An ingredient that is created from the attachment of the water-loving sugar molecule, glucose, and an oil-loving 20 carbon long fatty chain. This makes it a partly water- and partly oil-soluble material, meaning it functions as an emulsifier helping oil and water to mix. Most often, it comes to the formula coupled with two fatty alcohol friends, Arachidyl and Behenyl alcohol, to make up an emulsifier trio trade named Montanov 202. As described by its manufacturer, the main thing of Montanonv 202 is the evanescent and light feel with a matt finish that it gives to creams. It leaves the skin soft, but not oily, is hypoallergenic and non-comedogenic making it perfect for both oily skin and sensitive skin formulas.
An ester that comes from Cetearyl alcohol and the fatty acids of olive oil. It often comes to the formula coupled with Sorbitan Olivate as the two together form the well-known, natural emulsifier trade named Olivem 1000. Other than helping oil and water to blend, the main thing of Olivem 1000 is generating liquid crystal structures that are similar to the lipid structures of the stratum corneum (the outermost layer of the skin). Thanks to this, Olivem 1000 doubles as an active ingredient with significant moisturizing, barrier-repairing and soothing properties. It also helps to deliver water-soluble actives such as caffeine more effectively, and can even boost SPF in sunscreen formulas. Its typical use level is 1-5% and has wide compatibility with other actives and oils. Overall, a real multi-tasker with nice sensorial properties. No wonder it is so popular.
Houttuynia Cordata Extract
Houttuynia cordata is a flowering plant native to Southeast Asia. It is eaten as a leaf vegetable, and also has a long history of use in traditional Chinese medicine, including as an attempted treatment for SARS (it didn’t really work). Regarding cosmetics, however, houttuynia cordata extract has a good bit of potential! The main active components in the plant are these fancy chemicals called flavonoids. Houttuynia cordata specifically has a good amount of polyphenolic flavonoids, four common ones being quercetin, quercitrin, hyperoside, and rutin. All of these exhibit anti-inflammatory, antioxidant, and antibacterial properties. Quercitrin has also been shown to decrease damage from UVB rays, which is an added bonus. One thing to keep in mind, though, is that the flavonoid content of this extract can depend on if the extract is taken from the roots or the leaves, as well as if it’s a water extraction or an alcohol extraction. Another thing Houttuynia cordata extract contains are polysaccharides, i.e. big molecules from various sugar units (in this case it is galacturonic acid (29.4%), galactose (24.0%), rhamnose (17.2%), arabinose (13.5%), glucuronic acid (6.8%), glucose (5.3%), xylose (2.1%) and mannose (1.8%) ). Polysaccharides and sugars in skincare are excellent humectants and skin hydrators, meaning they help the skin to hold onto water. Last but not least, we also found an in-vitro (made in test tubes) study showing that houttuynia cordata extract had strong anti-allergic effects and could be helpful in treating skin allergies such as eczema (atopic dermatitis).
Quercetin is a polyphenol flavonoid found in lots of plants, such as red onions, broccoli, and blueberries. The reason it is in cosmetics is that - similar to other polyphenols - it is a strong antioxidant and has anti-inflammatory properties. Other than that, a study also showed that adding quercetin to sunscreens helped to stabilize the otherwise not very stable chemical UV filters avobenzone and octinoxate against degradation -- and it did better than traditional stabilizers like octocrylene and vitamin E! There are also some studies into the use of quercetin as a skin whitening agent, but after some conflicting results, the conclusion is that "quercetin is not effective in cosmetic applications as a whitening ingredient". It also shows minor cytotoxicity when compared to some of its polyphenol derivatives (such as rutin), so quercetin is a good example where more is not better.
Rutin is a polyphenol flavonoid found in many plants, for example, citrus fruits. The main reason it's used in cosmetics is its high antioxidant and free radical-scavenging ability (similar to that of superstar ascorbic acid), but also has some antibacterial nature and wound-healing properties. There is also an in-vitro (made in Petri dishes on animal cell lines) study showing potential for rutin as a skin-whitening agent and people have even tried using it to increase the UV-blocking ability of SPF agents, but with inconsistent results. Either way, its antioxidant abilities should still help protect the skin against sun damage from the UV light that isn’t blocked by SPF agents!
Citrus Limon Fruit Extract
If life gives the cosmetic industry lemon, it makes lemon fruit extract. As to why, we can write here extremely similar things to our shiny description of orange fruit extract. Being both of them citruses, they contain very similar active compounds with very similar (potential) effects on the skin. Just like orange fruit, lemon fruit also contains citric acid so it is commonly used as a natural, mild exfoliating agent. If this is the case, it is usually combined with other AHA containing fruit extracts such as bilberry, sugar cane, orange, and sugar maple in a super popular ingredient mix trade named ACB Fruit Mix. But, citrus fruits are chemically complex mixtures with a bunch of other active components such as vitamin C, flavonoids, phenolics, carbohydrates and essential oil (this latter one coming from the rind of the fruit, but still present in some amount in the fruit extract). These have the potential to give lemon extract antioxidant, antibacterial, anti-dandruff, venotonic and moisturizing properties, but the essential oil also brings some questionable compounds such as fragrance allergen limonene or phototoxic compound bergaptene. If your skin is sensitive, be careful with citrus extracts.
