# Detection of Volatiles by HS-SPME-GC/MS and Biological Effect Evaluation of Buddha's Hand Fruit
## 4 Discussion
Many phenolic compounds may also exhibit significant antibacterial activity involving some sites of action at the cellular level [43]. Previously, the antioxidant activity of [PERSON]'s hand EO has been investigated by obtaining variable values in relation to various considered factors, such as isolation methods, heat stress, or maturity stage, as well as the involved target [16; 37; 44]. Our data were in line with those of [PERSON] et al. [16], who, among the test samples, reported the lowest scavenging ability against DPPH: for mature [PERSON]'s hand fruit. Nevertheless, the results of other works showed different DPPH radical-scavenging activities, with both lower and higher inhibition percentages [45; 46]. The same goes for the activity detected towards ABTS-+ [45; 47]. The discrepancy found could be explained by many factors, including those listed above, but also by different chemical compositions of the same _Citrus_ species due to varied growing areas and climatic conditions. A large variety of EOs also possess the capacity to inhibit microbiological growth, and their potential applications are always the subject of research [48; 49; 50]. In our study, the antibacterial activity of the EEX, MEX, EO, and Hy of Buddha's hand were investigated by the determination of MIC and MBC values against _B. cereus_ and _E. coli_. All the samples were more active against _B. cereus_ than _E. coli_; for the latter, MIC values were not attained at the tested concentrations except for the samples EEX and MEX, for which they were determined, although at a high concentration. Against _B. cereus_, EEX was more active than MEX. In particular, the highest activity recorded in EEX could be due to its major compound, coumarin, 5,7-dimethoxy, according to what was reported by [PERSON] et al. [51]. EO had low a MIC value, showing high antibacterial activity. Previous studies have reported the antibacterial activity of _Citrus medica_ L. var. _sarcodactylus_ EO against food-borne bacteria, and various human multi-drug-resistant pathogenic bacteria [17; 31; 52]. [PERSON] et al. [46] reported that the nano-emulsified EO showed an increased activity on _S. aureus_ and on _E. coli_ inhibiting the bacteria biofilm formation in tofu. Furthermore, the main constituents of EO, such as limonene and \(\gamma\)-terpinene, have been shown to have antimicrobial activity [53; 54; 55; 56]. EEX was also found to have a cytotoxic effect against HL60 human cell line. This power could be attributed to its chemical composition. In fact, coumarins and coumarin derivatives possess a broad range of biological activities, including anticancer activity by apoptosis induction, cell cycle arrest, and several other mechanisms of action [57; 58]. The 5-HMF compound has also been reported to have cytotoxic activity against HCT-8, A549, and SGC-7901 cell lines [59], as well as exert antioxidant activity [60]. In our investigation of the extracts, we also detected the 2-pyrone compound with considerable percentage values; previous studies have demonstrated both the antimicrobial and cytotoxic power of 2-pyrone derivatives [61]. In this work, the chosen techniques to investigate the volatile chemical composition and to study the biological activities, represent the first screening to be used [62; 63; 64; 65]. The results obtained by EO and Hy MTT assay expressed an interesting cytotoxic activity. Buddha's hand EO and limonene, its most abundant component, were shown to possess cancer-specific activity when tested against the skin melanoma A375 cells and normal skin cells [66]. Concerning Hy cytotoxicity, EC\({}_{50}\) results were quite low, which revealed a very good activity. In our investigation, Hy was rich in \(\alpha\)-terpineol and terpinen-4-ol, whose potential anticancer action, through cycle inhibition and apoptosis induction, has been demonstrated [67; 68]. These compounds could explain the Hy cytotoxicity that has, until now, never been investigated.