A brief review of nutrient content of capsicum (Shimla Mirch)

Antioxidant activity

In the pursuit of natural antioxidants derived from botanical origins, the antioxidant and radical scavenging properties of various medicinal plants and fruits have been subject to extensive investigation in recent decades. Fruits and vegetables harbor a plethora of antioxidants, which mounting experimental evidence suggests play a pivotal role in shielding cellular components, including DNA, proteins, and lipids, from detrimental free radicals. Moreover, these antioxidants have been linked to reduced incidence and mortality rates of cancer and cardiovascular disease, along with a spectrum of additional health advantages (Park et al., 2012) [31] . Flavonoids, ubiquitously present in plants, exert a myriad of biochemical and pharmacological effects, encompassing antioxidant, anti-inflammatory, and anti-allergic properties.

Their consumption has been associated with a reduced risk of cancer and inhibition of enzymes such as prostaglandin synthase, lipoxygenase, and cyclooxygenase, which are closely linked to tumorigenesis. [22][23] .

The values of phenolic compounds ranged from 0.058 to 0.085 mg/100 g (Perucka and Materska, 2007) [33] . Studies conducted on phytochemical compounds in nine fruit variants (morphotypes -Chile de Agua, Guero, Nanchita, Piquin, Solterito, Tusta, Costeno, Canario, and Tabaquero) of peppers revealed that the total phenol values ranged from 61 to 402 mg/100 g fresh weight (Guzman et al., 2011) [10] .

Bell peppers have risen in popularity among vegetables, largely due to their rich concentration of antioxidants. Among these antioxidants, polyphenols, a class of phytochemicals, stand out for their exceptional ability to scavenge free radicals. These compounds, which undergo significant fluctuations in levels throughout the growth and maturation stages of peppers, play a crucial role in determining the pungency, bitterness, color, and flavor of the fruits (Estrada et al., 2000) [6] .

Various studies have been conducted to evaluate the antioxidant compounds and activities in bell peppers of different colors, namely green, yellow, orange, and red (Capsicum annuum L.). One such study focused on the assessment of total phenolic content across these color variants. The findings indicated that the total phenolic content varied across the different colored peppers, with green peppers exhibiting 2.4 μmol catechin equivalent/g fresh weight, yellow peppers showing 3.3 μmol catechin equivalent/g fresh weight, orange peppers displaying 3.4 μmol catechin equivalent/g fresh weight, and red peppers boasting the highest content at 4.2 μmol catechin equivalent/g fresh weight (Nadeem et al., 2011) [26] . These detailed analyses shed light on the significant antioxidant potential inherent in bell peppers, particularly highlighting the role of polyphenols in contributing to their health benefits and sensory attributes. Such insights deepen our understanding of the nutritional value of bell peppers and underscore their importance in promoting overall wellbeing through dietary consumption (Alieozaman et al, 2023) [5] .

The chemical compounds present in bell peppers actively prevent the oxidation of essential fats within brain cells, which are considered necessary for optimal brain function (Oboh and Rocha, 2008) [28] . The stability of phenol compounds depends on various factors, such as pH value and temperature (Zhang et al., 2001) [44] . Shotorbani and colleagues conducted a study on the antioxidant activity in two different colored (red and green) sweet bell peppers at various temperatures. They reported that the total phenol and flavonoid contents of pepper extracts increased with rising temperatures up to 65 °C. They concluded that maintaining an appropriate temperature resulted in high antioxidant activity of phenolic compounds, possibly due to the combined effect of non-enzymatic reactions and phenolic compound stability (Shotorbani et al., 2012) [41] The bell pepper undergoes a transition in color as it matures, starting from green and progressing to various hues such as orange, red, or yellow. Phytochemicals found in fruits and vegetables can be influenced by several factors, including the stage of maturation, genotype, and storage and processing conditions (Lightbourn et al., 2008) [19] . Methanol extracts of four different colored bell peppers (red, orange, yellow, and green) exhibit varying levels of total phenolic content (TPC) and antioxidant activities.

Research indicates that red and orange bell peppers possess significantly higher TPC levels compared to yellow or green bell peppers. Among these, orange bell pepper demonstrates the highest radical scavenging activity and total antioxidant activity, while green bell pepper exhibits the highest superoxide dismutase-like activity. Researchers suggest that the disparity in antioxidant activities may be linked to the types of antioxidant compounds associated with the pepper's color (Park et al.,2012) [31] .

In aqueous extracts of Capsicum annuum (Bell Pepper), antioxidant activities, total phenolic contents, and total flavonoid contents range from 0.795 to 1.893 μmol BHA/g, 0.739 to 1.291 μmol of gallic acid equivalent, and 0.306 to 0.551 μmol of quercetin equivalent, respectively (Rahim and Mat, 2012) [34] . Due to the economic and nutritional significance of bell peppers, grafting is increasingly utilized in this crop, primarily for controlling nematodes and soil-borne diseases.

