CHEMICAL VARIATION OF FIVE NATURAL EXTRACTS BY NON-POLAR SOLVENT

Chemical compounds of wood preservation from plants vary and are not known specific to the species. Chemical analysis of plants is responsible to ensure active compound in natural extracts wood treatment. There are many sources of natural extracts found in Indonesia that were explored for wood preservatives chemicals. They are bark of acacia and alstonia, leaves of orthosiphon and azardirachta and Dioscorea tubers. The present study was aimed at investigating the variation of the chemical constituent of natural extracts material of wood preservative through GC-MS analysis. Five natural extract sources were acacia bark (Acacia spp.), pulai bark (Alstonia scholaris), kumis kucing leaves (Orthosiphon spp.), mimba leaves (Azardirachta indica), and gadung tubers (Dioscorea spp.). Two non-polar solvents, i.e., n-hexane and petroleum ether were used for five natural source extractions following ASTM soxhlet extraction. The research showed that triterpene and fatty acid derivatives were the major compounds present in five natural extracts. They were lupeol; 7,22-Ergostadienone; Lup-20(29)-en-3-one; Lup-20(29)-en-3-ol, acetate, (3.beta.)-; urs-12-en-3-one; ethanol,2,2-diethoxy-; stigmasta-5,22-dien-3-ol, acetate,(3.beta.)-; 5H-3,5a-Epoxynaphth(2,1-c)oxepin, dodecahydro-3,8,8,11a-tetramethyl-; linoleic acid; naphthalene, 1-methyl-. These compounds have been assigned as the possibly responsible to against termites or fungi.


INTRODUCTION
The new paradigm of wood preservation is related to the environmental safety. The use of synthetic preservative has long resulted in environs losses. Several synthetic chemicals have been banned recently for wood protection uses by the U.S. Environmental Protection Agency (EPA). Therefore, the search for natural, safe, friendly, and none non-polluting bioactive chemical compounds from plants as an alternative to synthetic preservative becomes essential (Hu et al. 2015).
Plant extract contains chemical constituent which has high potency for wood preservatives. Sources of plant extract are found many type such as leaves, barks, wood, tubers, seeds etc. The type of solvent to be used for plant extraction are found many type such as cold water, hot water, ethanol, benzene, ether and n-hexane. Many research have been conducted on natural plant extracts. Extractives of white mulberry heartwood were contained higher hydrocarbons, fatty acids, sterols, and phenols that were toxic against decay termites (Se Golpayegani et al. 2014). Fatty acid extracts from Acacia mollissima, Schinopsis lorentzii and Pinus brutia bark were indicated having an insecticide characteristic (Sen et al. 2017). The type of solvent has affected the extraction results and affected the resistance of termites (Kadir et al. 2015, Syofuna et al. 2012. N-hexane fraction from T. officinale leaves was detected and reported as antioxidant and antimicrobial (Ivanov et al. 2017). Prayitno et al. (2017) concluded that natural extracts have influenced the wood adhesion.
Acacia spp. belongs to the family Leguminosae and subfamily Mimosoideae. Acacia has been planted in more than eighty countries around the world and becomes prominent in tropical and subtropical regions of Asia, Africa, Central, and South America (Old et al. 2002). Extract of three species from Acacia leaf has po-tential in the development of natural food preservatives (Cock 2017). The heartwood of A. confusa possesses excellent decay resistance properties (Chen et al. 2013). A. mollissima bark extract could be used as alternative wood preservatives against Reticulitermes grassei termite (Tascioglu et al. 2012).
Orthosiphon plants are herbaceous shrubs from Lamiaceae family. Singh et al. (2015) reviewed that the plant has photochemical, pharmacological, and toxicological properties. Orthosiphon extracted with ethanol showed the highest efficiency to be anti-termite with mortality of termite 65% (Aziz et al. 2013).
Alstonia scholaris is tropical tree belongs to Apocynaceae family. A. scholaris stem bark has anti-inflammatory activity on methanolic extract (Subraya et al. 2012). Extract of A. scholaris leaf has exhibited the activity of causing mortality in termite (Ahmed et al. 2011). Padding application of A. scholaris extract on teakwood block test gives highest adhesion strength (Prayitno and Widyorini 2016).
Azadirachta indica is an evergreen tree native to Southeast Asia. The tree belongs to Meliaceae family and has commercial name neem tree. It has been used medicinally for centuries because of its bioactive compounds. A. indica bark extracts could be employed to control fungal stains and molds on easily attacked freshly harvested logs (Antawi-Boasiako and Damoah 2010). Neem seed extract (azadirachtin) offer considerable protection to wood (Ssemaganda et al. 2011). Combination neem extract and chlorpyriphos could be efficiently utilized for termite control (Sotannde et al. 2011) Dioscorea hipsida is a member of Dioscoreacea family. The plant produces tubers that contain toxic alkaloid (Dioscorides). The dioscorine within the tuber's starch would protect the coated materials from rotting by bacteria or fungi activity (Azman et al. 2015). Ragasa et al. (2016) reported the dichloromethane extracts of Dioscorea luzonensis Schauer were alkyl trans-ferulates ; β-sitosterol and ursolic acid. They were polyphenolic compound group. Kumar et al. (2017) reviewed the ethnopharmacological values and traditional use of Dioscorea spp. Savi et al. (2018) showed the potential antioxidant activity of the polysaccharide extracted from Dioscorea bulbifera. They suggested to analyze it by DPPH, ABTS, FRAP, OH radical removal, H2O2 removal and reducing power.
Chemical analysis of natural wood preservation is responsible for the development of wood preservative material. GC-MS is the best technique to identify the bioactive constituents of long chain hydrocarbons, alcohols, acids, esters, alkaloids, steroids, amino and nitro compounds, etc. (Karuppasamy et al. 2012). The combination of the best separation technique (GC) with the best identification technique (MS) made GC-MS an ideal method for qualitative analysis for volatile and semi-volatile bioactive compounds (Grover and Patni 2013). The objective of the present study was to know the variation of the chemical constituent of five natural extract sources potential for preservative material. Furthermore, the isolated matters produced by plants can be used as active principles in natural extracts wood treatment.

