* Futures down: Dow 0.85%, S&P 500 0.92%, Nasdaq 1.13%

* Jefferies dips after posting Q1 profit below estimates

* OECD warns Iran war erases global growth upgrade

* Weekly jobless claims in line with estimates

(Updates before markets open)

By Purvi Agarwal and Twesha Dikshit

March 26 (Reuters) - U.S. stock index futures pointed to

a lower open on Thursday following gains in the previous

session, as investors remained cautious about developments in

the Middle East while weighing the prospects for de-escalation

in the conflict.

U.S. President ​Donald Trump said Iran was desperate to make

a deal to end the fighting, contradicting the Iranian foreign

minister, who said Tehran was reviewing a U.S. proposal but had

​no intention of holding talks to wind down the war.

Contradictory signals from both sides left markets on edge,

as hopes for a breakthrough to restore shipping through the

crucial Strait of Hormuz remained uncertain.

"Hearing a lot of different things come out, you have the

market trying to figure out exactly what's going on. We're

watching oil prices ... We're still a little bit cautious there

just because some of the downside scenarios aren't good for kind

of the global economy," said Jack Herr, primary investment

analyst at GuideStone.

"But overall if we can get a quick resolution of this thing,

the backdrop for another good year in the market is there with

some of the fundamentals and growth numbers, we're seeing

earnings have been pretty strong."

At 8:37 a.m. ET, Dow E-minis were down 397 points,

or 0.85%, S&P 500 E-minis were down 61.25 points, or

0.92% and Nasdaq 100 E-minis were down 275.25 points, or

1.13%.

Wall Street's main indexes closed higher on Wednesday after

Washington delivered a proposal to Iran through Pakistan, while

comments from Iranian officials suggested Tehran might be open

to diplomatic offers even as it publicly denied any ongoing

negotiations.

The escalating conflict in the Middle East has knocked the

global economy off a stronger growth path, the OECD warned on

Thursday, with a closure of the Strait of Hormuz threatening to

push inflation sharply higher.

Central banks have been put in a tough spot with regard to

interest rates, with money market participants no longer pricing

in any easing from the U.S. Federal Reserve this year. Two rate

cuts had been expected before the Iran conflict erupted,

according to the CME Group's FedWatch Tool.

Data showed the number of new Americans filing for

unemployment benefits rose 21,000 for the week ended March 21,

in line with estimates, according to economists polled by

Reuters.

Comments from Federal Reserve officials Lisa Cook, Stephen

Miran, Michael Barr and Philip Jefferson will also be parsed

during the day.

Among individual movers, Jefferies Financial ( JEF ) dipped

1.1% in premarket trading, after the investment bank missed

analysts' estimates for first-quarter profit due to losses on

loans to collapsed companies.

Shares of Olaplex Holdings ( OLPX ) jumped 51% after

Germany's Henkel agreed to buy the hair-care brand in

a $1.4 billion deal.

U.S.-listed shares of gold miners slipped as bullion prices

declined more than 2%. Newmont ( NEM ) slipped 3.4%,

Sibanye Stillwater lost 4.8% and Harmony Gold

shed 4.1%.