Grafting has also been assessed for its impact on crop yield and fruit morphological characteristics. [14,29,17] . Different cultivar/rootstock combinations of bell pepper exhibit varied responses, with Fascinato/Robusto showing the highest concentration of total phenols and the greatest antioxidant activity among the combinations evaluated. The optimal sampling time for peppers to achieve the highest concentrations of bioactive compounds and antioxidant activity was found to be September (Celia et al., 2015)] [45] . Evaluation of phytochemical compounds in nine fruit variants of pepper reveals that flavonoid content ranges from 9.5 to 97 mg/100 g (Guzman et al., 2010) [10] .

Habanero pepper fruit is recognized as an excellent source of phytochemicals, including vitamins A and C, phenolic compounds, flavonoids, and carotenoids (Antonious et al., 2009) [2] . [4] . However, the values of DPPH radical scavenging activity (%) and total phenol content (mg/g) in Capsicum annuum Linn. var. grossum were recorded at 25.0 percent and 4.20 mg/100 g, respectively (Gacche et al., 2010) [8] . Research also suggests a decline in phenol concentration in Capsicum chinense Jacq. (Gayathri et al., 2016) [9] .

Ascorbic acid content (Vitamin C)

Peppers are renowned for their rich array of phytochemicals and serve as a notable source of vitamin C, which is hypothesized to play a role in cancer prevention by inhibiting the formation of N-nitroso compounds in the stomach and stimulating the immune system ( [3,30,11,21] . Vitamin C also stands out as the most abundant water-soluble antioxidant in the human body (Frei et al., 1989) [7] . Numerous reports have highlighted lower vitamin C content in infected capsicum (Murat et al., 2011) [25] . Range of Vitamin C is given in Table 1.

The quantity of vitamin C present in peppers depends on factors such as the cultivar, stage of maturity, and season of the crop. In Capsicum annuum, vitamin C values range from 101 to 114.85 mg/100 g (Perucka and Materska, 2007) [33] although these ranges may differ across variants. For instance, in nine fruit variants of pepper, vitamin C content ranged from 1.9 to 183.2 mg/100 g (Guzman et al., 2011) [10] . Capsicum annum Linn. var. grossum is reported to have a vitamin C content of 20.48 mg/100 g (Gacche et al., 2010) [8] .

Bell pepper holds a significant place among vegetables in India due to its delicacy, pleasant flavor, and richness in ascorbic acid, vital for a strong and healthy immune system (Agarwal et al., 2007) [1] . [15] . In Habanero Pepper (Capsicum chinense), ascorbic acid content varied from 187.24 to 281.73 mg/100 g sample (Majidi and Hazim, 2016) [20] . [16] . Maintenance of daily dietary intake of vitamin C is crucial for preventing scurvy, a deficiency disease state of vitamin C. An analysis of vitamin C content in Capsicum under fresh and storage conditions by the titrimetric method revealed that fresh red pepper and green pepper contained 81.53 mg/100 g and 27.62 mg/100 g of vitamin C, respectively, while under storage conditions, red pepper and green pepper contained 28.26 mg/100 g and 10.65 mg/100 g of vitamin C (Patrick et al., 2016) [32] . Overall, green bell peppers contain approximately 16.52 mg of vitamin C per 100 g, yellow bell peppers contain 159.61 mg per 100 g, orange bell peppers contain 121.38 mg per 100 g, and red bell peppers contain 81.19 mg per 100 g (Nerdy, 2018) [27] . The characterization of accessions with higher vitamin C content is of interest in plant breeding. In [38] .

Chlorophyll and carotenoids content

Chlorophyll, a natural pigment derived from green plants and algae, plays a crucial role in absorbing energy from the sun, which is then utilized in synthesizing carbohydrates from CO 2 through photosynthesis (Raven et al., 2005) [35] . Within the chloroplasts of higher plants, two main types of chlorophyll are found: chlorophyll a (blue-green) and chlorophyll b (yellow-green), distinguished by differences in the substituent of a pyrrole ring II. Apart from its pivotal role in photosynthesis, chlorophyll also finds application as a natural pigment in food and cosmetics (Humphery, 2004) [12] . In a study conducted by Sercan and colleagues, the effects of Tobacco mosaic virus (TMV) infection on growth and physiological parameters were analyzed in three pepper varieties (Capsicum annuum L) -Ergenekon F1, Kumsal F1, and 497 F1. A comparison between infected and noninfected plants revealed that TMV infection resulted in a reduction of chlorophyll a, chlorophyll b, and carotenoid content. Specifically, in the case of the Ergenekon variety infected with TMV, chlorophyll a content was reduced to 1.77 compared to 3.85 mg/L in the control group. Similarly, the Kumsal variety infected with TMV exhibited a chlorophyll a content of 2.82 compared to 3.13 mg/L in the control, while the 497 variety infected with TMV showed a chlorophyll a content of 1.49 compared to 3.73 mg/L in the control. Regarding chlorophyll b content, the Ergenekon variety infected with TMV displayed 0.59 mg/L compared to 0.72 mg/L in the control, the Kumsal variety showed 0.33 mg/L compared to 0.57 mg/L in the control, and the 497 variety exhibited 0.12 mg/L compared to 0.77 mg/L in the control (Sercan et al., 2013) [39] . Numerous reports have highlighted variations in chlorophyll content between healthy and diseased leaves of capsicum.

