Currently, bio-pesticide is relatively harmless to human and environment and thus desirable for its use in the control of insect vectors. Bio-pesticide has been increasingly important in both scale commercial agriculture and small plot, subsistence farming. One of the sources for bio-pesticide is ‘tuba’ plant, known as Derris elliptica. Derris elliptica contains bio-active compounds known as rotenone (C23H33O6) which is harmless to plants, highly toxic to many insects and relatively innocuous to mammals. The study was carried out to investigate the appropriate processing parameters with the aimed to acquire high yield of rotenone (mg) and concentration (mg/mL) of the exhaustive extraction process by evaluating the kinetics of the normal soaking extraction (NSE) method. The raw plants were collected from Kota Johor Lama, Johor and sorted to collect the root. The roots were sorted into 2 types of raw material particles size (mm in diameter) prior to the extraction process. Rotenone from the root part was extracted by using a NSE method at ambient temperature of 27±1oC. Three types of solvents and 2 solvent-to-solid ratios were utilized throughout the extraction process. The extraction was carried out for 50 h and the fractions of the liquid crude extract were collected for each interval time (2 h/mL/fraction) and further cleaned up to remove any fine debris prior to the determination of rotenone content (mg) and its concentration (mg/mL) via reverse-phase high performance liquid chromatography (RP-HPLC). From the kinetics result obtained, it was found that the fine Derris elliptica roots with particles size of 0.5 - 2 mm in diameter and solvent-to-solid ratio of 10 mL/g of acetone solvent system were considered the best processing parameters to procure high yield of rotenone and its concentration.
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 30oC 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 40oC) 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.