In Ngazidja, S. album is also the main plant species used (33.33%) in Msindzano production (Figure 5), but with a lower percentage than in Ndzuani. It is followed by three plant species with a percentage use higher or equal to 10%. These include S. indicum (22.22%), A. hypogaea (14.14%) and A. schimperi (10.1%). In contrast to what z is observed in Ndzuani, A. schimperi is not the second main plant species, but it is overtaken by S. indicum and A. hypogaea.

In contrast, in Ndzuani several plant species had a percentage use higher than or equal to 5%. They are Mté (local name) 7.07%, Cocos nucifera, Euphorbia hirta and C. longa (6.06%); K. comorensis, P. americana and Guetterda speciosa at 5% each; Mtamtam (local name) at 4%; Punica granatum and Lawsonia inermis at 4% each; Ricinus communis, Tambourissa species and Aloes species at 2% each. The other plants have a use percentage of 1%.

The applications of Msindzano

Comorian women use  Msindzano for various reasons. The common use is for cosmetic reasons, including skin lightening and softening (Figure 6). It can further be used for medical reasons in particular against acne, allergies and some skin problems such as eczema. It is sometimes used for preventive reasons, especially against heat or radiation as a sun block (Figure 6).

Most respondents use Msindzano to clear their skin. In this case, 44.17% of interviewed women in Ndzuani use Santalum   album,    5.62%    Tamtam    and    5.22%   for Sesamum indicum (Figure 6). S. album is also widely used against radiation as a sun block (24.49%), heat (15.26%) and to eliminate acne (13.65%).

In Ngazidja (Figure 7), most people also use Msindzano to clear their skin. S. album (19.19%) is the main plant species used in this case. It is followed by A. hypogea and C. indicum (7.07% each), Mté (local name),

A. schimperi and C. longa (5.05% each) and G. speciosa (4.04%). The main purpose of Sesamum indicum is application against radiation as a sun block (9.09%). S. album (8.08%) is also used as a sun block (radiation).

Msindzano can consist of a mixture of several plant species (Table 1). Twenty-one mixtures are only used in Ndzuani and 10 in Ngazidja. A Tamtam (local name) and S. album mixture is only used as a skin lightener. The mixture largely used in Ndzuani is composed of K. comorensis, S. album and A. schimperi, and used against heat and to eliminate acne. In Ngazidja, the most used mixture consists of S. album and A. schimperi, and it is used as a sun block against radiation. The mixture with the highest number of plant species contains nine species, which include Sesamum indicum, Tamtam (local name), Jasminium mummulariae folium, Tamarindus indicus, Loksi (local name), M. fragrans, P. americana, S. album and L. inermis.

This mixture is used to lighten the skin and as a sun block against radiation. Some mixtures are used on three or four applications. For example, a mixture composed of S. album, Tamtam  and  S. indicum is used in four applications, namely to lighten skin, to eliminate acne, as a sub block against radiation and against heat. With three applications, a mixture consisting of S. album and Dacus carota is used to lighten the skin, against allergies, and against heat. To eliminate acne only, women use six mixtures in Ndzuani and two in Ngazidja. The fight against allergies is the application that has the fewest mixtures in both islands, namely one in both islands. They are composed of A. schimperi and M. fragrans in Ndzuani and A. schimperi,

R.    communis and K. comorensis in Ngazidja.

However, in certain applications, only one plant can be used. In Ndzuani, S. album is largely used alone to brighten the skin, to eliminate acne and as a sun block against radiation. In Ngazidja, it is principally used as a sun block against radiation and to lighten the skin. In Ndzuani, M. fragrans can be only used to eliminate acne, to lighten skin and as a sun block.

Most of the plants in this survey are known for their use in traditional medicine and cosmetics in various countries.

S.    album, the principal plant used as Msindzano in Comoros, is largely discussed in the literature. Misra and Dey (2013) reported that this plant is used against skin infections, as cicatrizing and as antiseptic. The literature stipulates that this plant possesses effects like antimicrobial (Hussain et al., 2011; Sindhu et al., 2010), immunopharmacologic and antivirals (Gupta and Caphalkar, 2016), antioxidant (Misra and Dey, 2013).

A.    schimperi, the second plant used in Ndzuani is known to possess antibacterial (Taye et al., 2011) and acaricidal (Owino et al., 2015) activities. S. indicum oil, the second plant largely used in Ngazidja, is known as an ingredient in soap, lubricants, perfumery, cosmetics, pharmaceuticals, insecticides and paints and varnishes (Chemonics International Inc., 2002; Barel et al., 2001). It forms an occlusive layer on the skin, keeping water inside upper stratum corneum layers and consequently acting as moisturizers (Barel et al., 2001).

In   Southern   India   it  is  used  to  anoint  the  body and hair. Indians have used sesame oil as an antibacterial mouthwash and for relieving anxiety and insomnia (Pathak et al., 2014). A clinical trial proved the effectiveness of sesame oil for treating nasal mucosa dryness rather than isotonic sodium chloride solution (Johnson et al., 2001). In addition, sesame oil contains large amounts of linoleate in triglyceride form which selectively inhibited malignant melanoma growth (Smith and Salerno, 1992).

A.    hypogea, one of the most used plants in Ngazidja, is also known as a dietary source. It is capable of producing stilbene derived compounds  that   are  considered  as  anti-fungal (El-Sayed et al., 2012). In addition, their stilbenoids display diverse biological activities in mammalian cells like anti-inflammatory, antioxidant activities and anti-nitric oxide production (Sobolev et al., 2011). It is also reported that their flavonoids have anti-cancer, anti-androgen, anti-Leishmania, anti-nitric oxide production, and anti-bacterial activity (Yazaki et al., 2009). Moreover, it was found that A. hypogaea L. exhibited anti-bacterial activity (Parekh and Chanda, 2008).

Less used plants like C. longa, E. hirta and M. fragrans are also known for their uses in cosmetics  and   therapeutics.   In   the  literature, various studies suggest that curcuminoids, phenolic compounds of turmeric, have antioxidant effects (Dall'Acqua et al., 2016), anti-inflammatory (Cooney et al., 2016), antimicrobial (Zhang et al., 2012), antiviral (Chen et al., 2010) and radioprotective (Lopez-Jornet et al., 2016). Antioxidant and antimicrobial properties are also attributed to Turmeric essential oil (Avanço et al., 2017).

As for E. hirta, various properties are attributed to it. It possesses antioxidant (Sharma et al., 2014; Subramanian et al., 2011; Basma et al., 2011), antimicrobials (Perumal et al., 2012; Rajeh et  al.,  2010),  anti-inflammatory  and  anticancer activities (Sharma et al., 2014).

Studies on the essential oil and various extracts of M. fragrans have shown that it has antioxidant and antimicrobial properties (Gupta et al., 2013; Shafiei et al., 2012), anti-angiogenic pest control (Piaru et al., 2012), radioprotective, anticancer, antidepressant, antidiabetic and hepatoprotective (Shafiei et al., 2012).

The proven effects of these different plants as antimicrobials, antioxidants and radioprotectives can corroborate their use in the Comoros in the different applications of Msindzano.