Cycloastragenol CAS Number: 78574-94-4 vs 84605-18-5

By Chengdu King-tiger Pharm-chem. Tech. Co., Ltd. — a professional manufacturer of Astragalus extracts (astragaloside IV and cycloastragenol) since 2007. Last updated: September 2026.

Look up cycloastragenol from two different suppliers and you may see two different CAS numbers on their certificates of analysis: 78574-94-4 and 84605-18-5. Both are described as "cycloastragenol." Both claim the same molecular formula, C₃₀H₅₀O₅, and the same molecular weight, 490.72.

So are they the same compound? No — and the difference matters. This article explains where each CAS number comes from, how the two structures differ, and how to make sure the material you purchase matches the compound used in the telomerase research literature. This is a question we answer for buyers regularly, because we manufacture cycloastragenol ourselves.

1. The Quick Answer

Because the two registry entries describe closely related molecules with identical formula and weight, HPLC retention data cannot distinguish them definitively. Only structural methods — NMR — can confirm which compound is in the drum.

2. Where Cycloastragenol Comes From: Hydrolysis of Astragaloside IV

To understand the difference, start with the parent molecule. Astragaloside IV (CAS 84687-43-4) is the flagship saponin of Astragalus membranaceus (Huangqi). It is a glycoside: attached to its cycloartane triterpenoid core are sugar chains.

When astragaloside IV undergoes controlled hydrolysis, the sugar groups are cleaved off. What remains is the aglycone — the "sugar-free" core of the molecule.

This hydrolysis product is cycloastragenol, CAS 78574-94-4 — the molecule that has been studied as a telomerase activator since the late 2000s, first rose to commercial fame as the active principle of TA-65, and more recently appeared in immuno-oncology research targeting cathepsin B.

For a broader introduction to the molecule — its source, science and quality issues — see our guide: Cycloastragenol: A Buyer's Guide.

3. So What Is CAS 84605-18-5?

Some suppliers sell their "cycloastragenol" under CAS 84605-18-5. The registry entry is real — it appears in several chemical databases and reagent catalogs, sometimes under synonym names such as cyclogalegigenin or astramembrangenin. But when the two structures are placed side by side, the difference is visible in the bonding of the side chain.

The structure registered under 84605-18-5 is not the direct hydrolysis product of astragaloside IV. In other words: if you start from astragaloside IV and remove its sugars, you do not arrive at the 84605-18-5 structure. The two entries describe closely related cycloartane-type compounds — which is precisely why the market has confused them for years.

How did two CAS numbers end up on the market for one name?

This is a historical legacy, and it is more common in natural-product chemistry than outsiders might expect:

• Cycloartane triterpenoids from Astragalus were isolated and characterized independently by different research groups over decades. Compounds were registered under different names (cycloastragenol, cyclogalegigenin, astramembrangenin, cyclosieversigenin) before the naming settled.
• Different suppliers inherited different registry entries as "their" CAS number, and once a COA has been issued with one number, commercial documents tend to keep using it.
• Because formula and molecular weight are identical, routine QC (HPLC assay) never flags the discrepancy — only NMR comparison does.

The result is what buyers see today: one product name, two CAS numbers, and very few suppliers willing to explain the difference.

4. Why This Matters in Practice

4.1 Comparing quotations

Two offers for "cycloastragenol 98%" carrying different CAS numbers may not be offers for the same compound. Before comparing price, confirm you are comparing the same molecule.

4.2 Regulatory and customs documents

If your finished-product registration, customs declaration, or import documentation cites one CAS number while your supplier ships material under the other, you have a documentation mismatch that can surface during audits or customs review. Align the CAS number across your COA, specifications and filings before the first shipment.

4.3 Alignment with the research literature

The telomerase studies, the TA-65 story, and the recent cathepsin B immuno-oncology work all concern the aglycone of astragaloside IV — CAS 78574-94-4. If your R&D or your product claims reference that literature, your ingredient should be that compound.

4.4 Reagent benchmarking

Many reagent companies use CAS 78574-94-4 as the CAS number for cycloastragenol — for example, Sigma-Aldrich lists its cycloastragenol products under this number (see SMB00372). If you benchmark your bulk material against a reagent standard, confirm the CAS numbers match first.

5. How to Verify Which Compound You Are Receiving

Whatever the CAS number printed on the COA, verification is analytical, not administrative:

• Ask the supplier to state the CAS number explicitly — and to explain which structure it corresponds to. A manufacturer who knows the difference will answer immediately; hesitation is a warning sign.
• Request NMR spectra (¹H and ¹³C) for the batch and compare against published data for the astragaloside IV hydrolysis product.
• For high-stakes purchases, send a sample to an independent third-party laboratory for structural confirmation — the same due-diligence principle we recommend in our supplier selection guide.

6. Frequently Asked Questions