A Clinical Trial to Compare the Photoprotective Effects of Cucumber Seed Extract vs Placebo in Filipino Adults by Measurement of Minimal Erythema Dose

A Double-blind Randomized Controlled Trial on the Photoprotective Effect of Cucumber (Cucumis Sativus) Seed Extract vs Placebo in Terms of Minimal Erythema Dose Among Filipino Adults

A monocentric, randomized, split-body, double-blind, controlled trial was conducted on 29 Filipino adults with Fitzpatrick skin types III-V. Topical 2% and 4% cucumber seed extract gels and placebo were applied to randomized sites on the lower back, followed by incremental narrow-band UVB exposure. MED was assessed 24 hours post-exposure. Repeated measures ANOVA and paired t-tests were used for statistical analysis.

Study Overview

• Status: Completed
• Conditions: Sunburn, Erythema; Healthy Human Volunteers With Fitzpatrick Skin Type III-V
• Intervention / Treatment: Drug: Placebo gel; Drug: 2% cucumber seed gel; Drug: 4% cucumber seed gel

• Study Type: Interventional
• Enrollment (Actual): 29
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Philippines
  • National Capital Region
    • Manila, National Capital Region, Philippines, 1003
      • DOH-Tondo Medical Center Department of Dermatology and Venereology

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

- Filipinos aged 18 to 59 years with Fitzpatrick skin phototypes III to V were included in the study.

Exclusion Criteria:

• Elderly and pediatric populations were excluded due to differences in skin structure, immune responses, and the presence of age-related comorbidities that may confound study findings. Additional exclusions applied to individuals who were pregnant or breastfeeding; had a history of phototoxic, photoallergic, or abnormal responses to sunlight; or reported allergies to cosmetic products, sunscreens, topical drugs, cucumber, or any study formulation component. Participants were also excluded if they presented with pre-existing or dormant dermatologic conditions, sunburn, suntan, scars, active lesions, or uneven pigmentation on the lower back. Other exclusion criteria included current or recent use of medications known to cause hyperpigmentation (e.g., minocycline, clofazimine, amiodarone, antimalarials, chemotherapeutic agents), systemic treatments affecting skin status within the past 15-30 days, sun exposure of the lower back within four weeks prior to inclusion, or intake of skin-whitening supplements such as glutathione within one month before the study.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Single Group Assignment
• Masking: Quadruple

