cosmetics Review Cosmetic Potential of Cajanus cajan (L.) Millsp: Botanical Data, Traditional Uses, Phytochemistry and Biological Activities Duangjai Tungmunnithum 1,2,3,* and Christophe Hano 2,3,* 1 Department of Pharmaceutical Botany, Faculty of Pharmacy, Mahidol University, 447 Sri-Ayuthaya Road, Rajathevi, Bangkok 10400, Thailand 2 Laboratoire de Biologie des Ligneux et des Grandes Cultures (LBLGC), INRAE USC1328, Université d’Orléans, 21 rue de Loigny la Bataille, F-28000 Chartres, France 3 Bioactifs et Cosmétiques, CNRS GDR3711, CEDEX 2, 45067 Orléans, France * Correspondence: [email protected] (D.T.); [email protected] (C.H.); Tel.: +66-264-486-96 (D.T.); +33-237-309-753 (C.H.) Received: 5 October 2020; Accepted: 31 October 2020; Published: 6 November 2020 Abstract: Cajanus cajan (aka pigeon pea) is a terrestrial medicinal plant native to Asian and African countries before being introduced to the American continent. This protein-rich legume species, belonging to the Fabaceae family, has been traditionally used to cure various ailments in many traditional medicines. Recent works have highlighted it as a rich source of a wide array of flavonoids and other phenolic compounds. The major biological activities that are currently reported on are mainly focused on antioxidant and anti-inflammatory activities which are relevant for the cosmetic field. For example, hydroalcoholic extract from C. cajan has been highlighted as a particularly effective antioxidant in various scavenging assays for both reactive oxygen or nitrogen species. One of its constituents, cyanidin-3-monoglucoside, has been reported to suppress inflammatory cytokine production (e.g., TNF-α, IL-1β, and IL-6 in murine RAW264.7 macrophages). The present review provides an overview on the flavonoids and phenolics from C. cajan as well as their biological activities that can be applied for cosmetic applications. In addition, the botanical data including taxonomic description, flowering season, distribution, synonyms and traditional uses are illustrated, so as to provide an overview of pigeon pea’s cosmetic/cosmeceutical potentials. Keywords: Cajanus cajan; pigeon pea; flavonoids; phenolic acids; coumarins; antioxidant; anti-inflammatory 1. Introduction Cajanus cajan (L.) Millsp is a protein-rich legume species belonging to the Fabaceae family. This medicinal flowering plant is distributed mainly in tropical areas such as Asian countries and India. C. cajan is also known as its common name, pigeon pea [1–3]. This medicinal species is also called different things depending on its location of growth [1,2]. Due to being rich in protein and interesting flavonoid and phenolic compounds, it is continuously studied and reported on nowadays. This work aims to update the literature on the reported flavonoids and phenolics and their biological activities that can be applied for cosmetic applications. In addition, the botanical data including taxonomic description, flowering season, distribution, synonyms as well as the traditional uses are illustrated, so as to provide an overview of pigeon pea’s cosmetic/cosmeceutical potential. Cosmetics 2020, 7, 0084; doi:10.3390/cosmetics7040084 www.mdpi.com/journal/cosmetics Cosmetics 2020, 7, 0084 2 of 12 2. BotanicalCosmetics Data 2020, 7, x FOR PEER REVIEW 2 of 12 C. cajan This2. Botanical paragraph Data provides a complete botanical description of (Figure1). Perennial shrubs, stem: erect, 1–3.5 m, branchlets green to gray with pubescent. Leaf: stipulate, pinnately 3-foliolate, This paragraph provides a complete botanical description of C. cajan (Figure 1). Perennial ovate to lanceolate, abaxial densely pubescent with inconspicuous yellow glands, adaxial shrubs, stem: erect, 1–3.5 m., branchlets green to gray with pubescent. Leaf: stipulate, pinnately 3- pubescent,foliolate, apex ovate acute to lanceolate, or acuminate; abaxial petioledensely pubescent 1–5 cm long. with inconspicuousInflorescence: yellowraceme glands, 3.5–8 adaxial cm long; pedunclepubescent, 1.5–4 cm;apex bracts acute or ovate acuminate; or ovate-elliptic. petiole 1–5 cmFlowers: long. Inflorescence:calyx campanulate, raceme 3.5–8 5–7cm long; mm, green, pubescent;peduncle corolla 1.5–4 papilionaceous cm; bracts ovate form, or ovate-elliptic. yellow, standard Flowers: suborbicular calyx campanulate, with auricle, 5–7 mm, wings green, obovate with auricle;pubescent; keel corolla apex papilionaceous obtuse. Ovary: form,pubescent; yellow, standard style suborbicular slender, linear, with auricle, glabrous; wings stigma obovate capitate, ovule numerous.with auricle;Fruit: keel apexLegume, obtuse. oblong Ovary: orpubescent; linear-oblong. style slender,Seeds: linear,subspherical, glabrous; stigma 3–6 mm capitate, in diameter, ovule numerous. Fruit: Legume, oblong or