Citrus Aurantium Dulcis Fruit Extract
We have to start by writing that there are about 900 citrus species in the world, and plenty of them are used to make different kinds of extracts used in cosmetics. This particular one, Citrus Aurantium Dulcis Fruit Extract is a very common ingredient, however, the species "Citrus Aurantium Dulcis" seem to exist only on ingredient lists and the real world calls this guy Citrus Sinensis or, you know, orange. To complicate matters further, there are lots of varieties and lots of extraction methods, so it is a bit hard to know what you are getting with this one, but we will try our best to summarize the possibilities. A very common scenario is that Citrus Aurantium Dulcis Fruit Extract is on the ingredient list for its mild, natural exfoliant properties. It contains mainly citric acid and some malic acid, AHA exfoliants known for their skin renewing properties. If that's the case, it is usually combined with other AHA containing fruits such as bilberry, sugar cane, lemon, and sugar maple in a super popular ingredient mix trade named ACB Fruit Mix. But orange fruit is loaded with lots of other active compounds with a wide variety of possible effects. A well-known one is the antioxidant vitamin C, aka ascorbic acid, but the dosage will vary based on the extraction method, and it’s possible that some of the ascorbic acid content will degrade before extraction process even takes place. If you want vitamin C in your skincare, that is smart, but do not rely on orange fruit extract for it. Flavonoids (hesperidin, naringin, luteolin, and ferulic acid) are also nice active compounds with possible antioxidant, anti-inflammatory, and vasoprotective effects. Some of them (namely hesperidin and luteolin) might even have skin brightening activity by inhibiting tyrosinase, the famous enzyme needed for melanin production. The orange extract also contains carbohydrates, aka sugars (mostly glucose, fructose, and sucrose, but also some bigger polysaccharides such as pectin) giving the ingredient some moisturizing properties. Some essential oil content is usually also present in citrus fruit extracts, which means a nice scent and antibacterial properties, but also some questionable compounds such as fragrance allergen limonene or phototoxic compound bergaptene. If the amount is big enough to worry about is questionable, probably not, however, the same question applies to all the nice beneficial compounds. Overall, we think that the orange fruit extract is a very complex ingredient with lots of potentially good things in it, but we could not find proper in-vivo (made on real people) studies made with standardized extracts to validate what it really does or does not under real-world use cases.
Citrus Unshiu Peel Extract
Out of the more than 900 Citrus species known today, Citrus Unshiu is a seedless, easy to peel tangerine coming from the Japanese town Satsuma. The peel extract used in cosmetics is mainly created from the "press-cake", the by-product of the juice industry and as it turns out, what's waste to one industry is a useful ingredient to another. In cosmetics, the main thing of the Citrus Unshiu Peel Extract is being a skin-brightening or whitening agent. In-vitro (made in test tubes) and animal studies both show promising results for inhibiting tyrosinase, the famous enzyme regulating melanin production. It also contains antioxidant components such as carotenoids, coumarins, limonoids, and flavonoids that might be useful for the skin to protect itself from UV caused damages. The downside of citrus peel extracts (that prevents our goodie rating) is that they usually contain some amount of essential oil components, though the amount is probably way too low to worry about unless you're super-duper sensitive.
Menthol needs no introduction: it's the thing that causes the cooling sensation so well-known both from cosmetic products as well as a bunch of other things like chocolate, chewing gum, toothpaste or cigarette. It's a natural compound that comes from the essential oil of Mentha species (peppermint oil contains 40-50% menthol) and it gives them their typical minty smell and flavor. As for skincare, menthol seems to be a mixed bag. Apart from the cool cooling sensation (that might last up to 70 mins!), it also has painkilling, itch reducing, antibacterial, antifungal and even penetration enhancing properties. On the other hand, it also seems to act as a skin irritant that increases trans-epidermal water loss (the water that evaporates from the outer layer of the skin) and thus contributes to drying out the skin.
Glutamic acid is a little molecule and non-essential (our body can synthesize it) amino acid with the important job of being a neurotransmitter in the human body meaning that it helps your nervous system work correctly. As for what it's doing in cosmetics, Glutamic acids' main thing (similar to other amino acids) is being a humectant moisturizer and skin-conditioning agent (sidenote: if you attach lots of glutamic acid molecules, you get polyglutamic acid that is claimed to be a better than hyaluronic acid humectant). It also seems to affect skin barrier repair, however, it is not clear-cut in which direction. The complication is that glutamic acid has two distinct forms, L-glutamic acid and D-glutamic acid, that are the mirror images of each other (think of it like your left and right hand). Studies show that a topical application of L-glutamic acid on damaged skin delayed skin repair, while D-glutamic acid application sped up skin repair. As both forms are used by the industry, it is a bit uncertain what you are getting with just glutamic acid on the ingredient list (but if it is a Shiseido group product, it is probably the goodie D-form :)). Other than that, Glutamic acid can also be used as a pH adjuster and can be processed via biological pathways into pyrrolidone carboxylic acid, the sodium salt of which is a goodie and one of your skin’s natural moisturizing factors.