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Randomized Test Site on Back 1; Three test sites were delineated on each participant's lower back, and study treatments were randomly allocated to these sites using computer-generated randomization performed by a dermatology resident not involved in the trial. Three MED test patches were applied on three sun-protected areas on the lower back. The test patch had six windows of uniform sizes (2 cm × 2 cm) that were opened and exposed one at a time to incremental doses of excimer light. The gels were applied by the research assistant on the designated randomized areas on the lower back. The assistant researcher then applied the respective gels at an amount of 2 mg/cm2 (1/4 teaspoon) on each of the three test sites. Gels were massaged to the skin until fully absorbed.	Drug: Placebo gel; The placebo gel serves as the base formulation is composed of: the oil phase of the formulation comprising of octadecanol, stearic acid, and liquid paraffin, while the aqueous phase consisted of distilled water, glycerin, and ethylparaben. The two phases were emulsified and combined to make the base gel. The assistant researcher then applied placebo gel at an amount of 2 mg/cm2 (1/4 teaspoon) on the designated test site.; Drug: 2% cucumber seed gel; Cucumber seed gel preparations were compounded by an FDA-registered pharmaceutical company which were incorporated into the placebo base gel at 2% concentration. The assistant researcher then applied 2% cucumber seed gel at an amount of 2 mg/cm2 (1/4 teaspoon) on the designated randomized test site.; Drug: 4% cucumber seed gel; Cucumber seed gel preparations were compounded by an FDA-registered pharmaceutical company which were incorporated into the placebo base gel at 4% concentration. The assistant researcher then applied 4% cucumber seed gel at an amount of 2 mg/cm2 (1/4 teaspoon) on the designated randomized test site.
Experimental: Randomized Test Site on Back 2	Drug: Placebo gel; The placebo gel serves as the base formulation is composed of: the oil phase of the formulation comprising of octadecanol, stearic acid, and liquid paraffin, while the aqueous phase consisted of distilled water, glycerin, and ethylparaben. The two phases were emulsified and combined to make the base gel. The assistant researcher then applied placebo gel at an amount of 2 mg/cm2 (1/4 teaspoon) on the designated test site.; Drug: 2% cucumber seed gel; Cucumber seed gel preparations were compounded by an FDA-registered pharmaceutical company which were incorporated into the placebo base gel at 2% concentration. The assistant researcher then applied 2% cucumber seed gel at an amount of 2 mg/cm2 (1/4 teaspoon) on the designated randomized test site.; Drug: 4% cucumber seed gel; Cucumber seed gel preparations were compounded by an FDA-registered pharmaceutical company which were incorporated into the placebo base gel at 4% concentration. The assistant researcher then applied 4% cucumber seed gel at an amount of 2 mg/cm2 (1/4 teaspoon) on the designated randomized test site.
Placebo Comparator: Randomized Test Site on Back 3	Drug: Placebo gel; The placebo gel serves as the base formulation is composed of: the oil phase of the formulation comprising of octadecanol, stearic acid, and liquid paraffin, while the aqueous phase consisted of distilled water, glycerin, and ethylparaben. The two phases were emulsified and combined to make the base gel. The assistant researcher then applied placebo gel at an amount of 2 mg/cm2 (1/4 teaspoon) on the designated test site.; Drug: 2% cucumber seed gel; Cucumber seed gel preparations were compounded by an FDA-registered pharmaceutical company which were incorporated into the placebo base gel at 2% concentration. The assistant researcher then applied 2% cucumber seed gel at an amount of 2 mg/cm2 (1/4 teaspoon) on the designated randomized test site.; Drug: 4% cucumber seed gel; Cucumber seed gel preparations were compounded by an FDA-registered pharmaceutical company which were incorporated into the placebo base gel at 4% concentration. The assistant researcher then applied 4% cucumber seed gel at an amount of 2 mg/cm2 (1/4 teaspoon) on the designated randomized test site.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in minimal erythema dose (MED) after application of 2% and 4% cucumber seed extract compared with placebo	After 24 hours post-application, the principal investigator examined previously irradiated sites. A well-defined erythematous response at the lowest NBUVB dose was recorded as the MED, corresponding to E2 on the Visual Erythema Scale.	24 hours post application

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Adverse events such as pain, pruritus, tenderness, burning, blistering, or irregular pigmentation (Composite secondary outcome)	Participants were also assessed after 24 and 48 hours regarding any experience of adverse events such as, but not limited to, pruritus, pain, tenderness, blistering, or irregular pigmentation immediately after and then 24 and 48 hours after application of gels.	24 and 48 hours after application

Collaborators and Investigators

• Sponsor: DOH - Tondo Medical Center

Study record dates

Study Major Dates

• Study Start (Actual): January 27, 2025
• Primary Completion (Actual): February 26, 2025
• Study Completion (Actual): February 28, 2025

Study Registration Dates

• First Submitted: July 17, 2026
• First Submitted That Met QC Criteria: July 17, 2026
• First Posted (Actual): July 22, 2026

Study Record Updates

• Last Update Posted (Actual): July 22, 2026
• Last Update Submitted That Met QC Criteria: July 17, 2026
• Last Verified: October 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Wounds and Injuries; Skin Manifestations; Skin Diseases; Photosensitivity Disorders; Burns; Pathological Conditions, Signs and Symptoms; Skin and Connective Tissue Diseases; Signs and Symptoms; Sunburn; Erythema
• Other Study ID Numbers: REC-2024-00086

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: All de-identified individual participant data might be shared.
• IPD Sharing Time Frame: From: At the end of the study End: No end date
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No