Various antimicrobial constituents of camu-camu fruit were isolated. Acylphloroglucinol (compound 1) and rhodomyrtone (compound 2) were isolated from the peel of camu-camu (Myrciaria dubia) fruit, while two other acylphloroglucinols (compounds 3 and 4) were obtained from camu-camu seeds. The structures of the isolated compounds were characterized by spectrophotometric methods. Compounds 1 and 4 were confirmed to be new acylphloroglucinols with different substituents at the C7 or C9 position of 2, and were named myrciarone A and B, respectively. Compound 3 was determined to be isomyrtucommulone B. This is the first report of the isolation of 3 from a natural resource. The antimicrobial activities of compounds 1, 3, and 4 were similar to those of 2, and the minimum inhibitory concentrations were either similar to or lower than that of kanamycin. These results suggest that the peel and seeds of camu-camu fruit could be utilized for therapeutic applications.

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This work aimed to characterize the phenolic composition and in vitro antioxidant and antiproliferative properties of lyophilized camu-camu (Myrciaria dubia) seed extract (LCE), and to assess the effects of LCE on the antioxidant and sensory traits of yogurt. The LCE contained 46.3% (wt/wt) total phenolic content; the main compounds quantified were vescalagin, castalagin, gallic acid, procyanidin A2, and (−)-epicatechin. The LCE had antioxidant activity, as measured by different chemical assays (2,2-diphenyl-1-picrylhydrazyl, Folin-Ciocalteu reducing capacity, total reducing capacity, ferric reducing antioxidant power, and Cu 2+ chelating capacity), and inhibited the cell proliferation of HepG2 cells (human hepatoma carcinoma; IC 50 = 1,116 µg/ mL) and Caco-2 cells (human colorectal adenocarcinoma epithelial cells; IC 50 = 608.5 µg/mL). In addition, LCE inhibited the in vitro activity of α-amylase, α-glucosidase, and angiotensin-converting enzyme, and protected DNA from peroxyl radical-induced scission. When added to yogurts, different concentrations of LCE (0, 0.25, 0.5, 0.75, and 1.0 g/100 g) increased the chemical antioxidant and reducing capacities. The camu-camu yogurt containing LCE at 0.25 g/100 g had an acceptance index of 84%, showing that camu-camu seed extract may be a potential ingredient for addition to yogurts.

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Camu-camu (Myrciaria dubia, Myrtaceae) is a tropical fruit, and is known to be rich in vitamin C. The fruit is mainly used in juice or vinegar production, and large amounts of byproduct, composed of seed and peel, is generated as agricultural and industrial waste. Our studies on camu-camu seed and peel revealed that the seed contains large amounts of polyphenols (400 mg/g). Further studies on the seed resulted in the isolation of vescalagin and castalagin, C-glycosidic ellagitannins with a hexahydroxydiphenoyl group and a nonahydroxyterphenoyl group attached to the open chain d-glucose, as the main polyphenolic constituents. The structures of these tannins were characterized by their 1 H-and 13 C-NMR spectra and mass spectrum. The two C-glycosidic ellagitannins represent about 15% of the polyphenolics in the seed of camu-camu fruit, and are likely responsible for the anti-oxidative activity of the seed extract's anti-oxidative activity.Keywords: camu-camu, Myrciaria dubia, seed, polyphenol, vescalagin, castalagin, NMR *To whom correspondence should be addressed. E-mail: t1myouda@bioindustry.nodai.ac.jp IntroductionTropical fruits have been attracting attention from the food industry because of their unique appearance, flavor and nutritional value. Camu-camu (Myrciaria dubia, Myrtaceae) is a tropical fruit, and has recently been used for processed food in advanced countries. Camu-camu is a bushy tree native to the Amazon rainforest, mainly in Peru (Rodrigues et al., 2004). Its fruit is known to be rich in vitamin C, with higher levels reported than those of acerola fruit (Bradfield and Roca, 1964). Camu-camu fruit has a characteristically mild flavor, but its high acid content induces a bitter taste. Therefore, it is mainly consumed as a juice or used as an ingredient in prepared foods (Villachica, 1997;Franco and Janzantti, 2005). During juice production, byproduct, composed of peel and seed, is generated as agricultural and industrial waste on a large scale. Therefore, utilization of this residue is recommended from both a commercial and ecological point of view.In a previous paper (Myoda et al., 2010), we reported that the seed extract of camu-camu fruit contains a large amount of polyphenols (400 mg/g), approximately four and ten times that of the residues of acerola and passion fruit juice production, respectively (Oliveira et al., 2009). We also reported that the lipophilic fraction of the seed extract showed antimicrobial activity against Staphylococcus aureus at 1.0 mg/ mL. On the other hand, the hydrophilic fraction exhibited strong 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (IC 50 = 32.2 μg/mL), and the polyphenol content of the fraction was shown to be responsible for the activity. In this paper, we report the polyphenolic constituents in the seed extract of camu-camu fruit and their contributions to the anti-oxidative activity. Materials and MethodsMaterials and chemicals Dried powder of seeds obtained from camu-camu juice production was obtained from Empresa Agroindustrial del ...

Food companies should comply with the requirements of a zero‐waste concept to adapt to the circular economy requirements. In fruit companies, usually seeds are discarded without proper utilization and extraction of the bioactive compounds. Fruit seeds are sources of chemical compounds that can be extracted, studied, and applied in high value‐added products. Thus, in this work the experimental conditions for the water extraction of phenolic compounds from camu‐camu (Myrciaria dubia) seed coat were optimized using a central composite design and the desirability function. Total phenolic content (TPC), and condensed tannins (CT), DPPH radical scavenging activity, ferric reducing antioxidant capacity (FRAP), Folin‐Ciocalteu reducing capacity (FCRC), and Cu2+chelating ability were assessed. Seed coat extracted for 51.1 min using a 1:34.1 solid:liquid ratio was the optimal condition to extract 6,242 mg gallic acid equivalent (GAE)/100 g of TPC and 695 mg catechin equivalent (CE)/100 g of CT. The optimized extract displayed free‐radical scavenging activity, reducing properties and ability to chelate Cu2+, and inhibited the growth of Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella Typhimurium, Salmonella Enteritidis, Bacillus cereus, and Staphylococcus aureus. Additionally, the lyophilized water extract inhibited the in vitro activity of α‐amylase, α‐glucosidase, and angiotensin converting enzyme and showed cytotoxic effects towards Caco‐2, A549, and HepG2 cancer cells, but no cytotoxicity towards IMR90 cells. Vescalagin, castalagin, and 3,4‐dihydroxybenzoic acid were the major phenolic compounds identified in the optimized extract. In conclusion, the optimized camu‐camu seed coat water extract is a rich source of phenolic compounds with antioxidant, antidiabetic, antihypertensive, and antiproliferative effects. Practical Application Camu‐camu fruit pulp and seeds have been studied for their phenolic composition and bioactivity. However, seeds are usually discarded and represent an environmental problem in South American countries. We presented a methodological overview on the extraction optimization of the phenolic compounds from camu‐camu seed coat and studied the bioactivity of the optimized extract using chemical, enzymatic, and cell‐based experiments. Results can be used by camu‐camu processors to obtain a phenolic‐rich extract for industrial applications, without any further processing.