1. Introduction

Natural products from fruits source have promising biological activities as anti-ageing, anti-cancer, anti-inflammatory and against several infectious diseases [1,2]. The agriculture wastes of these fruits are produced in large quantities in most local and international markets and may cause several environmental problems [2,3]. Discarding of these wastes may occur by burning or unplanned landfilling. Therefore, researchers are looking for different ways to take the advantages of these agro-industrial wastes. As per literature, skins of different fruits contain several types of bioactive natural products which possibly have a high value of therapeutic importance [4]. Moreover, several types of outer peels as in kiwifruit peels, orange peels, lemon peels and pomegranate peels are used to produce vitamins, antioxidants antimicrobials and anticancer agents [5-7].

Physalis peruviana is one of the valued crops in Egypt [8]. The plant and its fruit are commonly called harankash, cape gooseberry and golden berry. It belongs to the Solanacea family and is closely related to the tomatoes. It is used in the traditional medicine as antimalarial, antispasmodic, a diuretic, anti-rheumatic and anti-hepatic therapeutic agent [9,10]. The fruit is rich with phenolic compounds, vitamins and minerals [11]. Several withanolides derivatives has been isolated from the fruit [12,13]. These compounds had several biological activities such as antitumor, antimicrobial, hepatoprotective and anti-inflammatory [14,15]. Additionally, the juice of harankash has dietary and antioxidant properties [16]. Peel and seeds of the fruit are also a rich source of oils, fibres and proteins [17,18]. The fruit of Physalis peruviana is surrounded by a papery calyx which protects the fruit against insects, pathogens, and adversative weather conditions. After eating harankash, the straw-colored calyces are thrown in the trash and become useless. As per literature, the calyx can be considered as agro-industrial wastes produced in fruit manufacture as well as an unexplored source of bioactive compounds. This study was designed to assess the chemical composition, antimicrobial and anticancer activities of the waste calyces of Physalis peruviana fruit growing in Egypt.

2. Materials and Methods

2.1. Sample Collection

Physalis was purchased from the different Egyptian local markets during January 2017. Calyces of Physalis peruviana were collected, air dried and stored in plastic bags.

2.2. Preparation of the Methanolic Extract

Dried calyces of Physalis peruviana was grounded to a finely coarse powder. Five grams of the powder was mixed with 20 ml of 80% methanol (v/v) using a Turrax mixer set at 11,000 rpm for 20 seconds [19]. The extract was then centrifuged at 3000 rpm for 30 minutes to remove the residues. The solvent was evaporated under vacuum.

2.3. Chemical Analysis

Ash, fats, fibres, moisture and crude protein were determined according to the AOAC methods (1995) [20]. Carbohydrate content was calculated by difference [21].

2.4. Mineral and amino acids profiles

Measurement of Fe, Zn and Cu was conducted according to the AOAC (2002) [22]. The amino acids were estimated by the AOAC protocol (2005) [23].

2.5. Gas chromatography analysis (GC-MS)

Analysis of the methanolic extract of the Physalis peruviana calyces was carried out using gas chromatography (Agilent Technologies 7890A) [24]. The components (Figure S1) were verified by matching their mass spectra and retention time with the database of National Institute of Standard and Technology (NIST) library.

2.6. Total phenolic, total flavonoids, saponins and antioxidant activity

The total phenolic, total flavonoids, saponins and antioxidant activity of the Physalis peruviana calyces were evaluated according to the reported methods in the literature [25-29].

2.7. Mycotoxin Determination

Total aflatoxin was performed according to AOAC (1998).

2.8. Antimicrobial Activity

Five microorganisms including two Gram-negative bacteria (E. coli and Salmonella sp.), two Gram-positive bacteria (Bacillus cereus and Bacillus subtilis) and one fungal strain (yeast) were used in our study. The strains were kindly supplied by Food Safety Laboratory, Regional Centre for Food and Feed, Agricultural Research Centre. The strains were maintained on slants of nutrient agar at 4 ^ºC in our laboratory. The microorganisms were cultured in Brain Heart Infusion broth at 37 ^ºC for 24 hours. The antibacterial activity of methanolic extract of Physalis peruviana calyces was evaluated by the disk diffusion method [30].

