Curcumin: a novel therapeutic for burn pain and wound healing

Zingiberaceae extracts for pain: a systematic review and meta-analysis

Background

Members of the family Zingiberaceae including turmeric, ginger, Javanese ginger, and galangal have been used for centuries in traditional medicine. Preclinical studies of Zingiberaceae extracts have shown analgesic properties. This study aims to systematically review and meta-analyze whether extracts from Zingiberaceae are clinically effective hypoalgesic agents.

Methods

Literature was screened from electronic databases using the key words Zingiberaceae AND pain OR visual analogue score (VAS) to identify randomized trials. From this search, 18 studies were identified, and of these, 8 randomized, double-blinded, placebo-controlled trials were found that measured pain by VAS for inclusion in the meta-analysis.

Results

Findings indicated significant efficacy of Zingiberaceae extracts in reducing subjective chronic pain (SMD − 0.67; 95 % CI − 1.13 to − 0.21; P = 0.004). A linear dose-effect relationship was apparent between studies (R² = 0.71). All studies included in the systematic review reported a good safety profile for extracts, without the renal risks associated with non-steroidal anti-inflammatory drugs, and with similar effectiveness.

Conclusion

Our findings indicated that Zingiberaceae extracts are clinically effective hypoalgesic agents and the available data show a better safety profile than non-steroidal anti-inflammatory drugs. However, both non-steroidal anti-inflammatory drugs and Zingiberaceae have been associated with a heightened bleeding risk, and there have been no comparator trials of this risk. Further clinical studies are recommended to identify the most effective type of Zingiberaceae extract and rigorously compare safety, including bleeding risk.

Mass-spectrometric identification of T-kininogen I/thiostatin as an acute-phase inflammatory protein suppressed by curcumin and capsaicin

Curcumin and capsaicin are dietary xenobiotics with well-documented anti-inflammatory properties. Previously, the beneficial effect of these spice principles in lowering chronic inflammation was demonstrated using a rat experimental model for arthritis. The extent of lowering of arthritic index by the spice principles was associated with a significant shift in macrophage function favoring the reduction of pro-inflammatory molecules such as reactive oxygen species and production and release of anti-inflammatory metabolites of arachidonic acid. Beyond the cellular effects on macrophage function, oral administration of curcumin and capsaicin caused alterations in serum protein profiles of rats injected with adjuvant to develop arthritis. Specifically, a 72 kDa acidic glycoprotein, GpA72, which was elevated in pre-arthritic rats, was significantly lowered by feeding either curcumin or capsaicin to the rats. Employing the tandem mass spectrometric approach for direct sequencing of peptides, here we report the identification of GpA72 as T-kininogen I also known as Thiostatin. Since T-kininogen I is an early acute-phase protein, we additionally tested the efficiency of curcumin and capsaicin to mediate the inflammatory response in an acute phase model. The results demonstrate that curcumin and capsaicin lower the acute-phase inflammatory response, the molecular mechanism for which is, in part, mediated by pathways associated with the lowering of T-kininogen I.

Curcumin-encapsulated nanoparticles as innovative antimicrobial and wound healing agent

Burn wounds are often complicated by bacterial infection, contributing to morbidity and mortality. Agents commonly used to treat burn wound infection are limited by toxicity, incomplete microbial coverage, inadequate penetration, and rising resistance. Curcumin is a naturally derived substance with innate antimicrobial and wound healing properties. Acting by multiple mechanisms, curcumin is less likely than current antibiotics to select for resistant bacteria. Curcumin's poor aqueous solubility and rapid degradation profile hinder usage; nanoparticle encapsulation overcomes this pitfall and enables extended topical delivery of curcumin. In this study, we synthesized and characterized curcumin nanoparticles (curc-np), which inhibited in vitro growth of methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa in dose-dependent fashion, and inhibited MRSA growth and enhanced wound healing in an in vivo murine wound model. Curc-np may represent a novel topical antimicrobial and wound healing adjuvant for infected burn wounds and other cutaneous injuries.

Role for heat shock protein 90α in the proliferation and migration of HaCaT cells and in the deep second-degree burn wound healing in mice

Inflammation, proliferation, and tissue remodeling are essential steps for wound healing. The hypoxic wound microenvironment promotes cell migration through a hypoxia—heat shock protein 90 alpha (Hsp90α)—low density lipoprotein receptor-related protein-1 (LRP-1) autocrine loop. To elucidate the role of this autocrine loop on burn wound healing, we investigated the expression profile of Hsp90α at the edge of burn wounds and found a transient increase in both mRNA and protein levels. Experiments performed with a human keratinocyte cell line—HaCaT also confirmed above results. 17-dimethylaminoethylamino-17demethoxygeldanamycin hydrochloride (17-DMAG), an Hsp90α inhibitor, was used to further evaluate the function of Hsp90α in wound healing. Consistently, topical application of Hsp90α in the early stage of deep second-degree burn wounds led to reduced inflammation and increased tissue granulation, with a concomitant reduction in the size of the wound at each time point tested (p<0.05). Consequently, epidermal cells at the wound margin progressed more rapidly causing an expedited healing process. In conclusion, these results provided a rationale for the therapeutic effect of Hsp90α on the burn wound management.