linear-oblong. Seeds: subspherical, 3–6 mm in diameter, gray with brown spots. gray with brown spots. Figure 1.FigureCajanus 1. Cajanus cajan (L.)cajan Millsp: (L.) Millsp: (A) habitat;(A) habitat; (B )(B leaves;) leaves; (C ()C Inflorescence) Inflorescence and fruits. fruits. The The photos photos were were taken by D.T. on 13 January 2019, in North-Eastern Thailand. taken by D.T. on 13 January 2019, in North-Eastern Thailand. Flowering season: Between June and November (according to our preliminary survey in the Flowering season: Between June and November (according to our preliminary survey in the natural habitats, some years its flowering season finishes in January). natural habitats,Distribution: some years Tropical its regions, flowering especially season Thailand, finishes China, in January). India. Distribution:Synonyms:Tropical Cajan indorum regions, Medik., especially Cajan inodorum Thailand, Medik., China, Cajanus India. cajan (L.) Huth, Cajanus cajan Synonyms:var. flavus (DC.)Cajan Purseglove, indorum CajanusMedik., cajanCajan var. bicolor inodorum (DC.) Purseglove,Medik., Cajanus Cajanus striatus cajan Bojer,(L.) Huth, CajanusCajanus cajan var.obcordifoliaflavus (DC.) Singh, Purseglove,Cajanus pseudo-cajanCajanus (Jacq.) cajan Schinzvar. andbicolor Guillaumin,(DC.) Cajanus Purseglove, indicus CajanusSpreng., Cajanus striatus Bojer, indicus var. flavus (DC.) Kuntze, Cajanus indicus var. bicolor (DC.) Kuntze, Cajanus indicus var. Cajanus obcordifolia Singh, Cajanus pseudo-cajan (Jacq.) Schinz and Guillaumin, Cajanus indicus Spreng., maculatus Kuntze, Cajanus luteus Bello, Cytisus guineensis Schumach. and Thonn., Cytisus pseudocajan CajanusJacq., indicus Cytisusvar. cajanflavus L., (DC.)Phaseolus Kuntze, balicus L.Cajanus indicus var. bicolor (DC.) Kuntze, Cajanus indicus var. maculatus Kuntze, Cajanus luteus Bello, Cytisus guineensis Schumach. and Thonn., Cytisus pseudocajan Jacq., Cytisus3. Traditional cajan L., UsesPhaseolus balicus L. Pigeon pea is a terrestrial medicinal plant native to Asian and African countries before being 3. Traditionalintroduced Uses to the American continent. This species, a member of the Fabaceae family, has been used Pigeonfor protein-rich pea is a terrestrialfood and medicines medicinal since plant prehistori nativec times to Asianin Asia, andEgypt African and African countries regions before[2–6]. being This herbal species was also called the meat of poor people because of its seeds that consist of high introduced to the American continent. This species, a member of the Fabaceae family, has been used protein content. In the past, C. cajan has been used mainly as food and traditional medicines. For for protein-richexample, people food and in some medicines areas of since Tamil prehistoric Nadu, India times use young in Asia, stems, Egypt leaves and and African seeds to regions cure [2–6]. This herbalgingivitis, species stomatitis was and also also called as a toothbrush the meat [7]. of In poor addition, people the leaf because of pigeon of pea its is seeds also applied that consist to of high proteintreat oral content. ulcers and In inflammations the past, C. cajan[2]. Fohasr the beentraditional used use mainly in Oman, as foodpeople and use C. traditional cajan seeds medicines.for For example,treatment people of various in some chronic areas diseases of Tamil [8]. Interestin Nadu,gly, India ancient use youngpeople used stems, juice leaves from the and leaves seeds of to cure pigeon pea to treat various skin problems even inside the human mouth [1,4,5]. This may be the gingivitis, stomatitis and also as a toothbrush [7]. In addition, the leaf of pigeon pea is also applied fundamental evidence to reveal the potential of C. cajan in skin care research and development. to treatNowadays, oral ulcers the and research inflammations interest in [2flavonoids]. For the and traditional other phenolics use in from Oman, this people medicinal use plantC. cajan is seeds for treatment of various chronic diseases [8]. Interestingly, ancient people used juice from the leaves of pigeon pea to treat various skin problems even inside the human mouth [1,4,5]. This may be the fundamental evidence to reveal the potential of C. cajan in skin care research and development. Nowadays, the research interest in flavonoids and other phenolics from this medicinal plant is Cosmetics 2020, 7, 0084 3 of 12 Cosmetics 2020, 7, x FOR PEER REVIEW 3 of 12 increasing, suggesting that more potential biological activities from these phytochemical compounds are waitingincreasing, to be investigated.suggesting that more potential biological activities from these phytochemical compounds are waiting to be investigated. 4. Phytochemical Characterization of the Main Phenolics from Pigeon Pea 4. Phytochemical Characterization