One study indicated that in fresh tissue weight, chlorophyll a, b, and total chlorophyll content were 0.2834 mg/g, 0.1650 mg/g, and 0.4932 mg/g, respectively. Conversely, in diseased leaves, chlorophyll a, b, and total chlorophyll content decreased significantly, reaching 0.0489 mg/g, 0.0779 mg/g, and 0.1425 mg/g, respectively (Kesh et al., 2016) [13] .

Additionally, chlorophyll content varies based on the hybrid of capsicum. The Indam Mamatha F1 hybrid exhibited the highest chlorophyll content at 13.30 mg/100 g, followed by the Natasha F1 hybrid at 12.00 mg/100 g, Bachata at 11.94 mg/100 g, and Indian F1 hybrid at 11.84 mg/100 g [29] . Carotenoid content in fresh capsicum fruit ranged from 4 to 1173 μg/g, while in dried fruit, it varied from 187 to 10,121 μg/g (Wall et al., 2001). In Habanero Pepper (Capsicum chinense), the carotenoid content ranged from 1.00 to 1.26 mg/100 g (Campos et al., 2013) [4] .

β -carotene content

Vitamin A plays a critical role in maintaining normal vision, supporting the integrity of epithelial tissues, and facilitating various metabolic functions within the body. In many developing regions, up to 80% of dietary vitamin A intake is derived from provitamin A-rich food sources. Provitamin A carotenoids serve as the precursor to vitamin A and are synthesized as pigments by numerous plants, particularly in green, orange, and yellow plant tissues. These provitamins, including alpha-carotene, beta-carotene, gamma-carotene, and cryptoxanthin, are commonly found in plant-based foods. Among these, beta-carotene emerges as the most predominant and active form in practical terms (Mclaren, 2012) [24] . Sweet bell pepper (Capsicum annuum L.) stands out as an excellent source of carotenoids, including beta-carotene, capsantin, and capsorubin. Research indicates that red peppers exhibit higher levels of beta-carotene, with a content of 5.4 μg/g, while yellow peppers have the lowest beta-carotene content at 0.2 μg/g (Nadeem et al.,2011) [26] . Studies utilizing high-performance liquid chromatography (HPLC) have demonstrated significant variability in betacarotene levels among ripe and dried peppers. In ripe fruit, beta-carotene levels range from 0 to 166 μg/g, while in dried fruit, the content varies from 2 to 739 μg/g and 24 to 1198 μg/g (Wall et al.,2001). Furthermore, phytochemical screening and antimicrobial activity assessments of Capsicum chinense Jacq. revealed an increase in carotenoid concentration as peppers reached maturity (Gayathri et al., 2016) [9] . These findings underscore the importance of sweet bell peppers as a valuable dietary source of carotenoids, particularly betacarotene, and highlight the potential health benefits associated with their consumption.

Mineral content

Sweet pepper is a valuable vegetable with unique healthpromoting and taste properties (Marin et al., 2004) [21] . High concentrations of mineral components important for human health have been identified in pepper (Rubio et al., 2002) [37] . Capsicum annuum serves as a good source of both micro and macro nutrients, including 0.08% calcium, 0.01% zinc, 0.02% sodium, 69.25% potassium, and 0.07% iron, respectively (Sharma et al., 2017) [37] . Moreover, pepper exhibits a vast genotypic diversity, influenced by factors such as genotype, fruit ripening stage, and the interaction between genotype and ripening stage. Consequently, variations occur in the mineral content of unripe and ripe fruit, with phosphorus (P) ranging from 190 to 351 mg/100 g in unripe fruit and 158 to 305 mg/100 g in fully ripe fruit, calcium (Ca) ranging from 25 to 61 mg/100 g in unripe fruit and 10 to 21 mg/100 g in fully ripe fruit, magnesium (Mg) ranging from 123 to 250 mg/100 g in unripe fruit and 102 to 274 mg/100 g in fully ripe fruit, and potassium (K) in fully ripe fruits ranging from 1509 to 2755 mg/100 g (Ribes et al., 2014) [36] .

Conclusion

The present review on Capsicum annuum (bell pepper) provides a comprehensive account of phytochemical constituents such as ascorbic acid, several carotenoid pigments, and a large amount of phenolic compounds. This article demonstrates that Capsicum is a natural source of nutrients, emphasizing the importance of consuming natural antioxidants over synthetic ones. In the current era, there is a growing trend towards selecting foods high in phytochemical and antioxidants to prevent diseases, and this article encourages people to consider consuming Capsicum as a source of antioxidants.

Acknowledgement

The authors are highly thankful to the Head of Department of Chemistry and Biochemistry for help and worthy suggestion.

Conflict of Interest Statement

The authors declare that there are no conflicts of interest regarding the publication of this paper.

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