Extraction procedure
Five plant materials were air dried, grinded, and sieved by 40 mesh. Each dry plant sample was extracted with n-hexane and petroleum ether according to ASTM D1108-96 (2007). Two grams plant sample was placed in soxhlet extraction apparatus with 300 cc of solvent.

GC/ MS analysis
Separation and identification were performed on a GC/MS QP 2010 (Shimadzu) with an RTx-5MS column, 30 m (Restek Corp.) Helium was used as the carrier gas. The injection of 1 µl (1 mg/ml) was made in a split less mode using electron impact ionization (EI, 70 eV). The injector and detector temperature were 2500°C. The program started at 500°C for 5 minutes, followed by an increase of 40°C min until 1200°C and remaining at this temperature for 1 minutes. Then, the temperature was set to 3000°C at 60°C/min and maintained for 15 minutes. Compounds were identified by comparison of the mass spectra with those in the NIST 147 libraries. The extractive composition was determined by peak area integration.
The primary compounds present in gadung tubers extract in petroleum ether were Naphthalene, 1-methyl-(23,26%). Naphthalene produced by from Magnolia flowers can inhibit natural fungi from proliferating (Chen et al. 1998). Muscodor vitigenus fungus also produced naphthalene which purports to be insect repellents (Daisy et al. 2002). Naphthalene, 1-methyl-occur naturally in fossil fuels and produced commercially from either coal tar or petroleum, and used for making insecticide carbaryl, leather tanning agents, and dye intermediates (ATSDR 2005).

Variation of five natural extracts
Type of solvent used have effects on the percentage of extraction result. Table 1 summarizes the total percentage extracts and the dominant compound in five plant extracts for the natural preservative. The highest extract percentage is found in pulai barks in both ether (1,97%)and n-hexana solvent (1,91%). The lowest extract is produced by gadung tubers in ether (0,19%) and n-hexane (0,22%). The comparison of the dominant compound of the extracts by different solvent gives a similar figure but different percentage. It is found petroleum ether solvent can detect the compound in lower retention time (Figure 1, Figure 2, Figure 3, Figure  4 and Figure 5). According to Efeovbokhan et al. (2015), petroleum ether solvent gave the highest oil yield from Moringa seed followed by hexane then isopropyl alcohol. The comparison of five extracts in terms of the identified compounds, derivatives, and the predicted activity are listed in Table 2. Triterpene derivatives were dominating in the five natural preservatives extract sources. Other compounds are the fatty acid, alcohol, steroid, hydrocarbon, and palmitic acid. It's clear that the most abundant chemical of five natural preservatives extracts by the non-polar solvent is belong to lipophilic constituents. The previous study reported that lipophilic extracts identified from the Pinus bark by GC and GC-MS were composed of four component families i.e., fatty acids and alcohols; monoterpenes and sesquiterpenes; resin acids; steroids and triterpenoids (Masendra et al. 2017). By GC-MS analyses, some potential bioactive compounds were detected for the development of natural preservatives from those 5 natural extracts. It is noticed that most of the detected lipophilic compounds here have not been assayed against wood degraders such as destroying-fungi, termites, and marine borers. Therefore three sets of work should be conducted in the near future, i.e., isolation and identification of bioactive compounds from the crude extracts; bioassay of isolated compounds, as well as impregnation and bioassay of bioactive extracts into the solid wood.   Mutai et al. 2009, 2 Pedemera et al. 2010, 3 USDA 2016, 4 Lucetti et al. 2010, 5 Malik 2016, 6 Surburg and Panten 2006, 7 Anburaj et al. 2016, 8 ATSDR 2005.