2.9. Cytotoxicity study

In this study, human hepatoma (Hep-3B), human gastric (AGS) and human breast (MDA-MB-231) cancer cell lines were supplied from the American Type Cell Culture Collection (ATCC, Manassas, VA, USA). The AGS and HeP-3B cells were cultured in Roswell Park Memorial Institute (RPMI) medium with 10% Fetal Bovine Serum (FBS). The MDA-MB-231 cells were cultured in Dulbecco's Modified Eagle's Medium (DMEM) supplemented with 4.5 g/L of glucose, 4 mmol/l of L-glutamine, and 10% heat-inactivated fatal calf serum [31]. Cancer cells (6000 cells/well) were seeded into a 96-well culture plate in 200 μl RPMI medium containing 10% FBS. Cells were cultured in a humidified atmosphere of 5% CO₂ at 37 ^°C. Extract concentrations ranged from 25-200 µg/ml were separately added to each well and monitored for their anticancer activity. After the 24-hourincubation period, cells were washed with of Phosphate-Buffered Saline (PBS). A 200 μl of PBS containing fluorescein diacetate (10 μg/ml) that was added to each well. The plates were incubated at 37 ^°C for one hour. Fluorescence was detected after one hour. Luteolin (17.5 µM) was used as a positive control [32].

3. Results and Discussion

3.1. Phytochemical Analysis

Phytochemical analysis of Physalis peruviana calyces that grows in Egypt is summarized in Tables 1-4. The percentages of ash, fat, fibre, moisture, protein, carbohydrates, minerals and amino acids are calculated based on dry weight of calyces. The results showed that calyces of Physalis peruviana are rich with carbohydrate (42.0%). Carbohydrates are the most abundant nutrient in several fruit peels [33]. Additionally, calyces contain fibre (32.0%), fat (2.1%) and protein (6.1%). The protein content of the Physalis peruviana calyces was higher compared with the protein content (1.02%) found in physalis fruit juice. Moreover, the ash and moisture content of calyces is 9.7% and 7.2%, respectively. The percentage of ash content reflects that calyces are rich with some minerals. As shown in Table 2, the level of calcium (7.50 mg) and iron (1.38 mg) is the highest in the calyces of Physalis peruviana. Calcium and iron are the major minerals in calyces of Physalis peruviana. It was reported that raw physalis juice had high contents of potassium (1210 mg/100 g) and sodium (1210 mg/100 g) [34]. Calcium plays an important role in the interactions between cells walls and ensures the structure of cells by hardening them. It’s also an important parameter in the synthesis of ethylene during maturing of the fruits [35]. Iron is vital for energy metabolism, temperature control and immune system [36].

To get more data about the phytochemical composition of Physalis peruviana calyces, the amino acids were determined and presented in Table 3. From the results, aspartic and glutamic acid were the major free amino acids in calyces with concentrations of 0.48% and 0.47%, respectively. Following in the order is leucine, alanine, glycine and the other amino acids. The amount of total phenolic, flavonoid, saponin and antioxidant capacity of the calyces from Physalis peruviana are presented in Table 4. The total phenolic contents were determined as mg gallic acid/100 g extract on comparison with a standard gallic acid curve. The extract showed a high total phenolic content (525 mg gallic acid/100 g). The total flavonoid content (61 mg quercetin /100 g) was determined as mg quercetin /100 g extract after comparison with the quercetin calibration curve. The extract also has 3.1% of crude saponin. As per literature, these compounds can be found not only in the eatable part of the fruits but also in the non-eatable portions and have different biological activities such as antioxidant, antihepatotoxic effects and anti-inflammatory activity [37-39]. The total antioxidant activity of the Physalis peruviana calyces was 395 mg Ascorbic Acid Equivalence (AAE)/100 g. The total antioxidant capacity may due to its flavonoids and phenol contents, compared to the fruit [40]. The lower value of the total antioxidant capacity of Physalis peruviana fruit was reported in the literature [41]. The dried calyces were free from aflatoxins.

