Phytochemical characterization and in vitro wound healing activity of leaf extracts from Combretum mucronatum Schum. & Thonn.: Oligomeric procyanidins as strong inductors of cellular differentiation.

ETHNOPHARMACOLOGICAL RELEVANCE: Leaves from Combretum mucronatum Schum. & Thonn. are traditionally used for wound healing in Western Africa. Aqueous and hydroalcoholic extracts of the dried leaves recently have been shown to stimulate viability of human keratinocytes and dermal fibroblasts. AIM OF THE STUDY: Phytochemical characterization of the herbal material, development of a validated HPLC methodology for quality control, and pinpointing the underlying pharmacological mechanism under in vitro conditions to understand the impact of C. mucronatum extracts on human skin cells. MATERIALS AND METHODS: Extracts obtained from the leaves from C. mucronatum by using solvents with different polarities (petrol ether, dichloromethane, ethanol-water 50%, water) were investigated concerning phytochemical composition by GC-MS, LC-MS and in part after fractionation and isolation of purified compounds. For quality control of the herbal material an ICH-2 validated UHPLC method was developed for quantification of the lead compounds epicatechin, procyanidin B2, vitexin and isovitexin. In vitro studies were performed using HaCaT keratinocyte cell line, primary keratinocytes and primary skin fibroblasts with determination of viability (MTT assay), cell proliferation (BrdU incorporation ELISA), cell toxicity (LDH release) and keratinocyte differentiation, using involucrin and keratin K10 as differentiation marker (confocal laser scanning microscopy, Western blot). RESULTS: A detailed phytochemical composition analysis of the extracts from the leaves from C. mucronatum was performed (compounds 1-34) and epicatechin, procyanidin B2, vitexin and isovitexin are assessed to be the lead compounds of the polar extract. Quantitative UHPLC investigations indicated mature leaves to have higher polyphenol content in comparison to young leaves. The drying process of the plant material was shown to have great influence on the content of the lead compounds. The aqueous extract (0.1-100µg/mL) did not change cell viability of dermal fibroblasts and keratinocytes but inhibited cellular proliferation rates significantly at 100µg/mL. The extract stimulated cellular differentiation of primary keratinocytes significantly at 1 and 10µg/mL. Procyanidin B2 at 1 and 10µM was shown to be responsible for the induction of this cellular differentiation, while epicatechin, and procyanidins B5, C1 and D1 were inactive. CONCLUSION: The in vitro effects of the aqueous extract on the skin cells rationalized the remedial effect in wound healing and possibly accounts for the reason why this plant may be widely used for this purpose. On the basis of this study extracts from the leaves of C. mucronatum therefore have potential for the use in wound healing.

Phase I trial, including pharmacokinetic and pharmacodynamic correlations, of combination paclitaxel and carboplatin in patients with metastatic non-small-cell lung cancer.

