Metabolites, elemental profile and chemical activities of Pinus strobus high temperature-derived pyroligneous acid

Abstract

Background Pyroligneous acid (PA) is an aqueous smoky fraction produced during pyrolysis of biomass. The chemical composition of PA from different plant biomass has been studied, but reports on PA metabolites and elemental profiles are rare. In this study, we examined the metabolites, elemental profiles and the associated chemical activities of PA derived from white pine (Pinus strobus) at 1100 °C compared to similar work done elsewhere using different biomass at lower temperatures. Results PA from P. strobus biomass exhibited a lower electrical conductivity (2.05 mS/cm), salinity (1.03 g/L) and total dissolved solids (1.42 g/L) but higher oBrix content (9.35 ± 0.06) compared to PA from other feedstock. The P. strobus PA showed a higher antioxidant activity characterized by enhanced radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl free-radical (78.52%) and accumulation of higher total phenolic (95.81 ± 1.45 gallic acid equivalents (GAE)/mL) and flavonoid content (49.46 µg quercetin/mL). Metabolite profiling by direct injection mass spectrometry with a reverse-phase liquid chromatography–mass spectrometry (DI/LC–MS/MS) identified a total of 156 metabolites. Four (4) main groups including organic acids (90.87%), hexose (8.60%), carnitine (0.3%) and phospholipids (0.24%) were found in the PA. Mineral element analysis revealed that the P. strobus PA contained high concentrations of nitrogen (N), potassium (K), calcium (Ca) and zinc (Zn), while the content of sodium (Na) and trace/heavy metals were present at levels below the reported limit. Conclusion This study indicates that P. strobus PA is a valuable product that can be used in agriculture to improve plant growth and productivity under normal and environmentally stressful conditions. Graphical Abstract

Foliar application of pyroligneous acid acts synergistically with fertilizer to improve the productivity and phytochemical properties of greenhouse-grown tomato

“…This result is consistent with previous studies where a similar increase in chlorophyll content with different PA concentrations have been reported 12,15,17,18,39 . Besides, the PA used in this study was previously revealed to contain high levels of N, K and Ca as well as other bioactive compounds 10 . In plants, N is a key modulator of nitrogenous compounds biosynthesis including chlorophyll and proteins, K is critical in enzyme activation, stomatal regulation and photosynthesis while Ca facilitate nutrient uptake and cell elongation 44,45 .…”

“…The increase in DPPH activity was highly expected and may be correlated with enhanced phytochemical content as previously reported 16,23 . Additionally, it was reported that the high phenolic content of PA exhibited high anti-lipid peroxidation and antioxidant capacity 10,11,33 . These ndings suggest that foliar PA application with NPK fertilizer combination may be considered as an environmentally friendly plant growth promotion technique to increase fruit nutritional quality and promote health bene ts.…”

“…PA is an aqueous translucent reddish-brown liquid that is produced during the pyrolysis of organic biomass 9 . As a natural byproduct of pyrolysis, it contains 80-90% water and rich in over 200 water-soluble bioactive compounds including organic acids, esters, polyphenols, alcohols, sugar derivatives and mineral elements [9][10][11] . However, these chemical properties are dependent on the feedstock, heating rate, temperature and resident time 9,10 .…”

“…As a natural byproduct of pyrolysis, it contains 80-90% water and rich in over 200 water-soluble bioactive compounds including organic acids, esters, polyphenols, alcohols, sugar derivatives and mineral elements [9][10][11] . However, these chemical properties are dependent on the feedstock, heating rate, temperature and resident time 9,10 . PA has been used extensively in agriculture as a biostimulant to increase seed germination and seedling growth [12][13][14] , crop photosynthetic performance [15][16][17][18] , crop biomass, crop yield (fruit number and weight) [19][20][21][22] and the nutrition and phytochemical properties of food crops 16,[23][24][25] .…”

“…The mode of action of karrikins in plants has been suggested to resemble that of known phytohormones and demonstrated to stimulate seed germination and plant growth [29][30][31][32] . Also, the high phenolic content of PA has been proven to exhibit high scavenging activities of reactive oxygen species (ROS) radicals, anti-lipid peroxidation and reducing power activities 10,11,33 . This suggests that a suitable PA rate and concentration can enhance plant growth and productivity.…”