The GC-MS analysis of the methanolic extract of Physalis peruviana calyces is shown in Table 5. Twenty-four compounds were identified, where the major predominant constituents were 2',5'-dimethoxyflavone (43.7%), 2',4'-dimethoxy-3-hydroxy-6-methylflavone (12.06%), 3-hydroxy-7,8,2'-trimethoxyflavone (6.39%) and xanthine (2.85%). Several polyphenols (phenolic and flavonoid) were identified in Physalis fruit by GC-MS [42]. According to the best of our knowledge, this research work is the first report about the phytochemical composition of calyces of Physalis peruviana cultivated in Egypt.

3.2. Antimicrobial and Cytotoxic Activities

The antibacterial activity of the methanolic extract of Physalis peruviana calyces (Table 6 and Figure 1) indicated that the extract had effect against Bacillus subtilis, Salmonella sp. and E. coli with inhibition zones of 27 mm, 24 mm and 24 mm, respectively. The extract showed no activity against Bacillus cereus but exhibited effect against yeast with inhibition zone diameter of 23 mm. The biological activities of calyces could be attributed to the presence of phenols, flavonoids, xanthine and saponins. Flavonoids had been demonstrated to possess antimicrobial, antifungal and antitumor activities [43].

The crude extract of Physalis peruviana calyces (Figure 2) were evaluated for their antitumor activities against a human hepatoma (Hep-3B), human gastric (AGS) and human breast (MDA-MB-231) cancer cell lines. Four different concentrations (25, 50, 100 and 200 µg/ml) were used in our study. Interestingly, the antitumor activity of the extract against a human gastric cancer cell line (AGS) is superior compared to the other cell lines. The anticancer activity of plants may be due to minerals, phenols and flavonoids [44]. As per literature, saponins had antibacterial, antioxidant and ant carcinogenic properties [45].

4. Conclusion

The agriculture waste of Physalis peruviana calyces cultivated in Egypt may be recommended as a good source of antimicrobial, antioxidant and anticancer agents. Toxicological and in-vivo studies should be carried out to evaluate the potential effectiveness and safety usage of the extract.

5. Acknowledgments

This research was funded by the Regional Centre for Food and Feed, Agriculture Research Center, Giza, Egypt.

6. Conflict of Interest

There is no conflict of interest.

Figure S1: GC-MS chromatogram Physalis peruviana calyces crude extract.

Figure 1: Antimicrobial activity of the methanolic extract of Physalis peruviana calyces.

Figure 2: Cytotoxic activity of the crude extract of Physalis peruviana calyces against AGS, Hep3-B and MDA-MB-231cell lines.

