Extraction And Bioactivity Of Tobacco Alkaloids

Botanical pesticides originate from the metabolism of plants and are characterized by safety,efficiency and environmental friendliness.Every year the tobacco harvesting and production process in our country produce a large amount of discarded tobacco leaves which contain pesticide active ingredients like alkaloids and have not been reasonably utilized.In this paper,three kinds of discarded tobacco leaves including flue-cured tobacco,burley tobacco and sun-cured yellow tobacco were used as raw materials to prepare botanical pesticides,and the following two aspects had been studied:1.To obtain tobacco extracts containing more tobacco alkaloids,orthogonal experiments of L16?4⁵?were designed to optimize the extraction process.The optimized extraction craft parameters were as follows:95%ethanol as an extractant,a solid-liquid ratio of 12:1,an extraction temperature of 60°C,an extraction time of 5 h and chloroform as an extraction agent.The chloroform could be recycled with a single recovery rate of more than 85%.The contents of the four main alkaloids including nicotine,anatabine,nornicotine and anabasine in tobacco extracts were determined using high performance liquid chromatography tandem mass spectrometry,and the reliability of the method was fully verified.The total contents of the four main alkaloids in the three tobacco extracts were as follows:flue-cured tobacco?62.13%?>sun-cured tobacco?58.19%?>burley tobacco?50.67%?.In burley tobacco extract nicotine content was the lowest and the other three alkaloids contents were all the highest.It is worth noting that the nornicotine content in burley tobacco extract was much higher than the other two tobaccos.2.The insecticidal activities of tobacco extracts against Nilaparvata lugens,Helicoverpa armigera,Spodoptera exigua,Bactrocera dorsalis and Aphis glycines Mats?mura were investigated.The results showed that the tobacco extracts had good activities against Aphis glycines Mats?mura,Bactrocera dorsalis and Nilaparvata lugens.The LC₅₀ of three tobacco extracts against Aphis glycines Mats?mura ranged from 3.13 to 8.33 mg/L.Burley tobacco extract was the most effective against Aphis glycines Mats?mura in three tobaccos and its activity was equivalent to anatabine,which was the most effective in four standard alkaloids.This showed that the organic combination of the four alkaloids in the extract had produced a synergistic effect.At the same time the antifungal activities of tobacco extracts and plant essential oils against eight plant pathogenic fungi such as Gibberella zeae were investigated.In the joint toxicity experiments of tobacco extract and plant essential oil against Colletotrichum fructicola,when the burley tobacco extract and eugenol were mixed at an IC₅₀ concentrations of 5:1,the co-toxicity factor reached 55.05and the synergistic effect was the best.In addition,the pot experiments of the tobacco extracts agaist four plant diseases indicated the tobacco extracts had different degrees of control effects on Rice sheath blight,Tomato corynespora leaf spot and Pestallozzia theae.The above studies showed that tobacco extracts had certain insecticidal and antifungal activities and were particularly suitable for the prevention and control of pests and diseases in crops such as foodstuffs,vegetables,teas and fruits.Tobacco extracts have potential for further exploitation and development.