Resveratrol is a naturally occurring polyphenolic compound found in grapes, peanuts, mulberries, Polygonum cuspidatum and several other plants. In the botanical extract and nutraceutical industries, trans-resveratrol is generally the main form considered in quality evaluation.

Resveratrol has been widely studied, but two concepts must be distinguished when interpreting the research: absorption and bioavailability.

Absorption Does Not Necessarily Mean High Bioavailability

Human studies indicate that resveratrol can be absorbed after oral intake. However, it is rapidly metabolized, primarily into glucuronide and sulfate conjugates. Consequently, the circulating concentration of unchanged resveratrol may remain relatively low.

In other words, absorption of a compound is not the same as maintaining a high concentration of the unchanged compound in the bloodstream.

It is also important to distinguish between different types of scientific evidence:

• In vitro cell studies;

• Animal studies;

• Human pharmacokinetic studies;

• Human intervention trials.

The doses, administration methods and experimental conditions used in these studies can differ substantially. Findings from cell or animal studies should therefore not be presented automatically as established effects in humans.

Why Is Purity Not the Only Quality Indicator?

Assay is an important factor when purchasing resveratrol, but comparing “50%” with “98%” alone is not sufficient. Buyers and formulation teams should also evaluate the following factors.

1. Form of resveratrol

Resveratrol occurs in trans and cis forms. Commercial raw materials are generally evaluated primarily according to their trans-resveratrol content. Technical documents should therefore specify whether the reported assay refers to total resveratrol or trans-resveratrol.

2. Botanical source

Polygonum cuspidatum is one of the principal botanical sources used for the industrial production of resveratrol. Buyers should confirm the botanical origin, plant part and relevant traceability information.

3. Analytical method

Resveratrol content is commonly measured by HPLC or another validated analytical method. When comparing specifications and quotations, buyers should confirm that the test object, method and calculation basis are consistent.

4. Stability and storage

Trans-resveratrol can be affected by light, temperature and storage conditions. Light-resistant packaging, suitable sealing and controlled storage are therefore important parts of quality management.

5. Formulation and intended application

Different applications have different requirements for purity, color, odor, particle size and cost.

A 50% specification may be suitable for products that prioritize cost efficiency and botanical extract positioning. A 98% specification is generally more appropriate when higher assay, accurate formulation and tighter impurity control are required.

The final selection should be based on the formulation, product positioning and applicable regulatory requirements.

What Should Buyers Check?

In addition to assay, buyers should review:

• Product and botanical names;

• Botanical source and plant part;

• Trans-resveratrol content;

• Analytical method;

• Appearance, color and odor;

• Particle size;

• Moisture and ash;

• Heavy metals;

• Microbiological limits;

• Residual solvents;

• Packaging and storage conditions;

• COA, TDS and batch traceability documents.

Our Approach to Quality

Hubei Shengmei Kang Pharmaceutical Co., Ltd. produces resveratrol from Polygonum cuspidatum and supports different specifications according to customers’ intended applications.

We believe that professional ingredient selection should extend beyond a single assay result. Ingredient identity, analytical methods, batch consistency, quality control and final application requirements should all be included in the purchasing decision.

This article is provided for ingredient and scientific information purposes only. It is not intended as advice for the prevention, diagnosis or treatment of any disease.

References

1. Boocock DJ, et al. Phase I Dose Escalation Pharmacokinetic Study in Healthy Volunteers of Resveratrol. Cancer Epidemiology, Biomarkers & Prevention. 2007;16(6):1246–1252.

2. Walle T, et al. High Absorption but Very Low Bioavailability of Oral Resveratrol in Humans. Drug Metabolism and Disposition. 2004;32(12):1377–1382.