# Advanced and Potential Methods for Extraction of Bioactive Compounds from Avocado Peel--A Review
## 4 Advanced Methods for Extraction of Bioactive Compounds from Avocado Peel
### Three-Phase Partitioning (TPP)
\begin{table}
\begin{tabular}{c c} \hline
**Extraction Method** & **Important Finding** & **Ref.** \\ \hline \multirow{4}{*}{Maceration} & The extract contained 48 compounds, where the major components were \\  & flavonoids and procyanids. The extract inhibited platelet aggregation (at 1, \\  & 0.75, and 0.5 mg/mL) and reduced enzymatic inhibition, especially inhibition of \\  & xanthine oxidase, hyaluronidase, and acetylcholinesteraseinesterase. \\ \hline \multicolumn{3}{l}{Avocado peel methanolic extract contained phenolic compounds} \\  & (21.833 \(\pm\) 0.118 mg/100 g extract), flavonoids (2.607 \(\pm\) 0.111 mg/100 g extract), \\  & tannins (38.357 \(\pm\) 0.202 mg/100 g extract), saponins (8.874\% \(\pm\) 0.031\%), and \\  & alkaloids (9.95 \(\pm\) 0.035 mg CE/g extract) that contributed to its antioxidant \\  & activities. Its IC\({}_{50}\) was 185.891 \(\pm\) 1.598 ppm. \\ \hline \multicolumn{3}{l}{The ethanolic extract inhibited the growth of _Staphylococcus_. A longer extraction} \\ \multicolumn{3}{l}{time (1.5, 3, and 4 h) showed a higher antioxidant and antibacterial activity.} \\ \hline \multicolumn{3}{l}{The optimal maceration of avocado peel was obtained with 40\% ethanol, 49.3 \({}^{\circ}\)C,} \\  & solvent/feed ratio of 14.3 mL/g, and 60 min process. The optimal extract \\  & showed the highest total phenolic content (44.24 mg GAE/g peel dw), total \\  & flavonoid content (786.08 mg QE/g peel dw), antioxidant capacity against DPPH \\  & (564.82 \(\upmu\)mTE/g peel dw), FRAP (1006.21 82 \(\upmu\)mTE/g peel dw), and ABTS \\  & (804.40 82 \(\upmu\)mTE/g peel dw). \\ \hline \multicolumn{3}{l}{The total polyphenic content of avocado peel, pulp, and seed ethanolic extract} \\  & was 200, 245, and 424 mg GAE/100 g DW, respectively. The total flavonoid \\  & contents of avocado peel, pulp, and seed ethanolic extract were 36.06, 36.98, and \\  & 32.54 mg RE/100 g DW, respectively. The radical scavenging activity of avocado peel, pulp, and seed extract was 4.90, 3.24, and 3.63 \(\upmu\)g/mL, respectively. \\ \hline \multicolumn{3}{l}{The extract contained the phenolic compound (59.55 GAE mg/gram extract), flavonoid (2.96 QE mg/gram extract), and tannin (22.63 TAE mg/gram extract).} \\ \multicolumn{3}{l}{The extract significantly changed hydration levels, collagen, and skin elasticity} \\ \multicolumn{3}{l}{with 2 times application per day for 4 weeks in male rats (in vivo).} \\ \hline \multicolumn{3}{l}{The avocado peel extract contained phenolics compounds (309.95 \(\pm\) 25.33 mmol} \\  & GA/100 g of extract), flavonoids (12.54 \(\pm\) 0.52 mmol Caet.eq/100 g of extract), and anthocyanins (622.37 \(\pm\) 17.26 mmol Cyanidin-3-glucose deg./100 g of \\  & extract). The extract showed an antiproliferative effect mediated by apoptosis, oxidative stress reduction, and antiproliferative effect.} \\ \hline \multicolumn{3}{l}{The extracts showed a high content of Ca, Mg, Fe, Zn, \(\upmu\)-6 linoleic acid, and flavonoids. The extract showed acetylcholinesteraseinesterase inhibition with no} \\  & [60] \\ \hline \multicolumn{3}{l}{The wet grinding plus maceration showed the highest value of total phenols} \\  & (2143.1 mg GAE/100 g dry weight), chlorogenic acid (244.3 mg/100 g dry \\  & matter), and epicatechin (181.7 mg/100 g dry matter). The wet grinding plus \\  & [61] \\ \hline \end{tabular}
\end{table} 
Table 1: Various extraction methods for retrieving bioactive compounds from avocado peels.