Limited success for Aedes control program has impelled the necessities for new insecticide search. Hence, alternative plant compounds may be competent to overcome the pesticide resistance problem and to lead a chemical-free environment. Following go-green conceptions, larvicidal effects of the Azolla pinnata extracts using methanol and acetone solvent against Aedes albopictus late 3rd instar larvae were evaluated. The A. pinnata fresh plant from Kuala Krai, Kelantan, Malaysia (5° 31′ N 102° 12′ E) was used for crude extraction with Soxhlet apparatus using methanol and acetone solvents. Next, larvicidal test following WHO guidelines was tested against late 3rd instar to early 4th instar larvae of Ae. albopictus mosquitoes. Meanwhile, the chemical composition of extracts and their structures have been identified using GCMS-QP2010 Ultra (Shimadzu) fitted with Rtx-5MS capillary column (30 m × 0.25 mm inner diameter, ×0.25 μm film thickness; maximum temperature, 370°C), coupled to QP2010 Ultra (Shimadzu) MS. Results of methanol solvent showed the highest larvicidal activity against late 3rd instar to early 4th instar Ae. albopictus larvae with LC50 and LC95 values of 867 ppm and 1293 ppm at 24 hours, respectively, and 647 ppm and 972 ppm at 48 hours, respectively. Meanwhile, acetone solvent compounds were recorded with LC50 and LC95 values of 1072 ppm and 1302 ppm at 24 hours, respectively, and 904 ppm and 1126 ppm at 48 hours, respectively. Finally, the chemical composition of A. pinnata plant extracts has been characterized for 35 active compounds from methanol solvent and 37 active compounds with acetone solvent. In conclusion, A. pinnata plant bioactive molecules are efficient and could be developed as an eco-friendly, “go-green” approach for mosquitoes' larvicidal control programs. Thus, our study suggests that future research can be conducted on A. pinnata bioactive ingredients against Ae. albopictus larvae in small-scale field trials as botanical insecticide for environmentally friendly approach.

In this study, an efficient micropropagation protocol was developed for A. longiloba and the antioxidant properties of field-grown plant, in vitro-derived greenhouse-grown plant and in vitro-derived callus extracts were compared. The A. longiloba seeds tested using tetrazolium chloride salt exhibited 89% viability. Due to poor germination capacity of A. longiloba seeds, the seeds were treated with gibberellic acid (GA3) or sulfuric acid (H2SO4). The maximum seed germination of 87% was observed at 30% H2SO4 treatment after 19.00 d, whereas GA3 treatment showed maximum germination of 53% after 22 d. In vitro shoot multiplication was carried out using various types of cytokinins alone or in combination with auxin. Among them, 6-benzyl amino purine (BAP) single treatment was found to be the best hormone. The highest shoot-length (7.26 cm) and maximum number of shoots per explant (18) were recorded at 3-mg L−1 BAP. For in vitro rooting, indole-3-acetic acid at 0.5-mg L−1 was found to be the optimum concentration. Callus was induced using various types of auxins alone or in combinations with cytokinins. The highest percentage of callus of 91 and fresh weight of 6 g was obtained with 3-mg L−1 IAA. The plantlets produced in the current study were subjected to acclimatization. The combination of topsoil and peat moss at 1:2 ratio was found to be the best soil media. In this study, in vitro-derived callus extract showed the highest phenolic content (538 mg GAE), followed by extracts of field-grown plant parts, i.e., fruit and petiole (504 and 300 mg GAE) while in vitro plant extract showed the lowest (98 mg GAE). Meanwhile, the highest flavonoids was recorded in petiole extract. Comparative antioxidant activity study shows, in vitro-derived callus exhibited better DPPH-radical-scavenging activity (IC50: 0.113-mg mL−1) whereas the extracts of petiole, fruit and in vitro plant showed 0.126-, 0.137- and 0.173-mg mL−1, respectively. At the same time, the fruit extract showed better (IC50: 0.088-mg mL−1) ABTS radical scavenging activity than all extracts tested. In conclusion, the in vitro-derived callus extract could be favored for high TPC and better DPPH scavenging activity. Hence, the present study was conducted to establish an efficient micropropagation protocol and to compare the antioxidant activity of the field-grown plant, in vitro plant and in vitro derived callus extracts of A. longiloba.

Alocasia longiloba, locally known as ‘Keladi Candik’, has been used traditionally to treat wounds, furuncle and joint inflammations. A. longiloba can be a new source of herbal medicine against hyperuricemia by inhibiting the activity of xanthine oxidase enzyme, the enzyme which is responsible for the development of hyperuricemia in human. Existing xanthine oxidase inhibitors (XOI drugs) show several side effects on gout patients. Therefore, an alternative herbal medicine from plants, with high therapeutic property and free of side effects, are greatly needed. This study was conducted to evaluate XO inhibitory activity, chemical composition, antioxidant activity and GC-MS profile of A. longiloba. Our results showed that ethanolic petiole extract exhibited the highest XO inhibitory activity (70.40 ± 0.05%) with IC50 value of 42.71 μg/mL, followed by ethanolic fruit extracts (61.44 ± 1.24%) with the IC50 value of 51.32 μg/mL. In a parallel study, the phytochemical analysis showed the presence of alkaloid, flavonoid, terpenoids, glycoside and saponin in petiole and fruit extracts, as well as higher total phenolic and flavonoid contents and strong scavenging activity on DPPH and ABTS antioxidant assay. The GC-MS analysis of fruit and petiole extracts revealed the presence of various compounds belonging to different chemical nature, among them are limonen-6-ol, α-DGlucopyranoside, paromomycin, aziridine, phenol, Heptatriacotanol, Phen-1,2,3-dimethyl and Betulin found in ethanolic fruit extract, and Phen-1,4-diol,2,3-dimethyl-, 1-Ethynyl-3,trans(1,1-dimethylethyl), Phenol,2,6-dimethoxy-4-(2-propenyl)- and 7-Methyl-Z-tetradecen-1-olacetate found in ethanolic petiole extract. Some compounds were documented as potent anti-inflammatory and arthritis related diseases by other researchers. In this study, the efficiency of solvents to extract bioactives was found to be ethanol > water, methanol > hexane > chloroform. Together, our results suggest the prospective utilization of fruit and petiole of A. longiloba to inhibit the activity of XO enzyme.

