Psoralen, also known as psoralene, is actually the parent compound that belongs to a family of natural products called furocoumarins. As far as the structure of this product is concerned, it has a relation with coumarin when it adds a fused furan ring. Moreover, it may also be regarded as a umbelliferone derivative.
Psoralen occurs naturally in Psoralea corylifolia seeds. It is also commonly found in celery, fig, West Indian satinwood, parsley and nearly all types of citrus fruits. Among all the fruits and vegetables containing psoralen, fig has the maximum content of this natural compound. In addition to figs other vegetables like carrots, celeriac and parsnips too contain significant amounts of psoralen. All of them are excellent natural sources of this compound. Some herbs and spices such as anise, caraway, cumin, coriander, chervil, mustard and dill also contain psoralen in rich amounts.
Psoralen has a number of therapeutic uses. For instance, this natural compound is used extensively in PUVA (psoralen + UVA) for curing conditions like eczema, cutaneous T-cell lymphoma, vitiligo and psoriasis. Several furocoumarins are very poisonous to fish, while people in Indonesia deposit some in the streams to catch fish.
Psoralen is actually a cluster of naturally occurring organic compounds that are present in plants belonging to the genus Psoralea. This genus includes plants like carrots, celery and turnips. The numerous flowering plant in the psoralen family also includes the Chinese herb called po gu zi, which is also referred to as bug u zhi (Psoralea corylifolia). Together all these plants produce specific compounds with the ability to make the human skin very reactive to the ultraviolet A or UVA light. As a result, these natural chemicals are known as PUVA compounds (which is mentioned earlier in this article), which are employed for treating a variety of skin problems including psoriasis, hair loss and vitiligo.
However, when taken in larger doses psoralen is toxic, because it hinders the deoxyribonucleic acid (DNA) production. As a result it can result in burns, skin rashes and even various types of skin cancer in healthy people, especially farm workers who harvest parsnips and celery, which contain this natural compound.
Psoralen is generally derived from furocoumarin, the parent composite family, which is composed of a ring of five furan compound resembling the six-carbon ring of benzene. In combination with coumarin, a substance with a fragrance, it is called benzopyrone. In fact, plants produce these compounds for their defence from insects as well as animals. As these compounds are very toxic in nature, they work as natural pesticides. In addition, they are also used by plants as agents to protect them against infects as well as invading micro-organisms. Psoralen molecules are quite small and, hence, they are capable of penetrating the cell wall and attaching to the thymine and adenine bases in the structure of the DNA. Once they bind to the DNA, these compounds remain static until they come in contact with UVA light. However, when they are exposed to such light, the compounds once again become active and stop the usual cell division process.
Before you start using foods containing psoralen in the form of a natural remedy for skin conditions like eczema, psoriasis and vitiligo, it is essential for you to check with your physician or healthcare provider. Using psoralen has some unwanted side effects, because this natural compound is highly toxic, especially when used in elevated doses. When psoralen comes in contact with sunlight or is exposed to any other ultraviolet light source, they may possibly result in mutagenic, phototoxic as well as photo-carcinogenic consequences. As a result, foods containing high amounts of psoralen may lead to development of age spots (also called liver spots), dermatitis and sunburn once your skin comes in contact with sunlight. Ingestion of elevated amounts of psoralen and your skin is exposed to any ultraviolet right source it may enhance the chances of developing various types of skin cancer. All the safety concerns regarding the use of psoralen notwithstanding, the Food and Drug Administration (FDA) have already approved PUVA for treating acute cutaneous psoriasis. When we talk of PUVA we actually refer to psoralen plus ultraviolet A or UVA.
In case you are keen to stay away from consuming foods containing psoralen, as they can make the skin reactive to sunlight, you need to remember that even touching such foods may result in undesirable reactions, especially in people who are photosensitive. When you handle foods containing elevated amounts of psoralen, these organic compounds may sometimes accumulate on the skin and when the skin comes in contact with the ultraviolet rays of the sun you may suffer from age spots, serious sunburn and other types of skin damage. Therefore, it is advisable that you always wear protective gloves while handling plants or foods that contain psoralen. Doing this will greatly reduce the risks of coming in contact with the compound.
In Chinese herbal medicine psoralen has been employed in small doses in the form of a topical cream to promote melanin production when exposed to sunlight or administered in the form of a muscle injection. Owing to this exceptional property psoralen is also used extensively in suntan lotions in the form of a suntan activator. It is especially effective in conditions wherein the levels of sunlight are reduced owing to climate. However, Switzerland banned the use of psoralen in suntan lotions in 1987. A decade later it was established that the use of psoralen in suntan lotions caused melanoma and, hence, a wider ban was imposed on the use of this chemical worldwide in 1996.
Subsequently, compounds containing psoralen chemicals blocking ultraviolet B (UVB) were introduced as a substitute in a number of countries, including France. Use of these replacement compounds was encouraged in the form of compounds that were safe for tanning, especially for people having a difficult time in tanning their skin. Nevertheless, the objective as well as the safety claims of these replacement compounds still remains controversial. It is worth mentioning here that some manufactures also use a related compound called umbelliferone in their tanning products, which is believed to possess photo mutagenic properties. This compound occurs naturally in coriander, carrots and several other plants.
The therapeutic use of psoralen for treating various skin conditions was pioneered in Egypt in the 1940s. Initially, this natural compound was used for curing vitiligo. In fact, generally psoralen is preferred to steroid therapy despite its elevated rate of adverse side effects. When used to treat conditions like psoriasis, this natural compound dries up the skin. As a result the infection of the skin is reduced considerably. Till 2011, scientists have been conducting studies to examine and find different means how blood banks can use psoralen for disinfecting the blood after it is exposed to UVA radiation. Psoralen will not have any harmful effect on erythrocytes (red blood cells) and plasma, while it will cause the DNA of leukocytes (white blood cells) in the blood to become inert.