PURPOSE: To determine the maximum-tolerated dose of paclitaxel with carboplatin with and without filgrastim support in patients with metastatic non-small-cell lung cancer (NSCLC) and to investigate the pharmacokinetics of paclitaxel and carboplatin and correlate these with the pharmacodynamic effects. PATIENTS AND METHODS: Thirty-six chemotherapy-naive patients with metastatic NSCLC were entered into this phase I dose-escalation and pharmacokinetic study. Paclitaxel was initially administered as a 24-hour infusion at a fixed dose of 135 mg/m2, and the carboplatin dose was escalated in cohorts of three patients, using Calvert's formula [dose(mg) = area under the concentration time curve (glomerular filtration rate + 25)], to target areas under the concentration time curve (AUCs) of 5, 7, 9, and 11 mg/mL x minute. A measured 24-hour urinary creatinine clearance was substituted for the glomerular filtration rate. Once the maximum-tolerated AUC (MTAUC) of carboplatin was reached, the paclitaxel dose was escalated to 175, 200, and 225 mg/m2. When the paclitaxel dose escalation began, the AUC of carboplatin was reduced to one level below the MTAUC. RESULTS: Myelosuppression was the major dose-limiting toxicity. Thrombocytopenia was observed at a carboplatin AUC of 11 mg/mL x minute after course 2 and thereafter. End-of-infusion plasma paclitaxel concentrations and median duration of time above 0.05 microM were similar in course 1 versus course 2 at the 135 and 175 mg/m2 dose levels. The neutropenia experienced by patients was consistent with that observed in patients who had received paclitaxel alone. Measured carboplatin AUCs were approximately 12% (20% v 3% with course 1 v course 2, respectively) below the desired target, with a standard deviation of 34% at all dose levels. A sigmoid-maximum effect model describing the relationship between relative thrombocytopenia and measured free platinum exposure indicated that patients who received the combination of carboplatin with paclitaxel experienced less severe thrombocytopenia than would be expected from carboplatin alone. Of the 36 patients entered onto the study, one experienced a complete response and 17 had partial responses, for an overall response rate of 50%. The recommended doses of paclitaxel (24-hour infusion) and carboplatin for future phase II studies of this combination are (1) paclitaxel 135 mg/m2 with a carboplatin dose targeted to achieve an AUC of 7 mg/mL x minute without filgrastim support; (2) paclitaxel 135 mg/m2 with a carboplatin dose targeted to achieve an AUC of 9 mg/mL x minute with filgrastim support; and (3) paclitaxel 225 mg/m2 with a carboplatin dose targeted to achieve an AUC of 7 mg/mL x minute with filgrastim support. CONCLUSION: The regimen of paclitaxel and carboplatin is well-tolerated and has promising activity in the treatment of NSCLC. There is no pharmacokinetic interaction between paclitaxel and carboplatin, but there is a pharmacodynamic, platelet-sparing effect on this dose-limiting toxicity of carboplatin.

A pilot trial of paclitaxel, carboplatin, and concurrent radiotherapy for unresectable squamous cell carcinoma of the head and neck.

Combined chemoradiotherapy is superior to radiotherapy alone for stage III and IV squamous cell carcinoma of the head and neck, and concurrent use of both offers the advantage of synergistic interactions. Our prior trial demonstrated the ease and convenience of administering carboplatin during radiotherapy. Since paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) has activity in squamous cell carcinoma of the head and neck and can act synergistically with both radiotherapy and platinum drugs, we initially added paclitaxel at 45 mg/m2/wk to carboplatin given at 100 mg/m2 during radiotherapy given at conventional fractions. The initial dose of paclitaxel was subsequently reduced to 40 mg/m2/wk. Thirteen of 18 patients entered so far have sufficient follow-up data; 12 are assessable for toxicity and 11 are assessable for response. One died early of progressive disease, two achieved a complete response, six achieved a partial response, and two had stable disease. Toxicities have so far been manageable for the 76 weekly doses administered. Chemotherapy dose reduction was needed in 10 patients. For the planned 100 doses of chemotherapy, 53 (53%) were administered as planned, 23 (23%) were reduced, and 24 (24%) were withheld due to neutropenia or mucositis. There were no toxic deaths, and no patient stopped therapy for toxicity. Paclitaxel/carboplatin can be administered during radiotherapy for squamous cell carcinoma of the head and neck with acceptable toxicities, and further accrual is needed to evaluate the effect of this combination.

Pharmacokinetics of paclitaxel and carboplatin in combination.

We studied the pharmacokinetics of paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) and carboplatin administered in combination to 21 patients with advanced non-small cell lung cancer. Paclitaxel was administered as a 24-hour intravenous infusion at doses of 135 to 200 mg/m2. Carboplatin, dosed to a target area under the concentration-time curve of 5, 7, 9, or 11 mg/mL.min, was administered as a 20-minute infusion immediately following paclitaxel. Neither the paclitaxel concentrations at the end of the infusion nor the terminal elimination of paclitaxel, as assessed by the duration of time that plasma paclitaxel concentrations were 0.05 mumol/L or greater, were different compared with historical data of paclitaxel as a single agent. Thus, we concluded that carboplatin had no perceived effect on the pharmacokinetics of paclitaxel in this schedule. The observed areas under the concentration-time curves for carboplatin were consistently 10% to 15% less than the target values. Although this may indicate a possible interaction between paclitaxel and carboplatin, it also may have been a result of inadequate assessment of glomerular filtration rate, which was used to determine the carboplatin dose.