And just because it’s present in a plant doesn’t mean it can be drugged. It could have a short half life, high toxicity, etc., so derivatives are made to optimize it’s action.
Finally, even if a patent can’t be secured, the first version of a drug is given exclusivity by the FDA - they won’t approve another version up to 7 years (orphan drugs).
A cursory look at the top selling drugs of all time doesn't appear to show any plant derived drugs [0]. Obviously this does not disprove your statement but its the quickest heuristic i could think of
[0] https://en.wikipedia.org/wiki/List_of_largest_selling_pharma...
OP's statement was about sheer number of patented drugs. I don't know that OP's statement was accurate, but the wikipedia link doesn't really refute or confirm the idea.
[1] "pharmaceutical and biotechnology sales revenue increased from $534 billion to $775 billion between 2006 and 2015.... Drug industry spending for research and development increased from $82 billion in 2008 to $89 billion in 2014" (I assume there are other costs so one cannot simply divide to get gross profit but it seems illustrative)
In 2018 only like 12% of new FDA approved drugs were developed by big pharma. 63% were developed by small companies. A negligible amount were discovered by universities alone
Pharma acquired these drugs from startups through M&A which doesn't show up in profit and loss statements. It shows up on the balance sheet
That $84B r&d figure seems very low. The top 15 pharma companies spend something like $75B a year in r&d. VC backed startups spend like $10-15B. Then all the firms in between account for the majority of spending. Don't remember the source but I think total global pharma r&d is like $200B
https://www.nytimes.com/2014/11/19/upshot/calculating-the-re...
In 2018 only like 12% of new FDA approved drugs were developed by big pharma. 63% were developed by small companies. A negligible amount / zero were developed by universities
The $161M figure cited in that nytimes study is not at all representative because most early stage r&d is done outside of big pharma, and then big pharma buys the drugs and markets them
If drug research was profitable pharma would be doing more of it, not less