Sains Malaysiana 44(1)(2015): 121–126

A Thermal Degradation (Thermolysis) Study of Rotenone Extracted from Derris elliptica Roots Using Reverse-Phase High Performance Liquid Chromatography (RP-HPLC)

(Kajian Degradasi Terma (Termolisis) bagi Rotenon dalam Cecair Ekstrak Mentah Pekat (CLCE) Diekstrak daripada Akar Derris elliptica Menggunakan Fasa Keterbalikan Cecair Kromatografi Berprestasi Tinggi (HPLC))

SAIFUL IRWAN ZUBAIRI¹*, MOHAMAD ROJI SARMIDI² & RAMLAN ABDUL AZIZ²

¹School of Chemical Sciences & Food Technology, Faculty of Science & Technology

Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan, Malaysia

²Institute of Bioproduct Development, Universiti Teknologi Malaysiam 81310 Skudai,

 Johor Darul Takzim, Malaysia

Diserahkan: 20 Ogos 2013/Diterima: 2 Julai 2014

ABSTRACT

Bio-pesticides are becoming increasingly important as pest management tools in various cropping systems in the tropics essentially to remedy problems associated with the indiscriminate use of ‘hard’ and non-environmental friendly inorganic pesticide. In these past few decades, many bio-pesticidal products, both microbial-based (bacteria, fungi, microsprodia, entomopathogenic nematodes and viruses) and plant-based botanicals (rotenone and azadiracthin) have been studied for their use against insect pests in the tropics. In this study, the effects of the concentration process with respect to the yield of rotenone (mg) and its concentration (mg/mL) are presented extensively. The raw plants were collected from Kota Johor Lama, Johor and sorted to obtain the roots and stems. Only the roots and stems were utilized as raw materials of the extraction process. The rotenone from roots and stems was extracted using the normal soaking extraction (NSE) at 28 to 30^oC with 95% (v/v) of acetone as a solvent and the solvent-to-solid ratio of 10 mL/g. The extraction was carried out for 24 h. Next, the liquid crude extract was concentrated using the rotary evaporator at 50oC and 80 mbar of vacuum pressure to remove approximately 90% of solvent. The fractions of the liquid crude extract were collected (15 min/mL/fraction), diluted (1/100 with acetone) and cleaned up (to remove any fine debris) prior to determination of rotenone content (mg) and concentration (mg/mL) by using the reverse-phase high performance liquid chromatography (RP-HPLC). Finally, the results showed that there was a significant effect of thermal degradation or dissipation of rotenone content at higher operating temperature (greater than 40^oC) with a rapid rotenone reduction for the first 15 min of exposure. The possibilities for better exploitation and identification of the effective operating parameters based on the above mentioned results will be perhaps discussed in the future.

Keywords: Concentrated liquid crude extract; Derris elliptica; rotenone; thermal degradation

ABSTRAK

Bio-pestisid pada masa ini sedang mengalami peningkatan yang sangat penting sebagai kaedah mengawal makhluk perosak dalam variasi sistem tanaman tropika terutamanya sebagai jalan untuk mengatasi masalah yang berkaitan dengan penyalahgunaan pestisid bahan bukan organik berat yang tidak mesra alam. Dalam beberapa dekad yang lalu, banyak produk bio-pestisid, kedua-duanya bagi basis mikrob (bakteria, kulat, mikrosprodia, entomopatogenik nematod dan virus) dan bahan botani berasaskan tumbuhan (rotenon dan azadiraktin) telah dikaji berkesan untuk kegunaan serangga perosak dalam iklim tropika. Dalam kajian ini, kesan daripada proses pemekatan terhadap keberhasilan rotenon (mg) dan kepekatannya (mg/mL) telah dikaji secara menyeluruh. Sumber pokok mentah dikumpulkan dari Kota Johor Lama, Johor dan diasingkan untuk pengumpulan akar dan batang. Hanya akar dan batang sahaja digunakan sebagai sumber bahan mentah untuk proses pengekstrakan. Rotenon daripada bahagian akar dan batang diekstrak menggunakan pengekstrakan celuran norma pada suhu bilik iaitu 28 to 30^oC dengan 95% (v/v) aseton sebagai pelarut dan nisbah pelarut-kepada-pepejal bagi proses pengekstrakkan adalah 10 mL/g. Proses pengekstrakan dijalankan selama 1440 min. Seterusnya, cecair ekstrak mentah dipekatkan menggunakan alat penyejatan berpusing pada suhu 50oC dan tekanan vakum 80 mbar untuk mengeluarkan pelarut aseton sebanyak lebih kurang 90%. Fraksi cecair ekstrak mentah dikumpulkan (15 min/mL/fraksi), dicairkan (1/100 dengan aseton) dan ditapis (untuk membuang sebarang habuk halus) sebelum proses analisis kandungan rotenon (mg) dan kepekatannya (mg/mL) menggunakan fasa terbalik cecair kromatografi berprestasi tinggi (HPLC). Akhirnya, keputusan uji kaji menunjukkan bahawa terdapat kesan signifikan degradasi terma terhadap kandungan rotenon pada suhu operasi tinggi (melebihi 40^oC) dengan kadar pengurangan pantas rotenon pada 15 min pertama operasi. Kebarangkalian untuk mengkaji dan mengenal pasti parameter operasi yang lebih effektif berdasarkan kepada keputusan uji kaji ini akan dibincangkan kelak.

Kata kunci: Cecair ekstrak mentah pekat; degradasi terma; Derris elliptica; rotenon

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*Pengarang untuk surat-menyurat; email: saiful-z@ukm.edu.my