Objective: To investigate the proximate and mineral composition of the Piper retrofractum (P. retrofractum) vahl. Fruit and to evaluate its total alkaloids, phenol and flavonoid. Methods: The proximate composition of P. retrofractum fruit was ananlyzed using standard protocols according to Indonesian Standard and Association of Official Analytical Chemist. Meanwhile, mineral composition of the fruit was analyzed using inductively coupled plasma-mass spectrometry. Phytochemical screening and quantification were performed using standard protocols according to Harborn and spectrophotometric methods. Results: The results showed that P. retrofractum fruit contained carbohydrate (63.4%), crude protein (11.4%), total ash (4.29%), dietary fiber (28.8%) and total fat (2.97%). The fruit also contained calcium, copper, iron, magnesium, phosphor, potassium, sodium and zinc in different concentrations. Additionally, quinone, sterol, glycosides and alkaloid were detected in both n-hexane and ethyl acetate extracts. Moreover, tannin was presented also in ethylacetate and methanol extracts. Meanwhile, methanol extract contained sterol, glycosides, flavones, tannin and alkaloid. The results also revealed that methanol extract of the fruit contained highest phenol compared to other extract. Finally, small quantity of flavonoid (0.060 0%±0.000 2%) was observed. Conclusions: The overall results show that P. retrofractum contains potential nutritional and phytochemicals values, which support their function for pharmaceutical purposes.

Aims: Tryptamine is an amine compound derived from tryptophan by decarboxylation process. This compound can be found in fermented food and beverages, and in human gut and skin as well. This study aims to investigate the effect of tryptamine, on Gram-negative bacteria, namely Escherichia coli, Serratia marcescens and Pseudomonas aeruginosa. Methodology and results: In this study, we used E. coli, S. marcescens and P. aeruginosa due to their relatively observable quorum sensing-regulated phenotype, such as motility, prodigiosin and pyocyanin sequentially. Our results showed that tryptamine started to inhibit the growth and prodigiosin production of S. marcescens at concentration 250 μg/mL, while it inhibits the growth and pyocyanin production of P. aeruginosa at concentration 250 μg/mL and 500 μg/mL, respectively. Tryptamine inhibits both the growth and motility of E. coli at concentration 100 μg/mL. Conclusion, significance and impact of study These results suggest that tryptamine is able to inhibit the growth of E. coli, S. marcescens and P. aeruginosa at relatively high concentration, thus decreases the quorum sensing-regulated phenotypes. It implies that the growth and quorum sensing of Gram-negative bacteria most likely will not be affected by the low concentration of tryptamine that present in the gut.
Tryptamines ; Gram-Negative Bacteria ; Serratia marcescens ; Pseudomonas aeruginosa ; Escherichia coli