EXTRACTION OF PIPERINE FROM BLACK PEPPER USING GREEN TECHNOLOGIES
Green technology encompasses the 12 principles of ‘Green Chemistry,’ which is an approach for synthesis and processing of products, with the aim to reduce consumption or generation of harmful compounds in product design and manufacture and in the utilization of chemicals (Anastas and Warner, 1998). These technologies not only reduce the amount of waste generated at the sources but also reduce pollution at the production ends (Ameta and Ameta, 2013). Therefore, the extraction of spiceutical employing green technologies is in compliance with regulatory guidelines and has gained significant importance in recent times. The green technologies involved in isolation of piperine by extraction using any of the following (singly or
FIGURE 5.3 Biotransformation of piperine in a rat model.
Source: Reprinted with permission from Srinivasan (2007). © Taylor & Francis.
in tandem or sequentially) are enzymatic digestion, solvent extraction by generally regarded as safe (GRAS) solvents, extractions using ultrasound waves and supercritical carbon dioxide (SC-CO,).
EXTRACTION BY ENZYMATIC DIGESTION
Enzymatic digestion is an approach for extraction of piperine from natural matrices. Chandran et al. (2012) used enzymatic digestion employing lumicellulase (a mixture of cellulase, pectinase, xylanase, and p-glucanase) enzyme to rupture the cell walls of black pepper for enhanced black pepper oil recovery. The essential oil of black pepper when analyzed by the hyphenated technique of gas chromatography-mass spectrometry (GC-MS), the chromatogram showed the presence of p-caryophyllene as one of the major active components in black pepper. Extraction of piperine from black pepper and allied spiceuticals by the enzymatic digestion technique has not been explored fully till date.
EXTRACTION USING GENERALLY REGARDED AS SAFE (GRAS) SOLVENTS
Health hazardous organic solvents are increasingly being replaced with GRAS solvents such as ethanol, water, and polyethylene glycol. These solvents are safe and non-hazardous to the environment. In a study by Dutta and Bhattacharjee (2015), the extract ofblackpepper oleoresin was obtained by reflux heating and by shake flask method using ethanol as the extracting solvent. The yield of black pepper oleoresin was higher in the case of the reflux method (9.1±0.1 g/100 g diy sample) vis-a-vis that of shake flask method (5.5±0.1 g/100 g dry sample). All extracts exhibited appreciable antioxidant activities.
Black pepper oleoresin from cv. Bragantina has been extracted using Soxlilet extraction assembly with GRAS status solvents such as ethanol (EtOH) and ethyl acetate (EtOAc) and also by //-hexane (conventionally used for Soxhlet extraction) (Andrade et al., 2017). Total yields of extracts were in the range of 4.1-10.3% (w/w) with the highest yield (10.3 ± 0.6%, w/w) obtained using EtOH.
EXTRACTION USING ULTRASOUND-ASSISTED SOLVENT EXTRACTION
In recent years, extraction employing ultrasound technology has also emerged as a potential technique in enhancing yields of bioactive. Application of ultrasonic field in a liquid medium (of solvents containing natural matrix in ground form) generates acoustic cavitation, i.e., creation, expansion, and implosive rupture of bubbles filled with gas- in the liquid disrupting the outer structure of the raw material to promote chemical reactions inside the cells of the same (Salazar et al., 2004). Andrade et al. (2017) had also worked on ultrasound-assisted extraction of black pepper (cv. Bragantina) using ethanol, ethyl acetate, and //-hexane. The extractions were conducted in an ultrasonic cleaner bath at 55 kHz frequency and power of 100 W for 45 min. The highest yield of extract was obtained with EtOAc (5.6 ± 0.1%) followed by those with EtOH (5.3 ± 0.5%) and hexane (3.1 ± 0.1%). GC-MS chromatogram revealed piperine to be the predominant compound in all extracts.
Among the extracts, the maximum predominance of piperine was found in EtOAc extract (70.97%) followed by that obtained by EtOH (56.46%) and hexane (39.82%). These findings are in strong favor of GRAS status solvents as extracting solvents over their conventional counterparts.
These green technologies of extraction discussed so far yield extracts which are safe for consumption. However, these processes still lack in the selectivity of extraction of piperine since their extracts contain several compounds co-extracted along with the desired analyte. Therefore, to obtain an extract predominantly rich in piperine (target compound), selective extraction of piperine from its source is necessary. Of all green technologies of extraction explored till date, this desired selectivity could be achieved only by supercritical fluid (SCF) (carbon dioxide being the most used fluid) extraction.
