Aloe vera (Aloe barbadensis) is utilized as an ingredient in a myriad of health and cosmetic products, principally due to its valuable moisturizing emollient effects. Scientific literature yields conflicting reports on the efficacy of aloe vera in the treatment of psoriasis. A randomized, double-blind, placebo-controlled study with 60 patients treated with aloe vera extract 0.5% in a hydrophilic creamthree times daily for up to 4 weeks showed the cream to be more effective than placebo without any adverse effects. Only 2 of 30 patients in the placebo group, but 25 of 30 in the treatment group, were rated as cured after 4 weeks, and the PASI score decreased from8.9 to 8.2 in the placebo group, and from9.7 to 2.2 under active treatment[60] [LOE-A]. In contrast, another double-blind, placebo-controlled study with 41 patients with slight to moderate psoriasis showed only a modest effect of a commercial, aloin-free aloe vera gel that was not superior to placebo. However, the high response rate of the placebo gel indicated a possible effect of the placebo in its own right, which could havemade the aloe vera gel appear less effective[61] [LOE-A]. The difference may also be due to the presence or absence of aloin, belonging to the anthranoids, which are known to have beneficial effects on psoriasis.
A double-blind, placebo-controlled, pilot study with 30 patients was conducted to determine the effectiveness of the oil of the kukui nut tree (Aleurites moluccana) as a topical treatment for psoriasis. No significant beneficial effect of the oil could be demonstrated [LOE-A], although anecdotal reports existed from psoriasis patients visiting Hawaii who seemed to benefit from topical kukui nut oil.[62]
In the treatment of psoriasis, TCHMs are commonly used. Randomized controlled clinical trials to assess the efficacy of Chinese herbs are difficult to undertake becauseTCHMs, similar to Japanese Kampo medicines, consist of a mixture of herbs individually formulated for oral intake by the patient. The specific combination utilized is often changed over timeaccording to the clinical status of the patient. Therefore, scientific literature yields little with regard to controlled clinical trials to substantiate the effects of those herbalmixtures. However, a great number of uncontrolled studies have been performed with TCHMs in psoriasis. In these trials, a total of 174 Chinese herbs have been used. The ten most commonly used herbs are Rhemannia glutinosa,A. sinensis, Salvia miltiorhiza, D. dasycarpus, Smilaxglabra, Oldenlandia diffusa, Lithospermum erythrorhizon,P. lactiflora, Carthamnus tinctorius, and Glycyrrhiza uralensis. Most of the key actions of these botanicals that are relevant to reducing psoriatic symptoms reflect anti-inflammatory activities, modulation of cytokine production, or inhibition of angiogenesis[67] [LOE-D]. More experimental studies are needed to elucidate the exact mode of action of the specific herbs.
One recent TCHM study investigated the effect of a new Pulian ointment (NPLO), consisting of two primary herbs, Radix Scutellariae (HuangQin) andCortexPhellodendri (Huang Bai). NPLO was applied twice daily in 108 psoriasis patients in addition to individual TCHM oral formulations. The effect of NPLO was assessed in a randomized, single-blind, vehicle-controlled study. After 4 weeks the NPLO was significantly superior (45%clearing) to the vehicle (12%clearing)[63] [LOE-A].
Indigo naturalis (Qing Dai) is a blue powder that is extracted from the stems and leaves of the plant Baphicacanthus cusia. In a prospective, non-randomized, half-side comparison study, indigo naturalis 20% ointment was compared with vehicle in 14 patients with chronic plaque psoriasis. After 8 weeks, marked improvement was seen in 80% of the plaques treated with indigo naturalis, whereas no improvement was seen with the vehicle[64] [LOE-B]. In a subsequent randomized, vehicle-controlled, observer-blind, intra-patient comparison study with 42 patients, these findings were confirmed (about 74% clearing of the indigo-ointment treated lesions)[65] [LOE-A].
India madder root (Rubia cordifolia) is a Chinese herb with antiproliferative properties. There is evidence that induction of apoptosis of keratinocytes is the underlying mechanism for the observed antiproliferative action of Radix Rubiae. Experimental results suggest that this drug is a promising source from which a herb-based topical agent could be developed for the treatment of psoriasis[68] [LOE-D].
2.2.3 Summary There are some promising herbal treatments for psoriasis, which is a difficult-to-treat and chronic disease requiring a number of well tolerated alternatives for individual therapy. In addition to the well established plant-derived molecules, Oregon grape root and capsaicin are interesting candidates, and it is definitely reasonable to conduct more controlled clinical trials to substantiate the positive effects of TCHM in the treatment of psoriasis. However, psoriasiswill require combination rather than monotherapy, and tolerability and cosmetic effects of botanical formulations are nearly as important as their therapeutic potency.
