysis of bioactive compounds extracted from the plants. Several such studies have already been carried on some of the species that are listed in Table 1. Mohd Zin et al. [10] had carried out antioxidative activity of extracts from Morinda citrifolia L. and had concluded that active compounds in root of the plant might be both polar and nonpolar in nature, whereas compounds that contribute to antioxidative activity of both its leaf and fruit are probably nonpolar in nature. Hakimi Wan Salleh et al. [11] studied the chemical compositions and antioxidant and antimicrobial activities of essential oils of Piper caninum Blume. Safrole, β-caryophyllene, β-pinene, and germacrene D were the main components from the leave and stem oil of the plant. They noted that the highest activity was observed for inhibition of lipid peroxidation in the β-carotene/ linoleic acid system by the stem oil and the essential oil showed strong antimicrobial activity. Ang et al. [12] studied that aphrodisiac property of Eurycoma longifolia Jack has been studied by examining the effects of E. longifolia Jack on sexual qualities in middle-aged male rats. They demonstrated that E. longifolia Jack enhanced the sexual qualities of the middle-aged male rats. Bhat and Karim [13] reviewed the ethnobotany and pharmacological importance and E. longifolia Jack and noted that the plant possesses adequate therapeutic potential and could be explored further for commercial purposes and could be designated as a "wonder drug plant." Information on usages of medicinal plants by the indigenous tribes was very limited in previous reports, thus making the assessment of this aspect of traditional culture practice difficult. Persistent usage of the medicinal plants by the tribes is important to ensure that the knowledge on the medicinal uses of plants is conserved and subsequently should contribute to the conservation of the plants. This is of concern because as modernization moves toward the

Indigenous tribe(s) [plant part(s) used]
Sources of information  [7] doorstep of the indigenous tribes, knowledge and usage of biodiversity decrease and eventually become adulterated or lost to humanity [4].

Future studies on medicinal plants of indigenous tribes in Peninsular Malaysia
Future studies on medicinal plants should be extended to more villages of the indigenous tribes in Peninsular Malaysia. The studies should include aspects that have not been adequately addressed in the previous studies. Other aspects that can be included in future studies are the use of geographical information system to analyze the spatial trend on medicinal plants of the indigenous tribes and also the development of automated identification system for medicinal plant species.
Geographic information systems (GIS) have not been used in any studies on the medicinal plants in Peninsular Malaysia, although the use of GIS for conserving medicinal and herbal plants elsewhere has been reported [14][15][16][17]. GIS application together with remote sensing data could be used for comprehensive vegetation mapping and analysis of data attained from ground surveys. In terms of mapping medicinal plants, remote sensing data can be useful to obtain information on land usage or coverage, vegetation, terrain attributes, distribution, and accessibility to area. Besides this, GIS could be used to produce map layers and to develop

No. Species Indigenous tribe(s) [plant part(s) used] Sources of information
comprehensive databases on physical, biological, and environmental parameters which govern the spatial distribution and abundance of medicinal plants.
Serious consideration should be given to the use of machine learning for rapid identification of medicinal plants, especially those utilized by the indigenous tribes in Peninsular Malaysia. As medicinal plants utilized by most of the indigenous tribes have not been studied, these techniques will facilitate urgent documentation of the plants which are needed for their conservation. Machine learning methods such as artificial neural networks (ANN) and support vector machine (SVM) have been used to develop automated plant species identification despite the claims that leaf morphology is not a reliable indicator in identifying tree species. ANN is a mathematical model composed of many processing units that communicate by interconnected variables. It is trained using data for which the classes are known, followed by being used for class prediction of unidentified data. Multilayer structure of ANN enables learning from complex input image features and generates single output. Support vector machine (SVM) is a supervised learning method proposed by Cortes and Vapnik [18], generating hyperplanes for classification, based on statistical learning theory and structural risk minimization. The boundary of hyperplanes separates the sample data mapped in space, clearly dividing them into categories. New data will be predicted to belong to a category by the hyperplanes.
Studies conducted by Clark et al. [19] applied ANN to extract features from species of the genus Tilia and achieved 44% accuracy rate. Kumar et al. [20] developed a "Leafsnap," a computerized system that searches on database for species matching and retrieval. Hearn [21] used a combination of Fourier analysis and Procrustes analysis (a simple shape registration method, based on rotation, translation, and scaling) to perform species identification using a large database of 2420 leaves from 151 different species.