Recent innovations of ultrasound green technology in herbal phytochemistry: A review

Abstract

Highlights Ultrasound enhances the phenolic compounds in extracted herbal oils by 44%. US (25–50 kHz) increases the yields of polyphenols, carotenoids, and flavonoids. Radicals generated by US have positive and negative effects on enzymes. US improves the efficiency of herbal extracts in Nanotechnology applications. Acoustic-based biosensors could be used for chemical imaging of herbal tissues.

Ultrasound-Assisted Extraction Optimization of Proanthocyanidins from Kiwi (Actinidia chinensis) Leaves and Evaluation of Its Antioxidant Activity

“…This is because US shows high potential in the field of herbal science due to its high ability to generate better yield and low scale-up finance compared to the other emerging techniques like a microwave (MW) and pulsed electric fields (PEF) [ 36 ]. On the other hand, special attention should be focused on the chemical composition and bioactivity of extracted PAs [ 4 ]. Thus, this study conducted a single-factor experimental design to show the optimum of four significant US factors represented in power, duration, temperature, and solvent to solid ratio that have significant influences on PA extraction.…”

“…These modifications in the structure of extracted compounds caused by US can facilitate the bioavailability of the bioactive molecules extracted from plants [ 16 ]. However, the US higher than 50% had a negative effect on the PAs due to the formed radicals and H 2 O 2 by the cavitation’s bubbles [ 4 ]. Therefore, 50% amplitude was selected as the optimum used power for the extraction of PAs.…”

“…This could be due to the potential impact of US to transform the disulfide bonds to thiol bonds of the molecules, which results in changing the covalently attached linear polymer chains in the β -position to a disulfide moiety [ 41 ]. However, long-time ultrasonic cavitation could result in the degradation of polyphenolics that declined the extraction yield [ 4 ]. Therefore, 20 min was selected as a suitable US time range for PAs.…”

“…These results might be related to the decrease of surface tension and viscosity of the solvent, which induced an increase in vapor pressure. With the increment of temperature, the sonochemical influents caused by the collapse of cavitation bubbles decreased, and polyphenols might be degraded at a higher temperature situation [ 4 ]. Therefore, controlling the temperature at an appropriate range is very necessary during the extraction process of bioactive compounds from plant materials, for which the extracted PAs by US can show a higher antioxidant capacity against DPPH, and hydroxyl radicals compared to heat reflux extraction based on the significant differences in the extracted chemical structure [ 42 ].…”

“…Kiwi ( Actinidia chinensis ) leaves are natural sources that are considered as a byproduct of kiwi fruit production and that contain a very high amount of natural bioactive phytochemicals that are generally considered as natural, safe extracts [ 1 , 2 ]. For instance, it has a high amount of polyphenols 189.39–440.71 mg GAE/g DW [ 3 ] that have a high bioactivity for human health (e.g., antioxidant and anti-tumor), due to their functional groups like hydroxyl groups on its phenolic rings [ 4 ]. In particular, proanthocyanidins (PAs) are a class of polyphenols that are divided into different types based on the hydroxylation patterns of their monomeric flavan-3-ols units [ 5 ], in which PAs oligo- or polymers are produced as an end product of the flavonoid biosynthetic pathway [ 6 ].…”