# Guineensine: Isolation, Synthesis, and Biological Activity
## 5 Discussion  
Studies on the biological activity of piperamides were conducted by various researchers [26; 102; 103]. The most studied is piperine, in contrast to guineensine and other \begin{table}
\begin{tabular}{c c c} \hline
**Biological Activity** & **Target** & **Concentration** & **Reference** \\ \hline \multicolumn{3}{c}{IC\({}_{50}\)} \\ Cholinesterase inhibition activity & AChE and BChE & 74.37 \(\pm\) 3.08 ug/mL(AChE) & [81] \\  & AChE & No activity against BChE & [82] \\ Antiviral activity & HBV & \textless{}0.05 mM & [83] \\  & HIV-1 & 651.9 uM & [45] \\ Antiplasmodial activity & _Plasmodium falciparum_ strain Pf 3D7 & 23.9 \(\pm\) 2.4 ug/mL & [84] \\  & _Plasmodium falciparum_ strain Pf Dd2 & 14.6 \(\pm\) 0.3 ug/mL & [88] \\  & & ED\({}_{50}\) & \\ Insecticidal activity & _Schistocerca gregaria_ & 0.50 ug/insect (at 48 h) & [88] \\  & & knockdown activity & \\  & & 0.90 ug/insect (48 h) lethal & \\  & & activity & \\  & & LD\({}_{50}\) & \\  & _C. pipiens pullens_ (adults) & 1.9 ug/g* & [85] \\  & _A. aegypti_ (adults) & 1.7 ug/g & [85] \\  & _C. pipiens pullens_ (larvae) & 0.17 ppm & [43] \\  & _A. aegypti_ (larvae) & 0.89 ppm & [43] \\  & _A. togoi_ (larvae) & 0.75 ppm & [43] \\  & _Plutella xylostella_ & 0.013 mg/mL & [88] \\  & _Stiophilus zemaiis_ & [89] \\  & \% Mortality at 48 h & 80.0 \(\pm\) 7.07 & \\  & Oviposition & 1.25 \(\pm\) 0.96 & \\  & Repellency & 72.5\% & \\  & & IC\({}_{50}\) & \\ Cholesterol homeostasis & ACAT & 3.12 uM & [93] \\ Anticancer & HepG2 & 14.90 \(\pm\) 0.62 uM & [99] \\  & Hela & 17.13 \(\pm\) 1.06 uM & \\  & SKOV-3 & 17.96 \(\pm\) 0.39 uM & \\ MAO inhibition & MAO & 139 \(\pm\) nM & [100] \\ Anti-inflammatory activity & THP-1 (Inhibition of ICAM-1/LFA-1 complex) & \textgreater{}50 & [80] \\ Protection against gastric ulcers & rats & [96] \\  & (binding affinity (kcal/mol) with protein 2 XZB) & \textless{}6.9 & \\ \hline \end{tabular} * \(\lx@sectionsign\): _Aales aegypti_ females.  
\end{table} 
Table 2: Biological activity of guineensine. piperamides. However, the data presented in this review indicate that guineensine is a compound that merits further investigation. Guinea is an alkamide found in various _Piper_ species, alongside other piperamides. Its structure consists of three distinct units: a benzodioxolyl group (tail), an isobutylamide group (head), and an unsaturated carbon chain serving as the linker. It is known as an endocannabinoid uptake inhibitor but was also studied for its insecticidal and larvicidal activities. Despite its potential, guineensine remains underexplored in terms of its broader biological properties. Compared to the extensive research on piperine, guineensine can be considered as a \"treasure molecule\" awaiting deeper investigation. A major factor contributing to its underrepresentation is its low isolation yield. Isolation methods to obtain guineensine were developed and present several advantages and disadvantages. Conventional extraction with stirring and ultrasound extraction are the fastest methods (total time of 30 min). In relation to cost, Soxhlet extraction, maceration, and ultrasound extraction are the most economical. Finally, accelerated solvent extraction gives higher yield than the other methods (209.7 mg/100 g of dry black pepper ethyl acetate extract) [50]. Even though the authors in this latter study do not explain the reason(s) for the high yield obtained in their experiment, this could be attributed to the sample used, which was cultivated in Costa Rica, and/or the method applied to isolate guineensine. Because of its low isolation yield, a more active involvement of synthetic chemistry to reach Gram-scale preparations will enable researchers to perform comprehensive studies of this promising natural product. So far, three research groups have described approaches to guineensine total synthesis. The major challenges were the construction of the isolated double bonds and the purification of the final product.