Atmospheric particulate matter (PM) has major threats to global health, especially in urban regions around the world. Dhaka, Narayanganj and Gazipur of Bangladesh are positioned as top ranking polluted metropolitan cities in the world. This study assessed the performance of the application of hybrid models, that is, Autoregressive Integrated Moving Average (ARIMA)-Artificial Neural Network (ANN), ARIMA-Support Vector Machine (SVM) and Principle Component Regression (PCR) along with Decision Tree (DT) and CatBoost deep learning model to predict the ambient PM2.5 concentrations. The data from January 2013 to May 2019 with 2342 observations were utilized in this study. Eighty percent of the data was used as training and the rest of the dataset was employed as testing. The performance of the models was evaluated by R2, RMSE and MAE value. Among the models, CatBoost performed best for predicting PM2.5 for all the stations. The RMSE values during the test period were 12.39 µg m−3, 13.06 µg m−3 and 12.97 µg m−3 for Dhaka, Narayanganj and Gazipur, respectively. Nonetheless, the ARIMA-ANN and DT methods also provided acceptable results. The study suggests adopting deep learning models for predicting atmospheric PM2.5 in Bangladesh.

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The widely used synthetic insecticide in the operation of mosquito control could result in unfavourable impacts to the environment, human health and non-target organism. Considering these issues, environmentally friendly insecticides from plant extract have been used as green alternatives by recent researchers. Unfortunately, the method of using plant extract as insecticide requires a large amount of raw plants. In relation to this problem, the use of nanoparticles that possesses unique characteristics including small size and potential in changing physical, chemical and biological properties of organisms were studied. Nano-synthesized silver particles (AgNPs) from Azolla pinnata extract were thus investigated in this study in order to determine its efficacy as Aedes aegypti larvicide. The present work focuses on extraction of the compounds in Azolla pinnata using soxhlet extraction method. The plant extract was mixed with 1 mM silver nitrate solution and the biosynthesized silver nanoparticles were then being characterized using UV-Vis spectrophotometer. AgNPs particles from Azolla pinnata extract were prepared in six different concentrations and set in plastic cups. Late third instar larvae of Aedes aegypti were being used in all tests. Based on the findings of the experiment, there was no mortality of larvae recorded in control groups after 24 hours of exposure. The lowest mortality recorded was at 10 ppm with only 7.5% mortality, while 95% mortality was recorded for the highest concentration which was 250 ppm. Meanwhile, the LC50 and LC95 obtained at 95% confidence interval after 24 hours of exposure were 121.570 ppm and 369.438 ppm respectively. Further studies should be done to determine the mechanisms of AgNPs in aiding Azolla pinnata as an effective larvicide in the future.

Four different tests showed the effectiveness of Azolla pinnata plant extracts against Aedes aegypti and Aedes albopictus mosquitoes. In the adulticidal test, there was a significant increase in mortality as test concentration increases and A. pinnata extracts showed LC50 and LC95 values of 2572.45 and 6100.74 ppm, respectively, against Ae. aegypti and LC50 and LC95 values of 2329.34 and 5315.86 ppm, respectively, against Ae. albopictus. The ovicidal test showed 100% eggs mortality for both species tested for all the concentrations tested at 1500 ppm, 1000 ppm, 500 ppm, 250 ppm and 125 ppm. Both tested samples of Ae. aegypti and Ae. albopictus did not lay any eggs in the plastic cups filled with the A. pinnata extract but instead opted to lay eggs in the plastic cups filled with water during the oviposition deterrence test. Similarly, the non-choice test of Ae. aegypti mosquitoes laid eggs on the sucrose solution meant for the nutrient source of the mosquitoes instead of in the plastic cup that was designed to facilitate oviposition filled with the extract. This clearly indicates the presence of bioactive compounds which are responsible in adulticidal and ovicidal activity in Aedes mosquitoes and at the same time inducing repellence towards the mosquitoes. The LC–MS results showed mainly three important chemical compounds from A. pinnata extracts such as 1-(O-alpha-D-glucopyranosyl)-(1,3R,25R)-hexacosanetriol, Pyridate and Nicotinamide N-oxide. All these chemicals have been used for various applications such as both emulsion and non-emulsion type of cosmetics, against mosquito vector such as Culex pipens and Anopheles spp. Finally, the overall view of these chemical components from A. pinnata extracts has shown the potential for developing natural product against dengue vectors.

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