1. Chatzigeorgiou S, Thai QD, Tchoumtchoua J, Tallas K, Tsakiri EN, et al. (2017) Isolation of natural products with anti-ageing activity from the fruits of Platanus orientalis. Phytomed 15: 53-61.
2. Ayala-Zavala JF, Rosas-Domínguez C, Vega-Vega V, González-Aguilar GA (2010) Antioxidant enrichment and antimicrobial protection of fresh-cut fruits using their own by products: looking for integral exploitation. J Food Sci 75: 175-181.
3. Ordoudi SA, Bakirtzi C, Tsimidou MZ (2018) The potential of tree fruit stone and seed wastes in greece as sources of bioactive ingredients. Recycling 3: 9.
4. Sagar NA, Pareek S, Sharma S, Yahia EM, Lobo MG (2018) Fruit and vegetable waste: Bioactive compounds, their Extraction, and possible utilization. Compr rev food sci 17: 512-531.
5. Sadh PK, Duhan S, Duhan JS (2018) Agro-industrial wastes and their utilization using solid state fermentation: a review. Bioresour Bioprocess 5: 1.
6. Adámez JD, Samino EG, Sánchez EV, González GD (2012) In vitro estimation of the antibacterial activity and antioxidant capacity of aqueous extracts from grape-seeds (Vitis vinifera L.). Food Control 24: 136-141.
7. Rodríguez CS (2008) Exploitation of biological wastes for the production of value-added products under solid-state fermentation conditions. Biotechnol J 3: 859-870.
8. Hassanien MFR (2011) Physalis peruviana: A rich source of bioactive phytochemicals for functional foods and pharmaceuticals. Food Rev Int 27: 259-273.
9. Wu SJ, Ng LT, Chen CH, Lin DL, Wang SS, et al. (2004) Antihepatoma activity of Physalis angulata and Physalis peruviana extracts and their effects on apoptosis in human Hep G2 cells. Life Sci 74: 2061-2073.
10. Puente LA, Pinto-Muñoz CA, Castro ES, Cortés M (2011) Physalis peruviana Linnaeus, the multiple properties of a highly functional fruit: A review. Food Res Int 44: 1733-1740.
11. Zhao Y (2007) Berry fruit, value-added products for health promotion. CRC Press, NW, USA.
12. Lan YH, Chang FR, Pan MJ, Wu CC, Wu SJ, et al. (2009) New cytotoxic withanolides from Physalis peruviana. Food Chem 116: 462-469.
13. Llano SM, Muñoz-Jiménez AM, Jiménez-Cartagena C, Londoño-Londoño J, Medina S (2018) Untargeted metabolomics reveals specific withanolides and fatty acyl glycoside as tentative metabolites to differentiate organic and conventional Physalis peruviana fruits. Food Chem 244: 120-127.
14. Fang ST, Liu JK, Li B (2012) Ten new withanolides from Physalis peruviana. Steroids 77: 36-44.
15. Baumann TW, Meier CM (1993) Chemical defense by withanolides during fruit development in Physalis peruviana. Phytochemistry 33: 317- 321.
16. Ramadan MF, Moersel JT (2007) Impact of enzymatic treatment on chemical composition, physicochemical properties and radical scavenging activity of goldenberry (Physalis peruviana L.) juice. J Sci Food Agric 87: 452-460.
17. Ramadan MF, Moersel JT (2009) Oil extractability treated goldenberry (Physalis peruviana L.) pomace: range of operational variables. Int J Food Sci Technol 44: 435-444.
18. Ramadan MF, Sitohy MZ, Moersel JT (2008) Solvent and enzyme-aided aqueous extraction of golden berry (Physalis peruviana L.) pomace oil: Impact of processing on composition and quality of oil and meal. Eur Food Res Techno l226: 1445-1458.
19. Medina-Medrano JR, Almaraz-Abarca N, González-Elizondo MS, Uribe-Soto JN, González-Valdez LS, et al. (2015) Phenolic constituents and antioxidant properties of five wild species of Physalis (Solanaceae). Bot Stud 56: 24.
20. AOAC Association of Official Agriculture Chemists (1995) Official Methods of Analysis. 16th ed., Washington DC, USA.
21. Sara YH, Nafisa MEH, Amro BH, Mohamed ME, Elfadil EB (2008) Nutritional evaluation and physicochemical properties of processed pumpkin (Telfairia ocidentalis Hook) seed flour. Pakistan J of Nutr 7 : 330-334.
22. AOAC Association of Official Agriculture Chemists (2002) Official Methods of Analysis. 17th ed., Washington D.C. USA 1: 40-41.
23. AOAC. Association of Official Agriculture Chemists (2005) Official Methods of Analysis. 18th ed., Washington D.C. USA.
24. Patricia MS, Migdalia M, Juan AP, Mario S, Víctor H, et al. (2013) Gas chromatography-mass spectrometry study from the leaves fractions obtained of Vernonanthura patens (Kunth) H. Rob. Int J of Org Chem 3: 105-109.
25. Badr SEA, Sakr DM, Mahfouz SA, Abdelfattah MS (2013) Licorice (Glycyrrhiza glabra L.): Chemical Composition and Biological Impacts. Res J Pharm Biol Chem Sci 4: 606-621.
26. 26.  Chew YL, Chan EW, Tan PL, Lim YY, Stanslas J, et al. (2011) Assessment of phytochemical content, polyphenolic composition, antioxidant and antibacterial activities of Leguminosae medicinal plants in Peninsular Malaysia. BMC Complement Altern Med 11: 12.
27. Muanda F, Koné D, Dicko A, Soulimani R, Younos C (2011) Phytochemical composition and antioxidant capacity of three Malian medicinal plant parts. Evid Based Complement Alternat Med 2011:674320.
28. SingletonVL, Orthofer R, Lamuela-Raventós RM (1999) Analysis of total phenols and other oxidation substrates and antioxidants by means of Folin-Ciocalteu reagent. Meth Enz 29: 152-178.
29. Prieto P, Pineda M, Aguilar M (1999) Spectrophotometric quantitation of antioxidant capacity through the formation of a phosphomolybdenum complex: Specific application to the determination of vitamin E. Anal Biochem 269: 337-341.
30. Senhaj O, Faid M, Kalalou I (2007) Inactivation of Escherichia coli O157: H7 by essential oil from Cinnamomum Zeylanicum. Braz J Infect Dis 11: 234-236.
31. Abdelfattah MS, Elmallah MIY, Hawas UW, Abou El-Kassem LT, Eid MAG (2016) Isolation and characterization of marine-derived actinomycetes with cytotoxic activity from the Red Sea coast. Asian Pac J Trop 6: 651-657.
32. Lindhagen E, Nygren P, Larsson R (2008) The fluorometric microculture cytotoxicity assay. Nat Protoc 3: 1364-1369.
33. Maniyan A, John R, Mathew A (2015) Evaluation of Fruit Peels for Some Selected Nutritional and Anti-Nutritional Factors. Emer Life Sci Res 1: 13-19.
34. El Sheikha AF, Piombo G, Goli T, Montet D (2010) Main composition of Physalis (Physalis pubescens L.) fruit juice from Egypt. Fruits 65: 255-265.
35. Bakshi P, Masoodi FA, Chauhan GS, Shah TA (2005) Role of calcium in post-harvest life of temperate fruits: A review. J Food Sci Tech Mys 42: 1-8.
36. Beard JL (2001) Iron biology in Immune Function, Muscle Metabolism and Neuronal Functioning. J Nutr 131: 568-579.
37. Aboul-Enein AM, Salama ZA, Gaafar AA, Aly HF, Abou-Elella FA, et al. (2016) Identification of phenolic compounds from banana peel (Musa paradaisica L.) as antioxidant and antimicrobial agents. J Chem Pharm Res 8: 46-55.
38. Suttirak W, Manurakchinakorn S (2014) In vitro antioxidant properties of mangosteen peel extract. J Food Sci Technol 51: 3546-3558.
39. Wu SJ, Tsai JY, Chang SP, Lin DL, Wang SS, et al. (2006) Super critical carbon dioxide extract exhibits enhanced antioxidant and anti-inflammatory activities of Physalis peruviana. J Ethnopharmacol 108: 407-413.
40. Eken A, Ünlü-Endirlik B, Baldemir A, İlgün S, Soykut B, et al. (2016) Antioxidant capacity and metal content of Physalis peruviana L. fruit sold in markets. J Clin Anal Med 7: 291-294.
41. Demir T, Özen MÖ, Hameş-Kocabaş EE (2014) Antioxidant and cytotoxic activity of Physalis peruviana. Med Plant Res 4: 30-34.
42. Ramadana MM, El-Ghoraba AH, Ghanemb KZ (2015) Volatile compounds, antioxidants, and anticancer activities of Cape gooseberry fruit (Physalis peruviana L.): an in-vitro study. J Arab Soc Med Res 10: 56-64.
43. Kanadaswami H, Lee L, Lee PH, Hwang J, Ke F, et al. (2005) The antitumor activities of flavonoids. In vivo 19: 895-910.
44. Kathiresan K, Boopathy NS, Kavitha S (2006) Costal vegetation- An underexplored source of anticancer drugs. Nat Prod Rad 5: 115-119.
45. Makkar HP, Francis G, Becker K (2007) Bioactivity of phytochemicals in some lesser-known plants and their effects and potential applications in livestock and aquaculture production systems. Animal 1: 1371-1391.